Publisher: Elsevier   (Total: 3206 journals)

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Showing 1 - 200 of 3206 Journals sorted alphabetically
Academic Pediatrics     Hybrid Journal   (Followers: 39, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 27, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 106, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 28, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 44, SJR: 1.771, CiteScore: 3)
Achievements in the Life Sciences     Open Access   (Followers: 8)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 6)
Acta Astronautica     Hybrid Journal   (Followers: 450, SJR: 0.758, CiteScore: 2)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 2)
Acta Biomaterialia     Hybrid Journal   (Followers: 30, SJR: 1.967, CiteScore: 7)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 3)
Acta de Investigación Psicológica     Open Access   (Followers: 2)
Acta Ecologica Sinica     Open Access   (Followers: 11, SJR: 0.18, CiteScore: 1)
Acta Histochemica     Hybrid Journal   (Followers: 5, SJR: 0.661, CiteScore: 2)
Acta Materialia     Hybrid Journal   (Followers: 337, SJR: 3.263, CiteScore: 6)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5, SJR: 0.504, CiteScore: 1)
Acta Mechanica Solida Sinica     Full-text available via subscription   (Followers: 9, SJR: 0.542, CiteScore: 1)
Acta Oecologica     Hybrid Journal   (Followers: 12, SJR: 0.834, CiteScore: 2)
Acta Otorrinolaringologica (English Edition)     Full-text available via subscription  
Acta Otorrinolaringológica Española     Full-text available via subscription   (Followers: 2, SJR: 0.307, CiteScore: 0)
Acta Pharmaceutica Sinica B     Open Access   (Followers: 2, SJR: 1.793, CiteScore: 6)
Acta Psychologica     Hybrid Journal   (Followers: 26, SJR: 1.331, CiteScore: 2)
Acta Sociológica     Open Access   (Followers: 1)
Acta Tropica     Hybrid Journal   (Followers: 6, SJR: 1.052, CiteScore: 2)
Acta Urológica Portuguesa     Open Access   (Followers: 1)
Actas Dermo-Sifiliograficas     Full-text available via subscription   (Followers: 3, SJR: 0.374, CiteScore: 1)
Actas Dermo-Sifiliográficas (English Edition)     Full-text available via subscription   (Followers: 2)
Actas Urológicas Españolas     Full-text available via subscription   (Followers: 3, SJR: 0.344, CiteScore: 1)
Actas Urológicas Españolas (English Edition)     Full-text available via subscription   (Followers: 1)
Actualites Pharmaceutiques     Full-text available via subscription   (Followers: 7, SJR: 0.19, CiteScore: 0)
Actualites Pharmaceutiques Hospitalieres     Full-text available via subscription   (Followers: 3)
Acupuncture and Related Therapies     Hybrid Journal   (Followers: 8)
Acute Pain     Full-text available via subscription   (Followers: 15, SJR: 2.671, CiteScore: 5)
Ad Hoc Networks     Hybrid Journal   (Followers: 11, SJR: 0.53, CiteScore: 4)
Addictive Behaviors     Hybrid Journal   (Followers: 18, SJR: 1.29, CiteScore: 3)
Addictive Behaviors Reports     Open Access   (Followers: 9, SJR: 0.755, CiteScore: 2)
Additive Manufacturing     Hybrid Journal   (Followers: 14, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 22)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 193, SJR: 4.09, CiteScore: 13)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 13, SJR: 1.167, CiteScore: 4)
Advanced Powder Technology     Hybrid Journal   (Followers: 17, SJR: 0.694, CiteScore: 3)
Advances in Accounting     Hybrid Journal   (Followers: 9, SJR: 0.277, CiteScore: 1)
Advances in Agronomy     Full-text available via subscription   (Followers: 20, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 30, SJR: 0.126, CiteScore: 0)
Advances in Antiviral Drug Design     Full-text available via subscription   (Followers: 2)
Advances in Applied Mathematics     Full-text available via subscription   (Followers: 12, SJR: 0.992, CiteScore: 1)
Advances in Applied Mechanics     Full-text available via subscription   (Followers: 12, SJR: 1.551, CiteScore: 4)
Advances in Applied Microbiology     Full-text available via subscription   (Followers: 24, SJR: 2.089, CiteScore: 5)
Advances In Atomic, Molecular, and Optical Physics     Full-text available via subscription   (Followers: 15, SJR: 0.572, CiteScore: 2)
Advances in Biological Regulation     Hybrid Journal   (Followers: 4, SJR: 2.61, CiteScore: 7)
Advances in Botanical Research     Full-text available via subscription   (Followers: 2, SJR: 0.686, CiteScore: 2)
Advances in Cancer Research     Full-text available via subscription   (Followers: 35, SJR: 3.043, CiteScore: 6)
Advances in Carbohydrate Chemistry and Biochemistry     Full-text available via subscription   (Followers: 9, SJR: 1.453, CiteScore: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5, SJR: 1.992, CiteScore: 5)
Advances in Cell Aging and Gerontology     Full-text available via subscription   (Followers: 5)
Advances in Cellular and Molecular Biology of Membranes and Organelles     Full-text available via subscription   (Followers: 14)
Advances in Chemical Engineering     Full-text available via subscription   (Followers: 29, SJR: 0.156, CiteScore: 1)
Advances in Child Development and Behavior     Full-text available via subscription   (Followers: 11, SJR: 0.713, CiteScore: 1)
Advances in Chronic Kidney Disease     Full-text available via subscription   (Followers: 11, SJR: 1.316, CiteScore: 2)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 27, SJR: 1.562, CiteScore: 3)
Advances in Clinical Radiology     Full-text available via subscription   (Followers: 1)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 21, SJR: 1.977, CiteScore: 8)
Advances in Computers     Full-text available via subscription   (Followers: 14, SJR: 0.205, CiteScore: 1)
Advances in Cosmetic Surgery     Full-text available via subscription   (Followers: 1)
Advances in Dermatology     Full-text available via subscription   (Followers: 16)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 14)
Advances in Digestive Medicine     Open Access   (Followers: 14)
Advances in DNA Sequence-Specific Agents     Full-text available via subscription   (Followers: 7)
Advances in Drug Research     Full-text available via subscription   (Followers: 26)
Advances in Ecological Research     Full-text available via subscription   (Followers: 44, SJR: 2.524, CiteScore: 4)
Advances in Engineering Software     Hybrid Journal   (Followers: 30, SJR: 1.159, CiteScore: 4)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 9)
Advances in Experimental Social Psychology     Full-text available via subscription   (Followers: 51, SJR: 5.39, CiteScore: 8)
Advances in Exploration Geophysics     Full-text available via subscription   (Followers: 2)
Advances in Family Practice Nursing     Full-text available via subscription   (Followers: 1)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 69, SJR: 0.591, CiteScore: 2)
Advances in Fuel Cells     Full-text available via subscription   (Followers: 17)
Advances in Genetics     Full-text available via subscription   (Followers: 21, SJR: 1.354, CiteScore: 4)
Advances in Genome Biology     Full-text available via subscription   (Followers: 11, SJR: 12.74, CiteScore: 13)
Advances in Geophysics     Full-text available via subscription   (Followers: 8, SJR: 1.193, CiteScore: 3)
Advances in Heat Transfer     Full-text available via subscription   (Followers: 26, SJR: 0.368, CiteScore: 1)
Advances in Heterocyclic Chemistry     Full-text available via subscription   (Followers: 11, SJR: 0.749, CiteScore: 3)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 4, SJR: 0.193, CiteScore: 0)
Advances in Immunology     Full-text available via subscription   (Followers: 37, SJR: 4.433, CiteScore: 6)
Advances in Inorganic Chemistry     Full-text available via subscription   (Followers: 10, SJR: 1.163, CiteScore: 2)
Advances in Insect Physiology     Full-text available via subscription   (Followers: 2, SJR: 1.938, CiteScore: 3)
Advances in Integrative Medicine     Hybrid Journal   (Followers: 6, SJR: 0.176, CiteScore: 0)
Advances in Intl. Accounting     Full-text available via subscription   (Followers: 3)
Advances in Life Course Research     Hybrid Journal   (Followers: 10, SJR: 0.682, CiteScore: 2)
Advances in Lipobiology     Full-text available via subscription   (Followers: 1)
Advances in Magnetic and Optical Resonance     Full-text available via subscription   (Followers: 8)
Advances in Marine Biology     Full-text available via subscription   (Followers: 21, SJR: 0.88, CiteScore: 2)
Advances in Mathematics     Full-text available via subscription   (Followers: 17, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 9, SJR: 0.694, CiteScore: 2)
Advances in Medicinal Chemistry     Full-text available via subscription   (Followers: 6)
Advances in Microbial Physiology     Full-text available via subscription   (Followers: 5, SJR: 1.158, CiteScore: 3)
Advances in Molecular and Cell Biology     Full-text available via subscription   (Followers: 26)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 8)
Advances in Molecular Pathology     Hybrid Journal   (Followers: 1)
Advances in Molecular Toxicology     Full-text available via subscription   (Followers: 7, SJR: 0.182, CiteScore: 0)
Advances in Nanoporous Materials     Full-text available via subscription   (Followers: 5)
Advances in Oncobiology     Full-text available via subscription   (Followers: 2)
Advances in Ophthalmology and Optometry     Full-text available via subscription   (Followers: 1)
Advances in Organ Biology     Full-text available via subscription   (Followers: 2)
Advances in Organometallic Chemistry     Full-text available via subscription   (Followers: 18, SJR: 1.875, CiteScore: 4)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7, SJR: 0.174, CiteScore: 0)
Advances in Parasitology     Full-text available via subscription   (Followers: 6, SJR: 1.579, CiteScore: 4)
Advances in Pediatrics     Full-text available via subscription   (Followers: 27, SJR: 0.461, CiteScore: 1)
Advances in Pharmaceutical Sciences     Full-text available via subscription   (Followers: 19)
Advances in Pharmacology     Full-text available via subscription   (Followers: 17, SJR: 1.536, CiteScore: 3)
Advances in Physical Organic Chemistry     Full-text available via subscription   (Followers: 10, SJR: 0.574, CiteScore: 1)
Advances in Phytomedicine     Full-text available via subscription  
Advances in Planar Lipid Bilayers and Liposomes     Full-text available via subscription   (Followers: 3, SJR: 0.109, CiteScore: 1)
Advances in Plant Biochemistry and Molecular Biology     Full-text available via subscription   (Followers: 10)
Advances in Plant Pathology     Full-text available via subscription   (Followers: 6)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Protein Chemistry     Full-text available via subscription   (Followers: 19)
Advances in Protein Chemistry and Structural Biology     Full-text available via subscription   (Followers: 20, SJR: 0.791, CiteScore: 2)
Advances in Psychology     Full-text available via subscription   (Followers: 69)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 7, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (Followers: 3, SJR: 0.263, CiteScore: 1)
Advances in Small Animal Medicine and Surgery     Hybrid Journal   (Followers: 3, SJR: 0.101, CiteScore: 0)
Advances in Space Biology and Medicine     Full-text available via subscription   (Followers: 7)
Advances in Space Research     Full-text available via subscription   (Followers: 434, SJR: 0.569, CiteScore: 2)
Advances in Structural Biology     Full-text available via subscription   (Followers: 6)
Advances in Surgery     Full-text available via subscription   (Followers: 13, SJR: 0.555, CiteScore: 2)
Advances in the Study of Behavior     Full-text available via subscription   (Followers: 36, SJR: 2.208, CiteScore: 4)
Advances in Veterinary Medicine     Full-text available via subscription   (Followers: 20)
Advances in Veterinary Science and Comparative Medicine     Full-text available via subscription   (Followers: 15)
Advances in Virus Research     Full-text available via subscription   (Followers: 6, SJR: 2.262, CiteScore: 5)
Advances in Water Resources     Hybrid Journal   (Followers: 57, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 398, SJR: 0.796, CiteScore: 3)
AEU - Intl. J. of Electronics and Communications     Hybrid Journal   (Followers: 8, SJR: 0.42, CiteScore: 2)
African J. of Emergency Medicine     Open Access   (Followers: 6, SJR: 0.296, CiteScore: 0)
Ageing Research Reviews     Hybrid Journal   (Followers: 12, SJR: 3.671, CiteScore: 9)
Aggression and Violent Behavior     Hybrid Journal   (Followers: 485, SJR: 1.238, CiteScore: 3)
Agri Gene     Hybrid Journal   (Followers: 1, SJR: 0.13, CiteScore: 0)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 18, SJR: 1.818, CiteScore: 5)
Agricultural Systems     Hybrid Journal   (Followers: 32, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 47, SJR: 1.272, CiteScore: 3)
Agriculture and Agricultural Science Procedia     Open Access   (Followers: 4)
Agriculture and Natural Resources     Open Access   (Followers: 3)
Agriculture, Ecosystems & Environment     Hybrid Journal   (Followers: 58, SJR: 1.747, CiteScore: 4)
Ain Shams Engineering J.     Open Access   (Followers: 5, SJR: 0.589, CiteScore: 3)
Air Medical J.     Hybrid Journal   (Followers: 8, SJR: 0.26, CiteScore: 0)
AKCE Intl. J. of Graphs and Combinatorics     Open Access   (SJR: 0.19, CiteScore: 0)
Alcohol     Hybrid Journal   (Followers: 12, SJR: 1.153, CiteScore: 3)
Alcoholism and Drug Addiction     Open Access   (Followers: 12)
Alergologia Polska : Polish J. of Allergology     Full-text available via subscription   (Followers: 1)
Alexandria Engineering J.     Open Access   (Followers: 2, SJR: 0.604, CiteScore: 3)
Alexandria J. of Medicine     Open Access   (Followers: 1, SJR: 0.191, CiteScore: 1)
Algal Research     Partially Free   (Followers: 11, SJR: 1.142, CiteScore: 4)
Alkaloids: Chemical and Biological Perspectives     Full-text available via subscription   (Followers: 2)
Allergologia et Immunopathologia     Full-text available via subscription   (Followers: 1, SJR: 0.504, CiteScore: 1)
Allergology Intl.     Open Access   (Followers: 5, SJR: 1.148, CiteScore: 2)
Alpha Omegan     Full-text available via subscription   (SJR: 3.521, CiteScore: 6)
ALTER - European J. of Disability Research / Revue Européenne de Recherche sur le Handicap     Full-text available via subscription   (Followers: 11, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 56, SJR: 4.66, CiteScore: 10)
Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring     Open Access   (Followers: 6, SJR: 1.796, CiteScore: 4)
Alzheimer's & Dementia: Translational Research & Clinical Interventions     Open Access   (Followers: 6, SJR: 1.108, CiteScore: 3)
Ambulatory Pediatrics     Hybrid Journal   (Followers: 5)
American Heart J.     Hybrid Journal   (Followers: 59, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 67, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 48, SJR: 0.604, CiteScore: 1)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 13)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 17, SJR: 1.524, CiteScore: 3)
American J. of Human Genetics     Hybrid Journal   (Followers: 40, SJR: 7.45, CiteScore: 8)
American J. of Infection Control     Hybrid Journal   (Followers: 35, SJR: 1.062, CiteScore: 2)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 37, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 51)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3, SJR: 1.967, CiteScore: 2)
American J. of Obstetrics & Gynecology MFM     Hybrid Journal   (Followers: 1)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 275, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 67, SJR: 3.184, CiteScore: 4)
American J. of Ophthalmology Case Reports     Open Access   (Followers: 5, SJR: 0.265, CiteScore: 0)
American J. of Orthodontics and Dentofacial Orthopedics     Full-text available via subscription   (Followers: 6, SJR: 1.289, CiteScore: 1)
American J. of Otolaryngology     Hybrid Journal   (Followers: 25, SJR: 0.59, CiteScore: 1)
American J. of Pathology     Hybrid Journal   (Followers: 32, SJR: 2.139, CiteScore: 4)
American J. of Preventive Medicine     Hybrid Journal   (Followers: 29, SJR: 2.164, CiteScore: 4)
American J. of Surgery     Hybrid Journal   (Followers: 39, SJR: 1.141, CiteScore: 2)
American J. of the Medical Sciences     Hybrid Journal   (Followers: 12, SJR: 0.767, CiteScore: 1)
Ampersand : An Intl. J. of General and Applied Linguistics     Open Access   (Followers: 7)
Anaerobe     Hybrid Journal   (Followers: 4, SJR: 1.144, CiteScore: 3)
Anaesthesia & Intensive Care Medicine     Full-text available via subscription   (Followers: 67, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 26, SJR: 0.411, CiteScore: 1)
Anales de Cirugia Vascular     Full-text available via subscription   (Followers: 1)
Anales de Pediatría     Full-text available via subscription   (Followers: 3, SJR: 0.277, CiteScore: 0)
Anales de Pediatría (English Edition)     Full-text available via subscription  
Anales de Pediatría Continuada     Full-text available via subscription  
Analytic Methods in Accident Research     Hybrid Journal   (Followers: 6, SJR: 4.849, CiteScore: 10)
Analytica Chimica Acta     Hybrid Journal   (Followers: 44, SJR: 1.512, CiteScore: 5)
Analytica Chimica Acta : X     Open Access  
Analytical Biochemistry     Hybrid Journal   (Followers: 224, SJR: 0.633, CiteScore: 2)
Analytical Chemistry Research     Open Access   (Followers: 13, SJR: 0.411, CiteScore: 2)
Analytical Spectroscopy Library     Full-text available via subscription   (Followers: 14)
Anesthésie & Réanimation     Full-text available via subscription   (Followers: 2)
Anesthesiology Clinics     Full-text available via subscription   (Followers: 25, SJR: 0.683, CiteScore: 2)

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Similar Journals
Journal Cover
International Journal of Hydrogen Energy
Journal Prestige (SJR): 1.116
Citation Impact (citeScore): 4
Number of Followers: 23  
  Partially Free Journal Partially Free Journal
ISSN (Print) 0360-3199 - ISSN (Online) 0360-3199
Published by Elsevier Homepage  [3206 journals]
  • Supporting the propane dehydrogenation reactors by hydrogen permselective
           membrane modules to produce ultra-pure hydrogen and increasing propane
           conversion: Process modeling and optimization
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): H. Jowkary, M. Farsi, M.R. Rahimpour The main aim of this research is supporting the moving bed radial flow reactors in the propane dehydrogenation unit by membrane modules to produce ultra-pure hydrogen and increasing equilibrium conversion. The propane dehydrogenation is a thermodynamically limited and endothermic reaction, which decreasing hydrogen concentration and increasing operating temperature in the system could increase equilibrium conversion. In the first step, the conventional and membrane supported reactors are heterogeneously modeled based on the mass and energy conservation laws considering catalyst decay. To verify the precision of developed model, the results of simulation are compared with the available plant data. Then, the performance of designed membrane configuration is compared with the conventional process at the same feed condition. It appears that the activity of catalyst decreases along the reactors due to coke build up on the catalyst surface, and it results in the lower propane conversion. The results show that supporting the conventional reactors by hydrogen permselective membrane module increases propane conversion up to 3.09%.Graphical abstractImage 1
  • Formation of hydrogen bubbles in Pd-Ag membranes during H2
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): T.A. Peters, P.A. Carvalho, M. Stange, R. Bredesen Palladium membranes used for hydrogen separation seemingly develop cavities filled with hydrogen, i.e. hydrogen bubbles, along the grain boundaries. These bubbles may represent initial stages of pinhole formation that lead to unselective leakage and compromise the long-term stability of the membranes. Alloying with Ag improves the permeability of Pd, but whether these H2 bubbles form in Pd-Ag membranes remained unknown. In this work, the microstructure of a Pd77Ag23 membrane was characterized by electron microscopy after H2 permeation testing for 50 days at 15 bar at temperatures up to 450 °C. The results show that Ag does not prevent bubbles from emerging along high-angle grain boundaries, but reduces the number of potential nucleation sites for cavity formation by supressing the development of dislocation networks when H-saturated Pd is cycled through the miscibility gap. Both magnetron-sputtered and electroless plated membranes are afflicted by H2 bubbles, thus their formation seems determined by intrinsic properties of the material independent of the fabrication technique. The qualitative discussion enables to point directions for enhancement of membrane stability.Graphical abstractImage 1
  • Ru+supported+membranes&rft.title=International+Journal+of+Hydrogen+Energy&rft.issn=0360-3199&">Hydrogen permeation and stability in ultra-thin PdRu supported membranes
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Jinxia Liu, Stefano Bellini, Niek C.A. de Nooijer, Yu Sun, David Alfredo Pacheco Tanaka, Chunhua Tang, Hui Li, Fausto Gallucci, Alessio Caravella In this paper, we report the performance of supported PdRu membranes for possible applications to hydrogen purification and/or production. For this purpose, we fabricated three ultra-thin α-alumina-supported membranes by combined plating techniques: a PdAg membrane (3 μm-thick ca.) and two PdRu (1.8 μm-thick ca.). The former is set as a benchmark for comparison. The membranes were characterised using different methodologies: permeation tests, thermal treatment and SEM analysis. Preliminary leakage tests performed with nitrogen has revealed that the two PdRu membranes, namely PdRu#1 and PdRu#2, show a non-ideal (non-infinite) selectivity, which is relatively low for the former (around 830 at 400 °C) and sufficiently high for the latter (2645 at 400 °C). This indicates a relevant presence of defects in the PdRu#2 membrane, differently from what observed for the PdAg and PdRu#1 ones. The permeation tests show that the hydrogen permeating flux is stable up to around 550 °C, with an apparently unusual behaviour at higher temperatures (600 °C), where we observe a slightly decrease of hydrogen flux with an increase of the nitrogen one. Moreover, a peculiar bubble-shaped structure is observed in the metal layer of all membranes after usage by means of SEM image analysis. This is explained by considering the effect of the Pd-alloy grain surface energy, which tends to minimise the exposed surface area of the grain interface by creating sphere-like bubble in the lattice, similar to what occurs for soap bubbles in water. The above-mentioned decrease in hydrogen flux at 600 °C is explained to be caused by the bubble formation, which pushes the alloy deeper in the support pores.Graphical abstractImage 1
  • Preparation of mixed matrix composite membrane for hydrogen purification
           by incorporating ZIF-8 nanoparticles modified with tannic acid
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Feng Chen, Songlin Dong, Zhi Wang, Jiayou Xu, Rui Xu, Jixiao Wang The incompatibility between nanofillers and polymer, caused by the agglomeration of nanoparticles and their weak interaction with each other, is still a challenge to develop mixed matrix composite membrane. Herein, we introduced the ZIF-8-TA nanoparticles synthesized by in situ hydrophilic modification into the hydrophilic poly(vinylamine) (PVAm) matrix to prepare composite membranes for H2 purification. The dispersion of ZIF-8 in water was improved by tannic acid modification, and the compatibility between ZIF-8 particles and PVAm matrix was enhanced by chemical crosslinking between the quinone groups in oxidized tannic acid (TA) and the amino groups in PVAm. Moreover, the compatibility between hydrophobic polydimethylsiloxane (PDMS) gutter layer and hydrophilic separation layer was achieved by the adhesion of TA-Fe3+ complex to the surface of PDMS layer during membrane preparation. The interlayer hydrophilic modification and the formation of separation layer were accomplished in one step, which simplified the preparation process. The experimental results indicated that when the TA addition used for modification was 0.5 g and the ZIF-8-TA0.5 content in membrane was 12 wt%, the prepared membrane showed the best separation performance with the CO2 permeance of 987 GPU and the CO2/H2 selectivity of 31, under the feed gas pressure of 0.12 MPa.
