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  Subjects -> MATHEMATICS (Total: 1051 journals)
    - APPLIED MATHEMATICS (85 journals)
    - GEOMETRY AND TOPOLOGY (23 journals)
    - MATHEMATICS (775 journals)
    - MATHEMATICS (GENERAL) (43 journals)
    - NUMERICAL ANALYSIS (23 journals)
    - PROBABILITIES AND MATH STATISTICS (102 journals)

MATHEMATICS (775 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 538 Journals sorted alphabetically
Abakós     Open Access   (Followers: 5)
Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg     Hybrid Journal   (Followers: 4)
Academic Voices : A Multidisciplinary Journal     Open Access   (Followers: 2)
Accounting Perspectives     Full-text available via subscription   (Followers: 8)
ACM Transactions on Algorithms (TALG)     Hybrid Journal   (Followers: 16)
ACM Transactions on Computational Logic (TOCL)     Hybrid Journal   (Followers: 3)
ACM Transactions on Mathematical Software (TOMS)     Hybrid Journal   (Followers: 6)
ACS Applied Materials & Interfaces     Hybrid Journal   (Followers: 38)
Acta Applicandae Mathematicae     Hybrid Journal   (Followers: 1)
Acta Mathematica     Hybrid Journal   (Followers: 12)
Acta Mathematica Hungarica     Hybrid Journal   (Followers: 2)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5)
Acta Mathematica Sinica, English Series     Hybrid Journal   (Followers: 6)
Acta Mathematica Vietnamica     Hybrid Journal  
Acta Mathematicae Applicatae Sinica, English Series     Hybrid Journal  
Advanced Science Letters     Full-text available via subscription   (Followers: 12)
Advances in Applied Clifford Algebras     Hybrid Journal   (Followers: 4)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 6)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 9)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 22)
Advances in Decision Sciences     Open Access   (Followers: 3)
Advances in Difference Equations     Open Access   (Followers: 3)
Advances in Fixed Point Theory     Open Access   (Followers: 8)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 17)
Advances in Linear Algebra & Matrix Theory     Open Access   (Followers: 10)
Advances in Materials Science     Open Access   (Followers: 17)
Advances in Mathematical Physics     Open Access   (Followers: 8)
Advances in Mathematics     Full-text available via subscription   (Followers: 15)
Advances in Nonlinear Analysis     Open Access  
Advances in Numerical Analysis     Open Access   (Followers: 7)
Advances in Operations Research     Open Access   (Followers: 12)
Advances in Porous Media     Full-text available via subscription   (Followers: 5)
Advances in Pure and Applied Mathematics     Hybrid Journal   (Followers: 8)
Advances in Pure Mathematics     Open Access   (Followers: 9)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aequationes Mathematicae     Hybrid Journal   (Followers: 2)
African Journal of Educational Studies in Mathematics and Sciences     Full-text available via subscription   (Followers: 7)
African Journal of Mathematics and Computer Science Research     Open Access   (Followers: 5)
Afrika Matematika     Hybrid Journal   (Followers: 1)
Air, Soil & Water Research     Open Access   (Followers: 13)
AKSIOMA Journal of Mathematics Education     Open Access   (Followers: 2)
Al-Jabar : Jurnal Pendidikan Matematika     Open Access   (Followers: 1)
Algebra and Logic     Hybrid Journal   (Followers: 7)
Algebra Colloquium     Hybrid Journal   (Followers: 4)
Algebra Universalis     Hybrid Journal   (Followers: 2)
Algorithmic Operations Research     Open Access   (Followers: 5)
Algorithms     Open Access   (Followers: 11)
Algorithms Research     Open Access   (Followers: 1)
American Journal of Computational and Applied Mathematics     Open Access   (Followers: 8)
American Journal of Mathematical Analysis     Open Access  
American Journal of Mathematical and Management Sciences     Hybrid Journal  
American Journal of Mathematics     Full-text available via subscription   (Followers: 6)
American Journal of Operations Research     Open Access   (Followers: 6)
American Mathematical Monthly     Full-text available via subscription   (Followers: 6)
An International Journal of Optimization and Control: Theories & Applications     Open Access   (Followers: 11)
Anadol University Journal of Science and Technology B : Theoritical Sciences     Open Access  
Analele Universitatii Ovidius Constanta - Seria Matematica     Open Access  
Analysis and Applications     Hybrid Journal   (Followers: 1)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 6)
Analysis Mathematica     Full-text available via subscription  
Analysis. International mathematical journal of analysis and its applications     Hybrid Journal   (Followers: 4)
Annales Mathematicae Silesianae     Open Access   (Followers: 2)
Annales mathématiques du Québec     Hybrid Journal   (Followers: 4)
Annales Universitatis Mariae Curie-Sklodowska, sectio A – Mathematica     Open Access   (Followers: 1)
Annales Universitatis Paedagogicae Cracoviensis. Studia Mathematica     Open Access  
Annali di Matematica Pura ed Applicata     Hybrid Journal   (Followers: 1)
Annals of Combinatorics     Hybrid Journal   (Followers: 4)
Annals of Data Science     Hybrid Journal   (Followers: 13)
Annals of Discrete Mathematics     Full-text available via subscription   (Followers: 7)
Annals of Mathematics     Full-text available via subscription   (Followers: 2)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 13)
Annals of PDE     Hybrid Journal  
Annals of Pure and Applied Logic     Open Access   (Followers: 4)
Annals of the Alexandru Ioan Cuza University - Mathematics     Open Access  
Annals of the Institute of Statistical Mathematics     Hybrid Journal   (Followers: 1)
Annals of West University of Timisoara - Mathematics     Open Access  
Annals of West University of Timisoara - Mathematics and Computer Science     Open Access   (Followers: 1)
Annuaire du Collège de France     Open Access   (Followers: 6)
ANZIAM Journal     Open Access   (Followers: 1)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 3)
Applications of Mathematics     Hybrid Journal   (Followers: 3)
Applied Categorical Structures     Hybrid Journal   (Followers: 4)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 14)
Applied Mathematics     Open Access   (Followers: 4)
Applied Mathematics     Open Access   (Followers: 8)
Applied Mathematics & Optimization     Hybrid Journal   (Followers: 10)
Applied Mathematics - A Journal of Chinese Universities     Hybrid Journal   (Followers: 1)
Applied Mathematics and Nonlinear Sciences     Open Access  
Applied Mathematics Letters     Full-text available via subscription   (Followers: 4)
Applied Mathematics Research eXpress     Hybrid Journal   (Followers: 1)
Applied Network Science     Open Access   (Followers: 3)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 6)
Arab Journal of Mathematical Sciences     Open Access   (Followers: 4)
Arabian Journal of Mathematics     Open Access   (Followers: 2)
