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Publisher: Elsevier   (Total: 3183 journals)

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Showing 1 - 200 of 3183 Journals sorted alphabetically
Academic Pediatrics     Hybrid Journal   (Followers: 38, SJR: 1.655, CiteScore: 2)
Academic Radiology     Hybrid Journal   (Followers: 26, SJR: 1.015, CiteScore: 2)
Accident Analysis & Prevention     Partially Free   (Followers: 102, SJR: 1.462, CiteScore: 3)
Accounting Forum     Hybrid Journal   (Followers: 28, SJR: 0.932, CiteScore: 2)
Accounting, Organizations and Society     Hybrid Journal   (Followers: 40, SJR: 1.771, CiteScore: 3)
Achievements in the Life Sciences     Open Access   (Followers: 7)
Acta Anaesthesiologica Taiwanica     Open Access   (Followers: 6)
Acta Astronautica     Hybrid Journal   (Followers: 436, SJR: 0.758, CiteScore: 2)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 2)
Acta Biomaterialia     Hybrid Journal   (Followers: 28, SJR: 1.967, CiteScore: 7)
Acta Colombiana de Cuidado Intensivo     Full-text available via subscription   (Followers: 3)
Acta de Investigación Psicológica     Open Access   (Followers: 3)
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: 312, 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: 1, SJR: 1.793, CiteScore: 6)
Acta Poética     Open Access   (Followers: 4, SJR: 0.101, CiteScore: 0)
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  
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: 11, SJR: 2.611, CiteScore: 8)
Additives for Polymers     Full-text available via subscription   (Followers: 23)
Advanced Drug Delivery Reviews     Hybrid Journal   (Followers: 183, SJR: 4.09, CiteScore: 13)
Advanced Engineering Informatics     Hybrid Journal   (Followers: 12, 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: 17, SJR: 2.384, CiteScore: 5)
Advances in Anesthesia     Full-text available via subscription   (Followers: 29, 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: 34, 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: 10, SJR: 1.316, CiteScore: 2)
Advances in Clinical Chemistry     Full-text available via subscription   (Followers: 26, SJR: 1.562, CiteScore: 3)
Advances in Colloid and Interface Science     Full-text available via subscription   (Followers: 20, SJR: 1.977, CiteScore: 8)
Advances in Computers     Full-text available via subscription   (Followers: 14, SJR: 0.205, CiteScore: 1)
Advances in Dermatology     Full-text available via subscription   (Followers: 15)
Advances in Developmental Biology     Full-text available via subscription   (Followers: 13)
Advances in Digestive Medicine     Open Access   (Followers: 12)
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: 43, SJR: 2.524, CiteScore: 4)
Advances in Engineering Software     Hybrid Journal   (Followers: 29, SJR: 1.159, CiteScore: 4)
Advances in Experimental Biology     Full-text available via subscription   (Followers: 8)
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: 1)
Advances in Fluorine Science     Full-text available via subscription   (Followers: 9)
Advances in Food and Nutrition Research     Full-text available via subscription   (Followers: 65, 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: 10, SJR: 12.74, CiteScore: 13)
Advances in Geophysics     Full-text available via subscription   (Followers: 7, 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: 25)
Advances in Imaging and Electron Physics     Full-text available via subscription   (Followers: 3, 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: 9, 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: 14, SJR: 3.027, CiteScore: 2)
Advances in Medical Sciences     Hybrid Journal   (Followers: 8, 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: 24)
Advances in Molecular and Cellular Endocrinology     Full-text available via subscription   (Followers: 8)
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 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: 5, 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: 9, 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: 67)
Advances in Quantum Chemistry     Full-text available via subscription   (Followers: 6, SJR: 0.371, CiteScore: 1)
Advances in Radiation Oncology     Open Access   (Followers: 1, 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: 6)
Advances in Space Research     Full-text available via subscription   (Followers: 421, SJR: 0.569, CiteScore: 2)
Advances in Structural Biology     Full-text available via subscription   (Followers: 5)
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: 37, 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: 53, SJR: 1.551, CiteScore: 3)
Aeolian Research     Hybrid Journal   (Followers: 6, SJR: 1.117, CiteScore: 3)
Aerospace Science and Technology     Hybrid Journal   (Followers: 384, 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: 475, 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: 31, SJR: 1.156, CiteScore: 4)
Agricultural Water Management     Hybrid Journal   (Followers: 44, 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: 10, SJR: 0.201, CiteScore: 1)
Alzheimer's & Dementia     Hybrid Journal   (Followers: 53, 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: 58, SJR: 3.267, CiteScore: 4)
American J. of Cardiology     Hybrid Journal   (Followers: 63, SJR: 1.93, CiteScore: 3)
American J. of Emergency Medicine     Hybrid Journal   (Followers: 46, SJR: 0.604, CiteScore: 1)
American J. of Geriatric Pharmacotherapy     Full-text available via subscription   (Followers: 12)
American J. of Geriatric Psychiatry     Hybrid Journal   (Followers: 14, SJR: 1.524, CiteScore: 3)
American J. of Human Genetics     Hybrid Journal   (Followers: 37, SJR: 7.45, CiteScore: 8)
American J. of Infection Control     Hybrid Journal   (Followers: 29, SJR: 1.062, CiteScore: 2)
American J. of Kidney Diseases     Hybrid Journal   (Followers: 36, SJR: 2.973, CiteScore: 4)
American J. of Medicine     Hybrid Journal   (Followers: 50)
American J. of Medicine Supplements     Full-text available via subscription   (Followers: 3, SJR: 1.967, CiteScore: 2)
American J. of Obstetrics and Gynecology     Hybrid Journal   (Followers: 255, SJR: 2.7, CiteScore: 4)
American J. of Ophthalmology     Hybrid Journal   (Followers: 66, 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: 28, 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: 66, SJR: 0.138, CiteScore: 0)
Anaesthesia Critical Care & Pain Medicine     Full-text available via subscription   (Followers: 24, 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: 5, 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: 209, 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)
Angiología     Full-text available via subscription   (SJR: 0.121, CiteScore: 0)
Angiologia e Cirurgia Vascular     Open Access   (Followers: 1, SJR: 0.111, CiteScore: 0)
Animal Behaviour     Hybrid Journal   (Followers: 223, SJR: 1.58, CiteScore: 3)
Animal Feed Science and Technology     Hybrid Journal   (Followers: 6, SJR: 0.937, CiteScore: 2)
Animal Reproduction Science     Hybrid Journal   (Followers: 7, SJR: 0.704, 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  [3183 journals]
  • New non-fluoridated hybrid proton exchange membranes based on commercial
           precursors
    • Abstract: Publication date: Available online 13 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Alexandra Chesnokova, Oksana V. Lebedeva, Ekaterina A. Malakhova, Tatiana V. Raskulova, Vaibhav Kulshrestha, Anton V. Kuzmin, Aleksandr S. Pozdnyakov, Yury N. Pozhidaev New hybrid proton conducting membranes based on sulfonated copolymers of styrene and allyl glycidyl ether using tetraethyl orthosilicate were syntheses. The composition and structure of the copolymers and membranes has been proven by elemental analysis, IR and NMR spectroscopy. Based on quantum chemical calculations a sulfonation mechanism of copolymers was proposed. The characteristics of membranes were evaluated by thermal analysis, dynamic mechanical analysis, electrochemical impedance spectroscopy, water uptake, swelling and ion exchange capacity tests. The hybrid membranes are characterized by high proton conductivity of 4.21 10−2 S cm−1 (70 °C, 75% RH), activation energy of proton transport (24.5 kJ mol−1), ion-exchange capacity (2.1 mmol g−1), and thermal stability up to 260°С. The hybrid membranes showed water uptake of 6 and 51% at 30 °C and 100 °C, respectively. The suitability of the hybrid membranes toward fuel cell applications was tested through a single cell analysis.Graphical abstractImage 1
       
  • First-principles study of oxygen reduction reaction on Pd-doped
           LaxSr1-xCoyFe1-yO3-δ cathodes of solid oxide fuel cells
    • Abstract: Publication date: Available online 13 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Mingrui Wei, Haizhao Li, Sheng Wu, Yun Wang, Guanlun Guo, Yihui Liu, Fuwu Yan, Dongju Zhang Surface adsorption, adissociation and bulk migration behaviors of oxygen species on Pd-doped LSCF (LSCF-Pd) cathode are investigated with first-principle method. Results show that Pd-doping reduces largely the formation energy of oxygen vacancy on LSCF-Pd surface. Oxygen adsorption abilities on LSCF and LSCF-Pd surfaces are comparable (1.30 vs 1.32 eV) with oxygen vacancies, while on perfect LSCF surface that is weakened by Pd-doping. The minimum dissociation energy barriers of oxygen molecules on LSCF and LSCF-Pd surface are 0.48 and 0.34 eV, respectively, which indicates that Pd-doping improves oxygen dissociation behaviors. Also, migration barriers of oxygen vacancy in LSCF-Pd bulk is comparable to that in LSCF bulk. The improved mechanisms can be attributed to the lowered formation energy of oxygen vacancy, oxygen dissiciation barriers of innate oxygen defect and migration barriers of oxygen vacancy in the bulk by Pd-doping.
       
  • ZnBi38O60/Bi2O3 photocathode for hydrogen production from water splitting
    • Abstract: Publication date: Available online 13 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Pedro Emílio Amador Salomão, Luele Ribeiro de Souza Barbosa, Tatiana Santos Andrade, Everson Junio da Cruz Ferreira, Márcio César Pereira Hydrogen production from water splitting into photoelectrochemical cells is a promising alternative for reducing the use of fossil fuels. Here, we synthesize by spray pyrolysis a porous ZnBi38O60/γ-Bi2O3 film with a surface area of 744 m2 g−1 for use as a photocathode in water-splitting cells. The film of ZnBi38O60 with 3 wt% Bi2O3 has 2.3 eV bandgap energy and a conduction band energy of −2.14 V vs. RHE at pH 6.99, which is thermodynamically suitable for reducing H+ to H2. Under illumination, the film produces a current density of −1.55 mA cm−2 at 0 V vs. RHE with an onset potential of 0.84 V vs. RHE. HC-STH efficiency is 0.09% at 0.17 V vs. RHE and IPCE at 0 V vs. RHE is 3.8% at 480 nm. Under continuous operation, the ZnBi38O60/γ-Bi2O3 film shows a stable photocurrent of −0.4 mA cm−2 at 0 V vs. RHE for 1800 s with 100% Faradaic efficiency.Graphical abstractImage 1
       
  • Magnesium hydride based hydrogen chemical source: Development and
           application perspectives
    • Abstract: Publication date: Available online 13 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): S.N. Potapov, I.A. Gvozdkov, V.A. Belyaev, V.N. Verbetsky, S.V. Mitrokhin In this paper, we studied the process of hydrolysis of magnesium hydride with water vapor and considered the possibility of creating a chemical source of hydrogen based on this process. To study the hydrolysis reaction of magnesium hydride powder at temperatures above 100 °C, an experimental setup with a quartz tube — a reactor 300 mm long — was designed. The mass and volume of a single powder load in a quartz reactor was 65 g and 130 ± 2 cm3, respectively. The length of the powder zone along the axis of the reactor was approximately 10 cm.Based on the data obtained during the experiment, it can be distinguished that the length of the reaction zone is greatest at the beginning and at the end of the hydrolysis process and is approximately 5–6 cm. In the middle of the hydrolysis process, for the time interval from 3000 to 5000 s, the reaction zone is the smallest - about 4–5 cm. The proposed design of the hydrolysis reactor and the experimental setup also made it possible to study the peculiarities of the hydrolysis of magnesium hydride powder with water vapor; magnesium, the composition of the reaction products and the controllability of the generation of a stream of hydrogen.
       
  • The inhibitory effect of carbon monoxide contained in hydrogen gas
           environment on hydrogen-accelerated fatigue crack growth and its loading
           frequency dependency
    • Abstract: Publication date: Available online 12 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Ryosuke Komoda, Kazuki Yamada, Masanobu Kubota, Patrick Ginet, Francoise Barbier, Jader Furtado, Laurent Prost The effect of carbon monoxide (CO) contained in H2 gas as an impurity on the hydrogen-accelerated fatigue crack growth of A333 pipe steel was studied in association with loading frequency dependency. The addition of CO to H2 gas inhibited the accelerated fatigue crack growth due to the hydrogen. The inhibitory effect was affected by the CO content in the H2 gas, loading frequency, and crack growth rate. Based on these results, it was revealed that the inhibitory effect of CO was governed by both competition between the rate of fresh surface creation by the crack growth and the rate of coverage of the surface by CO and time for hydrogen diffusion in the material to the crack tip with reduced hydrogen entry by CO.
       
  • Deposition of heterojunction of ZnO on hydrogenated TiO2 nanotube arrays
           by atomic layer deposition for enhanced photoelectrochemical water
           splitting
    • Abstract: Publication date: Available online 12 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Chih-Chieh Wang, Chih-Yu Chou, Shin-Ruey Yi, Huey-Dar Chen The heterojunction of ZnO was deposited on hydrogenated TiO2 nanotube arrays (H–TiO2) by atomic layer deposition (ALD) with various cycles. The ZnO was uniformly wrapped with the H–TiO2 samples and the thickness could be accurately controlled by the cycle numbers of ALD. The higher growth rate ~2.7 Å/cycle was obtained due to the surface amorphous layer, compared with the air-treated samples (A-TiO2), ~2.3 Å/cycle. When the cycle numbers increased to 200, nanowire arrays appeared. Interestingly, the absorption in the visible light region improved more significantly when ALD ZnO was employed for the H–TiO2 rather than the A-TiO2 samples. The H–TiO2 samples with 42 nm of ALD ZnO exhibited enhanced photoelectrochemical water splitting performances, compared with the A-TiO2 with 42 nm of ALD ZnO. This was related to the higher degree of the electronic band bending and improved photo-response in the UV and visible light region, resulting from the oxygen vacancies.
       
  • Improved hydrogen embrittlement resistance after quenching–tempering
           treatment for a Cr-Mo-V high strength steel
    • Abstract: Publication date: Available online 11 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Yafei Wang, Songyan Hu, Yun Li, Guangxu Cheng The effect of quenching-tempering (QT) treatment on the hydrogen embrittlement (HE) resistance of a reactor pressure vessel steel was studied. Decomposition of M3C/VC carbides and precipitation of M7C3 carbides were confirmed by transmission electron microscopy and atom probe tomography observations. Tensile tests showed that HE sensitivity decreased to a negligible level after QT treatment. The improvement of HE resistance was mainly attributed to the decreased number of M3C carbides which act as the reversible trapping sites for hydrogen. This was supported by the decreased concentration of reversible hydrogen as measured by thermal desorption spectroscopy. The amount of irreversible hydrogen (probably trapped at VC carbides) also decreased, which is however not considered responsible for the HE improvement.
       
  • Studies on new highly phosphonated poly (ether ether ketone) based
           promising proton conducting membranes for high temperature fuel cell
    • Abstract: Publication date: Available online 11 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Saleheen Bano, Yuvraj Singh Negi, K. Ramya The present study deals with the development of poly ether ether ketone (PEEK) based proton exchange membrane (PEM) having phosphonic acid as protogenic moiety. The synthesis of phosphonated PEEK was carried out in two simpler steps i.e. chloromethylation followed by phosphonation through Michaelis-Arbuzov reaction. The product was further investigated for structural property through FTIR, 1H NMR, 13C NMR, 31P NMR and XRD while thermal properties were analysed by TGA. Other physical properties such as ion exchange capacity, water uptake and proton conductivity were determined for the prepared membranes to execute their suitability as PEM. The presence of phosphonic acid group provides good thermal and chemical stability to the membranes. The high substitution degree (1.11–1.56) achieved in present case was favourable for providing significant proton conductivity of 0.047 S/cm at 120 °C under hydrated conditions to the corresponding membranes which entitle them as potential candidate for PEMs in fuel cells at high temperature.Graphical abstractImage 1
       
  • Analysis of hydrogen storage performance of metal hydride reactor with
           phase change materials
    • Abstract: Publication date: Available online 11 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Hafsa El Mghari, Jacques Huot, Jinsheng Xiao Using phase change materials (PCM) as thermal energy storage material in metal hydride reactor bed is an effective method to store the heat emitted during hydrogen charging and retrieving it later during discharging. The present work examines the effect of a PCM on the behaviour of the metal hydride in the reactor bed. A two-dimensional model was developed to describe the mass and heat transfer inside the metal hydride and the PCM as well as the interaction between them. The results were compared with other numerical simulation and experimental data. In the simulations, thermal conductivity and the latent heat were varied in order to evaluate the effect of these parameters on the kinetics of absorption, desorption and melting of the phase change material.
       