  • Identification of hydrogen permeability parameters of membrane materials
           in an aggregated experiment
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Yury V. Zaika, Nikolai I. Sidorov, Olga V. Fomkina The study of the hydrogen permeability of materials for membrane-based separation/purification technologies employs a variety of experimental methods with their own specific features, advantages and shortfalls. The method of penetration with vacuum pumping allows determining the diffusion coefficient from so-called lag time. The accuracy of the estimation depends on the degree of proximity to the DLR (diffusion limited regime) mode. The method of “communicating vessels” is more sensitive to surface processes. The thermal desorption (TDS) technique permits “scanning” the material dynamically across a wide range of temperatures. “Separate” application of these methods leads to a situation where the materials studied are in fact somewhat different (for example, due to different impacts on the surface), and significant differences in parameter estimates ensue. This paper suggests and implements a technique for a combined three-stage ‹‹penetration (with and without vacuum pumping)+TDS›› experiment and the corresponding mathematical toolkit. The informative capacity of the experiments and the accuracy of the estimation of hydrogen permeability parameters (adsorption, dissolution, diffusion and desorption) of the membrane materials under study are thus enhanced.
  • Single-step synthesized dual-layer hollow fiber membrane reactor for
           on-site hydrogen production through ammonia decomposition
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Hongda Cheng, Bo Meng, Claudia Li, Xiaobin Wang, Xiuxia Meng, Jaka Sunarso, Xiaoyao Tan, Shaomin Liu On-site hydrogen production via catalytic ammonia decomposition presents an attractive pathway to realize H2 economy and to mitigate the risk associated with storing large amounts of H2. This work reports the synthesis and characterization of a dual-layer hollow fiber catalytic membrane reactor for simultaneous NH3 decomposition and H2 permeation application. Such hollow fiber was synthesized via single-step co-extrusion and co-sintering method and constitutes of 26 μm-thick mixed protonic-electronic conducting Nd5.5Mo0.5W0.5O11.25-δ (NMW) dense H2 separation layer and Nd5.5Mo0.5W0.5O11.25-δ-Ni (NMW-Ni) porous catalytic support. This dual-layer NMW/NMW-Ni hollow fiber exhibited H2 permeation flux of 0.26 mL cm−2 min−1 at 900 °C when 50 mL min−1 of 50 vol% H2 in He was used as feed gas and 50 mL min−1 N2 was used as sweep gas. Membrane reactor based on dual-layer NMW/NMW-Ni hollow fiber achieved NH3 conversion of 99% at 750 °C, which was 24% higher relative to the packed-bed reactor with the same reactor volume. Such higher conversion was enabled by concurrent H2 extraction out of the membrane reactor during the reaction. This membrane reactor also maintained stable NH3 conversion and H2 permeation flux as well as structure integrity over 75 h of reaction at 750 °C.
  • Coating the porous Al2O3 substrate with a natural mineral of
           Nontronite-15A for fabrication of hydrogen-permeable palladium membranes
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Yan Huang, Qiang Liu, Xiaoxian Jin, Weihua Ding, Xiaojuan Hu, Haitao Li Substrate surface modification is a key pretreatment during fabrication of composite palladium membranes for hydrogen purification in hydrogen energy applications. The suspension of a natural porous material, Nontronite-15A mineral, without any organic additives was employed in dip-coating of the porous Al2O3 substrate. The Nontronite-15A mineral was characterized by SEM, XRD, TG−DSC and granulometry analysis. The surface and cross-section of the coated porous Al2O3 tubes were observed by SEM, and their pore size distribution and nitrogen flux were also measured. Palladium membranes were fabricated over the coated Al2O3 tubes by a suction-assisted electroless plating. The optimal loading amount of the Nontronite-15A mineral is just to fill in and level up the surface cavities of the Al2O3 substrate rather than to form an extra continuous layer. A thin and selective palladium membrane was successfully obtained, and its permeation performances were tested. The kinetic analyses on the hydrogen flux indicate that the hydrogen permeation behavior exhibits typical characteristics for most of the palladium membranes. During the stability test at 450 °C for 192 h, no membrane damage was detected, and the hydrogen flux increased slightly.Graphical abstractImage 1
  • Hydrogen permeation enhancement in a Pd membrane tube system under various
           vacuum degrees
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Wei-Hsin Chen, Jamin Escalante, Yen-Hsun Chi, Yu-Li Lin Hydrogen purification using palladium (Pd) membrane technology has been seen as a potential solution for producing pure hydrogen form hydrogen-rich gas. Compared to traditional practices of operating the permeate side of the membrane at atmospheric pressure, in this study, a vacuum is applied. The effects of various vacuum degrees applied to the permeate side of the Pd membrane are investigated and compared to the results under normal operation without a vacuum. The feed gas used for experiments consists of a mixture of hydrogen (70 vol%) and nitrogen (30 vol%). Three membrane operating temperatures (320, 350, and 380 °C), four pressure differences (2, 3, 4, and 5 atm) across the membrane, and four vacuum degrees (−15, −30, −45, and −53 kPa) applied to the permeate side are considered. For the three operating temperatures, the best improvements in the performance of hydrogen permeation are at 320 and 350 °C when a −53 kPa vacuum is applied, resulting in 79.4% and 79.1% improvements, respectively, compared to normal operations. Increasing temperatures leads to an increase in H2 permeation both with and without a vacuum; however, best performances of H2 permeation are observed in cases without a vacuum.Graphical abstractImage 1
  • A membrane-assisted hydrogen and carbon oxides separation from flare gas
           and recovery to a commercial methanol reactor
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Mina Khanipour, Azadeh Mirvakili, Ali Bakhtyari, Mehdi Farniaei, Mohammad Reza Rahimpour The push to control the greenhouse gas emissions is motivated by environmental regulations. For the aim to be achieved, the suggestion of eliminating or at least reducing gas flaring is currently taken under environment. In this regard, a new configuration for flare gas treatment is proposed in this study. This configuration is aimed to collect H2 and CO2 from flare gas, simultaneously. The collected components would be sent to the methanol synthesis reactor in the upstream section. The proposed configuration is made up of a multi-step membrane-assisted separation unit. In order to clarify what lies behind the idea, we proposed a mathematical formulation which is composed of conservation equations and kinetic rate equations is developed. H2 and CO2 elimination in the first step followed by a membrane-assisted water gas shift reactor for catalytic CO conversion and H2 recovery in tandem, and removing the remaining CO2 in the supplementary step is investigated numerically. The collected H2/CO2 mixture is aimed to recover into the upstream methanol synthesis reactor. The obtained results reveal that by utilizing such a strategy, about 2500 kmol/day CO2 (almost 98% of total input) is eliminated from the flare gas stream. Moreover, by considering the converted CO, about 4050 kmol/day CO2 is recovered to the methanol reactor. As a whole, 0.68% enhancement in the methanol generation and the reduction of about 4050 kmol/day flare gas pollutants are achieved in tandem when 98% N2 and 92.9% CH4 is separated the from purge gas.Graphical abstractImage 1
  • Stability of pore-plated membranes for hydrogen production in
           fluidized-bed membrane reactors
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): E. Tosto, D. Alique, D. Martinez-Diaz, R. Sanz, J.A. Calles, A. Caravella, J.A. Medrano, F. Gallucci Pd-based membranes prepared by pore-plating technique have been investigated for the first time under fluidization conditions. A palladium thickness around 20 μm was achieved onto an oxidized porous stainless steel support. The stability of the membranes has been assessed for more than 1300 h in gas separation mode (no catalyst) and other additional 200 h to continuous fluidization conditions. Permeances in the order of 5·10−7 mol s−1 m−2 Pa−1 have been obtained for temperatures in a range between 375 and 500 °C. During fluidization, a small decrease in permeance is observed, as consequence of the increased external (bed-to-wall) mass transfer resistances. Moreover, water gas shift (WGS) reaction cases have been carried out in a fluidized bed membrane reactor. It has been confirmed that the selective H2 separation through the membranes resulted in CO conversions beyond the thermodynamic equilibrium (of conventional systems), showing the benefits of membrane reactors in chemical conversions.Graphical abstractImage 1
  • Production strategies of asymmetric BaCe0.65Zr0.20Y0.15O3 -δ –
           Ce0.8Gd0.2O2-δ membrane for hydrogen separation
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Elisa Mercadelli, Angela Gondolini, Daniel Montaleone, Paola Pinasco, Sonia Escolástico, José M. Serra, Alessandra Sanson Mixed proton and electron conductor ceramic composites are among the most promising materials for hydrogen separation membrane technology especially if designed in an asymmetrical configuration (thin membrane supported onto a thicker porous substrate). However a precise processing optimization is needed to effectively obtain planar and crack free asymmetrical membranes with suitable microstructure and composition without affecting their hydrogen separation efficiency. This work highlights for the first time the most critical issues linked to the tape casting process used to obtain BaCe0.65Zr0.20Y0.15O3-δ – Ce0.8Gd0.2O2-δ (BCZY-GDC) asymmetrical membranes for H2 separation. The critical role of the co-firing process, sintering aid and atmosphere was critically investigated. The optimization of the production strategy allowed to obtain asymmetric membranes constituted by a dense 20 μm-thick ceramic-ceramic composite layer supported by a porous (36%) 750 μm-thick BCZY-GDC substrate. The asymmetric membranes here reported showed H2 fluxes (0.47 mL min−1 cm−2 at 750 °C) among the highest obtained for an all-ceramic membrane.
  • Theoretical evaluation of various configurations of silica membrane
           reactor in methanol steam reforming using CFD method
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): K. Ghasemzadeh, N. Jafar Harasi, A. Iulianelli, A. Basile The main purposes of this work was to evaluate from a theoretical point of view the performance of silica membrane reactors (MRs) in various configurations for generating hydrogen via methanol steam reforming (MSR) reaction using a two dimensional computational fluid dynamic (CFD) method, presenting details about molar fractions of gas species, velocity and pressure distributions at the simulated conditions. The CFD model was firstly validated and, then, used for the simulations, achieving an acceptable agreement between numerical outcomes and experimental data. The simulations were realized for MSR reaction carried out in three types of silica MRs, namely: 1) silica MR with cocurrent flow pattern (MR1); 2) silica MR with countercurrent flow pattern (MR2); 3) silica MR with countercurrent flow pattern including a water gas shift (WGS) reaction stage in the permeate side (MR3), meanwhile comparing the results with a traditional reactor (TR). The influence of several operating parameters (reaction temperature and pressure, and feed flow rate) on the performance of the aforementioned silica MRs in terms of methanol conversion, hydrogen yield and CO-selectivity was evaluated and the results compared with an equivalent TR. The simulations via CFD method indicated the MR3 results to be the best solution over the other MR proposed configurations and the TR as well, presenting the best simulation results at 10 bar of transmembrane pressure, 513 K, SF = 6, GHSV = 6000 h−1 and feed molar ratio = 3/1 with CO selectivity ≤0.04%, methanol conversion and hydrogen yield>90%.
  • Multi-scale model based design of membrane reactor/separator processes for
           intensified hydrogen production through the water gas shift reaction
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Seçgin Karagöz, Theodore T. Tsotsis, Vasilios I. Manousiouthakis This work aims to first quantify the impact of various diffusion models (Maxwell-Stefan, Wilke, Dusty-Gas) on the predictions of a multi-scale membrane reactor/separator mathematical model, and to then demonstrate this model's use for the design and process intensification of membrane reactor/separator systems for hydrogen production. This multi-scale model captures velocity, temperature and species' concentration profiles along the catalyst pellet's radial direction, and along the reactor's axial direction, by solving the momentum, energy, and species transport equations, accounting for convection, conduction, reaction, and diffusion mechanisms. In the first part of work, the effect of pellet-scale design parameters (mean pore diameter, volumetric porosity, tortuosity factor, etc.) and various species' flux models on the model predictions is studied. In the second part, the study focuses on the comparison, in terms of their process intensification characteristics, of various hydrogen production processes. These include a conventional high-temperature shift reactor (HTSR)/low-temperature shift reactor (LTSR) sequence, a novel HTSR/membrane separator (MS)/LTSR/MS sequence, and a process that involves low-temperature shift membrane reactors-LTSMR in a series.