Archive for Mathematical Logic     Hybrid Journal   (Followers: 3)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 6)
Archive of Numerical Software     Open Access  
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 6)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
Armenian Journal of Mathematics     Open Access   (Followers: 1)
Arnold Mathematical Journal     Hybrid Journal   (Followers: 1)
Artificial Satellites     Open Access   (Followers: 25)
Asia-Pacific Journal of Operational Research     Hybrid Journal   (Followers: 3)
Asian Journal of Algebra     Open Access   (Followers: 1)
Asian Research Journal of Mathematics     Open Access  
Asian-European Journal of Mathematics     Hybrid Journal   (Followers: 3)
Australian Mathematics Teacher, The     Full-text available via subscription   (Followers: 7)
Australian Primary Mathematics Classroom     Full-text available via subscription   (Followers: 5)
Australian Senior Mathematics Journal     Full-text available via subscription   (Followers: 2)
Automatic Documentation and Mathematical Linguistics     Hybrid Journal   (Followers: 5)
Axioms     Open Access   (Followers: 1)
Baltic International Yearbook of Cognition, Logic and Communication     Open Access   (Followers: 1)
Basin Research     Hybrid Journal   (Followers: 5)
BIBECHANA     Open Access   (Followers: 2)
Biomath     Open Access  
BIT Numerical Mathematics     Hybrid Journal   (Followers: 1)
Boletim Cearense de Educação e História da Matemática     Open Access  
Boletim de Educação Matemática     Open Access  
Boletín de la Sociedad Matemática Mexicana     Hybrid Journal  
Bollettino dell'Unione Matematica Italiana     Full-text available via subscription   (Followers: 2)
British Journal of Mathematical and Statistical Psychology     Full-text available via subscription   (Followers: 20)
Bruno Pini Mathematical Analysis Seminar     Open Access  
Buletinul Academiei de Stiinte a Republicii Moldova. Matematica     Open Access   (Followers: 13)
Bulletin des Sciences Mathamatiques     Full-text available via subscription   (Followers: 4)
Bulletin of Dnipropetrovsk University. Series : Communications in Mathematical Modeling and Differential Equations Theory     Open Access   (Followers: 3)
Bulletin of Mathematical Sciences     Open Access   (Followers: 1)
Bulletin of Symbolic Logic     Full-text available via subscription   (Followers: 2)
Bulletin of the Australian Mathematical Society     Full-text available via subscription   (Followers: 2)
Bulletin of the Brazilian Mathematical Society, New Series     Hybrid Journal  
Bulletin of the Iranian Mathematical Society     Hybrid Journal  
Bulletin of the London Mathematical Society     Hybrid Journal   (Followers: 3)
Bulletin of the Malaysian Mathematical Sciences Society     Hybrid Journal  
Calculus of Variations and Partial Differential Equations     Hybrid Journal  
Canadian Journal of Mathematics / Journal canadien de mathématiques     Hybrid Journal  
Canadian Journal of Science, Mathematics and Technology Education     Hybrid Journal   (Followers: 20)
Canadian Mathematical Bulletin     Hybrid Journal  
Carpathian Mathematical Publications     Open Access   (Followers: 1)
Catalysis in Industry     Hybrid Journal   (Followers: 1)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
CHANCE     Hybrid Journal   (Followers: 5)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chaos, Solitons & Fractals : X     Open Access  
ChemSusChem     Hybrid Journal   (Followers: 8)
Chinese Annals of Mathematics, Series B     Hybrid Journal  
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Mathematics     Open Access  
Clean Air Journal     Full-text available via subscription   (Followers: 1)
Cogent Mathematics     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 3)
Collectanea Mathematica     Hybrid Journal  
College Mathematics Journal     Hybrid Journal   (Followers: 4)
COMBINATORICA     Hybrid Journal  
Combinatorics, Probability and Computing     Hybrid Journal   (Followers: 4)
Combustion Theory and Modelling     Hybrid Journal   (Followers: 15)
Commentarii Mathematici Helvetici     Hybrid Journal  
Communications in Advanced Mathematical Sciences     Open Access  
Communications in Combinatorics and Optimization     Open Access  
Communications in Contemporary Mathematics     Hybrid Journal  
Communications in Mathematical Physics     Hybrid Journal   (Followers: 4)
Communications On Pure & Applied Mathematics     Hybrid Journal   (Followers: 4)
Complex Analysis and its Synergies     Open Access   (Followers: 3)
Complex Variables and Elliptic Equations: An International Journal     Hybrid Journal  
Composite Materials Series     Full-text available via subscription   (Followers: 9)
Compositio Mathematica     Full-text available via subscription  
Comptes Rendus Mathematique     Full-text available via subscription  
Computational and Applied Mathematics     Hybrid Journal   (Followers: 4)
Computational and Mathematical Methods     Hybrid Journal  
Computational and Mathematical Methods in Medicine     Open Access   (Followers: 2)
Computational and Mathematical Organization Theory     Hybrid Journal   (Followers: 2)
Computational Complexity     Hybrid Journal   (Followers: 4)
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 10)
Computational Mechanics     Hybrid Journal   (Followers: 5)
Computational Methods and Function Theory     Hybrid Journal  
Computational Optimization and Applications     Hybrid Journal   (Followers: 8)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 11)
Concrete Operators     Open Access   (Followers: 5)
Confluentes Mathematici     Hybrid Journal  
Contributions to Game Theory and Management     Open Access  
COSMOS     Hybrid Journal  
Cryptography and Communications     Hybrid Journal   (Followers: 13)
Cuadernos de Investigación y Formación en Educación Matemática     Open Access  
Cubo. A Mathematical Journal     Open Access  
Current Research in Biostatistics     Open Access   (Followers: 8)
Czechoslovak Mathematical Journal     Hybrid Journal   (Followers: 1)
Demographic Research     Open Access   (Followers: 15)
Demonstratio Mathematica     Open Access  
Dependence Modeling     Open Access  
Design Journal : An International Journal for All Aspects of Design     Hybrid Journal   (Followers: 31)
Developments in Clay Science     Full-text available via subscription   (Followers: 1)
Developments in Mineral Processing     Full-text available via subscription   (Followers: 3)
Dhaka University Journal of Science     Open Access  
Differential Equations and Dynamical Systems     Hybrid Journal   (Followers: 4)
Differentsial'nye Uravneniya     Open Access  
Digital Experiences in Mathematics Education     Hybrid Journal  
Discrete Mathematics     Hybrid Journal   (Followers: 8)
Discrete Mathematics & Theoretical Computer Science     Open Access  
Discrete Mathematics, Algorithms and Applications     Hybrid Journal   (Followers: 2)
Discussiones Mathematicae - General Algebra and Applications     Open Access  