  • Intrinsic and extrinsic natures make changes on the ionic transportation -
           Response to: “Comments on Int J Hydrogen Energy 42 (2017)
           17495–17503”
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Yan Wu, Bin Zhu Solid State Ionics (SSI) and ionic conducting systems have been well investigated in intrinsic ionic conducting systems from the structure, aliovalent ions doping and coherently controlling their dynamics. However, for extrinsic ionic conducting systems a coupling to an external environment to introduce extrinsic ions remains largely unexplored, which is actually challenging SSI fundamentals for developing emerging material functionalities. Such open-systems with extrinsic ionic nature and changeable with the coupled external environment have demonstrated interesting ionic conductive advantages over the conventional intrinsic SSI system where the defects and mobile ion type and concentration remain constant. Herein we give several examples/literatures from this kind of system based on semiconductor ionic composite in response to comments made by Näfe. It is very necessary to establish a basic understanding of extrinsic ionic conduction in the new materials and systems where the semiconductor-ionic CuFeO2-YSZ composite is belonging to. As said this field has not yet well studied in SSI, at the current status we may offer mostly experimental evidences and new aspects of understanding on such semiconductor-based systems with extrinsic ionic transportation properties.
       
  • Effect of N2 and CO2 on explosion behavior of syngas/air mixtures in a
           closed duct
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Kai Zheng, Xufeng Yang, Minggao Yu, Rongjun Si, Lei Wang The explosion behavior of syngas/air mixtures under the effect of N2 and CO2 addition is experimentally investigated in three cases of N2 and CO2 volume fractions (0, 20% and 40%). Tests are performed for syngas/air mixtures with varying equivalent ratios (from 0.8 to 2.5) and hydrogen fractions (from 25% to 75%). The effects of N2 and CO2 addition on flame structure evolution, flame speed and overpressure histories are analyzed. The results showed that the tulip shaped flames appear in all cases regardless of whether N2 and CO2 are added. After flame inversion, the appearance of tulip shaped flame distortion can be observed in syngas/air without N2 and CO2 addition and meanwhile the oscillations are seen in the flame front position and speed trajectories. The flame distortion becomes less pronounced with N2 and CO2 addition, and the oscillation amplitude of the flame front position and speed reduce accordingly. Both addition of N2 or CO2 decrease the flame speed and the maximum overpressure. Therefore, it increases the time required for flame arriving to the discharge vent. Whereas CO2 has evidently better inhibition performance for syngas/air explosion.
       
  • Effect of hydrogen in advanced high strength steel materials
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Sandeep Kumar Dwivedi, Manish Vishwakarma The effect of hydrogen in AHSS material (automobile and structural component) was discussed. Dual Phase steels were highly susceptible to hydrogen-related failure when working on hydrogen environment. The influence of hydrogen on TRIP steel was seen during fractographic examination where the brittle transgranular fracture was presented. TWIP steels results were inconsistent. The mechanisms which were responsible for crack growth are discussed. LIST and SSRT testing were performed for mechanical properties evaluation and SEM and TEM were used for microstructural examination of fractured samples. Simultaneous preventing methods to reduce hydrogen embrittlement such as coating, alloying and providing diffusion layer were discussed.
       
  • Onset of cellular instability and self-acceleration propagation of syngas
           spherically expanding flames at elevated pressures
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Haoran Zhao, Jinhua Wang, Zhijian Bian, Xiao Cai, Xiaotian Li, Zuohua Huang Systematic study on the onset of cellular instability and self-acceleration propagation for syngas spherically expanding flames is investigated. Three onsets of crack branching, uniform cellularity and transition acceleration are obtained from Schlieren images and Sb-κcurves. Effective Lewis number Leeff and thermal expansion ratio σ are controlled independently by adjusting equivalence ratio and oxygen-nitrogen ratio. Results show that the order of three onsets is crack branching 
       
  • A modified micro reactor fueled with hydrogen for reducing entropy
           generation
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Wei Zuo, Yuntian Zhang, Jing Li, Qingqing Li, Zhu He In order to reduce the entropy generation of premixed hydrogen/air flame in the micro combustion chamber, the combustion chamber of the old micro reactor is modified by gradually varying the diameter of the combustion chamber. Extensive numerical investigations about the entropy generation of premixed hydrogen/air flame in old and modified micro reactors are conducted under various hydrogen mass flow rates, hydrogen/air equivalence ratios, solid materials and inlet/outlet diameter ratios. Results suggest that the modified micro reactor has lower total entropy generation than that of the old micro reactor. This is attributed to that the temperature gradient of the burned gas in the modified micro reactor is lower than that in the old micro reactor after chemical reactions. Finally, the largest descent percentages of total entropy generation are achieved under various conditions, which provide significant reference values for hydrogen energy usage under micro scale combustion.Graphical abstractImage 1
       
  • Effect of hydrogen addition on the detonation performances of
           methane/oxygen at different equivalence ratios
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Jianxing Li, Jianfeng Pan, Chao Jiang, Jing Ni, Zhenhua Pan, Peter Otchere Detonation performances of methane/hydrogen/oxygen (CH4/H2/O2) mixtures were investigated experimentally in a 3000 mm long tube with an inner diameter of 30 mm at different initial pressures p0 (ranging from 10 kPa to 50.5 kPa). Mixtures with different proportions of H2 in the total fuel α (0%, 14.29% and 25%) and different equivalence ratios Φ (0.8, 1.0 and 1.2) were tested. Signals of flame front and pressure were obtained by ion probes and high frequency pressure transducers, respectively. Results showed that with the increase of p0, αand Φ, the average velocity of steady detonation Vave increased. For mixtures with the given α, when Φ increased by 0.2, Vave increased by 100 m/s. In the present study, velocity deficits were found to be within 5%, and when p0 was higher than 20 kPa, the velocity deficits were within 2%. The average peak pressure of steady detonation pave was close to the von Neumann pressure pvN. Both the increase of p0 and Φ led to the increase of the pave. But the addition of H2 led to the decrease of pave, and pave decreased with the increased of α.
       
  • Effects of Nb on stress corrosion cracking of high-strength low-alloy
           steel in simulated seawater
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Qianqian Qiao, Lin Lu, Endian Fan, Jinbin Zhao, Yanning Liu, Guangchun Peng, Yunhua Huang, Xiaogang Li In this study, simulated heat-affected zone (HAZ) of Nb-free and Nb-bearing steel were obtained, and SEM, TEM, and slow strain rate tensile (SSRT) tests were performed to investigate the effect of Nb on the stress corrosion cracking (SCC) behavior of high-strength low-alloy (HLSA) steel in simulated seawater with or without hydrogen charging. The addition of Nb significantly refined the grains and uniformed the microstructure of HLSA. Nb hardly affected the SCC susceptibility of BM and HAZ without hydrogen-charging. However, after charging with 10 mA cm−2, the SCC resistance of Nb-bearing steel, especially the coarse grain HAZ (CGHAZ) improved drastically, and the process of crack initiation and propagation was inhibited owing to the hydrogen trap function of NbC precipitates.
       
  • 2+with+natural+CuFe-oxide+mineral+heterogeneous+composite+for+low+temperature+solid+oxide+fuel+cells,+Int.+J.+Hydrogen+Energy+42+(2017)+17495–17503"&rft.title=International+Journal+of+Hydrogen+Energy&rft.issn=0360-3199&rft.date=&rft.volume=">Comments on "Enhanced ionic conductivity of yttria-stabilized ZrO2 with
           natural CuFe-oxide mineral heterogeneous composite for low temperature
           solid oxide fuel cells, Int. J. Hydrogen Energy 42 (2017) 17495–17503"
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): H. Näfe Recently, in this journal the phenomenon of ionic conductivity enhancement has again been claimed to boost the electrical characteristics of a solid electrolyte, this time of the classical oxygen ion conductor yttria-stabilized zirconia. It is demonstrated that the arguments to support the claim are flawed and that the criticized article is another example of a fallacy with regard to ionic conductivity enhancement.
       
  • Modelling the performance of an SOEC by optimization of neural network
           with MPSO algorithm
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Jing Han, Xi Wang, Limei Yan, Aida Dahlak This paper studies the Solid Oxide Electrolyzer Cell as a promising system in the sustainable development for the hydrogen economy and energy systems as a robust system. The Solid Oxide Electrolyzer Cell converts the steam and carbon-dioxide directly to functional fuels through consumption of the additional electrical power of green power sources or off-peak network powers. The present paper evaluates the static efficiency of the SOEC under four various gas mixtures. Modeling of this system is performed using Elman neural network (ENN) and modified particle swarm optimization (MPSO) algorithm. The MPSO algorithm is utilized to determine the optimal values for ENN adjustable parameters. It's known from the empirical results that the steam and carbon-dioxide concentrations can affect the SOEC efficiency. The operational potential and volume share of the hydrogen, carbon dioxide and steam are considered as the system inputs, and efficiency (current) is remarked as its output. The correlation factors of the achieved model are greater than 0.999, and its MSE (mean squared error) is lower than 0.017. It reveals that the forecasted values are almost equal to the empirical data. Subsequently, the efficiency of the SOEC is studied using the achieved model of the MPSO-based ENN in various feedstock concentrations. Thus, this dataset that is used for ENN model can be desirable for different applications of fast-modeling in a standalone group. It as well can be useful for cost, computing-time, and computing burden reduction in a model construction in the efficiency analyzing and system-level designing processes.
       
  • Fuel cell hybrid powertrains for use in Southern Italian railways
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Petronilla Fragiacomo, Francesco Piraino This paper analyses the use of a fuel cell hybrid powertrain for different uses on rail. Four vehicles are numerically tested on suitable tracks. The implemented model calculates the vehicle power demand, starting from track altitude, train speed and vehicle characteristics. For each track, a powertrain composed of a fuel cell system and an energy storage system, battery and/or supercapacitor, is used, suitable for the purpose. Each component is modelled separately and is validated. It should be underlined that the whole system is validated, by means of experimental data found in the literature. A comparison analysis between the simulation results is done: the H2 consumption varies between 5 kg/cycle and 160 kg/cycle, according to the track energy consumption, while the fuel cell efficiency is between 50% and 47%, since the fuel cell works at different power rates.
       
  • Cerium and Gadolinium co-doped perovskite oxide for a protonic ceramic
           fuel cell cathode
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Limin Zhang, Shuyan Yang, Shizhen Zhang, Yongxing Yang Proton-conducting ceramic fuel cells (PCFCs) show unique advantages over oxygen-ionic-conducting counterparts at intermediate and low temperatures, which have attracted significant attention worldwide in recent years. A critical issue for world-spread applications is inadequate performance due to the lack of appropriate cathodes for PCFCs. Here, cubic perovskite BaCo0.4Fe0.5-xCe0.1RexO3-δ (ReY, Gd x = 0, 0.1) materials are successfully synthesized and evaluated as the cathode in the PCFCs based on BaCe0.7Zr0.1Y0.1Yb0.1O3-δ as an electrolyte material. The Y- or Gd-doped perovskite BaCo0.4Fe0.4Ce0.1Y0.1O3-δ (BCFCeY), BaCo0.4Fe0.4Ce0.1Gd0.1O3-δ (BCFCeG) exhibit larger lattice parameters, and higher electrocatalytic activity comparing to their parent oxide BaCo0.4Fe0.5Ce0.1O3-δ (BCFCe). Among them, BCFCeG shows the best performance. The single cell with BCFCeG as the cathode material exhibits an interfacial polarization resistance as low as 0.12 Ω cm2 and delivers a promising peak power density of 504 mW cm−2 at 600 °C, while the BCFCe-based cell achieves only 437 mW cm−2 at 600 °C. The X-ray diffraction (XRD) results show good chemical compatibility for BCFCeG below 1050 °C. Moreover, it shows favorable stability in CO2-containing environment. This work confirms that BCFCeG could be a promising cathode for PCFCs.
       
  • A novel approach for reactive power compensation in hybrid wind-battery
           system using distribution static compensator
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): V.S.N. Narasimha Raju, M. Premalatha, D.V. Siva Krishna Rao K. This paper proposes a novel algorithmic approach to compensate the reactive power using distribution static compensator (DSTATCOM) for wind energy conversion system (WECS). Three phase bidirectional converter is utilized to exchange real and reactive power in both directions. The plug-in hybrid electric vehicle (PHEV) is enabled to consume during excess power availability. The battery is connected through a separate bidirectional DC-DC converter to adjust the power at the desired range. The compensated reference current is being generated based on the load requirement, wind power generations and state of charge (SOC) status. The proposed algorithmic approach helps to stabilize the grid by injecting accurate compensating current at the point of common coupling (PCC). Thereby, the proposed approach ensures the grid at balanced states under all operating cases. In order to validate the proposed approach, different case studies have been considered and validated through simulation results using PSCAD/EMDTC software.Graphical abstractReactive Power Compensation in Hybrid Wind-Battery System using Distribution Static Compensator.Image 1
       
  • Biohythane as an energy feedstock for solid oxide fuel cells
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): G.K. Veluswamy, C.J. Laycock, K. Shah, A.S. Ball, A.J. Guwy, R.M. Dinsdale Biogas (60%-CH4, 40%- CO2) is a potential source of renewable energy when used as energy feedstock for solid oxide fuel cells (SOFC), but releases biogenic CO2 emissions. Hybrid SOFC performance can be affected by fuel composition and reformer performance. Biohythane (58%-CH4, 35%-CO2 and 7% H2) can be a better alternative providing balance between energy and biogenic emissions. Biohythane performance is studied for a 120 kW SOFC stack using ASPEN process model and compared with other feed stocks. This work is the first to study and report on the application of biohythane in SOFC systems. Biohythane was found to produce less biogenic CO2 emissions and 6% less CO at the reformer than biogas. Comparisons show that biohythane provides better efficiencies in hybrid SOFC systems. Sensitivity studies recommends operation of stack with biohythane at Steam to Carbon Ratio (STCR) = 2.0, i = 200 mA cm−2 and UF = 0.85 respectively.
       
  • Theoretical prediction and experimental study on catalytic mechanism of
           incorporated Ni for hydrogen absorption of Mg
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Bogu Liu, Bao Zhang, Ying Wu, Wei Lv, Shixue Zhou Transition metals, including Ni, show good catalytic activity in the hydrogen storage reaction of Mg. In the present paper, first-principles calculation is performed to predict and analyze the hydriding reaction of Ni-incorporated Mg and experimental study is used to verify the accuracy of the forecast. Theoretical studies show that the hydriding reaction of Ni-incorporated Mg is a diffusion-controlled process. With Ni incorporation, the energy barrier of H2 dissociation is significantly decreased and the diffusion becomes the limiting step. Experimental studies confirm the results of theoretical studies. Besides, the material with Ni incorporation shows excellent activation performance and rapid absorption rates, leading to a high hydrogen content of 4.1 wt% in 60 s under 240 °C 3.0 MPa H2 and a low activation energy of 56.1 kJ mol−1 versus 0.4 wt% and 73.5 kJ mol−1 for the material without Ni incorporation. Atomic Ni only plays a role of catalyst.Graphical abstractImage 1
       
  • Concentration dependence of hydrogen diffusion in α-iron from
           atomistic perspectives
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Md Abdullah Al Hasan, Jiaqi Wang, Yong Chae Lim, Anming Hu, Seungha Shin Evaluation of hydrogen diffusion in structural materials is essential to predict the leakage and embrittlement of hydrogen storage applications. In this work, we investigate the atomic-scale diffusion of interstitial hydrogen (H) in α-iron (Fe) over a temperature range from 350 to 900 K with different H concentrations (0.01–5%), employing classical molecular dynamics (MD) simulations. The self-diffusivity of H atoms increases with increasing temperature and decreasing concentration. With low concentrations, the calculated diffusion properties agree well with prior experiments. However, with a higher concentration (≥1%), the H diffusivity at low temperatures deviates from a high-temperature Arrhenius behavior. Through the energetic and structural analysis, we suggest that this deviation is attributed to a reduced mobility due to increased energy barrier by other H interstitials. This work contributes to the effective design of H storage applications by identifying temperature and concentration effects on permeability and addressing possible microstructural transformation.
       