  • Influence of H2S on the hydrogen flux of thin-film PdAgAu
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Niek de Nooijer, Julio Davalos Sanchez, Jon Melendez, Ekain Fernandez, David Alfredo Pacheco Tanaka, Martin van Sint Annaland, Fausto Gallucci Pd-based membranes have the potential to be used for hydrogen purification and production in membrane reactors. However, the presence of impurities in the feedstock, such as H2S can poison the membrane, thus decreasing the hydrogen permeation by blocking and deactivating active sites of the Pd-alloy on the membrane surface. H2S at high concentrations can even destroy the membrane by the formation of Pd4S. It is known that alloying of Pd with Au enhances the membrane resistance to H2S. This work reports the performance of six PdAgAu/Al2O3 supported membranes, prepared by electroless plating combined with PVD under exposure to trace amounts (
  • Thin carbon hollow fiber membrane with Knudsen diffusion for
           hydrogen/alkane separation: Effects of hollow fiber module design and gas
           flow mode
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Ming-Yen Wey, Hsish-Han Chen, Yu-Ting Lin, Hui-Hsin Tseng Recovery of heavier hydrocarbons, C2~C4 olefins and paraffins, from gas streams is of great importance economically. In this study, asymmetric carbon hollow fiber membranes (CHFMs) were prepared by a one-step vacuum-assisted dip coating and pyrolysis, and investigated for H2/CO2, H2/C2H6, and H2/C3H8 separations. To increase the mechanical strength of the CHFMs, a porous alumina hollow fiber with ID/OD = 2 mm/4 mm was used as the supporting material. A solution of polyetherimide in N-methyl-2-pyrrolidone was used as the casting solution. The effects of (1) membrane preparation parameters, (2) fiber packing densities, (3) fiber packing arrangement, and (4) gas flow configuration (inside-out or outside-in) on the gas-separation performance were also investigated. The results showed that decreasing the concentration of the casting dope and the number of coating cycles was found to be the most effective approach to increase the H2 permeance, while maintaining the H2/CO2 selectivity. Further, as the fiber packing density was increased from 5.54% to 38.78% for the hexagonal packing configuration, the H2 permeance increased from 362.04 GPU to 711.61 GPU, without any decrease in the gas selectivity. The as-prepared CHFM exhibited the maximum gas permeance of 711.61 GPU for H2 and the following gas selectivity: 2.79, 4.65, and 5.34 towards H2/CO2, H2/C2H6, and H2/C3H8, respectively. The successful preparation and modularization of the CHFM is advantageous and industrially relevant for several gas-separation applications, such as H2 energy production from CO2, C2H6, and C3H8, and olefins/paraffins recovery.Graphical abstractImage 1
  • Pd-thickness reduction in electroless pore-plated membranes by using
           doped-ceria as interlayer
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): D. Martinez-Diaz, D. Alique, J.A. Calles, R. Sanz This work presents the use of doped CeO2 particles with palladium as intermediate barrier for the preparation of fully dense Pd films by Electroless Pore-Plating. The use of doped ceria particles instead of non-doped ones clearly helps to reduce the final palladium thickness required to prepare a fully dense membrane over porous stainless steel supports from 15 to 9 μm (average values by gravimetric analyses), thus saving around 40% of total palladium required in the process. Pure hydrogen permeation tests reveal a consequent increase in the H2 flux in the range 15–30%, depending on the operation mode. Thus, a H2 permeance of 6.26·10−4 mol m−2 s−1 Pa−0.5 at 400 °C and ΔP = 1 bar is reached, maintaining a really high H2/N2 ideal separation factor (≥10,000) and an activation energy within the typical range for these type of membranes, Ea = 13.1 kJ mol−1. Permeation of binary H2/N2 gas mixtures and the effect of feeding the mixture from the inner or the outer side of the membrane have been also studied. A significant concentration-polarization effect was observed, being higher when the gas is fed from the inner to the outer side of the membrane. This effect becomes more relevant for the membrane prepared with doped CeO2, instead of raw CeO2, due to its lower Pd thickness and higher relative influence of the surface processes. However, it should be emphasized that higher H2 permeance values were obtained for the entire set of experiments when using the Pd-membranes containing doped ceria. Finally, long-term permeation tests for more than 850 h with pure gases at T = 400 °C and ΔP = 1 bar were also carried out, demonstrating a suitable mechanical stability of membranes at these operating conditions.Graphical abstractImage 1
  • Process design for green hydrogen production
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Lorena Mosca, Jose Antonio Medrano Jimenez, Solomon Assefa Wassie, Fausto Gallucci, Emma Palo, Michele Colozzi, Stefania Taraschi, Giulio Galdieri A membrane assisted process for green hydrogen production from a bioethanol derived feedstock is here developed and evaluated, starting from the conventional Steam Methane Reforming (SMR) process. Such a process is suitable for centralized hydrogen production, and is here analyzed for a large-scale H2 production unit with the capacity of 40.000 Nm3/h. The basic Steam Ethanol Reforming (SER) process scheme is modified in a membrane assisted process by integrating the Pd-membrane separation steps in the most suitable reaction steps. The membrane assisted process, configured in three alternative architectures (Open architecture, Membrane Reactor and Hybrid architecture) was evaluated in terms of efficiencies and hydrogen yields, obtaining a clear indication of improved process performance. The alternative membrane assisted process architectures are compared to the basic SER process and to the benchmark SMR process fed by natural gas, for an overall comparative assessment of the efficiency and specific CO2 emissions and for an economic analysis based on the operating expenditures.
  • Special issue on “Hydrogen separation/purification via membrane
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): Adolfo Iulianelli, Angelo Basile
  • Experimental evaluation of graphene oxide/TiO2-alumina nanocomposite
           membranes performance for hydrogen separation
    • Abstract: Publication date: 4 March 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 12Author(s): R. Zeynali, K. Ghasemzadeh, A. Iulianelli, A. Basile In recent years, graphene oxide membranes showed interesting performances in terms of high permeating flux and perm-selectivity in several applications of gas separation because of their inherent properties combined to a low energy consumption. In this paper, a graphene oxide layer is coated on modified TiO2-alumina tubular substrate in order to prepare graphene oxide nanocomposite membranes useful for hydrogen separation. Nanocomposite graphene oxide membrane samples were obtained by using vacuum deep coating method, depositing the graphene oxide solution as single layers on TiO2-alumina substrate. Temperature and pressure variations were evaluated to achieve high H2 permeance, high H2/CO2 selectivity and membrane performance stability during the experimental tests. Furthermore, it was found that the temperature increase causes a perm-selectivity (H2/N2 and H2/CO2) decrease, while the transmembrane pressure increase involves a general improvement of the perm-selectivity.
  • Corrigendum to “Green synthesis of Ag/Fe3O4/RGO nanocomposites by Punica
           Granatum peel extract: Catalytic activity for reduction of organic
           pollutants” [Int J Hydrogen Energy, 44 (2019) 2711–2730]
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Sayyed Hamed Adyani, Esmaiel Soleimani
  • Responses to comments on the paper “Two-dimensional Sc2C: A reversible
           and high capacity hydrogen storage material predicted by first-principles
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Qianku Hu, Qinghua Wu, Libo Wang, Aiguo Zhou A recent commentary by Santhosh and Ravindran on our paper (Int. J. Hydrogen Energy 2014, 39:10606) demonstrated that the interaction between H2 and MXene (Sc2C and Ti2C) phases are not Kubas-type and should be of weak physisorption, and thus made a conclusion that 2D Sc2C and Ti2C are not suitable for practical hydrogen storage applications. In this responses, we recalculated hydrogen adsorption on 2D Sc2C and Ti2C by using different exchange-correlation functionals. And based on the calculated results, bare MXenes (especially the Ti2C) are suitable as hydrogen storage materials at temperatures of several tens degrees lower than room temperature. And the hydrogen adsorptions on the MXenes terminated with oxygen group were also investigated. Among the Ti2C, Sc2C and their oxygen-functional counterparts, the binding energy of H2 on Sc2CO2 surface is the closest to the ideal range of 0.16–0.42 eV/H2 at ambient conditions, and thus the Sc2C with oxygen group is expected to be more suitable as hydrogen storage materials.
  • Comment on the paper titled“Two-dimensional Sc2C: A reversible and high
           capacity hydrogen storage material predicted by first-principles
           calculations” by Hu et al., International Journal of Hydrogen Energy,
           2014; 69, 1–4
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Archa Santhosh, P. Ravindran Hu et al. reported the hydrogen storage properties of Sc2C and Ti2C based MXene phases utilizing density functional theory (DFT) as implemented in the CASTEP code [1, 2]. Based on such calculations, the authors suggest that the MXenes should be a new family of potential hydrogen storage media. Their results claim a maximum hydrogen storage capacity of 9.0 wt% with an average binding energy of 0.164 eV/H2 in Sc2C MXene indicating Kubas-type interaction between H2 and the MXene. These investigations are of prime importance since they provide insight about further applications of MXenes for hydrogen storage. In these calculations they have used local density approximation (LDA) to estimate the adsorption energies. However, binding energies for H2 with the MXene phases mentioned above obtained from more accurate calculations based on Generalised Gradient Approximation (GGA) and calculation including dispersion correction (GGA + vdW) show very weak binding energy (∼0.064eV/H2) suggesting weak physical interactions between H2 and the MXene phases. Our accurate DFT calculations predict that these MXene phases are not suitable for hydrogen storage at realistic conditions. So we conclude that appropriate exchange-correlation functional should be used to extract hydrogen adsorption energies in nano-phases to describe their hydrogen storage properties reliably.
  • Numerical investigation into the low-pressure detection sensor performance
           of hydrogen gas with variable soft sphere molecular model
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Xiaowei Wang, Wenqing Zhang, Tianyi Su, Shiwei Zhang, Zhijun Zhang Direct Simulation Monte Carlo (DSMC) method is used to simulate the hydrogen detection process with Microscale In-Plane Knudsen Radiometric Actuator (MIKRA). The variable soft sphere (VSS) model is applied to depict molecular diffusion in the gas mixtures that its results are compared with variable soft sphere (VSS) in literature. On the right side of the shuttle arm, the influence of molecular model (VSS and VHS) on the simulation results is small. And the temperature ratio, heat transfer ratio and pressure ratio are highly close to 1. But on the left side of the shuttle arm, the differences are significant resulting from molecular models. Especially, for the heat transfer on the left side of the shuttle arm, heat transfer ratio of VHS model to VSS model is maximally about 4.3. The influence of gas pressures and hydrogen concentrations on the detection performance of MIKRA is also discussed. The decrease of hydrogen concentration and the increase of gas pressure cause the center of the main vortex to move towards the heater arm, and the influence of the gas pressure is more significant. On the other hand, Knudsen force increases with the increase of the hydrogen concentration and its peak value is obtained in a higher gas pressure. For example, the peak value of Knudsen force can be attained for the gas pressure of about 387 Pa in the pure hydrogen domain while in the pure nitrogen domain, the gas pressure of about 260 Pa. Simultaneously, the relation of the linear dependence of Knudsen force on the hydrogen concentration is proposed to detect hydrogen concentration in N2–H2 mixtures.Graphical abstractImage 1
  • Low temperature and fast response hydrogen gas sensor with Pd coated
           SnO2 nanofiber rods
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Feipeng Wang, Kelin Hu, Hongcheng Liu, Qi Zhao, Kaizheng Wang, Yuxin Zhang In this work, we introduced a structure of Pd coated SnO2 nanofiber rods (NFRs) prepared by electrospinning and magnet sputtering. Pd was first deposited on the obtained nanofibers as a catalyst and then fully dispersed during the resulting of SnO2 to improve the hydrogen response. The gas sensing tests showed the palladium enhanced the hydrogen response at low temperature (160 °C). When the hydrogen gas concentration was 100 ppm, the limit of detection (LOD) of sensor was as low as 0.25 ppm and the response time was as short as 4 s. Moreover, Pd coated SnO2 also had excellent hydrogen selectivity and repeatability. The gas sensor was suitable for the detection of hydrogen in low-temperature environment. This work provided a new method for the low temperature hydrogen gas sensor with a fast response and low LOD.Graphical abstractThe unique Pd doped SnO2 nanofiber rods (NFRs) show enhanced sensing properties to hydrogen, providing a novelty method to fabricate low temperature, fast response and low LOD gas sensors for hydrogen.Image 1
  • Multilayer porous Pd-WO3 composite thin films prepared by sol-gel process
           for hydrogen sensing
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Zhongjun Han, Jun Ren, Junjing Zhou, Shiyun Zhang, Zili Zhang, Liu Yang, Chenbo Yin Based on sol-gel, multilayer porous Pd-WO3 composite thin films have been successfully prepared by utilizing a layer-by-layer deposition strategy. The crystal structure and microstructure were analyzed by various characterization methods. The sensing performance of the prepared films at different hydrogen concentrations and the temperature was studied. Results show that the performance of the hydrogen sensor can be improved greatly by the use of composite structure and soft template (Pluronic F127). The response performance of 1 mol% porous Pd-WO3 composite films was better than that of 2–10 mol% films. The porous Pd-WO3 composite films showed a high sensitivity (~346.5 times better than the sensitivity of pure WO3 films for 1000 ppm H2) and a fast response time (7 s) at the temperature of 250 °C. Porous Pd-WO3 composite films had good selectivity for hydrogen and stable sensing performance. The different response and recovery behavior of samples were contrasted and discussed to explain the effect of the special composite structure and porous structure on hydrogen sensing performance.Graphical abstractImage 1
  • On the propagation dynamics of lean H2/CO/air premixed flame
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Xufeng Yang, Minggao Yu, Kai Zheng, Pengpeng Luan, Shixin Han Syngas is a promising alternative fuel. The combustion of lean H2/CO meets the demand of high efficiency with low emission. In this paper, the propagation dynamics of lean H2/CO/air premixed flame in a closed duct were experimentally investigated at an atmospheric condition. Propagation of the premixed flame is recorded by using high-speed cinematograph, and results show that the tulip flame is attained in all cases while the occurrence of tulip distortion is determined by both equivalence ratios and hydrogen volume fractions. The flame tip location and speed are attained through using image processing technique. Results show that the analytical theory, which is firstly proposed to model the flame acceleration in tulip flame propagation phase, can be used to predict the early phase flame tip motion in some limited cases. In fuel-lean combustion, with the effect of the diffusive-thermal instability, the analytical theory underestimates the flame tip motion, but overestimates the time instant of the flame initial touching the lateral walls. The overpressure build-up is specially scrutinized in conjunction with the scaled flame tip speed. The disorderly scaled flame tip speed of distorted tulip flame indicates that the distorted tulip flame is a phenomenon which relates to pressure waves. The pressure wave is of importance for tulip distortion, but it cannot change the overpressure build-up directly. Finally, both the flame-wall interaction and the combustion instability have a crucial effect on flame propagation dynamics, and these factors should be accounted for the build of flame propagation models.
  • Effects of hydrogen concentration, non-homogenous mixtures and obstacles
           on vented deflagrations of hydrogen-air mixtures in a 27 m3 chamber
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Ye Chen, Ziting Li, Chao Ji, Xuanya Liu Experimental data from vented hydrogen deflagrations with concentrations from 15% to 21% are presented. The experiments were performed in a 27 m3 cubic chamber with a vent area of either 0.78 or 1.76 m2. Uniform and stratified mixtures were used in the test matrix, and the obstacle configuration also varied to achieve different volumetric blockage ratios. The purpose of this study was to investigate the effect of hydrogen concentration, vent area, non-homogeneous mixtures and obstacles on the explosion venting for lean hydrogen-air mixtures, and to evaluate the performance of an analytical model for calculating the maximum reduced overpressure. The results show that the maximum overpressure measured inside the empty chamber increases from 3 kPa to 28.5 kPa as hydrogen concentration increases from 15.3% to 20.2%. The raised vent location may affect the pressure development during explosion venting, and a third pressure peak caused by the occurrence of the maximum flame surface area could appear in the pressure profile when a large vent is located on the upper part of the side wall. Higher volumetric blockage ratio leads to higher maximum overpressure and flame velocity, and the increment of each pressure peak with the blockage ratio is more pronounced for the back ignition. Furthermore, when comparing with the volume of unburnt gases, the obstacles have a greater effect on the flame. However, the obstructions have a limited effect on the non-homogenous hydrogen deflagration, whose combustion behaviour is governed by the maximum hydrogen concentration in the chamber. Molkov’ best-fit model over-predicts the maximum reduced overpressure measured inside the empty chamber, but the predictions are relatively acceptable for the center ignition.
  • The Arctic: Ecology and hydrogen energy
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): R.N. Shulga, A.Y. Petrov, I.V. Putilova Hydrogen fuel cells being hydrogen energy storage devices are the most effective and environmentally friendly for energy accumulation and storage. Direct current provides the accumulation of electric energy and is therefore necessary when using renewable energy sources.The social and environmental aspects, as well as climatic and glaciological features of the Arctic development in terms of energy supply are considered. The most expedient ways of complex development of the Arctic are shown. In terms of large and unique stationary projects a number of shortcomings is marked. They are high cost and long-term construction, incomplete autonomy and insufficient solution of ecological and waste processing problems. Incomplete autonomy is due to the need for transportation of materials, products, replacement crews and personnel, as well as insufficient logistics and transportation difficulties on the mainland in summer and by sea in winter. Ecological and waste processing problems are associated with the use of traditional methods of burning solid and liquid fuel using coal or fuel oil, polluting the environment. Switching to the liquefied natural gas (LNG) for electric propulsion and power supply will significantly improve the environmental situation. The research performed on the mathematical model of the multifunctional energy complex (MEC) showed the possibility of uninterrupted power supply of local load from the centralized network, diesel generator (DG) and the electricity storage (ES); by that DG is used to save fuel as a backup source. The proposed technologies of power generation based on hydrogen or low-power nuclear power plants (LPNPPs) allow, along with improving the environment, to increase the energy efficiency of the direct fuel conversion plant and provide integrated waste processing. The small population of the Arctic, its mobility when using the rotational method require the integrated development of mobile energy and life support systems of low power up to 30 MW using LNG or LPNPPs, completed by renewable energy sources (RES). If the hydrogen installation is both a source and a storage of electricity, the use of LPNPPs and especially RES require energy storage devices. These hydrogen or electrochemical cycle storage devices are the most progressive in the world energy sector and their applicability significantly depends on the development of the service infrastructure. Typing and replication of power supply sources will solve the problem of development of remote and isolated regions of the Arctic through the integrated use of innovative technologies for generation, storage, transmission and distribution of electricity, life support, utilization and recycling of wastes, environmental conservation using hydrogen energy and digital control and monitoring systems.The climatic conditions of the Arctic and the presence of LNG determine the use of hydrogen as a source for generating electricity, heat, water and air.