        1 2 3 4 | Last

Similar Journals
Journal Cover
Chinese Journal of Catalysis
Journal Prestige (SJR): 0.833
Citation Impact (citeScore): 3
Number of Followers: 2  
 
  Full-text available via subscription Subscription journal
ISSN (Print) 1872-2067
Published by Elsevier Homepage  [3177 journals]
  • Simultaneous hydrogen and peroxide production by photocatalytic water
           splitting
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Lichao Wang, Shuang Cao, Kai Guo, Zhijiao Wu, Zhi Ma, Lingyu PiaoABSTRACTPhotocatalytic oxidation of water is a promising method to realize large-scale H2O2 production without a hazardous and energy-intensive process. In this study, we introduce a Pt/TiO2(anatase) photocatalyst to construct a simple and environmentally friendly system to achieve simultaneous H2 and H2O2 production. Both H2 and H2O2 are high-value chemicals, and their separation is automatic. Even without the assistance of a sacrificial agent, the system can reach an efficiency of 7410 and 5096 μmol g–1 h–1 (first 1 h) for H2 and H2O2, respectively, which is much higher than that of a commercial Pt/TiO2(anatase) system that has a similar morphology. This exceptional activity is attributed to the more favorable two-electron oxidation of water to H2O2, compared with the four-electron oxidation of water to O2.Graphical Photocatalytic water splitting into hydrogen and peroxide, two value-added chemicals, is achieved over a Pt/TiO2(anatase) photocatalyst, avoiding separation problems.Graphical abstract for this article
       
  • Direct electrospinning method for the construction of Z-scheme
           TiO2/g-C3N4/RGO ternary heterojunction photocatalysts with remarkably
           ameliorated photocatalytic performance
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Liming Hu, Juntao Yan, Chunlei Wang, Bo Chai, Jianfen LiABSTRACTA series of Z-scheme TiO2/g-C3N4/RGO ternary heterojunction photocatalysts are successfully constructed via a direct electrospinning technique coupled with an annealing process for the first time. They are investigated comprehensively in terms of crystal structure, morphology, composition, specific surface area, photoelectrochemical properties, photodegradation performance, etc. Compared with binary TiO2/g-C3N4 and single-component photocatalysts, ternary heterojunction photocatalysts show the best photodegradation performance for RhB under stimulated sunlight. This can be attributed to the enlarged specific surface area (111.41 m2/g), the formation of Z-scheme heterojunction, and the high separation migration efficiency of photoexcited charge carriers. A potential Z-scheme mechanism for ternary heterojunction photocatalysts is proposed to elucidate the remarkably ameliorated photocatalytic performance based on active species trapping experiments, PL detection test of hydroxyl radicals, and photoelectrochemical properties.Graphical Z-scheme TiO2/g-C3N4/RGO ternary heterojunction photocatalysts are constructed successfully via a direct electrospinning method coupled with annealing, and it exhibits the best photodegradation efficiency of 99.1% within 60 min among the photocatalysts achieved. Moreover, the Z-scheme mechanism is proposed to elucidate the remarkably enhanced photocatalytic performance.Graphical abstract for this article
       