  • Hydrogenation of Pd/Mg films: A quantitative assessment of transport
           coefficients
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Efi Hadjixenophontos, Kun Zhang, Andreas Weigel, Patrick Stender, Guido Schmitz Due to increasing energy demands, interest in hydrogen storage is substantial. Magnesium is one of the most attractive systems, yet, development for practical application remains challenging. By combination of X-ray diffraction, electron microscopy and in-situ measurements of resistivity we determine the diffusion coefficient of hydrogen in MgH2 at technically relevant pressure (20 bar). Pd coated thin films of well-defined thickness enable a quantitative evaluation of the hydrogenation rate. From this, we detect linear to parabolic kinetic transition and obtain the diffusion coefficient of hydrogen in MgH2. Measurements at different temperatures (RT-300 °C) demonstrate an Arrhenius behaviour with an activation energy Ea = 28.1 kJ mol−1. This low value and the transformation into a nanocrystalline microstructure upon hydrogenation indicate grain boundary diffusion as the essential mechanism. In completion, the interface Pd/Mg is studied. Mg5Pd2 and Mg6Pd form at elevated temperatures required for dehydrogenation. These phases affect, but do not prevent, further hydrogen loading.Graphical abstractImage 1
       
  • Ruthenium decorated boron-doped carbon nanotube for hydrogen storage: A
           first-principle study
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Pei Liu, Jiawei Liang, Ruihao Xue, Quanpei Du, Mingrui Jiang In this paper, the adsorption of molecular hydrogen on Ruthenium (Ru) decorated boron-doped single-walled carbon nanotube (CNT) is theoretically studied, based on the density-functional theory (DFT). The projected density of states (PDOS) and charge density difference are computed, and Mulliken population analysis is conducted to investigate the molecular hydrogen adsorption ability of a boron-doped CNT (BCNT) system and a pure CNT system. As for the pure CNT system, a single Ru atom can absorb up to four H2 molecules with a binding energy of −1.057eV/H2; and for the boron-doped CNT system, the binding energy of H2 molecules increases to −1.151eV/H2 and it displays much higher binding energy of Ru with the increase of 21.19%. This implies that the BCNT system is more stable and has better ability to adsorb hydrogen molecules. The enhanced ability to adsorb H2 molecules implies that Ru decorated BCNT may be a useful and promising nanomaterial for hydrogen energy storage.Graphical abstractImage 1
       
  • Improved hydrogen storage properties of TiFe alloy by doping (Zr+2V)
           additive and using mechanical deformation
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Peng Lv, Zhichen Liu, Viney Dixit In this paper, the effects of doping, cold rolling and forging on the microstructure and hydrogen storage properties of air exposed TiFe + x wt.% (Zr+2V) (x = 0, 4, 5 and 6) alloys were studied. The results showed that all doped samples had similar crystal structure: bcc TiFe main phase and hcp secondary phase. Doping (Zr+2V) can improve obviously the first hydrogenation kinetics of TiFe alloy due to the presence of hcp secondary phase. Further study, we found that the process of cold rolling and forging could reduce the crystallite size of x = 4 sample but forged sample showed a smaller crystallite size. Then it also should be noted that x = 4 forged sample showed the fastest hydrogenation kinetics, highest hydrogen capacity and good cycling stability. By analyzing the kinetic model, all handled x = 4 samples agreed with GB3D model, which meant 3D growth, diffusion controlled with decreasing interface velocity.
       
  • Numerical investigations on flow characteristics and energy separation in
           a Ranque Hilsch vortex tube with hydrogen as working medium
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Sirajuddin Syed, Manimaran Renganathan In the last decades, the theory of energy separation in vortex tubes is debated broadly based on the heat transfer and work transfer between core and peripheral flow layers. Many parameters were considered in the literature. However, the present study involves the inlet energy considered collectively towards energy separation. In this paper, three-dimensional computational fluid dynamic simulations are discussed in vortex tube to analyze the energy separation phenomena in different cases by varying the working medium such as hydrogen and air having specific heat variation. The energy at the inlet is maintained same in both cases by adjusting the inlet mass flow rate. The results from this study are validated with recently published literature using hydrogen as a working medium. Vortex tube with hydrogen as working medium yields a temperature separation of 8 K lower than air as working medium. Further studies on vortex tube with hydrogen as a working fluid is explored at different inlet temperatures relative to the room temperature. Vortex tube with hydrogen at an inlet temperature of 400 K gives better temperature separation as compared to other inlet temperatures considered in this study.
       
  • Theoretical design of a novel 2D tetragonal ZnS/SnO hetero-bilayer as a
           promising photocatalyst for solar water splitting
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Jia Zhou Van der Waals (vdW) hetero-bilayers are emerging as unique structures to enhance the performance of two-dimensional (2D) layered nanomaterials for next-generation electronic and optoelectronic devices. In this work, we employ first-principles calculations to study the novel tetragonal ZnS/SnO hetero-bilayer (BL). The state-of-the-art computations based upon quasiparticle GW and Bethe−Salpeter equation (BSE) are utilized to study the electronic and optical properties of this novel vdW hetero-bilayer. We reveal that ZnS/SnO BL is a polarized semiconductor with a clear built-in electric field, and possesses a special band characteristic favorable for reducing the carrier recombination. It is also demonstrated that strain and external electric field are among the effective methods to modulate the electronic and optical properties of ZnS/SnO BL. Our work suggests that ZnS/SnO BL has an excellent optical absorption in the solar spectrum, rendering the material a viable candidate for optoelectronic applications, in particular for solar water splitting.Graphical abstractImage 1
       
  • Template-free synthesis of biomass-derived hierarchically mesoporous
           carbon with ultra-small FeNi nanoparticles for oxygen evolution reaction
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Yang Gao, Shuqi Hu, Yuanguang Zhou, Shiguo Zhang Highly active and stable catalysts towards electrochemical oxygen evolution reaction are crucial for efficient water splitting and sustainable hydrogen generation. Here we report a carbon supported FeNi catalyst synthesized from an in situ freeze-drying method (fd-FeNi/C) with a commonly seen biomass, jasminum mesnyi flower. The fd-FeNi/C exhibits a N-doped hierarchically mesoporous carbon structure decorated with small FeNi nanoparticles with a small diameter of ∼ 4 nm. Electrochemical measurements show excellent catalytic performance in 1 M KOH solution with an overpotential of 301 mV at the current density of 10 mA cm−2. The value is 41 mV lower than that of the commercial IrO2/C. A small Tafel slope (64.5 mV dec−1) and high stability are also recorded. This work provides a facile, scalable, and template-free approach to convert biomass into highly active electrochemical catalysts, which shows great potential for future applications.Graphical abstractImage 1
       
  • Preparation of CdS-CoSx photocatalysts and their photocatalytic and
           photoelectrochemical characteristics for hydrogen production
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Lizi Chu, Yuan Lin, Yunpeng Liu, Hongjuan Wang, Qiao Zhang, Yuhang Li, Yonghai Cao, Hao Yu, Feng Peng A facile method of loading CoSx nanosheet onto CdS nanorod has been designed, and the prepared CdS-CoSx composite catalyst exhibited significantly improved performance for photocatalytic hydrogen evolution compared with CdS catalyst. This composite catalyst was also used as a photoanode for photoelectrochemical (PEC) hydrogen production. The hydrogen production rate reached 168.6 μmol cm−2 h−1 (37.77 L m−2 h−1) under the simulated solar light, which is 2.7 times that of CdS and the same as that of CdS–Pt. In addition, in the Na2S–Na2SO3 system for PEC hydrogen production, an abnormal relationship between photocurrent and the hydrogen production yield was found. By designing a series of experiments, the photocatalytic and photoelectrochemical characteristics for hydrogen production were reasonably revealed for the first time. In this work, the prepared structured catalyst is easy to be recycled, and CoSx can replace precious metal Pt, showing a promising application.Graphical abstractImage 1
       
  • Enhanced coke suppression by using phosphate-zirconia supported nickel
           catalysts under dry methane reforming conditions
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Ahmed Aidid Ibrahim, Ahmed Sadeq Al-Fatesh, Wasim U. Khan, Samsudeen Olajide Kasim, Ahmed Elhag Abasaeed, Anis Hamza Fakeeha, Giuseppe Bonura, Francesco Frusteri Ni based phosphate zirconium catalysts were prepared by impregnation technique and used under CH4 dry reforming conditions. Catalysts (x%Ni/8%PO4–Zr, where x = 5, 10, 15 or 20) were characterized by nitrogen physical adsorption-desorption, X-ray diffraction, temperature programmed reduction, CO2 and NH3 temperature programmed desorption, thermal gravimetric analysis and transmission electron microscopy (TEM-EDAX). Catalysts displayed a typical mesoporous structure and different reducibility grade as a function of Ni loading, diagnostic of a different extent of metal-support interaction. Activity and stability strongly depend upon Ni loading while the best performance was observed for catalyst characterized by a Ni loading of 10 wt%. The CO2-TPD profiles of spent catalysts indicated that such catalyst had more tendency to gasify coke formed over the catalyst surface. TGA analysis of used catalysts quantitatively showed that catalysts at higher Ni loading deactivated as result of huge graphitic carbon formation on catalyst surface. On the contrary, system 10%Ni8%PO4/ZrO2 turns out to be an excellent candidate to conduct the methane reforming reaction with CO2 without coke formation at high CH4 and CO2 conversions. Phosphate play a fundamental role in promoting Ni–ZrO2 interaction which reflects in the stabilization of catalytic system against metal sintering and coke formation.
       
  • Improved methane oxidation activity of P-doped γ-Al2O3 supported
           palladium catalysts by tailoring the oxygen mobility and electronic
           properties
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Xiaohua Chen, Yong Zheng, Yelin Chen, Yalan Xu, Fulan Zhong, Wen Zhang, Yihong Xiao, Ying Zheng Micro-mesoporous P-doped γ-Al2O3 with cluster morphology was obtained via an efficient ultrasound-assisted sol-gel process and taken as carrier to construct palladium catalysts for methane oxidation. It was revealed that the structure and properties of catalysts were significantly influenced by the phosphorus precursors with diverse valence and acidity. Dissimilar reducibility of surface hydroxyl and oxygen species is observed in the catalysts derived from different phosphorus sources, indicating the difference in the oxygen mobility and the capacity of the catalysts to convert intermediate CO. The behavior of charge-transfer transition and d-d transition, the transfer ability of electrons from palladium particles into the antibonding 2π* orbitals of CO, together with the surface acidity and electronic density of palladium species was likewise tailored, which demonstrated the metal-support interaction could be tuned, making palladium species behave with diverse status and electronic structures. The optimized properties cooperatively provided an enhancement in catalytic performance of P-containing catalysts.Graphical abstractImage 1
       
  • Mo-doped Co9S8 nanorod array as a high performance electrochemical water
           splitting catalyst in alkaline solution
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Xiaoqiang Du, Guangyu Ma, Xiaoshuang Zhang It is very important to exploit robust electrocatalysts for the water splitting in an alkaline medium. Hence, a series of Mo-doped Co9S8 nanorod array on Ni foam (Mo–Co9S8/NF) was successfully synthesized through hydrotherma and sulfuration processes for the first time and used as an efficient and stable difunctional electrocatalyst for the overall water splitting. Such Mo–Co9S8-3//Mo–Co9S8-2 electrodes couple display superior water splitting performance with the requirement of a cell voltage of 1.50 V to drive a catalytic current density of 10 mA cm−2, which is lower than that of RuO2//Pt/C (1.52 V). The activity of the catalyst is greatly enhanced by the molybdenum ion doping and the instability of the sulfide is resolved. The experiment result shows that the relationship between the current density and pH is different in neutral and alkaline media, which is most be likely assigned to the change of O–O formation by transforming the reactants from water molecule to the hydroxy ion.Graphical abstractWe indicate the development of Mo-doped Co9S8 nanorods arrays on nickel foam (Mo–Co9S8/NF) firstly as a robust earth-abundant electrocatalyst for the water splitting.Image 1
       
  • An autothermal reforming system for diesel and jet fuel with quick
           start-up capability
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Remzi Can Samsun, Matthias Prawitz, Andreas Tschauder, Joachim Pasel, Ralf Peters, Detlef Stolten A quick, low energy consuming and reliable start-up is essential for fuel cell systems utilizing diesel and jet fuel. A compact fuel processor for coupling with a high-temperature polymer electrolyte fuel cell is developed with electrically-heated reactors in the 28 kWth power class. Based on this set-up, start-up strategies are developed and validated. With the basic strategy, 14 min are required in the best case to commence reforming and achieve self-sustaining operation with desired CO concentration at full load using NExBTL diesel and, respectively, 16 min using Jet A-1. However, using premium diesel, the basic strategy leads to a strong increase in the concentrations of ethane and benzene. An advanced strategy enables 16 min start time with premium diesel suppressing these undesired side products. This result is within the 30 min start-up time target for auxiliary power units for 2020 and offers a reliable option for real world applications.
       
  • Biomass-derived CO2 rich syngas conversion to higher hydrocarbon via
           Fischer-Tropsch process over Fe–Co bimetallic catalyst
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Sonal, Ejaz Ahmad, Sreedevi Upadhyayula, Kamal K. Pant Biomass-derived syngas (CO2 + CO + H2) has emerged as a potential non-fossil fuel source to yield transportation fuel via Fischer Tropsch Synthesis (FTS) reaction. Thus, the present study demonstrates the conversion of CO2 containing syngas into fuel range hydrocarbon via Fischer Tropsch Synthesis over Fe–Co bimetallic catalyst. The experimental tests were carried out in a fixed bed continuous reactor to investigate the effect of CO2 on CO/CO2 conversion. Accordingly, obtained data were validated by FTS kinetic model for a plug flow reactor. It was found that the unique combination of Fe and Co bimetallic catalyst facilitates both FTS and water gas shift (WGS) reaction simultaneously that helps to convert CO2 along with CO. It was also observed that the presence of iron in the catalyst helps in conversion of CO2 into hydrocarbons, only when a particular concentration of CO2 in syngas is reached, i.e., critical ratio RC (CO2/CO + CO2) due to the occurrence of reverse water gas reaction (RWGS) which varies with the temperature and the feed gas composition (H2/CO/CO2 molar ratio). At 240 °C and hydrogen deficient condition, the critical ratio was measured to be 0.74 whereas for hydrogen balanced condition, it was measured 0.6. The kinetic model developed in the present study predicted trends for % CO conversion, % carbon conversion, and % CO2 conversion which is applicable for a wide range of critical ratio RC (CO2/(CO + CO2) = 0 to 1). The model also predicted that a positive conversion of CO2 could be achieved at lower CO2 concentration by increasing the reaction temperature. At 260 °C and 280 °C, the value of Rc were 0.31 and 0.18 were measured.
       
  • Study of synthesis gas composition, exergy assessment, and multi-criteria
           decision-making analysis of fluidized bed gasifier
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Parisa Mojaver, Samad Jafarmadar, Shahram Khalilarya, Ata Chitsaz A system based a fluidized bed gasifier with steam as a gasifying agent is investigated in details. Comparing the synthesis of gas compositions with experimental data available in the literature is used to validate the model. The synthesis of gas composition and efficiencies of the system is investigated respect to different biomasses considered as gasification fuels. The results indicate that the molar fractions of hydrogen and carbon dioxide are increased and the molar fraction of carbon monoxide is reduced with steam to biomass ratio (STBR). The hydrogen and cold gas efficiencies are improved with decreasing STBR. Hydrogen, cold gas, and exergy efficiencies are enhanced with temperature. The results illuminate that pine sawdust and straw have the highest hydrogen production and legume straw produces the lowest CO molar fraction. Straw has the highest hydrogen efficiency, eucalyptus and straw have the highest cold gas efficiency, and eucalyptus has the highest exergy efficiency. A systematical analytical hierarchy process (AHP)/technique for order preferences by similarity to ideal solution (TOPSIS) couple method are utilized to select the best alternative. The results illuminate that eucalyptus, straw, and pine sawdust are the best candidates, respectively as gasification fuel based on the considered criteria.
       