  • Effect of shot peening coverage on hydrogen embrittlement of a
           ferrite-pearlite steel
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Yanfei Wang, Honglin Xie, Zhiling Zhou, Xinfeng Li, Weijie Wu, Jianming Gong Effect of a wide range of shot peening (SP) coverage on hydrogen diffusion and hydrogen embrittlement (HE) of a steel consisting of ferrite and pearlite was investigated. Conventional SP (CSP) reduces diffusivity and HE because of increase of dislocation trapping sites. Although severe SP (SSP), which uses higher coverages than CSP, increases the area of ferrite grain boundaries as a result of grain refinement, it cannot suppress further the diffusion and HE, as it cannot induce a further evident increase in strong hydrogen trapping sites such as dislocations. However, when coverage is increased to so high that causes the breaking and refinement of pearlite phase, diffusion and HE is suppressed further, because the dispersed distribution of ultrafine pearlite particles within ferrite matrix provides more strong interface trapping sites. SP-induced change of trapping sites plays a more critical role in HE and diffusion, in comparison with induced residual compressive stresses.Graphical abstractImage 1
  • Influence of hydrogen on the low cycle fatigue performance of P91 steel
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Bimal Das, Akhilendra Singh The present work aims to assess the influence of hydrogen on strain controlled low cycle fatigue (LCF) properties of P91 steel. Specimens were electrochemically charged using H2SO4 solution, subsequently uniaxial tensile and LCF tests were performed at ambient temperature. An increase in strength and reduction in elongation are noticed for hydrogen charged samples relative to as received or uncharged specimens. Hydrogenated specimens depict drastic reduction in fatigue life as compared to the uncharged specimens. Irrespective of imposed strain amplitude, P91 steel show cyclic softening nature throughout its life. The peak stress amplitude and rate of cyclic softening for hydrogenated specimens are found to be more than the as received specimens at all strain amplitudes. The magnitude of proportional limit from master curve depicts that as received specimen exhibit near Masing behavior whereas hydrogenated specimens reveal non-Masing behavior. Local misorientation analyses carried out by electron back scattered diffraction technique are correlated with the evolution of local plastic strain and substructural development. The fracture morphology of tensile test transformed from dimple failure for uncharged specimen to quasi cleavage fracture for hydrogenated specimens. Finite element simulation considering Chaboche kinematic hardening rule is utilized to simulate the cyclic stress-strain behavior of as received and hydrogenated specimens.
  • Prediction of liquid hydrogen flow boiling critical heat flux condition
           under microgravity based on the wall heat flux partition model
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Yao Zheng, Huawei Chang, Yinan Qiu, Chen Duan, Jianye Chen, Hong Chen, Shuiming Shu Critical heat flux (CHF) of liquid hydrogen (LH2) flow boiling under microgravity is vital for designing space cryogenic propellant conveying pipe since the excursion of wall temperature may cause system failure. In this study, a two-dimensional axisymmetric model based on the wall heat flux partition (WHFP) model was proposed to predict the CHF condition under microgravity including the wall temperature and the CHF location. The proposed numerical model was validated to demonstrate a good agreement between the simulated and experimentally reported results. Then, the wall temperature distribution and the CHF location under different gravity conditions were compared. In addition, the WHFP and vapor-liquid distribution along the wall under microgravity were predicted and its difference with terrestrial gravity condition was also analysed and reported. Finally, the effects of flow velocity and inlet sub-cooling on the wall temperature distributions were analysed under microgravity and terrestrial gravity conditions, respectively. The results indicate that the CHF location moves upstream about 5.25 m from 1g to 10−4g since the void fraction near the wall reaches the breakpoint of CHF condition much earlier under the microgravity condition. Furthermore, the increase of the velocity and decrease of the sub-cooling have smaller effects on the CHF location during LH2 flow boiling under microgravity.
  • Hydrogen enrichment on diesel engine with biogas in dual fuel mode
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Narendra Khatri, Kamal Kishore Khatri Fossil fuels fulfill a major part of the world's energy demand. Higher demand for energy, depletion of fossil fuels and environmental impacts are the key motivational factors to explore alternate energy sources. Biogas and Hydrogen seem to be the promising alternate gaseous fuels. In this paper, the performance and emission studies were performed on a stationary dual fuel engine using fuel combinations of diesel, biogas-diesel, hydrogen-diesel, and hydrogen-biogas-diesel. Experimental results reveal that the performance of dual fuel mode with hydrogen-biogas-diesel fuel improved, and emissions were reduced in comparison to the neat diesel operation. The Brake Thermal Efficiency (BThEff) was improved by 3.09%, Brake Specific Diesel Consumption (BSDC) was reduced by 71.05%, and Brake Specific Energy Consumption (BSEC) decreased by 12.13%. The emission parameters CO, HC, and NOx, were reduced by 88.09%, 5.68%, and 83.01% respectively. Injection timing, which was obtained at 21°CA BTDC, was optimized experimentally for the selected optimum hydrogen-biogas-diesel fuel.Graphical abstractImage 1
  • Pollutant emissions, performance and combustion behaviour assessment of an
           Si gas engine fuelled with Lcv gas containing carbon monoxide and hydrogen
           diluted by nitrogen
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Grzegorz Przybyła, Willian Nadaleti This paper includes the experimental test data of an SI engine fuelled with simulated LCV gas (Low Calorific Value), which resembles synthesis gas in composition. The LCV gas was simulated by a mixture of carbon monoxide, hydrogen and nitrogen. During the experiment, the lower heating value of the LCV gas was altered by dilution with nitrogen. A single-cylinder Honda GX270 engine was adopted in the experiment to assess the impact of LCV gas on the system performance. This engine is typically used to power various machines and for electrical energy production in small generator sets. A modified engine was connected to an electric generator, which was loaded with an electric resistor. Engine operation was controlled using a microprocessor controller. All tests were performed at constant engine speed (3000 rpm). The engine was working at wide-open throttle for all mixtures. All mixtures were burned at stoichiometric conditions and with fixed value of ignition timing (30 deg bTDC). The indicated performance of the SI engine was evaluated based on the in-cylinder pressure measurements. No significant impact on the main internal parameters of the tested SI engine fuelled with simulated LCV gas diluted by nitrogen was observed. The experimental tests showed that the combustion duration increased for the mixtures with higher content of inert gas. Increase in the LHV raised the specific emissions of NOx and decreased specific emissions of CO and HC.
  • A review of ammonia as a compression ignition engine fuel
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Pavlos Dimitriou, Rahat Javaid During the past decades, the diesel engine has been through times of upheaval, boom and bust. At the beginning of the century, almost 50% of the new vehicle registrations in the European market were diesel-powered. However, the news of deadly diesel NOx emissions supported by the diesel emission scandals caused a shock to the diesel engine market, and the sustainability of the diesel engine is currently in dispute.Recently major automotive manufacturers announced the development of diesel-powered vehicles with negligible NOx emissions. Moreover, the NOx emissions production is of lower concern for heavy-duty, marine or power generations applications where the implementation of advanced aftertreatment systems is feasible. However, despite the tackle of NOx emissions, the decarbonisation of the automotive, marine and power generation markets is mandatory for meeting greenhouse gas emissions targets and limiting global warming.The decarbonisation of the diesel engine can be achieved by the implementation of a carbon-free fuel such as ammonia. This paper provides a detailed overview of ammonia as a fuel for compression ignition engines. Ammonia can be combusted with diesel or any other lower autoignition temperature fuel in dual-fuel mode and lead to a significant reduction of carbon-based emissions. The development of advanced injection strategies can contribute to enhanced performance and overall emissions improvement. However, ammonia dual-fuel combustion currently suffers from relatively high unburned ammonia and NOx emissions because of the fuel-bound nitrogen. Therefore, the implementation of aftertreatment systems is required. Hence, ammonia as a compression ignition fuel can be currently seen as a feasible solution only for marine, power generation and possibly heavy-duty applications where no significant space constraints exist.
  • Modeling and optimization of composite thermal insulation system with HGMs
           and VDMLI for liquid hydrogen on orbit storage
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Ping Wang, Lun Ji, Jing Yuan, Zhenguo An, Kaiqi Yan, Jingjie Zhang The passive thermal insulation system for liquid hydrogen (LH2) on orbit storage mainly consists of foam and variable density multilayer insulation (VDMLI) which have been considered as the most efficient and reliable thermal insulation system. The foam provides main heat leak protection on launch stage and the VDMLI plays a major role on orbit stage. However, compared with the extremely low thermal conductivity of VDMLI (1 × 10−5 W/(m·K)) at high vacuum, the foam was almost useless. Recently, based on hollow glass microspheres (HGMs) we have proposed the HGMs-VDMLI system which performs better than foam-VDMLI system. In order to improve insulation performance and balance weigh and environmental adaptability of passive insulation system, the HGMs-VDMLI insulation system should be configured optimally. In this paper, the thickness of HGMs and the number and arrangement of spacers of VDMLI were configured optimally by the “layer by layer” model. The effective thicknesses of HGMs were 25 mm for 60 layers MLI and 20 mm for 45 layers VDMLI. Compared with 35 mm foam and 45 layers VDMLI system, the heat flux of 20 mm HGMs and 45 layers VDMLI system was reduced by 11.97% with the same weight, or the weight of which was reduced by 9.91% with the same heat flux. Moreover, the effects of warm boundary temperature (WBT) and vacuum pressure on thermal insulation performance of the system were also discussed.
  • The numerical investigation of a planar single chamber solid oxide fuel
           cell performance with a focus on the support types
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Majid Kamvar, Majid Ghassemi, Robert Steinberger-Wilckens Single chamber solid oxide fuel cells (SC-SOFCs) could be an alternative to the conventional dual chamber types since they do not need any sealant and electrolyte crack growth does not lead to failure in performance. However, the reduced reactant activity due to spectator species present at anode and cathode results in a significantly decreased performance. The focus of this paper is to present a comparative study on the performance of single-chamber anode-, cathode, and electrolyte-supported cells. Our results show that anode-supported cells offer significantly better performance compared to electrolyte-supported cells. The cathode-supported cells show a similar performance to anode-supported cell close to open circuit voltages, i.e. voltages above 0.92 V, after which the cell current density decreases due to lack of oxygen at the cathode catalyst layer. Finally, a time-dependent performance study of the cathode-supported cell concept is presented and discussed.
  • Durability of direct internal reforming of methanol as fuel for solid
           oxide fuel cell with double-sided cathodes
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Yanlei Ru, Junkang Sang, Changrong Xia, Wen-Cheng J. Wei, Wanbing Guan Direct internal reforming of methanol is applied as fuel for a Ni-YSZ anode-supported solid oxide fuel cell with a flat tube based on double-sided cathodes. It achieves a power density (PD) of 0.25 W/cm2 at 0.8 V, reaching about 90% of that is fueled by H2. And the cell has been operated for more than 120 h by the direct internal reforming of methanol. The durability and apparent advantage for using humidified methanol may lead to widespread applications by direct internal reforming method for this new designed SOFC in the future.
  • Copolymer synergistic coupling for chemical stability and improved gas
           barrier properties of a polymer electrolyte membrane for fuel cell
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Hicham Ben youcef, Dirk Henkensmeier, Sandor Balog, Günther G. Scherer, Lorenz Gubler A novel radiation grafted ETFE based proton conducting membrane was prepared by double irradiation grafting of two different monomers. The intrinsic oxidative stability of the ETFE-g-poly(styrene sulfonic acid-co-divinylbenzene) membrane was improved by reducing the gas crossover through incorporation of polymethacrylonitrile (PMAN) containing the strong polar nitrile group. A fuel cell test was carried out at 80 °C under constant current density of 500 mA cm−2 for a time exceeding 1′900 h. The incorporation of PMAN considerably improves the interfacial properties of the membrane-electrode assembly. No significant change in the membrane hydrogen crossover and performance over the testing time was observed, except for a measured decrease in the membrane ohmic resistance after 1′000 h. The combination of the double irradiation induced grafting with the use of the PMAN as gas barrier in addition to its chelating abilities (e. g. Ce3+) offers a promising strategy to develop more durable membranes for fuel cells.Graphical abstractImage 1
  • Characterization of novel graphene-based microporous layers for Polymer
           Electrolyte Membrane Fuel Cells operating under low humidity and high
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Marco Mariani, Saverio Latorrata, Stefano Patrignani, Paola Gallo Stampino, Giovanni Dotelli Water management is one of the major issues hindering the employment of Polymer Electrolyte Membrane Fuel Cells on a large scale. Microporous layers are fundamental for water removal from the cathode, oxygen mass transfer and electrolyte hydration. In this paper, we have employed multiple carbon phases in the MPL composition to identify possible strategies for cell performance improvement at critical conditions such as high temperature and low relative humidity. In particular, we have employed a series of graphene-based particles, in addition to conventional carbon black, because of their excellent electrical and thermal conductivities. Moreover, mixed compositions have been tested to assess possible synergic effects between the two phases. We have determined which properties are responsible for performance improvements at 80 °C and relative humidity of 60% and how MPLs morphological and microstructural features could be tuned in order to increase mass transfer while preserving the electrolyte membrane hydration. Promising results have been obtained and specific morphological properties of graphene nanoplatelets have been identified for a possible optimization of the MPL, however the samples produced are still at an early-stage development and further improvements are needed.
  • Investigation of PEMFC performance for cruising hybrid powered fixed-wing
           electric UAV in different temperatures
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Zehra Ural Bayrak, Ufuk Kaya, Eyyup Oksuztepe In this paper, the performance of the proton exchange membrane fuel cell (PEMFC) for cruising hybrid powered fixed-wing unmanned aerial vehicle (UAV) is investigated in different temperatures. The hybrid powered UAV has two power sources: FC and battery. In this regard, Lithium-Ion (Li-ion) and Nickel Metal Hydride (Ni-MH) are selected as battery types. The PEMFC performance is analysed in three scenarios determined as FC, FC & Li-ion and FC & Ni-MH. The linearized UAV model is simulated in MATLAB/Simulink and only cruise phase of flight considered. Simulation results shown that the UAV model with pure FC has the longest endurance. The endurance has influenced from total weight of the UAV and hybrid system characterization. Furthermore, temperature changes also affect fuel consumption. This paper provides a general description of the proposed UAV model with three types of hybrid power source and describes the design methods and simulation cases for long endurance.
  • Pulse-reverse electrodeposition of Pt–Co bimetallic catalysts for oxygen
           reduction reaction in acidic medium
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Jittima Sriwannaboot, Arunachala Kannan, Nisit Tantavichet Pt–Co electrodeposited by pulse reverse current on carbon cloth (CC) and glassy carbon (GC) are studied. On both substrates, applying a higher reverse current or a longer reverse-time increases the Pt content due to higher Co dissolution from Pt–Co structures, but does not affect the morphology. Despite similar morphologies and compositions deposited on CC or GC, the electrochemical behaviors of Pt–Co on both substrates are significantly different. Distinct hydrogen under-potential deposition (HUPD) adsorption/desorption peaks are not observed on CC, while well-defined peaks are established on GC. Oxygen reduction reaction (ORR) of Pt–Co on CC is significantly higher than on GC due to its highly porous structure. The ORR on GC changes with the Pt content controlled by varying the reverse pulse during electrodeposition, where Pt–Co with 58 at.% Pt or higher provides a better activity than Pt, with 77 at.% Pt having the highest ORR activity.
  • Thermodynamic performance analysis of the influence of multi-factor
           coupling on the methanol steam reforming reaction
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Shuang Xing, Chen Zhao, Shuai Ban, Yifan Liu, Haijiang Wang This work presents the H2 production from methanol steam reforming (MSR) process by thermodynamic equilibrium analysis using the Gibbs free energy minimization method and multi-factor coupling method. To determine desirable procedure parameters with maximum methanol conversion and H2 content and minimum CO content, the impacts of the temperature: 100–400 °C, steam-to-methanol (S/C) molar ratio: 1.0–3.0, and pressure: 0.5–3.0 atm were investigated. The dominant factor under the action of multiple factors and the specific influence of each factor on the MSR process were verified, simultaneously. For proton exchange membrane fuel cell (PEMFC), to keep the CO content of the reformate within a desired range, and under the premise of complete methanol conversion, the MSR process can be operated at lower temperature, higher S/C ratio and atmospheric pressure. Combined with practice process, the optimum values of the temperature, S/C ratio and pressure to produce reformate were identified to be 200–300 °C,1.6–2.0 and 1.0 atm, respectively.
  • Online adaptive water management fault diagnosis of PEMFC based on
           orthogonal linear discriminant analysis and relevance vector machine
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Shangwei Zhou, Jaspreet Singh Dhupia A data-driven strategy for characterizing the water management failure in a Proton Exchange Membrane Fuel Cell (PEMFC) is presented in this paper. To carry out the diagnosis of water management failure, first the original single cell voltages are projected into lower-dimension features by applying orthogonal linear discriminant analysis (OLDA). Then, a classification methodology termed relevance vector machine (RVM) is employed to classify the lower-dimension features into different categories that indicate the respective health states of the system. The initially trained projecting vectors and classifiers lose their efficiency gradually the characteristics of PEMFC system change, such as the cell voltages decaying with time due to the normal degradation due to aging. An online adaptive diagnostic strategy based on the posterior probability of RVM is proposed, so as to keep the diagnostic accuracy over time. The efficiency and reliability of this online adaptive diagnostic strategy is validated using an experimental database from a 90-cell PEMFC stack.
  • Atomically thin titanium carbide used as high-efficient, low-cost and
           stable catalyst for oxygen reduction reaction
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Chengdong Wang, Songlin Zhang, Mingxun Zheng, Ruoyu Shu, Shengxu Gu, Jiahao Guo, Chuan Liu, Jing Tang, Junming Chen, Xuchun Wang Addressed herein, a highly effective, low-cost and stable TiC nanocatalyst was successfully synthesized through ultrasonic exfoliation of commercial TiC in deionized water and its application as a catalyst in the oxygen reduction reaction is outlined. A facile ultrasonic exfoliation was applied to fabricate atomically thin TiC. The structure, morphology, composition and catalytic properties of atomically thin TiC were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), atomic force microscopy (AFM), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. Atomically thin TiC possesses superior ORR activity in terms of catalytic performance, methanol tolerance, and long-term durability. This work has been provided a low-cost, efficient and stable substitute catalyst for Pt/C to promote the industrialization for energy storage and conversion devices.
  • Multi-agent direct current systems using renewable energy sources and
           hydrogen fuel cells
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): R.N. Shulga, I.V. Putilova Direct current provides accumulation of electricity and is therefore necessary when using renewable energy sources. Hydrogen energy storage devices in the form of fuel cells are the most effective and environmentally friendly way of energy storage and conservation. Shortcomings of electric power networks compared with DC networks in terms of stability, controllability, reliability and redundancy are noted. The necessity of transition from digitalization in the form of automated process control systems to smart grids, and subsequently to multi-agent DC networks with a high degree of redundancy, is revealed. Besides, the paper deals with application of distributed generation consisting of traditional and renewable energy sources, as well as accumulators and static converters. Characteristics of the above mentioned elements are given for simulating the modes in order to select the structure and control algorithms that provide increased power supply reliability.