  • Preparation of a p-n heterojunction 2D BiOI nanosheet/1DBiPO4 nanorod
           composite electrode for enhanced visible light photoelectrocatalysis
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Sen Liu, Mengyu Zhao, Zetian He, Yi Zhong, Hao Ding, Daimei ChenABSTRACTIn this study, a 2D BiOI nanosheet/1D BiPO4 nanorod/fluorine-doped tin oxide (FTO) composite electrode with a p-n heterojunction structure was prepared by a two-step electrodeposition method. Field-emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflectance spectroscopy, and electrochemical testing were used to characterize its composition, crystal morphology, and optical properties. The BiOI/BiPO4/FTO composite electrode has higher photoelectrocatalytic (PEC) activity for the degradation of tetracycline than pure BiPO4 and BiOI. The PEC activity of the composite was 1.98 times and 2.46 times higher than those of the BiOI/FTO and BiPO4/FTO electrodes, respectively. The effects of the working voltage and BiOI deposition time on the degradation of tetracycline were investigated. The optimum BiOI deposition time was found to be 150 s and the optimum working voltage is 1.2 V. Trapping experiments showed that hydroxyl radicals (•OH) and superoxide radicals (•O2−) are the major reactive species in the PEC degradation process. The BiOI/BiPO4/FTO composite electrode has good stability, and the tetracycline removal efficiency remains substantially unchanged after four cycles in a static system. The reason for the PEC efficiency enhancement in the BiOI/BiPO4/FTO composite electrode is the increased visible light absorption range and the p-n heterojunction structure, which promotes the separation and migration of the photogenerated electrons and holes.Graphical The p-n heterojunction structure promotes the separation and migration of photogenerated charges leading to enhanced photoelectrocatalytic efficiency in the BiOI/BiPO4/FTO electrode.Graphical abstract for this article
       
  • Enhanced photocatalytic H2 production over dual-cocatalyst-modified g-C3N4
           heterojunctions
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Zong Li, Yongning Ma, Xiaoyun Hu, Enzhou Liu, Jun FanABSTRACTAg nanoparticles (NPs) were deposited on the surface of g-C3N4 (CN) by an in situ calcination method. NiS was successfully loaded onto the composites by a hydrothermal method. The results showed that the 10 wt%-NiS/1.0 wt%-Ag/CN composite exhibits excellent photocatalytic H2 generation performance under solar-light irradiation. An H2 production rate of 9.728 mmol·g−1·h−1 was achieved, which is 10.82-, 3.45-, and 2.77-times higher than those of pure g-C3N4, 10 wt%-NiS/CN, and 1.0 wt%-Ag/CN composites, respectively. This enhanced photocatalytic H2 generation can be ascribed to the co-decoration of Ag and NiS on the surface of g-C3N4, which efficiently improves light harvesting capacity, photogenerated charge carrier separation, and photocatalytic H2 production kinetics. Thus, this study demonstrates an effective strategy for constructing excellent g-C3N4-related composite photocatalysts for H2 production by using different co-catalysts.Graphical g-C3N4 co-decorated with Ag nanoparticles and NiS co-catalysts exhibits enhanced migration and separation of photoexcited charge carriers and, thus, improved photocatalytic H2 generation owing to Ag and NiS serving as electron acceptors, surface-active sites, and H2-evolution co-catalysts.Graphical abstract for this article
       
  • Defect-assisted surface modification enhances the visible light
           photocatalytic performance of g-C3N4@C-TiO2 direct Z-scheme
           heterojunctions
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Xibao Li, Jie Xiong, Ying Xu, Zhijun Feng, Juntong HuangABSTRACTTo increase the number of active sites and defects in TiO2 and promote rapid and efficient transfer of photogenerated charges, a g-C3N4@C-TiO2 composite photocatalyst was prepared via in situ deposition of g-C3N4 on a carbon-doped anatase TiO2 surface. The effects of carbon doping state and surface modification of g-C3N4 on the performance of g-C3N4@C-TiO2 composite photocatalysts were studied by X-ray diffraction, X-ray photoelectron spectroscopy, UV-visible diffuse-reflectance spectroscopy, transmission electron microscopy, electrochemical impedance spectroscopy, photoluminescence, and electron paramagnetic resonance. With increasing carbon doping content, the carbon doping state in TiO2 gradually changed from gap to substitution doping. Although the number of oxygen vacancies gradually increased, the degradation efficiency of g-C3N4@C-TiO2 for RhB (phenol) initially increased and subsequently decreased with increasing carbon content. The g-C3N4@10C-TiO2 sample exhibited the highest apparent reaction rate constant of 0.036 min−1 (0.039 min−1) for RhB (phenol) degradation, which was 150 (139), 6.4 (6.8), 2.3 (3), and 1.7 (2.1) times higher than that of pure TiO2, 10C-TiO2, g-C3N4, and g-C3N4@TiO2, respectively. g-C3N4 was grown in situ on the surface of C-TiO2 by surface carbon hybridization and bonding. The resultant novel g-C3N4@C-TiO2 photocatalyst exhibited direct Z-scheme heterojunctions with non-local impurity levels. The high photocatalytic activity can be attributed to the synergistic effects of the improved visible light response ability, higher photogenerated electron transfer efficiency, and redox ability arising from Z-type heterojunctions.Graphical Novel g-C3N4@C-TiO2 heterojunction exhibiting a direct Z-scheme photocatalytic mechanism. Appropriate amounts of carbon doping introduced new non-local impurity levels into the catalyst, which more efficiently transferred photogenerated electrons, enhancing the photocatalytic activity.Graphical abstract for this article
       