  • Effect of partial shading conditions on off-grid solar PV/Hydrogen
           production in high solar energy index regions
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Başak Doğru Mert, Fırat Ekinci, Tuğçe Demirdelen In present work, the effect of partial shading on off-grid solar PV/hydrogen production in solar energy has been studied. The study was designed to stimulate future work in this area and to help demonstrate PV/hydrogen production. Four different electrodes in the study were coated and used in PV/Hydrogen Production. Pt anode and four different cathode materials which were Cu, Cu/Ni, Cu/NiBi and Cu/NiMo were used in the study. Data obtained from 105 W PV panel via automation system installed at ATU University, Adana, in Turkey were used for data of days representing different seasons by electrolysis experiment. The experiments were carried out between 08:00 and 16:00. The main contribution of this study is to produce hydrogen by using a part of the electrical energy gained from the solar panels, and at the same time to reveal the effect of the electrical energy produced by the partial shading of the panels on the hydrogen production. Furthermore, the effect of cathode material type was investigated for the impact of partial shading on hydrogen production. Results showed that Cu/NiMo has better hydrogen production efficiency than Cu/Ni, Cu/NiBi. The lowest efficiency was observed in the bare Cu electrode.Graphical abstractImage 1
       
  • K and halogen binary-doped graphitic carbon nitride (g-C3N4) toward
           enhanced visible light hydrogen evolution
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Qiu-Hui Zhu, Zhou Chen, Li-Na Tang, Yue Zhong, Xiu-Feng Zhao, Li-Zhong Zhang, Jian-Hui Li Water splitting driven by solar energy to produce hydrogen, which is highly dependent on the designing of semiconductor photocatalyst, is an efficient technology to address energy shortage problems and environment issues simultaneously. Here, the halogen and potassium binary-doped graphitic carbon nitride (named as X-K-C3N4, X = F, Cl, Br, I) photocatalysts were synthetized via simply one pot thermal polymerization method, which shown optimized band structure, enhanced optical absorption, higher separation rate of photogenerated carriers, and thus improved photocatalytic performance under visible light irradiation. As result, F–K–C3N4 is demonstrated to be highly efficient in the separation and transfer of carriers owing to the existence of C–F bond, CN triple bond and K junction. The F–K–C3N4 shows a highest H2 evolution rate of 1039 μmol g−1 h−1 and a remarkable stability under visible light irradiation (λ ≥ 420 nm), which is about 8.5 times higher than that of pristine g-C3N4.
       
  • Strategies for improving flow rate control of hydrogen generated by
           Al-rich alloys for on-board applications
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Qi An, Hongyu Hu, Nan Li, Jilun Wei, Cundi Wei, Hongchao Wang, Jerry M. Woodall, Qian Gao The Mg-bearing Al-Ga-In-Sn alloy with more stable hydrogen generation rate during hydrolysis reaction was synthesized, which is great suitable for the on-board hydrogen supply applications. The test results show that the hydrogen release rate of the Mg-bearing alloys could be effectively controlled. In particular, when the Mg dosage is 0.5 wt.%, the average hydrogen generation rate can even be reduced to 2.1 ml/min·g, while the total energy conversion efficiency of Al has not been affected and still reaches to nearly 100%. Further analysis shows that the reduction of hydrogen production rate during the Al-water reaction process is closely related to the changes of the phase compositions and the microstructure of grain boundary phase (GB-phase) particles in these alloys. Moreover, the electrochemical tests further clarify the reactivity of the alloys with different Mg dosage.
       
  • Tuning quaternary hybride Co–Ni–S–Se composition as a bifunctional
           electrocatalyst for hydrogen and oxygen evolution reactions
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Xiaojiao Fang, Zegao Wang, Yin Wang, Shifei Kang, Zaixing Jiang, Mingdong Dong Developing high-efficiency and earth-abundant electrocatalysts for electrochemical water splitting is of paramount importance for energy conversion. Although tremendous effort has been paid to transition metal (TM) material-based electrocatalysts, rational design and controllable synthesis of fine structures to fully utilize the latent potential of TM materials remain great challenges. We herein report a composition-tuning strategy to achieve rational structure control of quaternary Co–Ni–S–Se materials through a facile one-pot hydrothermal method, in which earth-abundant Ni is introduced into a CoSxSe2-x matrix to optimize the morphology and electronic structure of the quaternary electrocatalyst. Because of the introduction of Ni, this novel Co–Ni–S–Se quaternary system shows better catalytic activity for water splitting with Tafel slopes of 42.1 mV dec−1 for hydrogen evolution reaction (HER) and 65.5 mV dec−1 for oxygen evolution reaction (OER), respectively, compared with its precursor Co–S–Se ternary system. For stability, there is negligible fading after long-term electrochemical test. Our work not only provides a novel thinking to introduce nickel into Co–S–Se ternary system by a facile hydrothermal synthesis for electrochemical water splitting, but also this quaternary system realizes bifunctional catalysis and better electrochemical performance relative to the ternary counterpart.
       
  • Thermodynamic analysis of in-situ hydrogen from hot compressed water for
           heavy oil upgrading
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Morteza Hosseinpour, Amir Hossein Hajialirezaei, M. Soltani, Jatin Nathwani Due to many benefits of heavy oil upgrading in the green medium of hot compressed water (HCW), the present study considers the thermodynamic analysis of in-situ hydrogen created by partial oxidation of light hydrocarbons (HC) in HCW. The aim is seeking the upgrading condition where light hydrocarbons create hydrogen (H2) and carbon monoxide (CO) assisted by partial oxidation of light hydrocarbons. The formed CO collaborates in in-situ active hydrogen through water gas shift reaction (CO+H2O↔H2+CO2) which is more effective than external hydrogen for hydrogenation of heavy oil in HCW. Applying the powerful capability of Aspen Plus®, i.e., sensitivity analysis, the effect of significant parameters, such as temperature, pressure (water density), water to oil ratio, and oxygen (O2) to oil ratio are studied comprehensively in order to maximize the amount of active hydrogen. The results indicate that higher temperatures and the amount of water (H2O/heavy oil) are two favorable factors to increase the contribution of active hydrogen, while the pressure is not a determinant factor at supercritical condition (P ≥ 25 MPa). The formation of methane is also decreased at high temperature which is desired for upgrading system. The higher amount of water implies more quantity of O2 since partial oxidation affords the enthalpy of auto-thermal reforming of HO. Hence there should be a compromise in the selected ratios of H2O/HC and O2/HC in HCW upgrading system. A set of experiments are conducted in order to compare the simulation and experimental results. Although the experimental results are established on kinetic data which also reflect the physical effect of HCW during HO upgrading, however, the thermodynamic study provides valued information, in agreement with experiments, that improves our understanding of HO upgrading in HCW with less coke.Graphical abstractImage 1
       
  • Defects-rich nickel nanoparticles grown on nickel foam as integrated
           electrodes for electrocatalytic oxidation of urea
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Xiaodong Yan, Wen-Da Zhang, Qing-Tao Hu, Jiangyong Liu, Tao Li, Yuan Liu, Zhi-Guo Gu Designing highly efficient, low cost and long-term stable electro-catalysts is the key step for the commercial applications of fuel cells. Electro-oxidation of urea, a hydrogen-rich fuel, is the anodic reaction of direct urea fuel cells. Herein, defects-rich nickel nanoparticles grown on nickel foam as integrated electrodes have been designed and easily fabricated by incomplete reduction of Ni(OH)2. The Ni2+ defects coupled with oxygen vacancies are proposed to be mainly present in the form of amorphous NiOx, which is the island phase in the metallic nickel nanoparticles and confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. The synergistic effect between metallic metal with high conductivity and numerous defects with good affinity to O contributes to the high catalytic activity towards oxidation of urea with an onset potential of 0.35 V vs Hg/HgO in 2 M KOH +0.33 M urea. Additionally, the defects-rich nickel nanoparticles present good long-term stability.
       
  • Experimental analysis of materials in proton exchange membrane
           electrolysis cells
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): T. Ferriday, P.H. Middleton An accelerated supply and demand of energy has resulted in an increased need for efficient energy storage options, where storing energy in hydrogen gas emerges as one of the most attractive. In this study, a singular proton exchange membrane (PEM) electrolysis cell was designed using adequately low-cost materials, and tested using polarisation curves, cyclic voltammetry and AC impedance. A comparative study of various micro porous layer (MPL) materials was performed in an effort to find suitable options which are able to steadily operate under anodic conditions. The best performance was achieved using carbon cloth, however this material was unstable. Untreated porous titanium and nickel displayed increased stability, though these materials require further development to match the initial performance of carbon cloth as an MPL material.
       
  • Review and analysis of demonstration projects on power-to-X pathways in
           the world
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Zaher Chehade, Christine Mansilla, Paul Lucchese, Samantha Hilliard, Joris Proost Transforming the energy system towards more sustainability can only be achieved through a combination of low-carbon energy, energy efficiency, and the coupling of energy sectors. In this context, the application of Power-to-Hydrogen concepts for managing demand, providing seasonal storage, and linking elements between different sectors has attracted significant interest during the last decade.Demonstration is a key first step towards large-scale market introduction. This paper presents the results of a review of 192 Power-to-X demo projects in 32 countries. Results show that the features of demonstrations have evolved significantly over the years: electrolysis capacity has increased, both for PEM and alkaline systems, and the potential for balancing and ancillary services is increasingly investigated via grid-connected demos. The scope of Hydrogen-to-X pathways has also evolved over the years, mainly to include industry applications. This work was carried out under the umbrella of Task 38 of the IEA Hydrogen Technology Collaboration Programme.
       
  • Ductility and fatigue properties of low nickel content type 316L
           austenitic stainless steel after gaseous thermal pre-charging with
           hydrogen
    • Abstract: Publication date: 22 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 51Author(s): Thanh Tuan Nguyen, Jaeyeong Park, Seung Hoon Nahm, Naehyung Tak, Un Bong Baek The susceptibility of low nickel content type 316L austenitic stainless steel to hydrogen was quantified using low strain rate tensile tests and strain-controlled low-cycle fatigue life measurements. Both tests were performed under air condition after charging with high-pressure 10-MPa hydrogen gas at 300 °C for eight days. No significant influence of hydrogen was recognized in 0.2% proof stress, but the strain at fracture and reduction area was decreased significantly in both hydrogen pre-charged and in gaseous hydrogen conditions compared to companion tests conducted in air. The decrease of fatigue life in the high strain amplitude region was related to a significant decrease in the plastic component while the effect of hydrogen on the elastic component was negligible. Highly localized deformation and a pronounced martensite transformation occurred near the site of the fracture surface in the high strain amplitude regime, resulting in the early formation of abundant micro-surface cracks in this regime of the hydrogen pre-charged samples.
       
  • Cu substituted ZnAl2O4 ex-LDH catalysts for medium-temperature WGS –
           effect of Cu/Zn ratio and thermal treatment on catalyst efficiency
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Katarzyna Antoniak-Jurak, Paweł Kowalik, Robert Bicki, Kamila Michalska, Wiesław Próchniak, Paweł Wiercioch The effect of Cu/Zn ratio of ex-LDH oxide-based catalysts for medium–temperature water–gas shift reaction (MT–WGS) was investigated. A series of CuZnAl–LDH precursors with different Cu/Zn molar ratio were synthesized by co-precipitation and oxide (Zn,Cu)xAl2O4 catalysts were prepared via subsequent calcinations at 380 °C or 700 °C. The prepared materials were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetry with evolved gas analysis (TG/DTG/EGA), N2 adsorption, N2O chemisorption and temperature-programmed reduction (H2-TPR). MT-WGS activity evaluation was carried out on the basis of measurements made in a differential reactor in kinetic regime. Catalysts’ properties were investigated and effect of composition (Cu/Zn molar ratio) and the calcination temperature of CuZnAl-LDH precursors on structural transformation, active surface area and MT-WGS rate constant was shown. The highest activity of (Zn,Cu)xAl2O4 catalyst with Cu/Zn molar ratio of 1.5 calcined at mild conditions was attributed to easy reducible and accessible Cu surface.Graphical abstractImage 1
       
  • Ultrasound propagation in two-layer gas flow
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Mahjabin Taskin, Takuya Kido, Masahiro Inoue, Yoshimine Kato The ultrasonic signal propagation in two-layer gas flow was studied. The intensity degradation of the signal was observed while the signal was propagating through the air-hydrogen-air two-layer gas flowing system. The concentration of flowing hydrogen (H2) gas was measured using ultrasound from the exterior of the pipe, and it was calculated that the intensity degradation of signal did not simply depend on the H2 concentration, however, the intensity varied every second. Schlieren photography was taken to visualize the motion of H2 gas after injecting into the flowing air of 2 m/s. It was observed that high concentration H2 gas was flowing in the middle of the airflow without quick diffusion into the air. A two-dimensional air-H2-air gas flow model was considered where 100% H2 was flowing in the middle of the airflow, and the gas layers were separated by two fluctuated interfaces. According to the calculation using this model, only limited conditions of the signals can reach to the receiver due to the refraction at the fluctuating air-H2-air gas interfaces while propagating. It was found that the receiver could hardly detect the signals; hence, the intensity of the signal looked degraded.Graphical abstractThe intensity degradation of ultrasonic signal propagation through two fluctuated interfaces of air-hydrogen two-layer gas flow is due to the refraction at the interfaces.Image 1
       
  • Active-passive controls of liquid di-hydrogen mono-oxide based nanofluidic
           transport over a bended surface
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Nilankush Acharya This study unfolds the hydrothermal features of nanofluidic transport over a curved surface. The texture of the curved surface has been assumed to be stretched and the bended structure is coiled inside a circular section having radius R. Active passive controls of tiny ingredients at the surface influenced by Brownian and thermophoretic migration are incorporated at molecular level to frame the analysis. The nanoparticles are dispersed into base solution of liquid Di-Hydrogen Mono-Oxide to explore the heat and mass diffusion. Foremost system of equations are provided to explore the hydrothermal integrity and diffusivity of nanofluidic liquid Di-Hydrogen Mono-Oxide in an extensive way. After that, those equations are simplified using RK-4 based shooting scheme. Influence of dynamic parameters on the transport systems are deliberated using requisite graphs, tables. Deviation in streamlines, 3D view of pressure and pressure gradient, velocity are depicted. Heat and mass diffusion are reviewed and discussed in detail. Results extract that mass diffusion of liquid di-Hydrogen mono-oxide based nanofluid intensifies for Brownian motion plus Lewis factor. Low reduction in heat transport is assured for passive flow. Rheological analysis of such liquid Di-Hydrogen Mono-Oxide based nanofluidic diffusive flows renders truthful submission in diverse fields of thermal, mechanical and industrial sectors and rheological study and behaviour of such flows are very rare in open literature. Thus we hope our study would advance the thermal energy and diffusivity analysis of nanofluidic transport in most promising way.Graphical abstractImage 1
       
  • Comment on the paper “Numerical assessment of solar energy aspects on 3D
           magneto-Carreau nanofluid: A revised proposed relation, M. Khan, M. Irfan,
           W.A. Khan, Int J Hydrogen Energy 42(2017) 22054–220675”
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Asterios Pantokratoras
       
  • Thermoeconomic analysis of SOFC-GT-VARS-ORC combined power and cooling
           system
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Pranjal Kumar, Onkar Singh The integration of the gas turbine cycle and organic Rankine cycle with the solid oxide fuel cell for power generation is quite prevalent. However, the need is also felt for systems capable of providing power with cooling. Therefore, it is proposed to integrate solid oxide fuel cell with gas turbine cycle, vapour absorption refrigeration system and organic Rankine cycle through the heat available with fluid in the cycle. Here intercooled and reheat gas turbine cycle is integrated with solid oxide fuel cell. Heat rejected in intercooling is used in vapour absorption refrigeration system for cooling. This paper presents thermoeconomic analysis. Results show that the combination of solid oxide fuel cell-gas turbine-vapour absorption refrigeration system-organic Rankine cycle yields increase in efficiency to 68.79% as compared to 58.88% from combined solid oxide fuel cell-gas turbine cycle. The cost of electricity per unit power output is found as 1939.93 $/kW.
       