  • Multi-objective optimization for efficient modeling and improvement of the
           high temperature PEM fuel cell based Micro-CHP system
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Yu Yang, Hao Zhang, Ping Yan, Kittisak Jermsittiparsert Fuel cells due to different useful features such as high efficiency, low pollution, noiselessness, lack of moving parts, variety of fuels used and wide range of capacity of these sources can be the main reasons for their tendency to use them in different applications. In this study, the application of a high temperature proton exchange membrane fuel cell (HT-PEMFC) in a combined heat and power (CHP) plant has been analyzed. This study presents a multi-objective optimization method to provide an optimal design parameters for the HT-PEMFC based micro-CHP during a 14,000 h lifetime by considering the effect of degradation. The purpose is to optimize the net electrical efficiency and the electrical power generation. For the optimization process, different design parameters including auxiliary to process fuel ratio, anodic stoichiometric ratio, steam to carbon ratio, and fuel partialization level have been employed. For optimization, A new technique based on Tent mapping and Lévy flight mechanism, called improved collective animal behavior (ICAB) algorithm has been employed to solve the algorithm premature convergence shortcoming. Experimental results of the proposed method has been applied to the data of a practical plant (Sidera30) for analyzing the efficiency of the proposed ICAB based system, it is compared with normal condition and another genetic algorithm based method for this purpose. Final results showed that the difference between the maximum electrical power production under normal condition and ICAB based condition changes from 2.5 kW when it starts and reaches to its maximum value, 3.0 kW, after 14,000 h lifetime. It is also concluded that the cumulative average for the normal and the ICAB based algorithm are 24.01 kW and 27.04 kW, respectively which showed about 3.03 kW cumulative differences.
  • Water-alcohol dispersible and self-cross-linkable sulfonated poly(ether
           ether ketone): Application as ionomer for direct methanol fuel cell
           catalyst layer
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Shu Dong, Zhouying Yue, Huidong Qian, Wenhao Li, Jianfeng Xu, Hui Yang A sulfonated poly(ether ether ketone) containing hydroxyl groups (HO-SPEEK) has been synthesized for investigation as the ionomer in cathode of direct methanol fuel cells. Na salt-formed HO-SPEEK shows excellent solubility in some aqueous solutions of monohydric alcohol and can be successfully self-cross-linked in-situ during the hot-pressing process of membrane-electrode assembly (MEA) fabrication. The resulted cross-linked HO-SPEEK displays improved stability and mechanical strength. MEA incorporating the HO-SPEEK as both membrane and ionomer shows excellent peak power density of 29.0 mW cm−2 at 25 °C with 4 M methanol, which is comparable to the Nafion reference MEA (31.8 mW cm−2) and 2.9-fold higher than that of the MEA prepared from catalyst ink that contained dimethyl sulfoxide (10.3 mW cm−2). Thanks to the avoidance of high-boiling point solvent, the resulted HO-SPEEK-based cathode is loosened with many large pores for reactant gas and product transportation. These results demonstrate that water-alcohol dispersible and cross-linkable sulfonated hydrocarbons hold technological promise as ionomer for electrode.Graphical abstractThe incorporation of water-alcohol dispersible and cross-linkable hydrocarbon ionomer into the electrode improves the cell performance of MEA.Image 1
  • High-performance solid oxide fuel cells with fiber-based cathodes for
           low-temperature operation
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Joseph Parbey, Qin Wang, Jialong Lei, Mayken Espinoza-Andaluz, Feng Hao, Yong Xiang, Tingshuai Li, Martin Andersson Low-temperature operation of solid oxide fuel cells (SOFCs) results in deterioration in electrochemical performance due to sluggish oxygen reduction reaction (ORR) at the cathode. To enhance the reaction pathway for ORR, La0.8Sr0.2MnO3 (LSM) nanofibers were fabricated by electrospinning and used for low-temperature solid oxide fuel cells operated at 600–700 °C. The morphological and structural characteristics show that the electrospun LSM nanofiber has a highly crystallized perovskite structure with a uniform elemental distribution. The average diameter of the LSM nanofiber after sintering is 380 nm. A symmetric cell of nanofiber-based LSM cathode on scandia-stabilized zirconia (SSZ) electrolyte pellet exhibits much lower area specific resistances compared to commercial LSM powder-based cathode. A single cell based on the nanofiber LSM cathode on yttrium-doped barium cerate-zirconia (BCZY) electrolyte exhibits a power density of 0.35 Wcm−2 at 600 °C, which increases to 0.85 Wcm−2 at 700 °C. The cell has an area specific resistance (ASR) of 0.46 Ωcm2 at 600 °C, which decreases to 0.07 Ωcm2 at 700 °C. The results indicate that the LSM electrode fabricated by the electrospinning process produces a nanostructured porous electrode which optimizes the microstructure and significantly enhances the ORR at the cathode of SOFCs.
  • Potential of thermoelectric waste heat recovery in a combined geothermal,
           fuel cell and organic Rankine flash cycle (thermodynamic and economic
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Shoaib Khanmohammadi, Morteza Saadat-Targhi, Faraedoon Waly Ahmed, Masoud Afrand The present work aim is performance improvement of an integrated geothermal system by proposing the integration of organic Rankine flash cycle (ORFC) with the Proton exchange membrane fuel cell (PEMFC) and waste heat recovery from condensers using thermoelectric generator (TEG) modules. To achieve this goal, a novel integrated system is proposed, thermodynamically modeled, investigated, and compared with the conventional system. To assess the performance of proposed system, thermodynamic and economic evaluations are performed. The results indicate that R123 as working fluid, has the best performance for the conventional and proposed systems. The findings demonstrate that with employing TEG modules an increase of 2.7% and 2.8%, for the first and second law efficiencies can be obtained respectively. Additionally, the results of parametric analysis indicate that however the geothermal fluid temperature increment decreases the first and second law efficiencies of the system, it leads to the net output power enhancement. Also, enhancement of the flash vessel pressure ratio increases the first and second law efficiency as well. Additionally, the simple payback method showed that a payback time between 1.25 years and 25 years according to the TEG modules cost can be achieved.
  • Effect of non-solvent from the phase inversion method on the morphology
           and performance of the anode supported microtubular solid oxide fuel cells
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Cong Ren, Yanxiang Zhang, Qi Xu, Tian Tian, Fanglin Chen The microstructure of the anode in anode-supported solid oxide fuel cells has significant influence on the cell performance. In this work, microtubular Ni-yttria stabilized zircona (Zr0.8 Y0.2O2, YSZ) anode support has been prepared by the phase inversion method. Different compositions of non-solvent have been used for the fabrication of the Ni-YSZ anode support, and the correlation between non-solvent composition and characteristics of the microstructure of the anode support has been investigated. The presence of ethanol or isopropanol in the non-solvent can inhibit the growth of the finger-like pores in the anode support. With the increase of the concentration of ethanol or isopropanol in the non-solvent, a thin dense layer can be observed on the top of the prepared tubular anode support. In addition, the mechanism of pore formation is explained based on the inter-diffusivity between the solvent and the non-solvent. The prepared microtubular solid oxide fuel cells (MT-SOFCs) have been tested, and the influence of the anode microstructure on the cell electrochemical performance is analyzed based on a polarization model.
  • Simulation of SOFC performance using a modified exchange current density
           for pre-reformed methane-based fuels
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): K. Takino, Y. Tachikawa, K. Mori, S.M. Lyth, Y. Shiratori, S. Taniguchi, K. Sasaki Numerical simulations can be used to visualize and better understand various distributions such as gas concentration and temperature in solid oxide fuel cells (SOFCs) under realistic operating conditions. However, pre-existing models generally utilize an anode exchange current density equation which is valid for humidified hydrogen fuels – an unrealistic case for SOFCs, which are generally fueled by hydrocarbons. Here, we focus on developing a new, modified exchange current density equation, leading to an improved numerical analysis model for SOFC anode kinetics. As such, we experimentally determine the exchange current density of SOFC anodes fueled by fully pre-reformed methane. The results are used to derive a new phenomenological anode exchange current density equation. This modified equation is then combined with computational fluid dynamics (CFD) to simulate the performance parameters of a three-dimensional electrolyte-supported SOFC. The new modified exchange current density equation for methane-based fuels reproduces the I–V characteristics and temperature distribution significantly better than the previous models using humidified hydrogen fuel. Better simulations of SOFC performance under realistic operating conditions are crucial for the prediction and prevention of e.g. fuel starvation and thermal stresses.
  • Three-dimensional simulation of solid oxide fuel cell with metal foam as
           cathode flow distributor
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Ruobing Zhan, Yang Wang, Meng Ni, Guobin Zhang, Qing Du, Kui Jiao In this study, the use of metal foam as a flow distributor at cathode is evaluated numerically by a comprehensive three-dimensional solid oxide fuel cell (SOFC) model. The results show that the adoption of metal foam improves the power density by 13.74% at current density of 5000 A m−2 in comparison with conventional straight channel design. It is found that electronic overpotential, oxygen concentration and reaction rates distribute more uniformly without the restriction of ribs. The effects of cathode thickness on the two different flow distributors are compared. Compared with conventional straight channel, the metal foam is found to be more suitable as a distributor for anode supported SOFC with thin cathode gas diffusion layer. Moreover, when metal foam is applied to the fuel cell with a larger reaction area, a more uniform velocity distribution and a lower temperature distribution can be achieved. It is also found that an appropriate permeability coefficient should offer a reasonable pressure drop, which is beneficial for the fuel cell system performance improvement.
  • Complexing of NixMny sulfides microspheres via a facile solvothermal
           approach as advanced electrode materials with excellent charge storage
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Diab khalafallah, Chong Ouyang, Muhammad A. Ehsan, Mingjia Zhi, Zhanglian Hong Mixed metal sulfides with high specific capacitances and superior rate capabilities can meet the need of new materials for technological advancement of energy storage systems. We demonstrate in this study a facile fabrication of microspheres-like NixMny sulfides with different molar ratios of metallic salts through a one-step solvothermal route. The hierarchical NixMny sulfides-based compounds feature spherical architectures with relatively rough surfaces and assembled from ultrasmall and self-aggregated nanoprimary crystals. Especially, the NixMny sulfide (x/y = 1:1) presents an excellent battery-like performance with a high specific capacitance (219.4 mAh g−1 at current density of 1 A g−1) and a good rate capability (123 mAh g−1 at 50 A g−1), benefiting from the greatly improved faradaic redox processes boosted by the synergistic effect of Ni and Mn electroactive components and as well as fast mass transfer. Furthermore, the as-fabricated asymmetric supercapacitor based on NixMny sulfide (x/y = 1:1) presents a maximum energy density of 34 W h kg−1 at a power density of 868.1 W kg−1 with both superior rate and long-term cycling stabilities. In view of low cost and improved electrochemical performance, such integrated compound proposes a new and feasible pathway as a potential electrode configuration for energy storage devices.
  • ZnMn2O4/milk-derived Carbon hybrids with enhanced
           Lithium storage capability
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Ye Lin, Lei Zhang, Hongdong Liu One of the effective ways to improve the conductivity and structural stability of binary metal oxide nanostructures is to tightly composite them with nano-carbon materials with excellent conductivity. However, the introduction of low density carbon materials also reduces the energy density of batteries. Therefore, we provides a new idea to enhance the lithium storage performance of carbon/binary transition metal oxide anode materials by multi-element co-doping carbon. ZnMn2O4 provides high lithium storage capacity; non-metallic heteroatoms in milk-derived carbon greatly improve the conductivity of carbon materials; metal heteroatoms in milk-derived carbon increase the density of carbon materials. Multicomponent co-doping carbon can build up the mass specific capacity, ratio performance, cyclic life and mechanical properties of binary metal oxides/porous carbon nanocomposites. As the anode materials of lithium-ion batteries, the ZnMn2O4/MC (milk-derived carbon) hybrids deliver a high reversible capacity of 1352 mAh g−1 after 400 cycles at 0.1 A g−1, and a remarkable long-term cyclability with 635 mAh g−1 after 300 cycles at 1.0 A g−1.Graphical abstractImage 1
  • Hydrogen & hydrogen energy creating the universe: Spin-Top Theory
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): T. Nejat Veziroğlu Using the Spin-Top Theory of the universe, and the available information about the universe, the characteristics of the universe-seed (or U-Seed), creation of the universe and its life cycle have been estimated. With the explosion of the U-Seed, made of hydrogen, hydrogen and its thermonuclear reaction products start spreading, and forming an ever growing ellipsoid on the way out, while circling the universe center (U-Center). Then, as a result of the gravitational pull, heavenly bodies start moving towards and eventually reaching the universe center (U-Center) to reform the U-Seed. During this expansion and contraction periods, the universe boundaries and the pertinent times have been calculated. It is shown that a universe cycle is about 148 billion years, and it repeats itself forever.Graphical abstractImage 1
  • Analytical and numerical predictions of hydrogen gas flow induced by wall
           and corner leakages in confined space
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Qihua Wang, Chunjie Zhai, Junhui Gong, Zhirong Wang, Juncheng Jiang, Yang Zhou This contribution addresses a newly developed semi-analytical model coupling the zone model, virtual point source buoyancy plume theory and mirror theory to predict the gas flow behaviors of leaked hydrogen restricted by a wall or a corner in confined space with an opening. The effects of leaked hydrogen mass flux, opening geometry and the leakage location on interface height, outflow velocity and hydrogen molar fraction in upper layer, were thoroughly investigated at steady stage. A computational fluid dynamics tool, FLACS, was employed to simulate the dispersion process in different leakage scenarios and validate the capability of the derived analytical model. The results show that in all center, wall and corner leakage circumstances, the interface height declines with larger leakage mass flux, whereas the outflow velocity and hydrogen molar fraction change inversely. The interface height, outflow velocity and hydrogen molar fraction are positively, negatively and negatively correlated with the opening dimension, respectively. The opening height plays a more important role in determining the interface height and hydrogen molar fraction but hardly affects the outflow velocity. The interface height keeps unchanged with varying leakage locations when other parameters remain constants. However, according to the mirror theory the outflow velocities in corner and wall leakage conditions are 0.63 and 0.4 times of those in center leakage case. Meanwhile, the hydrogen molar fractions of corner and wall leakages are 1.59 and 2.52 times of the ones in center leakage. All these ratios are validated by the corresponding analytical and numerical predictions. The credibility of the analytical model is verified by the good agreement with the numerical estimations.
  • Enhancing selectivity and reducing cost for dehydrogenation of
           dodecahydro-N-ethylcarbazole by supporting platinum on titanium dioxide
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Xiang Gong, Zhao Jiang, Tao Fang N-ethylcarbazole/dodecahydro-N-ethylcarbazole (NECZ/12H-NECZ) was a promising system for hydrogen storage applications. 1.0 wt% Pt/TiO2 was regarded as the optimal loading in Pt/TiO2 catalyst applied in the 12H-NECZ dehydrogenation reaction. The hydrogen release amount, selectivity to NECZ and TOF of 12H-NECZ dehydrogenation are 5.75 wt %, 98% and 229.73 min−1 at 453 K. Compared with the commercial 5.0 wt% Pd and Pt-based catalysts, it exhibited very high activity, selectivity and stability for 12H-NECZ dehydrogenation with low Pt loading. Combined with the XRD, XPS, HRTEM, TPR analysis, it was indicated that the enhanced catalytic performance was due to the SMSI (strong metal-supporting interaction) between Pt and TiO2 support, which accelerated the rate-limiting step and enhanced the whole dehydrogenation reaction. This work may be beneficial for the commercial application of Pt/TiO2 catalysts in the Liquid Organic Hydrogen Carrier (LOHC) system.Graphical abstractImage 1
  • A novel joint bidding technique for fuel cell wind turbine photovoltaic
           storage unit and demand response considering prediction models analysis
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Chenghao Sun, Sebastian leto The stake of distributed generation resources like fuel cell in daily market is proved to be a major uncertain problem. The volatile character of market price together with the unbalanced nature of power can take hold of economic advancement of distributed generation resources which in turn can culminate in diversion retribution while the market is being struck. This study introduces a market participation model in share conditions to improve the profit for Fuel Cell/wind turbine/storage/photovoltaic and demand response. To solve the mentioned problem, an accurate prediction model is presented in this paper. This model is based on complete ensemble empirical mode decomposition, and multiple artificial neural network which is coupled with Broyden water cycle algorithm. By this algorithm, the prediction accuracy of proposed forecast engine is enhanced and could get the better results. A sure-footed stochastic optimization approach was deployed in order to take prices of markets and distributed generation resources into account. In the generation of distributed generation resources, forecasting error database in everyday, modified, and depressed market was drawn on to induce probabilistic scenario. Improbable variables were discarded by a neuro-fuzzy model. Eventually, to illustrate the joint model strategy suggested in the study, a testing system contains fuel cell/wind turbine/storage unit/photovoltaic and demand response was utilized and the attained results were calculated in two different periods.Graphical abstractImage 1
  • Activation and de/ hydriding behavior in Ti23V40Mn37 alloy by Hf and Hf/Cr
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): X.Y. Chen, R.R. Chen, X. Ding, S. Wang, Y.Q. Su, J.J. Guo To improve absorption/desoprtion rate and hydrogen desorption capacity of Ti–V–Mn alloy, Ti23V40Mn37 alloys by Hf and Hf/Cr substitutions were prepared, the activation and hydriding/dehydriding behaviors of the alloys are investigated. Results show that the lattice parameter of BCC phase increases and the ratio of C14 Laves phase also increases by the substitutions. Ti19Hf4V40Mn35Cr2 alloy exhibits the rapid absorption/desoprtion rate and the highest hydrogen desorption capacity of 1.58 wt% H2 at 293 K. The Hydrogenation kinetic mechanism of the alloys is transformed from nucleation-growth to diffusion, and the dehydrogenation kinetic mechanism is only nucleation-growth. The activation energy of Hf/Cr substituted alloy is lower than that of Hf-free alloy, with the values of 53.79 kJ mol−1 H2 and 90.13 kJ mol−1 H2 respectively, which is accounted for the easily absorption of hydrogen molecules on the particle surface and the rapid H diffusion of the interior of alloy, thus the substituted alloys have rapid absorption/desoprtion rate.