  • Prolonging charge-separation states by doping lanthanide-ions into
           {001}/{101} facets-coexposed TiO2 nanosheets for enhancing photocatalytic
           H2 evolution
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Yongan Zhu, Zhenyi Zhang, Na Lu, Ruinian Hua, Bin DongABSTRACTUltrathin TiO2 nanosheets with coexposed {001}/{101} facets have attracted considerable attention because of their high photocatalytic activity. However, the charge-separated states in the TiO2 nanosheets must be extended to further enhance their photocatalytic activity for H2 evolution. Herein, we present a successful attempt to selectively dope lanthanide ions into the {101} facets of ultrathin TiO2 nanosheets with coexposed {001}/{101} facets through a facile one-step solvothermal method. The lanthanide doping slightly extended the light-harvesting region and markedly improved the charge-separated states of the TiO2 nanosheets as evidenced by UV-vis absorption and steady-state/transient photoluminescence spectra. Upon simulated sunlight irradiation, we observed a 4.2-fold enhancement in the photocatalytic H2 evolution activity of optimal Yb3+-doped TiO2 nanosheets compared to that of their undoped counterparts. Furthermore, when Pt nanoparticles were used as cocatalysts to reduce the H2 overpotential in this system, the photocatalytic activity enhancement factor increased to 8.5. By combining these results with those of control experiments, we confirmed that the extended charge-separated states play the main role in the enhancement of the photocatalytic H2 evolution activity of lanthanide-doped TiO2 nanosheets with coexposed {001}/{101} facets.Graphical The lanthanide ions were selectively doped into the {101} facets of the TiO2 nanosheets with coexposed {001}/{101} facets by using a one-step solvothermal method. These samples exhibited a remarkable enhancement of photocatalytic activity for H2 evolution due to the prolonged charge-separation states, as evidenced by the kinetics analyses.Graphical abstract for this article
       
  • Effects of crystallinity, {001}/{101} ratio, and Au decoration on the
           photocatalytic activity of anatase TiO2 crystals
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Jiangyan Wang, Baoshun Liu, Kazuya NakataAnatase TiO2 nanocrystals and sub-microcrystals with truncated octahedral bipyramidal morphologies were prepared by direct calcination of TiOF2 precursors. The as-prepared TiO2 samples were thoroughly characterized by X-ray diffraction, Raman spectroscopy, field-emission scanning electron microscopy, N2 adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and UV-visible diffuse spectroscopy. It was found that the crystallinity, grain size, and {001}/{101} ratio of the samples can be increased by raising the calcination temperature from 500 to 800 °C. The higher crystallinity and {001}/{101} facet ratio resulted in an increase in both aqueous and gas-phase photocatalytic activities, by inhibiting the recombination and separation of electrons and holes. After selecting two TiO2 samples with high crystallinity and {001}/{101} ratio, Au nanoparticles were decorated on their surfaces, and the photocatalytic activity of the resulting samples under visible light illumination was studied. It was found that the visible light-induced photocatalytic activity increased by 2.6 and 4.8 times, respectively, upon Au decoration of the samples prepared by calcination of TiOF2 at 700 and 800 °C.Graphical abstractThe photocatalytic activity of anatase TiO2 materials prepared by calcination of TiOF2 can be substantially improved by increasing their crystallinities and {001}/{101} ratios; moreover, Au decoration can effectively enhance the visible light-induced photocatalytic activity.Graphical abstract for this article
       
  • Controllable design of Zn-Ni-P on g-C3N4 for efficient photocatalytic
           hydrogen production
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Yanbing Li, Zhiliang Jin, Lijun Zhang, Kai FanSynthesizing a stable and efficient photocatalyst has been the most important research goal up to now. Owing to the dominant performance of g-C3N4 (graphitized carbonitride), an ordered assemble of a composite photocatalyst, Zn-Ni-P@g-C3N4, was successfully designed and controllably prepared for highly efficient photocatalytic H2 evolution. The electron transport routes were successfully adjusted and the H2 evolution was greatly improved. The maximum amount of H2 evolved reached about 531.2 μmol for 5 h over Zn-Ni-P@g-C3N4 photocatalyst with a molar ratio of Zn to Ni of 1:3 under illumination of 5 W LED white light (wavelength 420 nm). The H2 evolution rate was 54.7 times higher than that over pure g-C3N4. Moreover, no obvious reduction in the photocatalytic activity was observed even after 4 cycles of H2 production for 5 h. This synergistically increased effect was confirmed through the results of characterizations such as XRD, TEM, SEM, XPS, N2 adsorption, UV-vis DRS, transient photocurrent, FT-IR, transient fluorescence, and Mott-Schottky studies. These studies showed that the Zn-Ni-P nanoparticles modified on g-C3N4 provide more active sites and improve the efficiency of photogenerated charge separation. In addition, the possible mechanism of photocatalytic H2 production is proposed.Graphical abstractThe existence of Zn-Ni-P was the main reason for the efficient electronic separation and transmission observed in Zn-Ni-P@g-C3N4, which could accelerate the rapid transfer of electrons and the depletion of holes through the sacrificial reagent TEOA. Thus, the recombination of the photoelectrons and photoholes was inhibited, and the photocatalytic activity was enhanced.Graphical abstract for this article
       