  • Nanocomposite membrane electrolyte of polyaminobenzene sulfonic acid
           grafted single walled carbon nanotubes with sulfonated polyether ether
           ketone for direct methanol fuel cell
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Avanish Shukla, P. Dhanasekaran, S. Sasikala, N. Nagaraju, Santoshkumar D. Bhat, Vijayamohanan K. Pillai Nanocomposite membranes of sulfonated polyether ether ketone (sPEEK) are prepared with polyaminobenzene sulfonic acid grafted single-walled carbon nanotubes copolymer (PABS-SWCNT) and its zwitterion interactions are studied. The nanocomposite membranes are prepared through solution cast technique using PABS-SWCNT as additive in different weight % (0.1, 0.15, and 0.2) ratio. The additive and nanocomposite membranes are characterized for its surface morphology, composition, thermal and physico-chemical properties. The nanocomposite membrane comprising optimized content of PABS-SWCNT (0.15 wt %) shows improved proton conductivity and reduced methanol crossover resulting in enhanced DMFC peak power density of 150 mW cm−2 in comparison to 110 mW cm−2 for sPEEK and 80 mW cm−2 for Nafion® 117 respectively. The improved durability till 100 h for sPEEK/PABS-SWCNT (0.15 wt %) compared to sPEEK and Nafion-117 confirms its viability in DMFC application.Graphical abstractZwitterion interaction between sulfonic acid and amine groups for sPEEK/PABS-SWCNT (0.15 wt %) nanocomposite membrane facilitate ion transport along with significant restriction in methanol permeability for enhanced direct methanol fuel cell power output.Image 1
       
  • Energy management of a thermally coupled fuel cell system and metal
           hydride tank
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): D. Chabane, M. Ibrahim, F. Harel, A. Djerdir, D. Candusso, O. Elkedim Being produced from renewable energy, hydrogen is one of the most efficient energy carriers of the future. Using metal alloys, hydrogen can be stored and transported at a low cost, in a safe and effective manner. However, most metals react with hydrogen to form a compound called metal hydride (MH). This reaction is an exothermic process, and as a result releases heat. With sufficient heat supply, hydrogen can be released from the as-formed metal hydride. In this work, we propose an integrated power system of a proton exchange membrane fuel cell (PEMFC) together with a hydride tank designed for vehicle use. We investigate different aspects for developing metal hydride tanks and their integration in the PEMFC, using water as the thermal fluid and a FeTi intermetallic compound as the hydrogen storage material. Ground truth simulations show that the annular metal hydride tank meets the hydrogen requirements of the fuel cell, but to the detriment of the operating temperature of the fuel cell (FC).
       
  • Distributed control of a user-on-demand renewable-energy power-source
           system using battery and hydrogen hybrid energy-storage devices
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Daiji Yamashita, Katsuhiko Tsuno, Kayo Koike, Katsushi Fujii, Satoshi Wada, Masakazu Sugiyama A user-on-demand power source based on renewable energy requires storage devices to balance power sources and power demands because of the fluctuation of power sources like solar cells or wind power generators. The role of the control system is defined as two different tasks: allowing a power-flow imbalance between demand and power sources; and balancing the power flow inside the system. Since this control is complicated, many control methods using precise calculation of the power balance have been proposed. An analogue-like distributed control method - named “modified DC-bus signalling” - for controlling a renewable-energy power source without the need for a central processing unit is proposed. The modified DC bus signalling method discussed in this paper is composed of a DC-bus line connected with a battery, water-splitting electrochemical cell, and a fuel cell for hydrogen-energy storage via converters. The proposed control method was demonstrated to be able to control step-like and random changes in input and output power. The battery compensated high-frequency fluctuations in power demand, and the electrochemical cell and fuel cell handled the remaining low-frequency ones, which were matched to their response speeds.
       
  • In-situ formation of ultrafine MgNi3B2 and TiB2 nanoparticles:
           Heterogeneous nucleating and grain coarsening retardant agents for
           magnesium borate in Li–Mg–B–H reactive hydride composite
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Xu Huang, Xuezhang Xiao, Xuancheng Wang, Zhendong Yao, Jiahuan He, Xiulin Fan, Lixin Chen Li–Mg–B–H reactive hydride composite (RHC) has attracted extensive attention over the past decades for its extremely high hydrogen storage capacity (11.5 wt%). But the sluggish desorption kinetics for the second step dehydrogenation reaction need to be further improved. Herein, short rod-like TMTiO3 (TM = Co, Ni) bimetallic oxides, which contain two kinds of transition metal elements, were synthesized and introduced into Li–Mg–B–H RHC for the first time. The NiTiO3 exhibits excellent catalytic effect on the hydrogen desorption kinetic performance of Li–Mg–B–H RHC, and the incubation period for the second step dehydrogenation reaction is eliminated completely by reducing the apparent activation energy for the generation of MgB2 from 296 kJ/mol to 269 kJ/mol. The NiTiO3 doped Li–Mg–B–H RHC can desorb about 9.0 wt% H2 without obvious attenuation of kinetic performance in five cycles. Mechanism analyses reveal that the in-situ generated nano-sized MgNi3B2 and TiB2 species (∼5 nm) both meet the critical value ( 
       
  • Effect of boron substitution on hydrogen storage in Ca/DCV graphene: A
           first-principle study
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Esra Eroglu, Sezgin Aydin, Mehmet Şimşek By using density functional calculations, the effects of boron are investigated in the new hydrogen storage systems, which are formed by substituting different numbers of boron atoms to the first (BDDCV-F) and the second (BDDCV-S) neighbor of double carbon-vacancy (DCV). The layered host systems of boron-substituted DCV graphene are decorated with Ca metal to increase the number of adsorbed H2 molecules. Storing of H2 applications are performed by using two coordinate algorithms as CLICH (Cap-Like Initial Conditions for Hydrogens) and RICH (Rotational Initial Conditions for Hydrogens). The adsorption properties of (1–14) H2 molecules on the constructed systems are examined. The results for BDDCV-F and BDDCV-S boron-doped systems are compared with each other and those of the pure-DCV graphene. To compare the stabilities of BDDCV-systems, the formation energies are calculated. It is concluded from Mulliken charge analysis, the partial density of states and electron density differences that boron substitution process to different locations of the DCV graphene plays a crucial role on the charge transfer between Ca atom the layered host system, ionic nature and the binding properties of the systems. The herringbone-like anisotropic electron density is transformed to isotropic density with the substitution of the boron atoms. Then, the electric field, which is induced by ionic interactions and governs H2 adsorption processes, is changed and intensified along with the sheet. In this way, it can be achieved more effective H2 adsorption. It is seen from the adsorption energies of single- and double-side Ca-decorated systems that the processes of boron-substitution and Ca-decoration can considerably improve the hydrogen storage capability of pure-DCV graphene system, thus (8 and 10)H2 can be adsorbed per Ca-atom in these-type systems. The high gravimetric density of 5.80% is calculated, although larger cell and empty surface states. Moreover, the average desorption temperatures are calculated by using van't Hoff equation, and it is seen that the DCV including boron-substituted systems have closer desorption temperatures to the room temperature than pure-DCV. To check the H2 desorption of the systems, molecular dynamics simulations are performed at 200 K and 300 K temperatures.Graphical abstractImage 1
       
  • Co3O4-loaded ZnO nanofibers for excellent hydrogen
           sensing
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Jae-Hyoung Lee, Jin-Young Kim, Jae-Hun Kim, Ali Mirzaei, Hyoun Woo Kim, Sang Sub Kim The development of outstanding H2-sensing materials is vital for the realization of ecofriendly devices using H2-based energy. ZnO nanofibers have excellent H2-sensing performance. In this study, we synthesized a series of Co3O4-loaded ZnO nanofibers with the formula (1-x)ZnO-xCo3O4 (x = 0.03, 0.05, 0.1, and 0.15, representing the molar ratio of Co3O4) via electrospinning to improve the H2-sensing properties of pristine nanofibers. The sensing results indicated that a sensor with a nominal composition of 0.95ZnO-0.05Co3O4 had the highest response of ~133 to 10 ppm H2 gas, with good H2 selectivity. The main mechanisms underlying the excellent H2-sensing capability of the optimized gas sensor involved ZnO surface/grain boundaries and Co3O4.Graphical abstractChange of potential barriers at ZnO/ZnO homointerfaces in the H2 atmospheres, energy levels of ZnO and Co3O4 after intimate contact, and responses of Co3O4 loaded ZnO to H2, CO, NO2 gases.Image 1
       
  • Structure and hydrogen permeability of V–15Ni alloy
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): A. Baraban, I. Gabis, S. Kozhakhmetov, M. Murzinova, V. Piven, N. Sidorov, I. Sipatov, A. Voyt The structure of the V–15Ni at.% alloy before and after hydrogen permeability tests was investigated by means of XRD and SEM with EDS analysis. We have found that decomposition of supersaturated V-based solid solution with variable Ni content occurred during testing. The volume fraction of the solid solution decreased and the fraction of V3Ni phase increased during permeability testing, thus bringing the alloy to nearly equilibrium. The membrane without Pd coating showed satisfactory hydrogen fluxes with a significant impact of the surface dissociation rate of hydrogen. The shape of hydrogen permeation curves at the downstream side of the membrane at various temperatures was unusual. We attribute it to the high concentration of dissolved hydrogen in the metal lattice and its effect on the hydrogen diffusivity and solubility. In addition, the multiphase structure with non-uniform distribution of nickel both between the phases and within the BCC solid solution (and, consequently, different hydrogen concentrations) may cause dilatation or compressing effect on neighbouring micro-volumes of the alloy.
       
  • Tungsten phosphide nanosheets seamlessly grown on tungsten foils toward
           efficient hydrogen evolution reaction in basic and acidic media
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Qi Qin, Jing Li, Zhengang Guo, Chuanyong Jian, Wei Liu Exploring earth-abundant electrocatalyst with active and stable hydrogen evolution reaction (HER) properties is desirable but still challengeable. Herein, WP2 nanosheets are seamlessly grown on W foil (WP2 NSs/W) through phosphorization of WO3/W. This seamless WP2/W structure is beneficial to reducing the resistance between WP2 and W. Along with the exposed large density of active sites, WP2 NSs/W displays outstanding HER activity with a lower onset potential of about 0 V, a smaller overpotential of 90 mV for the current density of 10 mA/cm2 in basic media. Notably, WP2 NSs/W electrode also catalyzes HER efficiently in acid. The synthesis of WP2 NSs/W provides us a straightforward strategy to gain more cost-effective cathode for HER.Graphical abstractImage 1
       
  • Hydrogen evolution reaction on metallic rhenium in acid media with or
           without methanol
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): J.G. Rivera, R. Garcia-Garcia, E. Coutino-Gonzalez, G. Orozco The cathodic behavior of metallic rhenium in acid media in the presence of absence of methanol was studied in this report. Voltammetry, polarization curve and the impedance spectra were analyzed to determine the behavior of the hydrogen evolution reaction (HER) on polycrystalline rhenium. Only one single charge transfer resistance was observed, and then Randles equivalent circuit fulfills the impedance characteristics of the HER on metallic rhenium. Exchange density current in acid media, with or without methanol, is in the order of magnitude of ∼10−6 Acm−2, and Tafel slope is 63 ± 4.66 mV decade−1. The HER on rhenium proceeds via the Volmer–Heyrovsky reaction mechanism in all solutions. The electrodes were polarized at −0.1 V, and subsequently ex-situ XPS experiments were performed after removal of the electrodes from the electrolyte, with or without methanol. Ex-situ XPS spectra indicate that the atomic surfaces consist of Re0 and suggest a minor formation of Re1+. In addition, XPS spectra suggest that the Volmer–Heyrovsky reaction mechanism generate adsorbed water (H2Oads). These molecules dissociate and generate adsorption of hydroxyl groups (HOads). It is proposed that the HER electroactivity on rhenium is directly strengthened by the interaction between hydrogen ad-atom (Hads) and protonated species, which are different in solutions with or without methanol. The H-bonds formed in sulfuric acid−methanol−water probably required higher energy to surpass the energy barrier in the Heyrovsky reaction. The HOads species can effectively prevent the Hydrogen Oxidation Reaction, the Hydrogen under-potential deposition and methanol adsorption.Graphical abstractImage 1
       
  • ZIF-67-derived Co, Ni and S co-doped N-enriched porous carbon polyhedron
           as an efficient electrocatalyst for oxygen evolution reaction (OER)
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Youjin Zheng, Lei Zhang, Hailiang Huang, Fangbiao Wang, Longcheng Yin, Hongwei Jiang, Dan Wang, Juan Yang, Guihong Zuo Rational fabrication of highly efficient and non-precious metal electrocatalysts for oxygen evolution reaction (OER) are of great importance for renewable energy exploitation to solving the energy crisis and environmental problems. In this paper, we report a novel hybrid nanostructure with Co, Ni and S co-doped N-enriched porous carbon polyhedron (CoNixSy/NCP) via a absorption-pyrolysis-sulfuration strategy derived from zeolitic imidazolate framework-67 (ZIF-67) and explored its electrocatalytic performance for OER. During the synthesis process, Ni2+ is abosrbed within the pores or surface of ZIF-67 and Ni/ZIF-67 can be transformed into the Co and Ni co-doped porous carbon frameworks when it is sulfurazed at 800 °C. NiS2 and NiCo2S4 nanoparticles formed at high temperature are homogeneously dispersed in porous carbon and can activate its electrocatalytic performance. The porous carbon can enhance the electrochemical surface area and charge transfer efficiency. Benefiting from the synergistic effects between highly active NiS2, NiCo2S4, and porous carbon, CoNixSy/NCP electrocatalyst exhibits excellent electrocatalytic performance. The results show that CoNixSy/NCP also exhibits a potential as low as 1.51 V to achieve 10 mA/cm2 current density and extremely stability towards OER. The good electrocatalytic activity of CoNixSy/NCP further suggest its great potential as an efficient eletctocatalyst for sustainable energy applications.
       
  • Facile one-pot aqueous fabrication of interconnected ultrathin PtPbPd
           nanowires as advanced electrocatalysts for ethanol oxidation and oxygen
           reduction reactions
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Jiao-Jiao Duan, Jiu-Ju Feng, Lu Zhang, Junhua Yuan, Qian-Li Zhang, Ai-Jun Wang The catalytic features of Pt-based advanced materials closely correlate with the compositions, morphology and structure. Hence, interconnected trimetallic PtPbPd ultrathin nanowires (PtPbPd NWs) were synthesized by octylphenoxypolyethoxyethanol (NP-40)-mediated one-pot aqueous method, using in-situ generated hydrogen bubbles as the dynamic template. It is found that the types of the precursors and the amount of NP-40 are critical in this synthesis. The as-obtained architectures showed remarkable improvement in the electrocatalytic properties for ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR), surpassing those of commercial Pt/C (20 wt%), homemade PtPd NWs, PtPb NWs and PdPb NWs. Specifically, the mass activity (MA)/specific activity (SA) of PtPbPd NWs (1.20 A mg−1/2.78 mA cm−2) is higher than those of Pt/C (0.86 A mg−1/1.79 mA cm−2) in 0.5 M KOH solution. Furthermore, the as-synthesized catalyst displayed a positive-shift of the onset potential (Eonset, 0.993 V) for ORR over Pt/C (0.895 V) in 0.1 M KOH electrolyte. These scenarios manifest that this approach provides some new valuable guidelines for preparing novel trimetallic nanocatalysts in energy storage and conversion applications.Graphical abstractImage 1
       
  • Construction of carboxyl functional groups and their enhancement effect
           for methanol electrocatalytic oxidation reaction
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Xiaomei Chang, Fang Dong, Zhicheng Tang, Fei Zha In this paper, we investigated the effect of ozone oxidation on properties of commercial carbon black supported platinum (Pt) nanoparticles for the methanol electro-oxidation reaction. The results indicated that the oxygenated functional groups could be introduced on the carbon black evenly with the increase of processing time. Apparently, mainly introduced oxygenated functional group is carboxyl. Platinum nanoparticles could be uniformly immobilized on the surfaces of carbon black treated with ozone, which has significant high electro-catalytic activity and stability for methanol electrooxidation. This phenomenon is attributed to the fact that oxygen-containing groups (mainly for carboxyl functional groups) produced by ozone oxidation are good for improving the dispersion and strengthening the interaction between support and platinum nanoparticles. The ozone oxidation conditions had significant effects on the defects properties of carbon black which showed a positive correlation between the defect levels and methanol electro-oxidation performances. This paper also fully demonstrated the positive relationship between carboxyl functional groups and the performance of methanol electrocatalytic oxidation.Graphical abstractExperimental results demonstrated that ozone oxidation increase the density of oxygenated functional groups on the commercial carbon black, especially the –COOH, which content will increase with the pretreatment time prolonging. The –COOH plays an important role in anchoring the Pt nanoparticles, which is benefit for the dispersion and size distribution of Pt nanoparticles. In addition, the poisoning resistance of catalyst enhanced through the –OH provided by oxygenated functional groups react with COads. The carbon black treated with ozone for 30 min supported Pt (Pt/C-OT-30) with the higher electro-catalytic activity for methanol oxidation.Image 1
       
  • Preparation and characterization of Ni catalysts supported on pillared
           nanoporous bentonite powders for dry reforming reaction
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Bahareh Daroughegi Mofrad, Mehran Rezaei, Majid Hayati-Ashtiani The Ni/pillared-bentonite catalysts with high BET area were synthesized and used in dry reforming reaction. The effects of different parameters such as calcination temperature, OH−/Al3+ ratio, temperature and time of pillaring process and the content of nickel on the textural and catalytic properties of the synthesized catalysts were studied. The results indicated that the 15 wt% Ni catalyst supported on pillared bentonite prepared under specified conditions (OH−/Al3+ = 2.2, pillaring temperature of 40 °C and pillaring time of 3 h) possessed the highest BET area (90.80 m2/g). Also, this catalyst possessed higher catalytic activity and stability with lower amount of deposited carbon in comparison to other prepared catalysts in methane reforming with CO2.
       