  • Pseudo catalytic ammonia synthesis by lithium–tin alloy
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Toshiro Yamaguchi, Keita Shinzato, Kyohei Yamamoto, Yongming Wang, Yuki Nakagawa, Shigehito Isobe, Tomoyuki Ichikawa, Hiroki Miyaoka, Takayuki Ichikawa In this work, nitrogenation, ammonia generation, regeneration reactions of lithium-tin alloy is investigated as pseudo catalytic process of ammonia synthesis. Li17Sn4 synthesized by thermochemical method at 500 °C can react with 0.1 MPa of N2 below 400 °C. Nano or amorphous lithium nitride would be formed by the nitrogenation. By reaction of the nitrogenated samples and H2, ammonia is generated at 300 °C under 0.1 MPa. The initial alloy phase Li17Sn4 is regenerated below 350 °C from the products after the ammonia generation process. Based on the above three step process, ammonia can be pseudo-catalytically synthesized from N2 and H2 below 400 °C under ambient pressure. Furthermore, the reactivity for the ammonia synthesis using Li–Sn alloy is preserved during the NH3 synthesis cycles due to the characteristic reaction process based on the Li extraction and insertion.Graphical abstractImage 1
  • Technical potential of salt caverns for hydrogen storage in Europe
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Dilara Gulcin Caglayan, Nikolaus Weber, Heidi U. Heinrichs, Jochen Linßen, Martin Robinius, Peter A. Kukla, Detlef Stolten The role of hydrogen in a future energy system with a high share of variable renewable energy sources (VRES) is regarded as crucial in order to balance fluctuations in electricity generation. These fluctuations can be compensated for by flexibility measures such as the expansion of transmission, flexible generation, larger back-up capacity and storage. Salt cavern storage is the most promising technology due to its large storage capacity, followed by pumped hydro storage. For the underground storage of chemical energy carriers such as hydrogen, salt caverns offer the most promising option owing to their low investment cost, high sealing potential and low cushion gas requirement. This paper provides a suitability assessment of European subsurface salt structures in terms of size, land eligibility and storage capacity. Two distinct cavern volumes of 500,000 m3 and 750,000 m3 are considered, with preference being given for salt caverns over bedded salt deposits and salt domes. The storage capacities of individual caverns are estimated on the basis of thermodynamic considerations based on site-specific data. The results are analyzed using three different scenarios: onshore and offshore salt caverns, only onshore salt caverns and only onshore caverns within 50 km of the shore. The overall technical storage potential across Europe is estimated at 84.8 PWhH2, 27% of which constitutes only onshore locations. Furthermore, this capacity decreases to 7.3 PWhH2 with a limitation of 50 km distance from shore. In all cases, Germany has the highest technical storage potential, with a value of 9.4 PWhH2, located onshore only in salt domes in the north of the country. Moreover, Norway has 7.5 PWhH2 of storage potential for offshore caverns, which are all located in the subsurface of the North Sea Basin.
  • Hydrogen storage in Ca-decorated carbyne C10-ring on either Dnh or D(n/2)h
           symmetry. DFT study
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Luis A. Desales-Guzmán, Juan H. Pacheco-Sánchez, Frank J. Isidro-Ortega, Karen De la Mora-Zarco We computationally investigate the hydrogen storage properties of carbyne C10-ring structure on either Dnh or D(n/2)h symmetry decorated with calcium (Ca) atoms adsorbed on its outer surface. The calculations are carried out on DFT-GGA-PW91 and DFT-GGA-PBE levels of theory as implemented in Biovia Materials Studio modeling and simulation software. To account for van der Waals interactions we also carried out calculations using DFT-D method of Grimme. Dmol3 is used to calculate total energies, HOMO-LUMO electronic charge density, Mulliken population analysis, and electrostatic potential fitting charges (ESP). Based on these results: i) the average binding energy of Ca atom doping to C10-ring is ~2.3 eV (PW91) and ~2.1 eV (PBE). ii) Up to seven H2 molecules per Ca atom can be physically adsorbed with an average energy of ~0.2 eV per H2 molecule. iii) This physisorption leads to 8.09 wt percentage (wt. %) for the gravimetric storage capacity. According to these results, calcium-decorated carbyne C10-ring structure is excellent candidate for hydrogen storage at ambient conditions with application to fuel cells.
  • Remarkable synergistic effects of Mg2NiH4 and transition metal carbides
           (TiC, ZrC, WC) on enhancing the hydrogen storage properties of MgH2
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Linglong Yao, Xuanyu Lyu, Jiguang Zhang, Yana Liu, Yunfeng Zhu, Huaijun Lin, Yao Zhang, Liquan Li Nanostructuring and catalyzing are effective methods for improving the hydrogen storage properties of MgH2. In this work, transition-metal-carbides (TiC, ZrC and WC) are introduced into Mg–Ni alloy to enhance its hydrogen storage performance. 5 wt% transition-metal-carbide containing Mg95Ni5 (atomic ratio) nanocomposites are prepared by mechanical milling pretreatment followed by hydriding combustion synthesis and mechanical milling process, and the synergetic enhancement effects of Mg2NiH4 and transition-metal-carbides are investigated systematically. Due to the inductive effect of Mg2NiH4 and charge transfer effect between Mg/MgH2 and transition-metal-carbides, Mg95Ni5-5 wt.% transition-metal-carbide samples all exhibit excellent hydrogen storage kinetic at moderate temperature and start to release hydrogen around 216 °C. Among them, 2.5 wt% H2 (220 °C) and 4.7 wt% H2 (250 °C) can be released from the Mg95Ni5-5 wt.% TiC sample within 1800 s. The unique mosaic structure endows the Mg95Ni5-5 wt.% TiC with excellent structural stability, thus can reach 95% of saturated hydrogen capacity within 120 s even after 10 cycles of de-/hydrogenation at 275 °C. And the probable synergistic enhancement mechanism for hydrogenation and dehydrogenation is proposed.Graphical abstractImage 1
  • Tuning the hydrogen storage properties of MOF-650: A combined DFT and GCMC
           simulations study
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Suye Yu, Guoliang Jing, Shina Li, Zhifang Li, Xin Ju Combined density functional theory and grand canonical monte Carlo (GCMC) calculations were performed to study the electronic structures and hydrogen adsorption properties of the Zn-based metal-organic framework MOF-650. The benzene azulenedicarboxylate linkers of MOF-650 were substituted by B atoms, N atoms, and boronic acid B(OH)2 linkers, and the Zn atoms were substituted by Mg and Ca atoms. The calculated electronic densities of states (DOSs) of MOF-650 showed that introduction of B atoms reduces the band gap but damages the structure of MOF-650. Introduction of single N bonds cannot provide active electrons to attract H2 molecules. Thus, substitutions of B and N into MOF-650 are not suggested. B(OH)2 substitute in MOF-650 decreased its band gap, slightly improved its hydrogen storage ability and made H2 molecules more intensively distributed besides organic linkers. GCMC calculations were carried out by estimating the H2 storage amount of the pure and modified MOFs at 77 and 298 K and from 1 bar to 20 bar. B(OH)2 linker and Mg/Ca co-doped MOF-650 showed increased H2 adsorption by approximately 20 wt%. The adsorption of H2 around different bonds showed the order N–C 
  • Density functional theory based molecular dynamics study on hydrogen
           storage capacity of C24, B12N12, Al12 N12, Be12O12, Mg12O12, and Zn12O12
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): M. Ghorbanzadeh Ahangari, A. Hamed Mashhadzadeh In the current study, the density functional theory calculations (DFT) were employed to determine the hydrogen storage properties of some nanoclusters including C24, B12N12, Al12 N12, Be12O12, Mg12O12, and Zn12O12. After full geometrical optimization of all nanocages under the DFT framework, we found that C24 and B12N12 were unstable structures even in case of incorporating only one hydrogen molecule to them due to positive obtained formation energy magnitudes while Al12N12 and Be12O12 were able to adsorb one hydrogen molecules and became thermodynamically unstable for more than one hydrogen molecule. Also, Mg12O12 and Zn12O12 were capable of storing up to 4 hydrogen molecules according to negative achieved formation energies. Also, calculated bulk modulus revealed that when all studied structures stored H2 molecules the bulk modulus decreased compared to pristine nanoclusters. The highest reduction in bulk modulus was 10% which occurred in C24 while storing 5H2. Furthermore, the adsorption properties of these nanocages were considered using DFT and the results showed that Zn12O12 was a stronger adsorbent for H2 in comparison to the rest of the studied nanocages.
  • Non-dimensional assessments to estimate decompression failure in polymers
           for hydrogen systems
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Maximiliano Melnichuk, Frédéric Thiébaud, Dominique Perreux Polymer materials subjected to gases at high-pressure can have issues during decompression. For instance, a sudden decompression can promote the formation of cavities inside the material. This phenomenon is known as cavitation or eXposive Decompression Failure (XDF). There is a body of scientific articles discussing different aspects of cavitation phenomenon, which indicate that the degree of damage is proportional to saturation pressure, depressurisation rate, and material thickness, among other parameters.In this article we propose a general approach by non-dimensional parameters to estimate the risk of cavitation. Numerical results were validated with bibliographic evidence of cavitation in polymers, for both thermoplastics and elastomers. Present results can be used as guidelines for design of systems involving polymers under high pressure, such as o-rings or liners in type IV hydrogen containers.
  • Density functional theory study on catalytic dehydrogenation of
           methylcyclohexane on Pt(111)
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Fengtao Chen, Yanping Huang, Chengjing Mi, Kui Wu, Weiyan Wang, Wensong Li, Yunquan Yang Density Functional Theory (DFT) method was used to study the step-by-step dehydrogenation of methylcyclohexane (MCH) to toluene on a Pt(111) surface to understand adsorption properties of the reactants, intermediates and the products involved. The results indicate that dehydrogenation occurs preferentially in the para position. Methylcyclohexane is a saturated molecule and its adsorption on the surface of Pt(111) falls into the category of physical adsorption. 4-methyl-cyclohexene and methyl-cyclohexadiene are the most likely dehydrogenation intermediates. The C–C bond on the six-membered ring has a significant shrinkage after the dehydrogenation reaction. The highest energy barrier of 32.46 kcal/mol is calculated for the first dehydrogenation step, which may potentially be the rate-determining step for the entire reaction network. These are consistent with the experimental results.
  • Hydrogen storage mechanism in transition metal decorated graphene oxide:
           The symbiotic effect of oxygen groups and high layer spacing
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Pei Pei, Michael B. Whitwick, Sahida Kureshi, Mark Cannon, Grace Quan, Erik Kjeang Transition metal nanoparticle decoration is widely used to enhance the hydrogen storage properties of carbon materials. However, little efforts have been devoted to unveil structural interaction between nanoparticles and substrate and understand the underlying kinetic mechanism for hydrogen sorption. In this work, a suite of TiO2 nanoparticles decorated graphene oxide (GO) composites is fabricated and characterized to determine the interactions between material structure and hydrogen storage kinetics. EELS and XPS results show that interactions between nanoparticles and GO cause changes of the chemical states of C–O, CO and C–OH groups; furthermore, reactions of C–OH, HO–CO and C–O–C groups with TiO2 nanoparticles create C–Ti and Ti–O–C bonding. Decoration of TiO2 nanoparticles improves the capacity of GO by 2.3×, and 80% of the adsorption is reversible. By means of semi-empirical kinetic analysis, it is determined that hydrogen adsorption is controlled by two-dimensional diffusion regardless of layer spacing; while desorption is controlled by multiple diffusion processes and is sensitive to layer spacing. Collectively, these new findings deepen the understanding of transition metal nanoparticles decorated GO materials in the aspects of nanoparticle incorporation and hydrogen storage kinetic mechanism. In particular, oxygen groups enhance nanoparticle decoration, while high layer spacing improves desorption kinetics and reversibility.
  • Tunable microstructure, de-/hydrogenation kinetics and thermodynamics
           performance of Mg–Ni–La–Ti–H systems
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Fenghai Guo, Tiebang Zhang, Limin Shi, Lin Song In the light of positive effects of rare earth and transition metals on the hydrogen absorption/desorption properties of magnesium, the Mg20La–5TiH2, Mg20Ni–5TiH2 and Mg10Ni10La–5TiH2 composites have been prepared in this work to ameliorate the de-/hydrogenation kinetics and thermodynamic performance. The results indicate that the as-prepared composites are mainly composed of Mg, Mg2Ni/LaH3 and TiH2 phases after activation, and LaH3 and TiH2 are stable during de-/hydrogenation cycles. The morphology observations give evidences that LaH3 with size about ~20 nm and Mg2Ni with size about ~1 μm are uniformly distributed in the composites. It is noted that the de-/hydriding kinetics of the as-prepared composites are significantly improved after internal and surface modification, of which the Mg10Ni10La–5TiH2 composite can desorb as high as 5.66 wt% hydrogen within 3 min at 623 K. Moreover, the thermodynamic properties of the experimental composites have also been investigated and discussed according to the pressure-composition isothermal curves and corresponding calculation by Van't Hoff equation. The improved hydrogen storage properties of the as-prepared composites are mainly attributed to the uniformly distributed LaH3, Mg2Ni and TiH2 phases, which provide a large amount of phase boundaries, diffusion paths and nucleation sites for de-/hydrogenation reactions.Graphical abstractImage 1
  • Methods for measuring the effective thermal conductivity of metal hydride
           beds: A review
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Wenli Zhao, Yi Yang, Zewei Bao, Dong Yan, Zezhi Zhu The effective thermal conductivity of metal hydride beds is a crucial parameter for metal hydride reactor design. In this review, methods and principles for the measurement of the effective thermal conductivity of metal hydride beds are discussed, including steady-state techniques (the radial heat flow, comparative cut bar, guarded heat flow meter, and guarded hot plate methods) and transient techniques (the hot-wire, thermal probe, transient plane source, and laser flash methods). Reports of effective thermal conductivity measurements for characterizing metal hydride beds have been reviewed, including the measurement methods, material composition, measurement results, temperature, and gas pressure. The advantages, disadvantages, and applications of each measurement method have been presented, and an assessment regarding different techniques of measurement has been conducted. Laser flash and transient plane source are found to be the most frequently used methods, and have been increasingly applied in recent years. Finally, a brief discussion of recommended future development of effective thermal conductivity measurement is presented.
  • Comparing exergy losses and evaluating the potential of catalyst-filled
           plate-fin and spiral-wound heat exchangers in a large-scale Claude
           hydrogen liquefaction process
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Geir Skaugen, David Berstad, Øivind Wilhelmsen Detailed heat exchanger designs are determined by matching intermediate temperatures in a large-scale Claude refrigeration process for liquefaction of hydrogen with a capacity of 125 tons/day. A comparison is made of catalyst filled plate-fin and spiral-wound heat exchangers by use of a flexible and robust modeling framework for multi-stream heat exchangers that incorporates conversion of ortho-to para-hydrogen in the hydrogen feed stream, accurate thermophysical models and a distributed resolution of all streams and wall temperatures. Maps of the local exergy destruction in the heat exchangers are presented, which enable the identification of several avenues to improve their performances.The heat exchanger duties vary between 1 and 31 MW and their second law energy efficiencies vary between 72.3% and 96.6%. Due to geometrical constraints imposed by the heat exchanger manufacturers, it is necessary to employ between one to four parallel plate-fin heat exchanger modules, while it is possible to use single modules in series for the spiral-wound heat exchangers. Due to the lower surface density and heat transfer coefficients in the spiral-wound heat exchangers, their weights are 2–14 times higher than those of the plate-fin heat exchangers.In the first heat exchanger, hydrogen feed gas is cooled from ambient temperature to about 120 K by use of a single mixed refrigerant cycle. Here, most of the exergy destruction occurs when the high-pressure mixed refrigerant enters the single-phase regime. A dual mixed refrigerant or a cascade process holds the potential to remove a large part of this exergy destruction and improve the efficiency. In many of the heat exchangers, uneven local exergy destruction reveals a potential for further optimization of geometrical parameters, in combination with process parameters and constraints.The framework presented makes it possible to compare different sources of exergy destruction on equal terms and enables a qualified specification on the maximum allowed pressure drops in the streams. The mole fraction of para-hydrogen is significantly closer to the equilibrium composition through the entire process for the spiral-wound heat exchangers due to the longer residence time. This reduces the exergy destruction from the conversion of ortho-hydrogen and results in a higher outlet mole fraction of para-hydrogen from the process.Because of the higher surface densities of the plate-fin heat exchangers, they are the preferred technology for hydrogen liquefaction, unless a higher conversion to heat exchange ratio is desired.Graphical abstractImage 1
  • Evaluation of sorbents for high temperature removal of tars, hydrogen
           sulphide, hydrogen chloride and ammonia from biomass-derived syngas by
           using Aspen Plus
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Vera Marcantonio, Enrico Bocci, Jan Pieter Ouweltjes, Luca Del Zotto, Danilo Monarca Biomass gasification is a promising technology to produce secondary fuels or heat and power, offering considerable advantages over fossil fuels. An important aspect in the usage of producer gas is the removal of harmful contaminants from the raw syngas. Thus, the object of this study is the development of a simulation model for a gasifier including gas clean-up, for which a fluidized-bed gasifier for biomass-derived syngas production was considered, based on a quasi-equilibrium approach through Gibbs free energy minimisation, and including an innovative hot gas cleaning, constituted by a combination of catalyst sorbents inside the gasification reactor, catalysts in the freeboard and subsequent sorbent reactors, by using Aspen Plus software. The gas cleaning chain simulates the raw syngas clean-up for several organic and inorganic contaminants, i.e. toluene, benzene, naphthalene, hydrogen sulphide, hydrogen chloride and ammonia. The tar and inorganic contaminants final values achieved are under 1 g/Nm3 and 1 ppm respectively.
  • CuO–CeO2/SiO2 coating on ceramic monolith: Effect of the nature of the
           catalyst support on CO preferential oxidation in a H2-rich stream
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Inés S. Tiscornia, Albano M. Lacoste, Leticia E. Gómez, Alicia V. Boix Powder and structured catalysts based on CuO–CeO2 nanoparticles dispersed on different silica are studied in CO preferential oxidation. Silica of natural origin (Celite) and fumed silica (aerosil), both commercial materials, and synthesized mesoporous SBA-15 with 20, 200 and 650 m2g-1 respectively, are selected as supports. CuCe/Celite coated on cordierite monolith displays the highest activity, reaching CO conversion above 90% between 140 and 210 °C and more than 99% around 160 °C. The addition of 10% CO2 and 10% H2O partially deactivates the monolithic catalyst.The lower surface area of CuCe/Celite favors the contact between CuO and CeO2 nanoparticles promoting a better interaction of Cu+2/Cu+ and Ce+3/Ce+4 redox couples. Raman spectroscopy reveals oxygen vacancies and XPS results show high metal lattice surface oxygen concentration and surface enrichment of Cu and Ce which promote the catalytic activity.Graphical abstractImage 1
  • N-doped bamboo-like CNTs combined with CoFe–CoFe2O4 as a highly
           efficient electrocatalyst towards oxygen evolution
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Deyao Xu, Beibei Liu, Guiyu Liu, Kanda Su, Chunming Yang, Haixia Tong, Dong Qian, Junhua Li In this work, we developed a novel hybrid with N-doped bamboo-like carbon nanotubes combined with the CoFe alloy and its oxide (denoted as CoFe–CoFe2O4/N-CNTs) via an extremely facile one-step pyrolysis method. When applied as an electrocatalyst towards OER in 1.0 M KOH solution, CoFe–CoFe2O4/N-CNTs exhibits a small overpotential of 334 mV to afford a current density of 10 mA cm−2 associated with a low Tafel slope of 80 mV dec−1 and long-term stability. The remarkable OER electrocatalytic performance of CoFe–CoFe2O4/N-CNTs is mainly attributed to the synergistic effect between CoFe and CoFe2O4 as well as the increased active sites resulting from the introduction of N-CNTs. More impressively, the introduction of Fe can significantly cut down the usage of relatively toxic and expensive Co accompanied with the dramatic enhancement of OER electrocatalytic performance originating from the robust synergistic effect between Co and Fe.