  • Accelerating photocatalytic hydrogen evolution and pollutant degradation
           by coupling organic co-catalysts with TiO2
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Jun Shen, Rui Wang, Qinqin Liu, Xiaofei Yang, Hua Tang, Jin YangAccelerating the separation efficiency of photoexcited electron-hole pairs with the help of highly active co-catalysts has proven to be a promising approach for improving photocatalytic activity. Thus far, the most developed co-catalysts for semiconductor-based photocatalysis are inorganic materials; the employment of a specific organic molecule as a co-catalyst for photocatalytic hydrogen evolution and pollutant photodegradation is rare and still remains a challenging task. Herein, we report on the use of an organic molecule, oxamide (OA), as a novel co-catalyst to enhance electron-hole separation, photocatalytic H2 evolution, and dye degradation over TiO2 nanosheets. OA-modified TiO2 samples were prepared by a wet chemical route and demonstrated improved light absorption in the visible-light region and more efficient charge transport. The photocatalytic performance of H2 evolution from water splitting and rhodamine B (RhB) degradation for an optimal OA-modified TiO2 photocatalyst reached 2.37 mmol g-1 h-1 and 1.43 × 10−2 min−1, respectively, which were 2.4 and 3.8 times higher than those of pristine TiO2, respectively. A possible mechanism is proposed, in which the specific π-conjugated structure of OA is suggested to play a key role in the enhancement of the charge transfer and catalytic capability of TiO2. This work may provide advanced insight into the development of a variety of metal-free organic molecules as functional co-catalysts for improved solar-to-fuel conversion and environmental remediation.Graphical abstractAn organic molecule, oxamide, is utilized as a co-catalyst to enhance the photocatalytic H2 evolution and dye-degradation performance of TiO2 nanosheets. Oxamide, which has a unique π-conjugated structure, can provide hole-transfer sites and thus greatly promote the separation and transfer of photo-generated electron-hole pairs in TiO2.Graphical abstract for this article
       
  • One-pot hydrothermal synthesis of willow branch-shaped MoS2/CdS
           heterojunctions for photocatalytic H2 production under visible light
           irradiation
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Zhen-Wei Zhang, Qiu-Hao Li, Xiu-Qing Qiao, Dongfang Hou, Dong-Sheng LiWillow branch-shaped MoS2/CdS heterojunctions are successfully synthesized for the first time by a facile one-pot hydrothermal method. The as-prepared samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption measurements, diffuse reflectance spectroscopy, and photoelectrochemical and photoluminescence spectroscopy tests. The photocatalytic hydrogen evolution activities of the samples were evaluated under visible light irradiation. The resulting MoS2/CdS heterojunctions exhibit a much improved photocatalytic hydrogen evolution activity than that obtained with CdS and MoS2. In particular, the optimized MC-5 (5 at.% MoS2/CdS) photocatalyst achieved the highest hydrogen production rate of 250.8 μmol h-1, which is 28 times higher than that of pristine CdS. The apparent quantum efficiency (AQE) at 420 nm was 3.66%. Further detailed characterizations revealed that the enhanced photocatalytic activity of the MoS2/CdS heterojunctions could be attributed to the efficient transfer and separation of photogenerated charge carriers resulting from the core-shell structure and the close contact between MoS2 nanosheets and CdS single-crystal nanorods, as well as to increased visible light absorption. A tentative mechanism for photocatalytic H2 evolution by MoS2/CdS heterojunctions was proposed. This work will open up new opportunities for developing more efficient photocatalysts for water splitting.Graphical abstractNovel willow branch-shaped MoS2/CdS heterojunctions synthesized via a one-pot hydrothermal method show excellent photocatalytic H2 evolution activity.Graphical abstract for this article
       
  • A Bi/BiOI/(BiO)2CO3 heterostructure for enhanced photocatalytic NO removal
           under visible light
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Yanjuan Sun, Jiazhen Liao, Fan Dong, Sujuan Wu, Lidong SunNarrow-band BiOI photocatalysts usually suffer from low photocatalysis efficiency under visible light exposure because of rapid charge recombination. In this work, to overcome this deficiency of photosensitive BiOI, oxygen vacancies, Bi particles, and Bi2O2CO3 were co-induced in BiOI via a facile in situ assembly method at room temperature using NaBH4 as the reducing agent. In the synthesized ternary Bi/BiOI/(BiO)2CO3, the oxygen vacancies, dual heterojunctions (i.e., Bi/BiOI and BiOI/(BiO)2CO3), and surface plasmon resonance effect of the Bi particles contributed to efficient electron-hole separation and an increase in charge carrier concentration, thus boosting the overall visible light photocatalysis efficiency. The as-prepared catalysts were applied for the removal of NO in concentrations of parts per billion from air in continuous air flow under visible light illumination. Bi/BiOI/(BiO)2CO3 exhibited a highly enhanced NO removal ratio of 50.7%, much higher than that of the pristine BiOI (1.2%). Density functional theory calculations and experimental results revealed that the Bi/BiOI/(BiO)2CO3 composites promoted the production of reactive oxygen species for photocatalytic NO oxidation. Thus, this work provides a new strategy to modify narrow-band semiconductors and explore other bismuth-containing heterostructured visible-light-driven photocatalysts.Graphical abstractPhotoexcited electrons spontaneously migrate through the heterojunction from Bi to OV-BiOI and then to (BiO)2CO3 under the driving force of the energy difference between the dual heterojunction. The holes remain in the VB of BiOI, and the electrons on the CB of (BiO)2CO3 react with O2 to produce •O2− radicals. The residual holes in the VB of OV-BiOI react with the OH− to produce •OH radicals.Graphical abstract for this article
       