  • Doping sp-hybridized B atoms in graphyne supported single cobalt atoms for
           hydrogen evolution electrocatalysis
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Xiaoping Gao, Yanan Zhou, Zhiwen Cheng, Yujia Tan, Shiqiang Liu, Zhemin Shen Electrochemical water splitting to hydrogen is considered as a promising approach for clean H2 production. However, developing highly active and inexpensive electrocatalysts is an important part of the hydrogen evolution reaction (HER). Herein, we present a multifaceted atom (sp2-and sp-hybridized boron) doping strategy to directly fine-modify the electronic structures of the active site and the HER performance by the density functional theory calculations. It is found that the binding strength between the Co atom and the B doped graphyne nanosheets can be enhanced by doping B atoms. Meanwhile, the Co@B1-GY and Co@B2-GY catalysts exhibit good thermodynamic stability and high HER catalytic activity. Interestingly, the Co@B2-GY catalyst has an ideal HER performance with the ΔGH* value of −0.004 eV. Moreover, the d-band center of the Co atoms is upshifted by the sp2-or sp-hybridized B dopants. The concentrations of the sp-hybridized B atoms have a positive effect on the electrons transformation of the Co atoms. The interaction between the H and Co atoms becomes strong with the increase of the concentrations of the sp-hybridized B atoms and thus the corresponding catalysts show sluggish HER kinetics. This investigation could provide useful guidance for the experimental groups to directly and continuously control the catalytic activity towards HER by precisely doping multifaceted atoms.Graphical abstractThe sp-hybridized B atoms doped Co@GY (Co@B2-GY) catalyst delivers excellent catalytic activity toward HER with the calculated hydrogen adsorption free energy of −0.004 eV.Image 1
       
  • 2D-2D heterostructured CdS–CoP photocatalysts for efficient H2 evolution
           under visible light irradiation
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Qixiao Gai, Xiaochun Zheng, Wenjun Liu, Quanli Dong, Yingying Wang, Renxi Gao, Shoutian Ren Visible-light photocatalytic water splitting for hydrogen evolution has attracted tremendous attention in past decades, but it still suffers from low solar-hydrogen conversion efficiency. In this paper, two-dimensional (2D) CdS was synthesized by the hydrothermal method, and 2D CoP nanosheets were synthesized by successive hydrothermal, oxidation and phosphodation process. Then 2D-2D CdS–CoP photocatalysts were formed by ultrasonically dispersing the mixed solution of CdS and CoP, and their heterostructure was confirmed by transmission electron microscopy, X-ray photoelectron spectroscopy, fluorescence spectrometer and so on. CdS–CoP with 2% CoP loading amounts exhibits a maximum photocatalytic performance of 56.3 mmolg−1h−1 under visible light irradiation, which is 11.3 times as high as bare CdS. The enhanced photocatalytic performance of CdS–CoP should be due to the following two points: (1) high catalytic activity of CoP; (2) highly efficient separation and transfer of electron-hole pairs photogenerated in CdS due to the synthesized 2D-2D heterostructure.Graphical abstractImage 1
       
  • Preparation of mesoporous nanocrystalline CuO–ZnO–Al2O3 catalysts for
           the H2 purification using catalytic preferential oxidation of CO (CO-PROX)
           
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Mahmood Andache, Ali Nemati Kharat, Mehran Rezaei In this article, CuO–ZnO–Al2O3 catalysts with various copper contents were synthesized by a co-precipitation method and employed for the elimination of carbon monoxide from a mixture of 97% H2, 1% CO and 2% O2 at atmospheric pressure via carbon monoxide preferential oxidation (CO-PROX). The influence of the copper and zinc contents on the physicochemical characteristics and catalytic performance was investigated. The prepared samples were characterized using the N2 adsorption-desorption (BET), X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM) and temperature programmed reduction (TPR) techniques. The increment in CuO loading improved the activity of CuO–ZnO–Al2O3 catalysts for CO oxidation reaction. Among the prepared catalysts, the 50%CuO-3% ZnO-47% Al2O3 catalyst calcined at 400 °C with a BET area of 82.3 m2/g exhibited the best activity with a CO conversion of 88.9% at 125 °C. The effects of the presence of CO2 and H2O in the reaction feed stream and gas hourly space velocity (GHSV) were also studied.
       
  • The effect of H2 pressure on the reduction kinetics of hematite
           at low temperatures
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): N. Thüns, B.M. Krooss, Q. Zhang, H. Stanjek Two novel experimental approaches to study the reduction kinetics of hematite (Fe2O3) by hydrogen at low temperatures are presented. Experiments were carried out in batch reactors at 200 °C and at H2 pressures of 3, 6 and 8 MPa, respectively. Complementary experiments were performed in an open system at atmospheric H2 pressure and 270 °C. Here the reaction product water in the effluent gas was quantified in short intervals by gas chromatography (Thermal Conductivity Detector; TCD). The mineralogical changes over time were assessed by X-ray powder diffraction with Rietveld analysis, scanning electron microscopy and the measurement of magnetic hysteresis loops.While the phase conversions of hematite → magnetite → Fe(0) are occurring consecutively in open systems (p(H2)≈0.1 MPa), in closed systems at elevated H2 pressure both reduction products are observed simultaneously. At 200 °C the reaction rates are about one order of magnitude lower than at 270 °C. The conversion rate of magnetite → Fe(0) is highly sensitive to the hydrogen pressure with a rate increase by a factor of 2.5 upon an increase of p(H2) from 3 to 6 MPa and by 2.0 between 6 and 8 MPa.
       
  • A metal-organic framework-derived Fe–N–C electrocatalyst with highly
           dispersed Fe–Nx towards oxygen reduction reaction
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Xiangkun Zhang, Xiaobo Huang, Wenhui Hu, Yongmin Huang Metal and nitrogen co-doped catalysts have been promising alternatives to platinum group metal (PGM) catalysts for oxygen reduction reaction (ORR) over the past few decades. Herein, we have synthesized an efficient Fe–N–C catalyst by the co-calcination of NH2-MIL-101@PDA and melamine. The best Fe–N–C shows a positive half-wave potential of 0.844 V, which is 14 mV higher than that of Pt/C catalyst, as well as superior methanol resistance and long-term durability in alkaline electrolyte. In addition, Fe–N–C also exhibits pronounced catalytic activity and a direct 4e− reaction pathway in acid electrolyte. We ascribed the excellent ORR performance of Fe–N–C to its crumpled structure, large specific surface area (584.6 m2 g−1) and high content of Fe-Nx sites (1.22 at. %). This study provides a simple way for the fabrication of excellent PGM-free ORR catalysts.Graphical abstractImage 1
       
  • CdS@3DOM TiO2–ZrO2 composites with high efficiency photocatalytic
           properties prepared by template method combined with in-situ self-assembly
           technology
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Yu Tian, Li Li, Yuting Hao, Xumei Song, Fengyan Ma, Lixian Wang The three-dimensional ordered macroporous composites CdS@3DOM TiO2–ZrO2 were prepared by the template method combined with in-situ self-assembly technique. The composition, structure, morphology and surface physicochemical properties of composites were characterized by XRD, XPS, UV–vis/DRS, SEM, TEM, HR-TEM, PL, N2 adsorption−desorption and EIS tests. The results show that CdS@3DOM TiO2–ZrO2 composites have strong light absorption in the visible region. And the in-situ self-assembled CdS particles in the composite do not destroy the excellent open pore structure, and the introduction of CdS further improves the charge separation efficiency. The results of multi-mode photocatalytic degradation of CdS@3DOM TiO2–ZrO2 show that the photocatalytic properties of CdS@3DOM TiO2–ZrO2 composites are obviously enhanced. In addition, the hydrogen production of CdS@3DOM TiO2–ZrO2 can reach 1323 μmol/g (8 h) in the photolysis of water experiment, which is 94.5 times than that of the commercially available P25, showing excellent photocatalytic performance.Graphical abstractCdS@3DOM TiO2–ZrO2 composites prepared by the template method combined with in-situ self-assembly technology show an open and stable three-dimensional ordered macroporous structure, as well as excellent photocatalytic degradation and water splitting ability.Image 1
       
  • In situ self-assembly synthesis of carbon self-doped graphite carbon
           nitride hexagonal tubes with enhanced photocatalytic hydrogen evolution
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Yun Yang, Jinzhe Liu, Chencheng Zhou, Peilin Zhang, Shouzhi Guo, Shuo Li, Xingjun Meng, Yue Lu, Huajiang Xu, Haojie Ma, Luyang Chen Novel carbon self-doped graphitic carbon nitride tube (denoted as C-CNT) was fabricated by the means of a facile in situ solvothermal method with melamine and glucose as precursor and additive, respectively. The C-CNT not only remained unique hexagonal tubular structure obtained from supramolecular self-assembly method, but also introduced aromatic carbon into CN framework under the glucose-assisted hydrothermal conditions. The as-prepared C-CNT exposed abundant nitrogen defects and dramatically improved the valid separation of photoexcited charge carriers, hence achieving excellent photocatalytic hydrogen evolution activity (32.3 μmol h−1, λ > 420 nm), which was up to 4.24 and 12-folds higher than pristine carbon nitride tube (CNT) and traditional bulk counterpart (BCN), respectively. Therefore, this work highlights an assisted hydrothermal approach to successfully prepare carbon-rich graphitic carbon nitride with hexagonal tubular structure.
       
  • Copper zinc oxide heterostructure nanoflowers for hydrogen evolution
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Szymon Wojtyła, Tomasz Baran The nanoflowers copper-zinc oxide (CZO) heterostructure has been prepared using the hydrothermal method. As it exhibits a low band gap energy the material may absorb large amounts of natural sunlight. Under visible light irradiation, CZO showed signs of activity towards hydrogen production in the two conditions, which are: i) the condition of photocatalytic reaction with light as the only energy source, in the presence of a sacrificial electron donor and; ii) the photoelectrochemical conditions when the material was deposited onto biased conductive support, in pure water. The improved activity and stability of CZO results from a mutual charge transfer between copper oxide and zinc oxide. Therefore we can suggest that under illumination photogenerated electrons from the conduction band of copper oxide migrate to conduction band of zinc oxide, while holes migrate in the opposite direction, thus improving the charge separation and lowering the rate of unfavourable recombination.Graphical abstractImage 1
       
  • On the role of size controlled Pt particles in nanostructured
           Pt-containing Al2O3 catalysts for partial oxidation of methane
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Jesuina C.S. Araújo, Lais F. Oton, Alcineia C. Oliveira, Rossano Lang, Larissa Otubo, José M.C. Bueno The effect of the Pt loadings and particles sizes on the stability of Pt(x wt%)/Al2O3 catalysts were investigated in the partial oxidation of methane (POM) reaction. The Al2O3 support was prepared by sol-gel method and different Pt loadings, varying from 0.5 to 2.0 wt% were incorporated to alumina through the incipient wetness impregnation method. The physicochemical features of the catalysts were determined by XRD, ICP-OES, Nitrogen-sorption, UV–Visible, H2-TPR, CO-DRIFTS, SEM-EDS, XPS and HRTEM techniques. The metal dispersion was evaluated in the cyclohexane dehydrogenation reaction. Lower Pt loadings resulted in well dispersed Pto nanoparticles with an enhanced activity in cyclohexane dehydrogenation and POM reactions. With increasing Pt loading to 2.0 wt%, the Pt nanoparticles of the Pt(2.0 wt%)/Al2O3 showed a methane conversion of 63% in 24 h of time on stream, and the catalyst was very selective to H2 and CO. Based on the HRTEM, XPS and Raman spectroscopy techniques, an increment in the Pt loadings evidenced an enrichment of Pto clusters on the surface, however, no heavy carbon deposits formation was observed.Graphical abstractImage 1
       
  • Unsupported cobalt nanoparticles as catalysts: Effect of preparation
           method on catalytic activity in CO2 methanation and ethanol steam
           reforming
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Paola Riani, Gabriella Garbarino, Tullio Cavattoni, Fabio Canepa, Guido Busca Cobalt nanoparticles (10–50 nm) have been prepared by different procedures. Materials produced by reduction of cobalt chloride and nitrate by NaBH4 contain B impurities as borates or borides. They are very active in ethanol steam reforming at 673–773 K with up to 85% hydrogen yield at 773 K. B-free samples obtained by thermal decomposition of Co2(CO)8 is slightly less selective to hydrogen, due to its activity in ethanol cracking to methane which is probably poisoned by boron impurities on the other catalysts. B-containing samples are inactive in CO2 methanation and have weak activity in the reverse water gas shift (RWGS) reaction to CO. B-free nanoparticles have high activity in both CO2 methanation and RWGS. However, methanation activity is reduced fast by growth of encapsulating carbon species. These particles however also show quite stable activity in RWGS to CO, attributed to CoO impurities.Graphical abstractImage 1
       
  • Remarkable charge separation and photocatalytic efficiency enhancement
           through TiO2(B)/anatase hetrophase junctions of TiO2 nanobelts
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Xuesong Xu, Yichen Guo, Zhangqian Liang, Hongzhi Cui, Jian Tian Light harvesting and charge separation are both significant to the photocatalysis, but it is challenging to synchronously realize both in a single-component material. The surface coarsened TiO2 nanobelts with TiO2(B)/anatase hetrophase junctions and large BET surface area are prepared via a hydrothermal/annealing method. The presence of surface coarsened nanobelt structure enhances the light absorption through reflection/refraction of light. The TiO2(B)/anatase hetrophase junctions can efficiently promote the separation of photoinduced electrons and holes pairs and therefore decrease the charge recombination. The large BET surface area provides abundant active sites for the absorption and diffusion of reactants. As a consequence, the obtained TiO2 nanobelts exhibit an enhanced photocatalytic H2 evolution activity at the optimal annealing temperature (450 °C) with Pt as co-catalysts (0.786 mmol h−1g−1), exceeding that of pure anatase TiO2 nanobelts (TiO2 nanobelts-600 °C, 0.265 mmol h−1g−1). Interestingly, TiO2 nanobelts-450 °C still show a high hydrogen evolution rate of 0.601 mmol h−1g−1 in the absence of co-catalysts.Graphical abstractImage 1
       
  • Effect of ammonia concentration on hythane (H2 and CH4) production in
           two-phase anaerobic digestion
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Ahmed M. Mustafa, Xiang Chen, Hongjian Lin, Kuichuan Sheng Co-production of hydrogen and methane by two-phase anaerobic digestion (AD) may offer a sustainable solution for the centralized treatment of food waste (FW), while ammonia accumulation is potentially encountered. A mesophilic two-phase AD was investigated for hydrogen and methane production from FW at varying ammonia concentrations. The process achieved a hydrogen yield of 47.7 mL/g VS and a methane yield of 335 mL/g VS by optimizing the organic loading rate (OLR) and recirculation ratio. Total ammonia nitrogen (TAN) concentration of 4044 mg/L corresponded to a threshold in the hydrogen reactor, above which ammonia would initiate inhibition of hydrogenogenesis and acidogenesis. Methane yield was recovered in the methane reactor after acute inhibiting effects of TAN below 5800 mg/L, while TAN above 6200 mg/L caused chronic inhibition of methanogens. Adjusting hydraulic retention time (HRT) and recirculation ratio in hydrogen and methane reactors reduced TAN to 960 and 2105 mg/L respectively, resulting in successful recovery was achieved in the hydrogen reactor but not in the methane reactor. The two-phase AD for methane and hydrogen production can be a promising solution for ammonia accumulation in AD from FW.
       