  • Synthesis of Zn(In x Ga1-x )2O4 solid-solutions with tunable band-gaps for
           enhanced photocatalytic hydrogen evolution under solar-light irradiation
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Qiaoqi Li, Lili Zhang, Chao Tang, Pusu Zhao, Chengzhu Yin, Jingzhou Yin The systematic investigation of In3+ ions doped ZnGa2O4 applying to photocatalytic H2 evolution (PHE) under simulated solar-light irradiation was first reported here. A series of Zn(InxGa1-x)2O4 (x = 0 to 0.4) solid-solutions were obtained by sol-gel method and characterized by XRD, SEM, elemental mapping, XPS, UV–Vis DRS and N2 adsorption measures. The concentration of In3+ ions remarkably enhanced the light-harvesting capability of Zn(InxGa1-x)2O4 solid-solutions in the visible-light region, and successfully regulated the positions of the CB-bottom potential, ultimately improving the photocatalytic capabilities under simulated solar-light irradiation. Among composites containing different In3+ ions dosages, Zn(In0.1Ga0.9)2O4 demonstrated the most excellent photocatalytic capability for solar-light-driven PHE reaction (H2: 240.6 μmol/h/g), in which the stability of the Zn(In0.1Ga0.9)2O4 was confirmed by several techniques.Graphical abstractImage 1
  • Preparation of mesoporous nanostructure NiO–MgO–SiO2 catalysts for
           syngas production via propane steam reforming
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): F. Barzegari, M. Kazemeini, F. Farhadi, M. Rezaei, A. Keshavarz In this research, the propane steam reforming (PSR) as a promising alternative route over a mesoporous NiO–MgO–SiO2 catalyst to produce syngas (SG) was undertaken. This catalyst was prepared using a co-precipitation method followed by hydrothermal treatment. The influence of such catalyst preparation factors as the hydrothermal time and temperature, pH and calcination temperature on the physicochemical characteristics of the prepared samples were examined. Next, these materials were characterized through the BET-BJH, XRD, TPR, and FTIR analyses. The thermal stability of this catalyst was tested through the TGA and DTA techniques. Furthermore, the deactivation of the calcined catalysts at different temperatures was investigated via the TPO analysis. The utilized synthesis method led to preparation of a species with a mesoporous structure possessing a rather high surface area of 741 m2g-1. The catalyst performance at a reaction temperature of 550 °C revealed that, the increment in calcination temperature from 500 to 800 °C led to lowering of the propane conversion as well as the hydrogen yield from 65 to 37.4% and 39.4 to 22.6%, respectively. Meanwhile, the extent of the deposited coke upon the catalyst surface was reduced when implementing the higher calcination temperature. This was attributed to high amounts of the NiO, which was included in the solid solution containing the MgO–SiO2 support. In other words, the isolation of Ni2+ with Mg2+ species and strong interaction between NiO and MgO decreased the NiO particle size hence, its reducibility. These in turn led to the formation of smaller active sites possessing higher deactivation resistance against sintering and coke deposition. Thus, a highly active and stable catalyst was developed.
  • A three-dimensional and porous bi-nanospheres electrocatalytic system
           constructed by in situ generation of Ru nanoclusters inside and outside
           polydopamine nanoparticles for highly efficient hydrogen evolution
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Jintao Cai, Tao Chen, Liang Cui, Qiang Jia, Maosheng Liu, Rongkun Zheng, Guowen Yan, Di Wei, Jingquan Liu Catalytic systems based on nanospheres usually show satisfied catalytic activities due to their huge specific surface areas for active sites immobilization. However, their catalytic activities are usually restricted by the absence of active sites inside the nanospheres and the inadequate communications between the interior and exterior of the nanospheres. Therefore, it can be anticipated that great improvement will be achieved if a porous three-dimensional catalytic system can be designed, through which the activity sites can be distribute interior and exterior. Herein, polydopamine (PDA) NPs with uniform sizes of 300 nm are prepared. Then, the Ru nanoclusters (Ru NCs) are uniformly generated inside and on the surface of the PDA NPs to afford the bi-nanospheres (Ru-PDA NPs). After annealing, the porous carbonized Ru-PDA NPs (Ru-cPDA-750 NPs) with electroactive nitrogen atoms are finally obtained, exhibiting small overpotential (42 mV at the current density of 10 mA cm−2), low value of Tafel slope (35 mV decade−1) and robust stability for hydrogen evolution reaction (HER), which are comparable to that of Pt/C catalyst. Moreover, the study on the effect of Ru NCs amount on electrocatalytic ability reveals that Ru-cPDA NPs loaded with 0.08 wt% of Ru NCs exhibit the best HER catalytic performance compared with the Ru-cPDA NPs loaded with other amount of Ru NCs (0.04–0.16 wt%).Graphical abstractPolydopamine nanoparticles (PDA NPs) were obtained by self-polymerization of dopamine and used as the porous framework to load nanoclusters (Ru NCs) either inside or outside for all-around generation of hydrogen. The catalytic system exhibited low overpotential, low value of Tafel slope, robust stability, and low cost for hydrogen evolution reaction, which are comparable to that of Pt/C catalyst.Image 1
  • Electrodeposited Ni–Co–S nanosheets on nickel foam as
           bioelectrochemical cathodes for efficient H2 evolution
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Ling Wang, Wenzong Liu, Thangavel Sangeetha, Zechong Guo, Zhangwei He, Chuan Chen, Lei Gao, Aijie Wang High overpotential and soaring prices of the cathode electrode are the bottlenecks for the development of microbial electrolysis technology for hydrogen production. In this study, a novel one-step electrodeposition method has been attempted to fabricate electrodeposited cathodes in situ growth of Ni–Co–S, Ni–S, Co–S catalyst on nickel foam (NF) to reduce the overpotential of electrodes. Finally, a uniform nanosheet with a high specific surface area and more active sites is formed on the NF surface, resulting in a lower overpotential than plain NF. At 0.8 V, the Co–S/NF cathode produces a favorable 42% increase in hydrogen yield (0.68 m3·m−3·d−1), 40% upsurge in current density (10.6 mA/cm3) and 39% rise of cathodic recovery rate (58.0 ± 3.2%) than bare NF, followed by Ni–Co–S/NF and Ni–S/NF cathode. All the electrodeposited electrodes demonstrate enhanced current density and reduced electron losses, thereby achieving efficient hydrogen production. These innovative varieties of electrodes are highly advantageous as they are relatively inexpensive and easy to manufacture with great potential in reducing costs and further real time application in large scale.
  • Ni2P as an electron donor stabilizing Pt for highly efficient
           isopropanol fuel cell
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Dan Chai, Xiongwen Zhang, Shicheng Yan, Guojun Li A key challenge for isopropanol fuel cell is to find efficient catalyst for the catalytic ability improvement of isopropanol electro-oxidation reaction. Here, we anchor Pt nanoparticles on the Ni2P/resin carbon (RC) to form a Pt–Ni2P/RC assembly. Strong interactions at Ni2P–Pt interface induce the Ni2P to donate electrons to stabilize Pt, thus effectively decreasing the adsorbed energy of isopropanol. As a result, Pt–Ni2P/RC exhibits much higher mass activity and better stability than those of Pt/RC and Pt/C. When assembled into a direct isopropanol fuel cell, Pt–Ni2P/RC shows a peak power density of 0.095 W cm−2, which is 31.9% greater than that of Pt/C catalyst. Our results offer a new strategy to stabilize Pt by an electron donor for developing affordable direct isopropanol fuel cells.Graphical abstractImage 1
  • A derivative of mesoporous oxygen reduction reaction electrocatalysts from
           citric acid and dicyandiamide
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Lin Li, Shuiyun Shen, Xiaolin Li, Liuxuan Luo, Guanghua Wei, Junliang Zhang It remains urgent to make continuous efforts on well-designed and highly active non-precious metal (NPM) electrocatalysts for the cathodic oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs), thus helping greatly reduce the fuel cell cost. Due to an unsatisfied stability caused by Fenton reaction for Fe-based materials, Co-based materials bear much more expectations as one type of NPM electrocatalysts to be applied in the ORR. Here we report a novel strategy to synthesize a series of mesoporous nitrogen-doped carbon-supported cobalt electrocatalysts (Co-DCD-CA), which takes full advantage of electrostatic interaction between carboxyl in citric acid (CA) and amidogen in dicyandiamide (DCD) as well as chelating interaction between citric acid and cobalt cation. When CA is employed as carbon source, the optimal derivative of the Co-DCD-2-CA-900 electrocatalyst exhibits a higher ORR activity with a half-wave potential at 0.75 V, which is 60 mV higher than that prepared using Ketjenblack EC 300 J (Co-DCD-2-EC-900) as the carbon support. Besides, the effects of pyrolysis temperature as well as DCD to CA ratio on the ORR activity are detailedly investigated.Graphical abstractImage 1
  • Biogas dry reforming over Ni-Al catalyst: Suppression of carbon deposition
           by catalyst preparation and activation
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Morgana Rosset, Liliana Amaral Féris, Oscar W. Perez-Lopez Biogas dry reforming is as an alternative renewable route for the hydrogen production. However, the major drawback of this process is the catalyst deactivation by carbon deposition and sintering. In this work, Ni-Al catalysts were studied aiming to suppress the carbon deposition in the dry reforming of biogas. The catalysts were prepared by coprecipitation and evaluated the washing step. The reactions were carried out with unreduced and reduced catalysts in a fixed bed tubular reactor using a synthetic biogas (60% CH4 and 40% CO2). The washing and activation steps influenced the characteristics of the catalysts and the catalytic properties in the biogas reforming. The unwashed sample resulted in an oxide containing potassium nickelate with high basicity and low surface area. Both washed samples, reduced and unreduced, showed a high amount of carbon formation, whereas no carbon formation was observed in the unwashed samples for the reactions in the temperature range of 500–750 °C. The unwashed and unreduced sample was the only one that maintained the activity during all the reaction time at 700 °C (40% CH4 conversion and 75% CO2 conversion), low coke amount and no evidence of sintering, which was confirmed by XRD, TPO, and SEM analyses. The carbon suppression was related to the nickelate phase and to the Ni carbide formation in the unwashed and unreduced catalyst. In summary, the carbon deposition in biogas dry reforming was completely controlled between 600 and 750 °C using the unwashed and unreduced Ni-Al catalyst.
  • Co–Ni alloy supported on CeO2 as a bimetallic catalyst
           for dry reforming of methane
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Yusan Turap, Iwei Wang, Tiantian Fu, Yongming Wu, Yidi Wang, Wei Wang Dry reforming of methane (DRM) is an effective route to convert two major greenhouse gas (CH4 and CO2) to syngas (H2 and CO). Herein, in this work, monometallic Ni/CeO2 and a series of bimetallic Co–Ni/CeO2 catalysts with Co/Ni ratios between 0 and 1.0 have been tested for DRM process at 600–850 °C, atmospheric pressure and a CH4/CO2 ratio of 1. The catalysts were characterized by X-ray diffraction, hydrogen-temperature programmed reduction, CO2-Temperature programmed desorption, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The catalyst with a Co/Ni ratio of 0.8 (labeled as 0.8 Co–Ni/CeO2) exhibited the highest catalytic activity (CH4 and CO2 initial conversion for 80% and 85% at 800 °C, respectively) and the highest stability (less carbon deposition after 600min). This improved activity can be attributed to the Co–Ni alloy, which formed after reduction. Its weak chemisorption with hydrogen results in inhibition of reverse water gas shift reaction. In addition, Co-promoted the adsorption of surface oxygen enhances carbon removal, making it more stable.Graphical abstractImage 1
  • Mn3O4 nanosheets coated on carbon nanotubes as efficient electrocatalysts
           for oxygen reduction reaction
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Yan Zhang, Yanhui Wang, Junjie Huang, Chan Han, Jianbing Zang MnO-MnCx coated carbon nanotubes (MnO/MnCx/CNTs) nanocomposites were prepared by a one-pot deposition method. The coating consisted of MnO, Mn5C2, Mn15C4 and Mn23C6 was formed on the surface of CNTs by heating a mixture of Mn particles and CNTs at 600 °C for 40 min under vacuum. Then after heated MnO/MnCx/CNTs in air at 350 °C for 2 h, MnO nanoparticles were partially converted to Mn3O4 nanosheets. Then Mn3O4-MnCx coated carbon nanotubes (Mn3O4/MnCx/CNTs) composed of interconnected nanosheets structure were successfully synthesized by a two-step method of one-pot deposition and heat post-treatment. The Mn3O4/MnCx/CNTs showed better oxygen reduction reaction performance in alkaline condition than MnO/MnCx/CNTs and pristine CNTs. Besides, the formed MnCx (Mn5C2 and Mn23C6) by one-pot deposition method provided a strong interface bonding between Mn3O4 and CNTs, leading to improved stability of Mn3O4/MnCx/CNTs as an electrode material.Graphical abstractImage 1
  • Ultrathin MoSe2 three-dimensional nanospheres as high carriers
           transmission channel and full spectrum harvester toward excellent
           photocatalytic and photoelectrochemical performance
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Jun Zhang, Penghui Tian, Tao Tang, Guozhou Huang, Xuan Chen, Jinghui Zeng, Bo Cui, Zhe Kong, Hongbo Wang, Junhua Xi, Zhenguo Ji MoSe2 ultrathin nanospheres with three-dimensional network structure (MSS) were prepared by improved solvothermal method. These MoSe2 nanospheres are only 10 nm in size and actually composed of ultra-thin MoSe2 nanosheets with a thickness of only 2–3 molecular layers. Compared with the MoSe2 nanosheets (6–8 molecular layer thicknesses) of the three-dimensional flower structure (MSF) prepared by ordinary hydrothermal method, the MSS are thinner resulting in higher specific surface area of 5 times than that of MSF, and the light absorption ability at all UV–vis spectrum is stronger. The photocatalytic and photoelectrochemistry results show that the photocatalytic activity of MSS is 17 times that of the MSF, and the photoelectrochemical performance is twice. The results of electrochemical impedance spectroscopy and fluorescence spectroscopy confirmed that the MoSe2 ultra-thin nanospheres with three-dimensional network structure have lower internal resistance and higher carrier transport and separation efficiency. In the most important three aspects that determine the photoelectrochemical performance of photocatalyst: specific surface area, light absorption capacity, carrier transport and separation efficiency, MSS exceed MSF. This three-dimensional network nanospheres structure can improve the performance of MoSe2. This research successfully demonstrates the enhancement of the properties of MoSe2 two-dimensional materials through structural regulation.Graphical abstractUltrathin MoSe2 three-dimensional nanospheres show excellent photocatalytic and photoelectrochemical performance.Image 1
  • Fabrication of antennae-like nanoheterostructure attached by porphyrin for
           increased photocatalytic hydrogen generation and electron transfer
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Peilin Wang, Mengya Xi, Shi-Zhao Kang, Lixia Qin, Sheng Han, Xiangqing Li In order to obtain a highly efficient photocatalyst for hydrogen evolution, an excellent photo active molecule, tetra (p-carboxylphenyl) porphyrin (TCPP) was introduced and orientedly attached on an antennae-like Cu2O/NiO heterostructure. Subsequently, heterogeneous Cu2O/NiO/TCPP nanocomposites were achieved. Assembly mechanism of the nanocomposites was investigated in detail. The results showed that, by coordination interaction and hydrogen bond, TCPP molecules can be strongly assembled onto the NiO-riveted Cu2O. Because of strong interaction among Cu2O, NiO and TCPP, and the enhanced light absorption, quick transfer of more photo-generated electrons can be achieved. Furthermore, the nanocomposite displayed a higher photocatalytic activity compared with other contrast materials (Cu2O/NiO/NiTCPP, Cu2O/NiO, Cu2O et al.). It was attributed to the improved separation of charges as well as light absorption, which was originated from the well-matched band structure and special heterogeneous interface. This study will open up new perspectives for the fabrication and application of heterojunction photocatalysts.Graphical abstractControllable fabrication of antennae-like Cu2O/NiO nanoheterostructure attached by porphyrin was achieved for increased photocatalytic hydrogen generation and electron transfer. More absorption and increased separation of electrons and holes made the nanocomposites show higher activity. Moreover, the species with low valence state in the nanocomposite had more positive effect on the activity.Image 1
  • Interfaces engineering of MoNi-based sulfides electrocatalysts for
           hydrogen evolution reaction in both acid and alkaline media
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Yan Xie, Yuanwei Liu, Zhongnian Yang Searching for efficiently noble-metal-free hydrogen evolution catalysts is critical to the development of hydrogen energy. In this work, we report an in-situ growing defect-rich heterointerfaces structure MoNi-based sulfides on carbon cloth via a facile and controllable hydrothermal process. The interface structure in MoNiS@NiS/CC can not only provide suffcient channel for transportation of electrolyte, but also release of produced gases in the catalytic process, thence enhance the sluggish hydrogen evolution efficiency. Furthermore, the defects in MoNiS@NiS/CC have significant impacts on hydrogen evolution behavior. Therefore, the as-synthesied MoNiS@NiS/CC shows a low overpotential of 33 mV to deliver a current density of 10 mAcm−2 and a small tafel slope of 80 mVdec−1, and also exhibits an excellent long-term stability in 0.5 M H2SO4. Additionaly, the MoNiS@NiS/CC offers outstanding hydrogen evolution reaction performances in 1 M KOH.