  • Novel PtPd alloy nanoparticle-decorated g-C3N4 nanosheets with enhanced
           photocatalytic activity for H2 evolution under visible light irradiation
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Nan Xiao, Songsong Li, Shuang Liu, Boran Xu, Yandong Li, Yangqin Gao, Lei Ge, Guiwu LuPtPd bimetallic alloy nanoparticle (NP)-modified graphitic carbon nitride (g-C3N4) nanosheet photocatalysts were synthesized via chemical deposition precipitation. Characterization of the photocatalytic H2 evolution of the g-C3N4 nanosheets shows that it was significantly enhanced when PtPd alloy NPs were introduced as a co-catalyst. The 0.2 wt% PtPd/g-C3N4 composite photocatalyst gave a maximum H2 production rate of 1600.8 μmol g–1 h–1. Furthermore, when K2HPO4 was added to the reaction system, the H2 production rate increased to 2885.0 μmol g–1 h–1. The PtPd/g-C3N4 photocatalyst showed satisfactory photocatalytic stability and was able to maintain most of its photocatalytic activity after four experimental photocatalytic cycles. In addition, a possible mechanism for the enhanced photocatalytic activity was proposed and verified by various photoelectric techniques. These results demonstrate that the synergistic effect between PtPd and g-C3N4 helps to greatly improve the photocatalytic activity of the composite photocatalyst.Graphical abstractPtPd/g-C3N4 photocatalysts were used as a photosensitizer and coupled with PtPd alloy nanoparticles for photocatalytic H2 production under visible light. The H2 production rate was ~800 times higher than with pure g-C3N4. This enhancement is probably due to a semiconductor/co-catalyst interface interaction between the PtPd alloy nanoparticles and the g-C3N4 nanosheets that increases the charge transfer process efficiency.Graphical abstract for this article
       
  • Ni nanoparticles as electron-transfer mediators and NiS x as interfacial
           active sites for coordinative enhancement of H2-evolution performance of
           TiO2
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Ping Wang, Shunqiu Xu, Feng Chen, Huogen YuThe development of efficient photocatalytic H2-evolution materials requires both rapid electron transfer and an effective interfacial catalysis reaction for H2 production. In addition to the well-known noble metals, low-cost and earth-abundant non-noble metals can also act as electron-transfer mediators to modify photocatalysts. However, as almost all non-noble metals lack the interfacial catalytic active sites required for the H2-evolution reaction, the enhancement of the photocatalytic performance is limited. Therefore, the development of new interfacial active sites on metal-modified photocatalysts is of considerable importance. In this study, to enhance the photocatalytic evolution of H2 by Ni-modified TiO2, the formation of NiSx as interfacial active sites was promoted on the surface of Ni nanoparticles. Specifically, the co-modified TiO2/Ni-NiSx photocatalysts were prepared via a two-step process involving the photoinduced deposition of Ni on the TiO2 surface and the subsequent formation of NiSx on the Ni surface by a hydrothermal reaction method. It was found that the TiO2/Ni-NiSx photocatalysts exhibited enhanced photocatalytic H2-evolution activity. In particular, TiO2/Ni-NiSx(30%) showed the highest photocatalytic rate (223.74 μmol h−1), which was greater than those of TiO2, TiO2/Ni, and TiO2/NiSx by factors of 22.2, 8.0, and 2.2, respectively. The improved H2-evolution performance of TiO2/Ni-NiSx could be attributed to the excellent synergistic effect of Ni and NiSx, where Ni nanoparticles function as effective mediators to transfer electrons from the TiO2 surface and NiSx serves as interfacial active sites to capture H+ ions from solution and promote the interfacial H2-evolution reaction. The synergistic effect of the non-noble metal cocatalyst and the interfacial active sites may provide new insights for the design of highly efficient photocatalytic materials.Graphical abstractThe TiO2/Ni-NiSx photocatalyst exhibited enhanced H2-evolution performance due to the excellent synergistic effect of Ni nanoparticles as electron-transfer mediators and NiSx as interfacial active sites to promote H2 evolution.Graphical abstract for this article
       
  • Rational design of ternary NiS/CQDs/ZnIn2S4 nanocomposites as efficient
           
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Bingqing Wang, Yao Ding, Zirong Deng, Zhaohui LiThe NiS/CQDs nanocomposite (CQDs represents carbon quantum dots), with a mass ratio of NiS/CQDs to be 1.19:1 based on the ICP result, was obtained via a facile hydrothermal method from a mixture of CQDs, Ni(OAc)2 and Na2S. The self-assembly of ZnIn2S4 microspheres on the surface of NiS/CQDs was realized under microwave conditions to obtain a ternary NiS/CQDs/ZnIn2S4 nanocomposite. The as-obtained NiS/CQDs/ZnIn2S4 nanocomposite was fully characterized, and its photocatalytic hydrogen evolution under visible light irradiation was investigated. The ternary NiS/CQDs/ZnIn2S4 nanocomposite showed superior photocatalytic activity for hydrogen evolution than ternary CQDs/NiS/ZnIn2S4, which was obtained by deposition of NiS in the preformed CQDs/ZnIn2S4. The superior photocatalytic performance of ternary NiS/CQDs/ZnIn2S4 is ascribed to the introduction of CQDs, which act as a bridge to promote the vectorial transfer of photo-generated electrons from ZnIn2S4 to NiS. This result suggests that the rational design and fabrication of ternary CQDs-based systems are important for the efficient photocatalytic hydrogen evolution. This study provides a strategy for developing highly efficient noble-metal-free photocatalysts for hydrogen evolution using CQDs as a bridge to promote the charge transfer in the nanocomposite.Graphical abstractCQDs act as a bridge to promote the charge transfer from ZnIn2S4 to NiS in the ternary NiS/CQDs/ZnIn2S4 nanocomposite.Graphical abstract for this article
       