  • Co-generation of hydrogen and electricity from biodiesel process effluents
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Sanath Kondaveeti, In-Won Kim, Sachin Otari, Sanjay K.S. Patel, Raviteja Pagolu, Venkatramana Losetty, Vipin Chandra Kalia, Jung-Kul Lee In this study, we apply a short-term voltage (0.2–0.8 V) to both crude glycerol (CG) and an anaerobic digestion (AD) effluent in a single-chamber microbial fuel cell (MFC) for power production. This improves the bioelectrogenesis in both CG (in MFC-1) and the AD effluent (in MFC-2), but higher power generation is attained in MFC-2. The use of domestic and synthetic wastewaters in the AD process leads to the generation of 195 and 350 mL H2/L-medium, respectively. MFC-2 performs better than MFC-1 in terms of both voltage generation and chemical oxygen demand (COD) reduction. The application of 0.8 V yields a power density of 311 mW/m2 (1.94 times higher than that of the control (160 mW/m2)). In addition, MFC-2 exhibits a 70% COD removal at 0.8 V, which decreases to 56% at 0.2 V. Thus, the application of a short-term voltage in MFC can stimulate both bioelectrogenesis and COD removal.
       
  • Hydrogen production from acidogenic food waste fermentation using
           untreated inoculum: Effect of substrate concentrations
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Yunhui Pu, Jialing Tang, Xiaochang C. Wang, Yisong Hu, Jin Huang, Yonggang Zeng, Huu Hao Ngo, Yuyou Li The effect of substrate concentrations (0, 7.5, 15, 22.5, 30, and 37.5 g-VS/L) on hydrogen production from heat-treated and fresh food waste (FW) using untreated inoculums was investigated in this work. The highest hydrogen yield (75.3 mL/g-VS) was obtained with heat-treated FW at 15 g-VS/L. Lower substrate content could not provide enough organic matter for hydrogen fermentation, while higher substrate concentrations shifted the metabolic pathways from hydrogen fermentation to lactic acid fermentation by enriching the lactic acid bacteria (LAB), which lowered the slurry pH and decreased enzyme activity, resulting in a lower chemical oxygen demand (COD), volatile solid (VS), carbohydrate removal rate, and hydrogen yield. Compared with fresh FW, heat-treated FW is preferred for biohydrogen process with acetate as the main organic product. Additionally, at the optimal concentration (15 g-VS/L) using fresh FW, lactic acid is first accumulated and then degraded to produce hydrogen with butyrate as the main metabolite.
       
  • Hydrogen production in reactors: The influence of organic loading rate,
           inoculum and support material
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Rogério Vilela, Flávia Talarico Saia, Gustavo Bueno Gregoracci, Rubens Duarte, Pedro Andrade, Bas van der Zaan, Alette Langenhoff, Márcia H.R. Z. Damianovic Hydrogen production was evaluated in two thermophilic structured bed (USBR) reactors. USBR1was inoculated with auto-fermented sugarcane vinasse and low-density polyethylene cubes were used as support material. USBR2 was inoculated with anaerobic sludge from an up-flow anaerobic sludge blanket (UASB) reactor treating sugarcane vinasse, and polyurethane foam matrices was used as support material. The reactors were operated in parallel with sugar cane molasses at organic loading rate (OLR) from 30 to 120 g COD L−1d−1 during 45 days. Hydrogen production was detected during the whole operational period, with maximum values of 1123 mL H2 d−1L−1 and 2041 mL H2 d−1L−1 for USBR1 and USBR2, respectively. The number of gene copies encoding for Fe-hydrogenase was higher in USBR2 for all OLR applied. DNA sequences related to Thermoanaerobacterium and Clostridium sensu stricto were predominant in USBR1. In USBR2, in addition to these microorganisms, Lactobacillus, Pseudomonas and Thermotuga, and sequences with low frequency of abundance (
       
  • Enhancing continuous hydrogen production by photosynthetic bacterial
           biofilm formation within an alveolar panel photobioreactor
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Chuan Zhang, Shuaishuai Ma, Guihong Wang, YiPing Guo Photofermentative hydrogen production at higher rate is desirable to make the technology of biological hydrogen production in practical application. An easy fabricating alveolar panel photobioreactor with high surface-to-volume ratio was proposed in this study to realize biofilm formation and used for developing a continuous bioprocess of hydrogen production. Effects of key operating parameters, i.e. variation in intensity of incident light, initial concentration of carbon substrate and flow rate on the rate of nitrogenase-based H2 production were investigated using response surface methodology (RSM) with Box-Behnken design. Surface and contour plots of the fitted regression model revealed that optimum H2 production rate of 57.6 mL/h/L was obtained at 125.9 μE/m2/s incident light intensity at 590 nm light wavelength, 52.4 mM initial concentration of carbon substrate and 209 mL/h flow rate. Regular groove surfaces within this photobioreactor were considered to have mutual effects on enhancement of continuous hydrogen production by enriching bacterial cell density, enhancing mass transfer of carbon substrate to facilitate release of protons and electrons, enhancing removal of molecular H2, and uniformly distribution of incident light within the photobioreactor for sufficient conversion into ATPs.
       
  • Modeling of a direct solar receiver reactor for decomposition of sulfuric
           acid in thermochemical hydrogen production cycles
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Claudio Corgnale, Zhiwen Ma, Sirivatch Shimpalee Hydrogen production thermochemical cycles, based on the recirculation of sulfur-based compounds, are among the best suited processes to produce hydrogen using concentrated solar power. The sulfuric acid decomposition section is common to each sulfur-based cycle and represents one of the fundamental steps. A novel direct solar receiver-reactor concept is conceived, conceptually designed and simulated. A detailed transport phenomena model, including mass, energy and momentum balance expressions as well as suitable decomposition kinetics, is described adopting a finite volume approach. A single unit reactor is simulated with an inlet flow rate of 0.28 kg/s (corresponding to a production of approximately 11 kgH2/h in a Hybrid Sulfur process) and a direct solar irradiation at a constant power of 143 kW/m2. Results, obtained for the high temperature catalytic decomposition of SO3 into SO2 and O2, demonstrate the effectiveness of the proposed concept, operating at pressures of 14 bar. A maximum temperature of 879 °C is achieved in the reactor body, with a corresponding average SO2 mass fraction of 27.8%. The overall pressure drop value is 1.7 bar. The reactor allows the SO3 decomposition into SO2 and O2 to be realized effectively, requiring an external high temperature solar power input of 123.6 kJ/molSO2 (i.e. 123.6 kJ/molH2).
       
  • Electrochemical investigation of novel reference electrode Ni/Ni(OH)₂ in
           comparison with silver and platinum inert quasi-reference electrodes for
           electrolysis in eutectic molten hydroxide
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Nawar K. Al-Shara, Farooq Sher, Aqsa Yaqoob, George Z. Chen An efficient and green energy carrier hydrogen (H2) generation via water splitting reaction has become a major area of focus to meet the demand of clean and sustainable energy sources. In this research, the splitting steam via eutectic molten hydroxide (NaOH–KOH; 49–51 mol%) electrolysis for hydrogen gas production has been electrochemically investigated at 250–300 °C. Three types of reference electrodes such as a high-temperature mullite membrane Ni/Ni(OH)2, quasi-silver and quasi-platinum types were used. The primary purpose of this electrode investigation was to find a suitable, stable, reproducible and reusable reference electrode in a molten hydroxide electrolyte. Cyclic voltammetry was performed to examine the effect on reaction kinetics and stability to control the working electrode at different scan rate and molten salt temperature. The effect of introducing water to the eutectic molten hydroxide via the Ar gas stream was also investigated. When the potential scan rate was changed from 50 to 150 mV s−1, the reduction current for the platinum wire working electrode was not changed with newly prepared nickel reference electrode that designates its stability and reproducibility. Furthermore, increasing the operating temperature of molten hydroxides from 250 to 300 °C the reduction potential of the prepared nickel reference electrode is slightly positive shifted about 0.02 V. This suggests that it has good stability with temperature variations. The prepared nickel and Pt reference electrode exhibited stable and reliable cyclic voltammetry results with and without the presence of steam in the eutectic molten hydroxide while Ag reference electrode exposed positive shifts of up to 0.1 V in the reduction potential. The designed reference electrode had a more stable and effective performance towards controlling the platinum working electrode as compared to the other quasi-reference electrodes. Consequently, splitting steam via molten hydroxides for hydrogen has shown a promising alternative to current technology for hydrogen production that can be used for thermal and electricity generation.Graphical abstractImage 1
       
  • Easily-prepared bimetallic metal phosphides as high-performance electrode
           materials for asymmetric supercapacitor and hydrogen evolution reaction
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Jianxia Gou, Yunmei Du, Shengli Xie, Yanru Liu, Xiangjin Kong Transition metal phosphides are very attractive because of the remarkable performance in energy storage and conversion. Herein, a series of bimetallic phosphides are synthesized through a one-step solid-state reaction. The obtained bimetallic phosphides show outstanding properties as supercapacitor electrode materials. Results show that the incorporation of secondary metal into phosphides tunes composition, electronic structure and then the electrochemical performance. And electrochemical properties are closely associated with the secondary metal content. Notably, the obtained NiCoP shows the best performance with 2011 F g−1 at 1 A g−1. And an asymmetric supercapacitor (ASC) based on NiCoP shows energy density of 47.6 W h kg−1, along with 90.5% of capacitance maintained after 10000 cycles. In addition, the NiCoP also possesses great performance toward hydrogen evolution reaction (HER), which displays the lowest potential of 0.221 V vs. RHE and 0.173 V vs. RHE at 10 mA cm−2 in 0.5 M H2SO4 as well as 1.0 M KOH, respectively. The excellent properties may result from the enhanced electrical conductivity, synergistic effects among metal elements and the increased local electrical dipole. The regulation of electronic structure through introduction of secondary metal atom sheds considerable light on realization and preparation of the bimetallic transition metal compounds as electrode materials.
       
  • Enhanced properties of LiFePO4/C cathode materials co-doped with V and F
           ions via high-temperature ball milling route
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Xuetian Li, Lina Yu, Yonghui Cui, Axiang Li, Hongmei Shao, Zhongcai Shao, Wei Zhang, Zhongbao Shao V and F ions co-doped LiFePO4/C (LFP-VF) cathode material is prepared via high-temperature ball milling route. Effects of V and F ions co-doped on the structure, morphology and electrochemical property of LiFePO4 are investigated in this work, and some analysis of X-ray diffraction, scanning electron microscope, transmission electron microscope, charge-discharge tests, electrochemical impedance spectroscopy and cyclic voltammetry are employed. The results confirm that prepared LFP-VF exhibits excellent electrochemical property. The specific capacities are 165.7 (0.1 C), 154.9 (1.0 C) and 124.9 (10 C) mAhg−1. Moreover, over 500 cycles at 1.0 C-rate, the discharge capacity is 148.2 mAhg−1 with a capacity retention rate of 95.7%. Experimental results indicate that the electrochemical performance of LiFePO4 can be greatly enhanced by co-doping with V and F ions.
       
  • Detecting and modeling oxygen bubble evolution and detachment in proton
           exchange membrane water electrolyzers
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): J.C. Garcia-Navarro, M. Schulze, K.A. Friedrich In this work, we discuss the effect of multiphase flow dynamics on the performance of a PEM electrolyzer. We obtained images of a flow system consisting of O2 and water at two stages of gas production: gas evolution via bubbles and gas exiting through the channels of a flow field. We processed the obtained images of bubble evolution with a MATLAB-based bubble detection and counting algorithm, and we found that the bubble detachment sizes remained invariant within a water flow range between 0.07 and 4.65 l h−1. We measured an average bubble detachment radius of 22.47 μm. We applied a bubble force balance developed by van Helden et al. [1] to model the observed effect of water flow on bubble evolution, and we found that the bubble detachment radius is a weak function of water flow when the water flow is below 60 l h−1. We found that the variables that affect the bubble detachment radius the strongest were the electrode's hydrophobicity and pore size.
       
  • Electrochemical characteristics of (PEM) electrolyzer under influence of
           charge transfer coefficient
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Alhassan Salami Tijani, M.F. Abdul Ghani, A.H. Abdol Rahim, Ibrahim Kolawole Muritala, Fatin Athirah Binti Mazlan In this paper a systematic understanding of how charge transfer coefficient (CTC) and exchange current density contributes to polarization and performance characteristics of PEM electrolyzer has been investigated. A detail discussion on the role played by charge transfer coefficient in influencing operating characteristics of PEM electrolyzer has been presented in this article. Experimental data was used to validate the accuracy of the finding of this research. Main interesting insights are that at CTC of 0.5 and 0.2 for anode and cathode respectively, the operating voltage at 1 A/cm2 (current density) is around 2.0 V, however at CTC of 2 and 0.5 for anode and cathode respectively, there was significant drop in operating voltage up to 1.62 V with current density of 1 A/cm2, this accounts for about 27% reduction in operating voltage. It was also discovered that with exchange current density of 1 × 10–7 for a Pt–Ir anode based electrode the CTC value for anode increase from 0.27 to 0.34 at current density of 0.05 A/cm2 to 2 A/cm2 respectively, whereas for Pt cathode catalyst with exchange current density of 1.8 × 10–3 the CTC values for cathode increased from 0.02 to 0.14 at current density of 0.1 A/cm2 to 2 A/cm2 respectively, these findings were in agreement with the CTC values reported in the literature.Graphical abstractImage 1
       
  • Mn-rich SmBaCo0.5Mn1.5O5+δ double perovskite cathode material for SOFCs
    • Abstract: Publication date: 18 October 2019Source: International Journal of Hydrogen Energy, Volume 44, Issue 50Author(s): Anna Olszewska, Yang Zhang, Zhihong Du, Mateusz Marzec, Konrad Świerczek, Hailei Zhao, Bogdan Dabrowski SmBaCo0.5Mn1.5O5+δ oxide with Sm-Ba cation-ordered perovskite-type structure is synthesized and examined in relation to whole RBaCo0.5Mn1.5O5+δ series (R: selected rare earth elements). Presence of Sm and 3:1 ratio of Mn to Co allows to balance physicochemical properties of the composition, with moderate thermal expansion coefficient value of 18.70(1)·10−6 K−1 in 300–900 °C range, high concentration of disordered oxygen vacancies in 600–900 °C range (δ = 0.16 at 900 °C), and good transport properties with electrical conductivity reaching 33 S cm−1 at 900 °C in air. Consequently, the compound enables to manufacture catalytically-active cathode, with good electrochemical performance measured for the electrolyte-supported laboratory-scale solid oxide fuel cell with Ni-Gd1.9Ce0.1O2-δ La0.4Ce0.6O2-δ La0.8Sr0.2Ga0.8Mg0.2O3-δ SmBaCo0.5Mn1.5O5+δ configuration, for which 1060 mW cm−2 power density is observed at 900 °C. Furthermore, the tested symmetrical SmBaCo0.5Mn1.5O5+δ La0.8Sr0.2Ga0.8Mg0.2O3-δ SmBaCo0.5Mn1.5O5+δ cell delivers 377 mW cm−2 power density at 850 °C, which is a promising result.
       