  • Design of efficient Mn-doped α-Fe2O3/Ti-doped α-Fe2O3 homojunction for
           catalyzing photoelectrochemical water splitting
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Shang-Mao Tao, Lu-Yin Lin To produce clean chemical fuel of hydrogen efficiently, applying photocatalysts for conducting photoelectrochemical water splitting is indispensable. Hematite (α-Fe2O3) has been considered as one of the most effective photocatalysts for water oxidation due to excellent visible-light responses, high stability and source abundance properties, but low electrical conductivity and slow oxidation evolution kinetics limit its application. In this study, a novel α-Fe2O3 homojunction is constructed via doping Ti and Mn in two layers using two-step hydrothermal synthesis followed by one-step annealing process. Co-doping effect of Ti and Mn in α-Fe2O3 and growing sequence of Mn doped α-Fe2O3 (Mn:Fe2O3) and Ti doped α-Fe2O3 (Ti:Fe2O3) are also investigated to illustrate the efficient design of Mn:Fe2O3/Ti:Fe2O3 homojunction. The optimized Mn:Fe2O3/Ti:Fe2O3 electrode shows the highest photocurrent density of 2.10 mA/cm2 at 1.60 VRHE respectively comparing to those of 0.10, 1.20 and 0.22 mA/cm2 for Ti:FeOOH, Ti:Fe2O3 and α-Fe2O3 electrodes. The outstanding performance of Mn:Fe2O3/Ti:Fe2O3 homojunction is attributed to the smaller charge-transfer resistance, higher carrier density, and less charge recombination. This work gives a rational design for hematite-based photocatalysts and successfully attains greatly improved photocatalytic ability for water oxidation. Development of homojunction using heteroatom doping in thus verified to be highly applicable on synthesizing promising photocatalysts.Graphical abstractImage 1
  • Enhanced H2 evolution and the interfacial electron transfer mechanism of
           titanate nanotube sensitized with CdS quantum dots and graphene quantum
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Jiayan Xue, Lizhen Long, Lin Zhang, Hongtian Luo, Li Yang, Fuchi Liu, Fengzhen Lv, Wenjie Kong, Jun Liu Synergistic the modulation of photon absorption capability and interfacial charge transfer of the photocatalyst are highly required for developing high-performance heterojunction photocatalysts. The ternary CdS-graphene quantum dots-titanate nanotubes (CdS-GQDs-TNTs) nanocomposite have been prepared by an in situ growth method. The physicochemical characterization reveals that the GQDs are firmly decorated on both inner and outer surface of TNT through the formation of Ti–O–C chemical bonding, and CdS QDs are loaded on the outer surface of TNTs through strong interfacial interaction. The intimate integrated CdS-GQDs-TNTs nanocomposite exhibits much superior photocatalytic performance toward H2 production compared with binary GQDs-TNTs and pure TNTs photocatalyst, which can be attributed to the combined interaction of the stronger visible light harvesting, the longer lifetime of photogenerated electron−hole pairs, faster interfacial charge transfer rate, fast and long-distance electron transport pass. The interfacial charge transfer mechanism of CdS-GQDs-TNTs ternary composite are proposed based on photoelectrochemical measurements.
  • Hybrid niobium and titanium nitride nanotube arrays implanted with
           nanosized amorphous rhenium–nickel: An advanced catalyst electrode for
           hydrogen evolution reactions
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Huibin Zhang, Xuanhan Chen, Zhimao Lin, Liqiang Zhang, Huazhen Cao, Linping Yu, Guoqu Zheng The scalable application of high-performance electrocatalysts with fine nanostructures for hydrogen evolution reactions (HER) depends on the development of durable and active electrode supports. Transition metal nitrides are considered as candidates due to their high conductivity, favorable catalytic activity, and excellent chemical stability in acidic or alkaline aqueous solutions. The present work proposed to fabricate self-ordered hybrid niobium–titanium (Nb–Ti) nitride nanotube arrays (NNAs) on Nb–Ti alloy panels by an anodization and subsequent nitridation process. Results showed that the highly ordered NNA is composed of mixed Nb4N5 and TiN and has merits of super hydrophilicity, outstanding corrosion resistance, and high conductivity. On the basis of the successful synthesis of Nb–Ti NNA, the nano–sized amorphous rhenium–nickel (Re–Ni) alloy was electrodeposited onto the NNA support, forming the Re–Ni/NNA composite electrode. Electrochemical tests exhibited that the Re–Ni/NNA composite electrode can provide a current density of 50 mA cm−2 in 1.0 M KOH at a potential of −0.18 V vs. RHE and maintain stability in a testing period of 100 h. This superior HER performance is attributed to the combination of Re–Ni particles and Nb–Ti NNA support, which can benefit the diminution of charge transfer resistance and the improvement of catalytic activity.Graphical abstractImage 1
  • Highly efficient methanol oxidation on durable PtxIr/MWCNT catalysts for
           direct methanol fuel cell applications
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Narayanamoorthy Bhuvanendran, Sabarinathan Ravichandran, Weiqi Zhang, Qiang Ma, Qian Xu, Lindiwe Khotseng, Huaneng Su Development of highly active and durable Pt based anode materials with higher utilization of Pt is quite crucial towards the commercial viability of direct methanol fuel cells (DMFCs). Herein, multi-walled carbon nanotube supported PtxIr nanostructures (PtxIr/MWCNT) are successfully prepared by one-pot wet chemical reduction without any surfactants. The role of Ir content and its bi-functional mechanism on kinetics of methanol oxidation reaction (MOR) was studied. The MOR on PtxIr/MWCNT follows Langmuir-Hinshelwood mechanism by successive oxidative removal of CO. The co-existence of IrO2 plays a vital role as catalytic promotor. Amongst, Pt2Ir/MWCNT shows enhanced electrocatalytic activity (mass activity (MA), 933.3 mA/mgPt) and durability (13.8% loss of MA after 5000 potential cycles) thru the well-balanced electronic and bi-functional effects. This study implies that the optimized composition of Pt2Ir/MWCNT exhibits efficient methanol oxidation and could be a potential catalyst for direct methanol fuel cells.Graphical abstractImage 1
  • Design and facile one-pot synthesis of uniform PdAg cubic nanocages as
           efficient electrocatalyst for the oxygen reduction reaction
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Jian Ju, Xiaodan Wang, Chunmei zhang, Wei Chen Shape-controlled synthesis of multicomponent metallic nano-alloy materials is of great significance for the design and preparation of high-efficiency electrocatalysts. In this work, a simplified one-pot synthetic strategy for the preparation of uniform three-dimensional (3D) PdAg cubic nanocages (PdAg–CNC) was developed. The morphology and structure of PdAg–CNC were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). We elucidate a series of reaction pathways for the formation of various morphologies (sphere, cubic nanocage and nanowire) of PdAg alloys by tuning the amount of glycine and controlling the Pd/Ag molar ratio. The PdAg–CNC shows enhanced electrocatalytic activity, good durability and excellent methanol tolerance in comparison with commercial Pd–C and Pt–C catalysts for the oxygen reduction reaction (ORR) in alkaline medium. The excellent ORR performance of the PdAg–CNC can be correlated to the Pd–Ag alloy formation and unique mesoporous nanocage structure. This work demonstrates a facile strategy for shape-controlled synthesis of multicomponent metallic nano-alloys materials and their catalytic application.Graphical abstractImage 1
  • Rapid polymerization synthesizing high-crystalline g-C3N4 towards boosting
           solar photocatalytic H2 generation
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Longyan Wang, Yuanzhi Hong, Enli Liu, Zhiguo Wang, Jiahui Chen, Shuang Yang, Jingbo Wang, Xue Lin, Junyou Shi Graphitic carbon nitride (g-C3N4) is a promising metal-free photocatalyst for solar photocatalytic hydrogen gas (H2) generation from water. In particularly, high-crystalline g-C3N4 (GCN-HC) material with fewer structural defects possesses the fast photoexcited electron-hole pair's separation efficiency as comparison with bulk g-C3N4 (GCN-B) powders, leading to the drastic improvement of photocatalytic activity. However, the fabrication of such GCN-HC photocatalyst by a simple and economical synthesis approach still remains a challenge. Herein, we firstly develop a one-step rapid polymerization strategy for synthesizing the GCN-HC, that is direct calcination of melamine at 550 °C not only without the early heating process, but also without the assistance of any additive or salt intercalation. As a result, the GCN-HC exhibits an obviously boosting visible-light-induced photocatalytic H2-generation performance, which is over 2.06-folds much greater than that of GCN-B. Our work provides an available one-step synthetic strategy for the large-scale preparation of high performance GCN-HC towards sustainable solar-to-chemical energy conversion.Graphical abstractImage 1
  • Autologous growth of Fe-doped Ni(OH)2 nanosheets with low overpotential
           for oxygen evolution reaction
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Peican Wang, Yuqun Lin, Lei Wan, Baoguo Wang Highly active and durable electrocatalysts for oxygen evolution reaction (OER) play a vital role in water splitting. Despite numerous efforts, the strategies to prepare durable and effective electrocatalysts via scalable methods still remain a great challenge. In this work, we fabricated Fe-doped Ni(OH)2 ultrathin nanosheets (Fe–Ni–OH/Ni) via autologous growing of Ni(OH)2 from Ni foam, and in situ electrochemical-assisted doping Fe into Ni(OH)2. Benefiting from the unique structure with large surface areas and strong coupling effects between Fe and Ni, the optimal Fe–Ni–OH electrodes exhibit remarkable catalytic performance toward OER, which requires an overpotential of 220 mV to achieve a current density of 10 mA cm−2 with a Tafel slope of 48.3 mV dec−1. The Fe–Ni–OH electrodes also possess high stability even under a high current density of 500 mA cm−2 for 600 h with an ultralow overpotential of 290 mV. Using Ni–Fe–OH electrodes as both anode and cathode for overall water splitting, only a small overpotential of 1.57 V is required to reach a current density of 10 mA cm−2. Moreover, the high catalytic performance and scalable preparation method can meet the emergency needs for the practical application.Graphical abstractImage 1
  • High-efficiency Co6W6C catalyst with three-dimensional ginger-like
           morphology for promoting the hydrogen and oxygen evolution reactions
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Shufang Cui, Austin Chipojola Mtukula, Xiangjie Bo, Liping Guo Development of electrocatalysts composed of low cost and abundant elements that exhibit catalytic activity comparable to noble metals is important for water splitting. As such, in this study, a catalyst material with a ginger-like morphology consisting of Co6W6C is synthesized via a hydrothermal reaction and pyrolysis treatment. The Co6W6C catalyst exhibits satisfactory electrochemical properties towards both hydrogen and oxygen evolution reactions in an alkaline electrolyte, with a low overpotential, low Tafel slope, and durable stability. Co6W6C possesses a high activity for the hydrogen evolution reaction in alkaline conditions, with an onset potential and overpotential of −0.024 V and 101 mV, respectively, and low Tafel slope of 80.5 mV dec−1 at a current density of 10 mA cm−2. In addition, Co6W6C achieves a current density of 10 mA cm−2 for the oxygen evolution reaction at an overpotential of only 343 mV. Furthermore, electrochemical stability tests indicate that the Co6W6C catalyst maintains 91% of the original current after 60,000 s for the hydrogen evolution reaction and 95% of the original current after 45,000 s for the oxygen evolution reaction. Moreover, electrochemical splitting of water via a two-electrode system employing this catalyst can hold 89% of the initial current after 40,000 s in 1 M KOH.Graphical abstractImage 1
  • Effect of cation substitution in MnCo2O4 spinel anchored over rGO for
           enhancing the electrocatalytic activity towards oxygen evolution reaction
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): A. Rebekah, E. Ashok Kumar, C. Viswanathan, N. Ponpandian Developing an efficient and durable electrocatalyst for catalyzing oxygen evolution reaction in electrochemical water splitting application is greatly desired and challenging. Herein, a simple and facile strategy was followed to prepare Ni-substituted MnCo2O4/rGO nanocomposite as an electrocatalyst for oxygen evolution reaction (OER). The structural and morphological analyses show the successful bonding between spinel-carbon hybrid. Nickel substitution and addition of rGO disclose a drastic change in the catalytic activity of the same towards OER. Among all the electrocatalysts, Mn1-xNixCo2O4/rGO with x = 0.6 exhibits low overpotential of 250 and 290 mV for attaining the current density of 10 mA/cm2 before and after potential cycling respectively. It also exhibits low onset potential of 1.48 V with a Tafel slope of value 78 mV/dec. The electrocatalyst also shows excellent stability, high ECSA and roughness factor (Rf) which are responsible for enhanced OER performance. These properties confirm that the present hybrid material would be an excellent electrocatalyst for catalyzing OER for hydrogen energy production.Graphical abstractImage 1
  • Tuning morphology and structure of Fe–N–C catalyst for ultra-high
           oxygen reduction reaction activity
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Yanping Huang, Weifang Liu, Shuting Kan, Penggao Liu, Rui Hao, Hang Hu, Jian Zhang, Hongtao Liu, Min Liu, Kaiyu Liu Exploring efficient and durable non-precious metal catalysts for oxygen reduction reaction (ORR) has long been pursued in the field of metal-air batteries, fuel cells, and solar cells. Rational design and controllable synthesis of desirable catalysts are still a great challenge. In this work, a novel approach is developed to tune the morphologies and structures of Fe–N–C catalysts in combination with the dual nitrogen-containing carbon precursors and the gas-foaming agent. The tailored Fe–N1/N2–C-A catalyst presents gauze-like porous nanosheets with uniformly dispersed tiny nanoparticles. Such architectures exhibit abundant Fe-Nx active sites and high-exposure surfaces. The Fe–N1/N2–C-A catalyst shows extremely high half-wave potential (E1/2, 0.916 V vs. RHE) and large limiting current density (6.3 mA cm−2), far beyond 20 wt% Pt/C catalyst for ORR. This work provides a facile morphological and structural regulation to increase the number and exposure of Fe-Nx active sites.Graphical abstractThe tailored Fe–N–C catalyst presents plentiful Fe-Nx active sites and highly exposed active surfaces, resulting in an ultra-high ORR activity far beyond the 20 wt% Pt/C catalyst.Image 1
  • First demonstration of photoelectrochemical water splitting by commercial
           W–Cu powder metallurgy parts converted to highly porous 3D WO3/W
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Majdoddin Mojaddami, Abdolreza Simchi Hydrogen evolution through photoelectrochemical (PEC) water splitting by tungsten oxide-based photoanodes, as a stable and environmental-friendly material with moderate band gap, has attracted significant interest in recent years. The performance of WO3 photoanode could be hindered by its poor oxygen evolution reaction kinetics and high charge carrier recombination rate. Additionally, scalable and cost-effective commercial procedure to prepare nanostructured electrodes is still challenging. We present, for the first time, a novel and scalable method to fabricate highly efficient self-supported WO3/W nanostructured photoanodes from commercial W–Cu powder metallurgy (P/M) parts for water splitting. The electrodes were prepared by electrochemical etching of Cu networks followed by hydrothermal growth of WO3 nanoflakes. Interconnected channels of W skeleton provided high active surface area for the growth of WO3 nanoflakes with a thickness of ~40 nm and lateral dimension of ~250 nm. The optimized photoelectrode having 35% interconnected porosity exhibited an impressive current density of 4.36 mA cm−2 comprising a remarkable photocurrent of 1.71 mA cm−2 at 1.23 V vs. RHE under 100 mW cm−2 simulated sunlight. This achievement is amongst the highest reported photocurrents for WO3 photoelectrodes with tungsten substrate reported so far. Impedance and Mott-Schottky analyses evidenced fast charge transfer, low recombination rate, and accelerated O2 detachment provided by optimum 3D porous WO3/W electrode. Due to the nature of the commercial P/M parts and low-temperature hydrothermal processing, the procedure is cost-effective and scalable which can pave a new route for the fabrication of highly porous and efficient water splitting electrodes.Graphical abstractImage 1
  • Phosphatized pseudo-core-shell Ni@Pt/C electrocatalysts for efficient
           hydrazine oxidation reaction
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Yahui Wang, Xianyi Liu, Juan Han, Yumao Kang, Yajun Mi, Wei Wang In this study, a series of phosphatized pseudo-core-shell Ni@Pt/C electrocatalysts has been obtained for efficient hydrazine oxidation reaction (HzOR). These (Ni@Pt–P/C) electrocatalysts were prepared by a primary replacement method followed by subsequent phosphating process. Among all Ni@Pt–P/C electrocatalysts, as-prepared Ni@Pt–P/C-400 electrocatalyst shows the highest HzOR performance (515 mA mg−1Pt), best stability, durability and lowest activation energy (12.60 kJ mol−1). The satisfactory HzOR performance is mainly resulted from the unique design of phosphating effect on core-shell structure which producing good synergistic effect between Ni, P and Pt. This work would pave a way for developing other low-Pt catalysts in the future.Graphical abstractNi@Pt–P/C-400 electrocatalyst with core-shell structure and P doped was obtained. Design of Ni@Pt–P/C-400 reduces mass and improves activity of Pt. It shows favorable electrocatalytic performance for hydrazine electrooxidation with higher current density, more lasting stability, durability and lower activation energy than that of commercial Pt/C.Image 1
  • The role of oxygen vacancies in the CO2 methanation employing Ni/ZrO2
           doped with Ca
    • Abstract: Publication date: 28 February 2020Source: International Journal of Hydrogen Energy, Volume 45, Issue 11Author(s): Oliver E. Everett, Priscila C. Zonetti, Odivaldo C. Alves, Roberto R. de Avillez, Lucia G. Appel The Ni/ZrO2 catalyst doped with Ca and Ni/ZrO2 were employed in the CO2 methanation, a reaction which will possibly be used for storing intermittent energy in the future. The catalysts were characterized by X-ray photoelectron spectroscopy (XPS, reduction in situ), X-ray diffraction (XRD, reduction in situ and Rietveld refinement), electron paramagnetic resonance (EPR), temperature-programmed surface reaction, cyclohexane dehydrogenation model reaction, temperature-programmed desorption of CO2 and chemical analysis. The catalytic behavior of these catalysts in the CO2 methanation was analyzed employing a conventional catalytic test. Adding Ca to Ni/ZrO2, the metallic surface area did not change whereas the CO2 consumption rate almost tripled. The XRD, XPS and EPR analyses showed that Ca+2 but also some Ni2+ are on the ZrO2 surface lattice of the Ni/CaZrO2 catalyst. These cations form pairs which are composed of oxygen vacancies and coordinatively unsaturated sites (cus). By increasing the number of these pairs, the CO2 methanation rate increases. Moreover, the number of active sites of the CO2 methanation rate limiting step (CO and/or formate species decomposition, rls) is enhanced as well, showing that the rls occurs on the vacancies-cus sites pairs.
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Heriot-Watt University
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