  • Improved hydrogen storage properties of Mg/MgH2 thanks to the addition of
           nickel hydride complex precursors
    • Abstract: Publication date: Available online 11 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Basile Galey, Aline Auroux, Sylviane Sabo-Etienne, Sameh Dhaher, Mary Grellier, Georgeta Postole In order to improve the hydrogenation/dehydrogenation properties of the Mg/MgH2 system, the nickel hydride complex NiHCl(P(C6H11)3)2 has been added in different amounts to MgH2 by planetary ball milling. The hydrogen storage properties of the formed composites were studied by different thermal analyses methods (temperature programmed desorption, calorimetric and pressure-composition-temperature analyses). The optimal amount of the nickel complex precursor was found to be of 20 wt%. It allows to homogeneously disperse 1.8 wt% of nickel active species at the surface of the Mg/MgH2 particles. After the decomposition of the complex during MgH2 dehydrogenation, the formed composite is stable upon cycling at low temperature. It can release hydrogen at 200 °C and absorb 6.3 wt% of H2 at 100 °C in less than 1 h. The significantly enhanced H2 storage properties are due to the impact of the highly dispersed nickel on both the kinetics and thermodynamics of the Mg/MgH2 system. The hydrogenation and dehydrogenation enthalpies were found to be of −65 and 63 kJ/mol H2 respectively (±75 kJ/mol H2 for pure Mg/MgH2) and the calculated apparent activation energies of the hydrogen uptake and release processes are of 22 and 127 kJ/mol H2 respectively (88 and 176 kJ/mol H2 for pure Mg/MgH2). The change in the thermodynamics observed in the formed composite is likely to be due to the formation of a Mg0.992Ni0.008 phase during dehydrogenation/hydrogenation cycling. The impact of another hydride nickel precursor in which chloride has been replaced by a borohydride ligand, namely NiH(BH4)(P(C6H11)3)2, is also reported.Graphical abstractImage 1
       
  • Liquid hydrogen releases show dense gas behavior
    • Abstract: Publication date: Available online 11 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Olav Roald Hansen The number of maritime initiatives with hydrogen as alternative fuel is increasing. While most of the early projects aim at using compressed hydrogen the use of liquid hydrogen (LH2) is more practical and is expected to become more attractive for implementation on larger vessels due to more efficient storage, bunkering and handling of the fuel. In the industry there seems to be some confusion regarding the behavior of LH2 releases, in particular whether a release into air will behave like a dense gas or a buoyant gas. The understanding of this aspect is critical to optimize design with regard to safety. This article will explain the expected behavior of LH2 releases and discuss expected hazard distances from LH2 releases relative to gaseous hydrogen releases and LNG. Some other safety concerns of LH2, like indoor releases, releases from vent masts, potential BLEVEs and RPTs are also discussed. The article explains why a higher safety standard may be required when designing hydrogen fueled vessels than for existing LNG fueled vessels.
       
  • Influence of machining parameters on surface roughness and susceptibility
           to hydrogen embrittlement of austenitic stainless steels
    • Abstract: Publication date: Available online 10 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Lucas Renato Queiroga, Gisele Fernanda Marcolino, Matheus Santos, Gabriele Rodrigues, Carlos Eduardo dos Santos, Pedro Brito In the present work, an investigation on the susceptibility to hydrogen embrittlement of AISI 304 and 310 austenitic stainless steels was performed. The hydrogen embrittlement process leads to degradation of mechanical properties and can be accelerated by the presence of surface defects combined with elevated surface hardness. Tensile test specimens of the selected materials were machined by turning with different cutting parameters in order to create variations in surface finish conditions. The samples thus prepared were submitted to tensile tests before and after hydrogen permeation by cathodic charging. Regarding the AISI 304 steel, it was possible to notice that the presence of strain-induced martensite on the material surface led to severe hydrogen embrittlement. In the case of the AISI 310 steel, due to its higher nickel amount, no martensite formation could be detected, and this steel was found to be less susceptible to embrittlement in the tested conditions.
       
  • Hydrogen evolution reaction of metal di-chalcogenides: ZrS2, ZrSe2 and
           Janus ZrSSe
    • Abstract: Publication date: Available online 10 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Narayan N. Som, Prafulla K. Jha Transition metal di-chalcogenides with stoichiometry MX2 (M: Mo, V, W, Pt and X: S, Se) are considered as one of the non-precious and effective catalysts for the production of clean hydrogen energy via water-splitting mechanism. The major drawback of these materials is their inactive basal plane as compared to their edge sites. Recently, Janus MoSSe-a novel sandwiched structure has been synthesized and predicted theoretically to obtain increased catalytic activity by applying strain, external electric field and by creating vacancy. In this work, we have used state-of-the-art density functional theory with dispersion correction (DFT-D3) to study the catalytic activity for hydrogen evolution reaction (HER) of ZrS2, ZrSe2 and Janus ZrSSe. From our calculations, we conclude that among these three systems, the Janus ZrSSe (ΔG=1.19eV;ΔG:Gibbsfreeenergy) is a good catalyst and can be utilized for HER at edge site. Janus ZrSSe shows enhanced catalytic activity at S-edge as compared to its basal plane and Se-edge site; whereas ZrSe2 shows good catalytic activity at Se-edge rather than at the basal plane. The ZrS2 shows good catalytic activity at S-edge. Further, we have doped Nb, Pt and W atoms in ZrS2, ZrSe2 and Janus ZrSSe to see their effect on catalytic activity of pristine compounds and found that the Nb-doped ZrSe2 shows good catalytic activity for HER and is best among all considered systems with ΔG=0.63eV followed by Pt-doped ZrS2. This study provides a theoretical basis for future application of ZrS2, ZrSe2 and Janus ZrSSe based catalysts for HER.Graphical abstractImage 1
       
  • Performance and long-term durability of direct-methane flat-tube solid
           oxide fuel cells with symmetric double-sided cathodes
    • Abstract: Publication date: Available online 10 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Hua Zhang, Wu Liu, Yuanhui Wang, Jianxin Wang, Jun Yang, Tongxiang Liang, Congling Yin, Bo Chi, Lichao Jia, Wanbing Guan In this work, we investigated the performance and stability of a large flat-tube SOFC with symmetric double-sided cathodes (DSC), which was directly fueled with methane. The effect of steam/carbon (S/C) ratio, temperature, and current density on the performance, and long-term stability of the DSC as well as the catalytic behavior of the anode was investigated in details. The thick anode support and inner channels of the DSC formed an efficient microreactor for steam-reforming of methane, resulting in high conversion rate of methane and CO selectivity. In particular, when the S/C was 2, the conversion of CH4 at 750 °C achieved 100% in the DSC and no carbon deposition was observed. Moreover, the voltage of DSC with was stable throughout 190 h under a discharge current density of 0.257 A cm−2.
       
  • B–N co-doped black TiO2 synthesized via magnesiothermic reduction for
           enhanced photocatalytic hydrogen production
    • Abstract: Publication date: Available online 10 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Yuxin Li, Rong Fu, Min Gao, Xiangdong Wang In this work, B–N co-doped TiO2 has been synthesized by a facile fast sol-gel method, and then, a controlled magnesiothermic reduction has been developed to synthesize B–N co-doped black TiO2 under a N2 atmosphere and at 580 °C followed by acid treatment. The prepared black TiO2 samples were characterized by X-ray diffraction, high resolution transmission electron microscopy, Raman spectrameter, photoluminescence emission spectra, X-ray photoelectron spectroscopy, and ultraviolet–visible diffuse reflectance spectra. It shows that the prepared samples possess a unique crystalline core-amorphous shell structure composed of disordered surface and oxygen vacancies, and exhibit enhanced photocatalytic activity in hydrogen production in the methanol-water system in the presence of Pt as a co-catalyst. Under the full solar wavelength range of light, the maximum hydrogen production rate of the B–N co-doped black TiO2 is 18.8 mmol h−1 g−1, which is almost 4 times higher than that of pure TiO2.
       
  • An easy and eco-friendly method to fabricate three-dimensional Pd-M (Cu,
           Ni) nanonetwork structure decorated on the graphene nanosheet with boosted
           ethanol electrooxidation activity in alkaline medium
    • Abstract: Publication date: Available online 10 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Majid Farsadrooh, Meissam Noroozifar, Ali Reza Modarresi-Alam A new rapid and facile strategy for the preparation of Pd-Ni/G and Pd-Cu/G catalysts with a three-dimensional porous structure are presented in this paper. Both catalysts are formed using the same strategies in two steps: 1) The reduction of Ni(OH)2 and Cu(OH)2 to the metallic form on the surface of G/GC Electrode using the Zn/HCl reducer, 2) The galvanic displacement of Ni and Cu by Pd2+. Afterwards, three-dimensional Pd nanonetwork is generated on the glassy carbon electrode via the galvanic displacement. Compared to the other routes, this strategy depicts several advantages (e.g. fast way, facile, surfactant and reductant free, cheap, and eco-friendly.) Both catalysts are applied towards Ethanol Oxidation Reaction (EOR). Both porous structures show higher electrocatalytic activity and stability toward EOR compared to the commercial Pd/C. The extraordinary catalytic activity and durability of the both proposed catalysts for EOR can be related to the two vital reasons:1) The combination of Ni and Cu with Pd will efficiently promote the catalytic performance of Pd-Ni/G and Pd-Cu/G samples due to synergetic effects. 2) The porous structure of the as-prepared catalysts renders a high surface area and leads easier mass transport through the pores.Graphical abstractImage 1
       
  • Study on catalytic effect and mechanism of MOF (MOF = ZIF-8, ZIF-67,
           MOF-74) on hydrogen storage properties of magnesium
    • Abstract: Publication date: Available online 10 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Yongqing Wang, Zhiqiang Lan, Xiantun Huang, Haizhen Liu, Jin Guo Using a deposition-reduction method, Mg/MOF nanocomposites were prepared as composites of Mg and metal-organic framework materials (MOFs = ZIF-8, ZIF-67 and MOF-74). The addition of MOFs can enhance the hydrogen storage properties of Mg. For example, within 5000 s, 0.6 wt%, 1.2 wt%, 2.7 wt%, 3.7 wt% of hydrogen were released from Mg, Mg/MOF-74, Mg/ZIF-8, Mg/ZIF-67, respectively. Activation energy values of 198.9 kJ mol−1 H2, 161.7 kJ mol−1 H2, 192.1 kJ mol−1 H2 were determined for the Mg/ZIF-8, Mg/ZIF-67, Mg/MOF-74 hydrides, which are 6 kJ mol−1 H2, 43.2 kJ mol−1 H2, and 12.8 kJ mol−1 H2 lower than that of Mg hydride, respectively. Moreover, the cyclic stability characterizing Mg hydride was significantly improved when adding ZIF-67. The hydrogen storage capacity of the Mg/ZIF-67 nanocomposite remained unchanged, even after 100 cycles of hydrogenation/dehydrogenation. This excellent cyclic stability may have resulted from the core-shell structure of the Mg/ZIF-67 nanocomposite.Graphical abstractImage 1
       
  • Parameter study of high-temperature proton exchange membrane fuel cell
           using data-driven models
    • Abstract: Publication date: Available online 10 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Guangya Zhu, Weiwei Chen, Shihua Lu, Xuewei Chen In this paper, a numerical model of high-temperature proton exchange membrane fuel cell (HT-PEMFC) was developed, in which the thermal and electrical properties were treated as temperature dependent. Based on the numerical simulation, the needed training data was acquired and used for the development of data-driven model via the artificial neural network (ANN) algorithm. The developed data-driven model was then used to predict the performance of HT-PEMFC. The simulation results indicated that the deviation of ANN prediction was less than 2.48% compared with numerical simulation. The effects of various influential factors, such as the geometry size of the gas flow channel, the thickness of the membrane and the operating temperature, could be predicted easily by using the ANN model. The ANN model prediction results showed that the more compact fuel cell and the higher operating temperature improved the performance of HT-PEMFC. The proposed ANN model and the parameters study will contribute to the further design and operation of HT-PEMFC.
       
  • Synthesis of low-cost catalyst NiO(111) for CO2 hydrogenation into
           short-chain carboxylic acids
    • Abstract: Publication date: Available online 10 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): S.Z. Hasan, K.N. Ahmad, W.N.R.W. Isahak, M.S. Masdar, J.M. Jahim Reducing gaseous carbon dioxide to valuable chemicals and fuels by using gaseous hydrogen can decrease the concentration of greenhouse gases that contribute to global warming. Carbon dioxide conversion into fuels such as methane, methanol, and formic acid is a good hydrogen-storage method. In this paper, a comparative study of CO2 conversion into formic and acetic acids on alumina-supported nickel oxide with and without the presence of carbon is reported. NiO (111) with high surface area was synthesized through a simple and one-pot fusion solid-state method at 550 °C and 700 °C. The synthesized catalysts were tested in carbon dioxide hydrogenation reaction in a batch slurry reactor at 130 °C and under mild pressure. Interestingly, the optimum condition of the reaction also successfully produced C2 carboxylic acid in significant amounts. The highest levels of formic acid and acetic acid production were 8.13 and 7.63 mmol/L, respectively.
       
  • Process kinetics for the electrocatalytic hydrogen evolution reaction on
           carbon-based Ni/NiO nanocomposite in a single-chamber microbial
           electrolysis cell
    • Abstract: Publication date: Available online 10 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Yu Zhao, Zhishuai Dong, Yuxue Wang, Jia Li, Xia An, Donghua Yang To explore the process kinetics of hydrogen evolution reaction (HER) on carbon-based Ni/NiO nanocomposite in the microbial electrolysis cells (MECs), the performance was systematically studied by different time-course sampling of five parallel single-chamber MECs operated under identical operating conditions, which included the electrochemical performance of anodes and cathodes, and the mechanism and kinetics of HER. It was hypothesized that the decreased performance of the nickel cathodes was due to corrosion and Ni dissolution. These results provide valuable insights into the effects of long-term operation on MEC performance.Graphical abstractImage 1
       
  • One-step synthesis in deep eutectic solvents of PtV alloy nanonetworks on
           carbon nanotubes with enhanced methanol electrooxidation performance
    • Abstract: Publication date: Available online 10 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Jun-Ming Zhang, Jia-Jie He, Xiao-Qu Wang, You-Jun Fan, Xiao-Jie Zhang, Jing-Ping Zhong, Wei Chen, Shi-Gang Sun We report a simple one-step chemical reduction strategy in deep eutectic solvents (DESs) for the fabrication of a PtV alloy nanonetwork (ANN)/multiwalled carbon nanotube (MWCNT) nanohybrid, which exhibits excellent electrocatalytic performance in both activity and stability for the methanol oxidation reaction (MOR). The as-synthesized nanohybrid was characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy, confirming the formation of a porous nanonetwork structure composed of smaller PtV alloy nanoparticles (~3.8 nm) and the presence of strong electronic transfer interactions between Pt and alloyed V. The electrochemical properties of catalysts for the MOR were evaluated by using cyclic voltammetry and chronoamperometry techniques. The electrocatalytic activity, durability and CO tolerance ability of PtV ANNs/MWCNTs toward the MOR are found to be considerably higher than those of the Pt/MWCNT and commercial Pt/C catalysts. This investigation of the effect of several reaction parameters (e.g., scan rate and methanol concentration) indicates that the electrocatalytic oxidation of methanol on PtV ANNs/MWCNTs is a diffusion-controlled electrochemical process. The performance enhancement mechanism of MOR on the PtV ANN/MWCNT catalyst is analyzed based on the structure and electrochemical studies.
       
  • Selenium vacancy and phosphorus-doping-induced phase transition
           engineering of cobalt diselenide as bi-functional catalyst for water
           electrolysis
    • Abstract: Publication date: Available online 10 October 2019Source: International Journal of Hydrogen EnergyAuthor(s): Tadele Hunde Wondimu, Guan-Cheng Chen, Daniel Manaye Kabtamu, Hsueh-Yu Chen, Anteneh Wodaje Bayeh, Hsin-Chih Huang, Chen-Hao Wang This study demonstrates a two-step approach for the synthesis of a cobalt phosphoselenide nanobelt (H–CoSe(2−x)Px NB) that has excellent activity for the hydrogen evolution reaction over a wide pH range (0–14), exhibiting low overpotentials of 112, 261, and 391 mV at a current density of 10 mA cm−2 in 0.5 M H2SO4, 1 M KOH, and 1 M phosphate-buffered solution, respectively. Conversely, the H–CoSe(2−x)Px NB can be used for the oxygen evolution reaction in basic media, for which its electrochemical performance is superior to that of a platinum catalyst. When a H–CoSe(2−x)Px NB is used on both sides of a single electrolysis cell, almost no degradation occurs at various constant potentials for 12 h period. Its high performance, electrode stability, and easy synthesis suggest that the H–CoSe(2−x)Px NB is an efficient and economic electrocatalyst for water electrolysis.Graphical abstractImage 1
       
 
 
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