  • Preparation of Z-scheme WO3(H2O)0.333/Ag3PO4 composites with enhanced
           photocatalytic activity and durability
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Zhen Li, Xia Wang, Jinfeng Zhang, Changhao Liang, Luhua Lu, Kai DaiAg3PO4 is widely used in the field of photocatalysis because of its unique activity. However, photocorrosion limits its practical application. Therefore, it is very urgent to find a solution to improve the light corrosion resistance of Ag3PO4. Herein, the Z-scheme WO3(H2O)0.333/Ag3PO4 composites are successfully prepared through microwave hydrothermal and simple stirring. The WO3(H2O)0.333/Ag3PO4 composites are characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis spectroscopy. In the degradation of organic pollutants, WO3(H2O)0.333/Ag3PO4 composites exhibit excellent performance under visible light. This is mainly attributed to the synergy of WO3(H2O)0.333 and Ag3PO4. Especially, the photocatalytic activity of 15%WO3(H2O)0.333/Ag3PO4 is the highest, and the methylene blue can be completely degraded in 4 min. In addition, the stability of the composites is also greatly enhanced. After five cycles of testing, the photocatalytic activity of 15%WO3(H2O)0.333/Ag3PO4 is not obviously decreased. However, the degradation efficiency of Ag3PO4 was only 20.2%. This indicates that adding WO3(H2O)0.333 can significantly improve the photoetching resistance of Ag3PO4. Finally, Z-scheme photocatalytic mechanism is investigated.Graphical abstractA Z-scheme WO3(H2O)0.333/Ag3PO4 composite with enhanced photocatalytic activity and durability is successfully constructed. Under visible light irradiation, electron-hole pairs are generated on the surfaces of Ag3PO4 and WO3(H2O)0.333. The photo-induced electrons of WO3(H2O)0.333 are transferred to the CB interface of Ag3PO4. Under the action of holes, –OH reacts with h+ to produce ·OH, and ·OH reacts with contaminants to form CO2 and H2O. Meantime, a great deal of H+ and O2 react with electrons to generate H2O2 at the conduction band interface of Ag3PO4. After that, H2O2 reacts with electrons to generate ·OH, and ·OH reacts with MB to form CO2 and H2O.Graphical abstract for this article
       
  • 3D flower-like heterostructured TiO2@Ni(OH)2 microspheres for solar
           photocatalytic hydrogen production
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Wei Zhang, Hongwen Zhang, Jianzhong Xu, Huaqiang Zhuang, Jinlin LongTiO2@Ni(OH)2 core-shell microspheres were synthesized by a facile strategy to obtain a perfect 3D flower-like nanostructure with well-arranged Ni(OH)2 nanoflakes on the surfaces of TiO2 microspheres; this arrangement led to a six-fold enhancement in photocatalytic hydrogen evolution. The unique p-n type heterostructure not only promotes the separation and transfer of photogenerated charge carriers significantly, but also offers more active sites for photocatalytic hydrogen production. A photocatalytic mechanism is proposed based on the results of electrochemical measurements and X-ray photoelectron spectroscopy.Graphical abstractWe report a solvothermal approach combined with an oil-bath-based chemical synthesis to prepare a 3D flower-like TiO2@Ni(OH)2 core-shell heterostructure, which results in a six-fold enhancement in the hydrogen production rate.Graphical abstract for this article
       
  • Interfacial engineering of graphitic carbon nitride (g-C3N4)-based metal
           sulfide heterojunction photocatalysts for energy conversion: A review
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Yijie Ren, Deqian Zeng, Wee-Jun OngAs one of the most appealing and attractive technologies, photocatalysis is widely used as a promising method to circumvent the environmental and energy problems. Due to its chemical stability and unique physicochemical, graphitic carbon nitride (g-C3N4) has become research hotspots in the community. However, g-C3N4 photocatalyst still suffers from many problems, resulting in unsatisfactory photocatalytic activity such as low specific surface area, high charge recombination and insufficient visible light utilization. Since 2009, g-C3N4-based heterostructures have attracted the attention of scientists worldwide for their greatly enhanced photocatalytic performance. Overall, this review summarizes the recent advances of g-C3N4-based nanocomposites modified with transition metal sulfide (TMS), including (1) preparation of pristine g-C3N4, (2) modification strategies of g-C3N4, (3) design principles of TMS-modified g-C3N4 heterostructured photocatalysts, and (4) applications in energy conversion. What is more, the characteristics and transfer mechanisms of each classification of the metal sulfide heterojunction system will be critically reviewed, spanning from the following categories: (1) Type I heterojunction, (2) Type II heterojunction, (3) p-n heterojunction, (4) Schottky junction and (5) Z-scheme heterojunction. Apart from that, the application of g-C3N4-based heterostructured photocatalysts in H2 evolution, CO2 reduction, N2 fixation and pollutant degradation will also be systematically presented. Last but not least, this review will conclude with invigorating perspectives, limitations and prospects for further advancing g-C3N4-based heterostructured photocatalysts toward practical benefits for a sustainable future.Graphical abstractThis review presents recent developments of g-C3N4-based metal sulfide heterojunction photocatalysts for the energy conversion. The state-of-the-art advancement of this emerging g-C3N4 field from the aspects of fabrication and charge separation will be elucidated.Graphical abstract for this article
       
  • Ni-based photocatalytic H2-production cocatalysts2
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Rongchen Shen, Jun Xie, Quanjun Xiang, Xiaobo Chen, Jizhou Jiang, Xin LiPhotocatalysis is believed to be one of the best methods to realize sustainable H2 production. However, achieving this through heterogeneous photocatalysis still remains a great challenge owing to the absence of active sites, sluggish surface reaction kinetics, insufficient charge separation, and a high thermodynamic barrier. Therefore, cocatalysts are necessary and of great significance in boosting photocatalytic H2 generation. This review will focus on the promising and appealing low-cost Ni-based H2-generation cocatalysts as the alternatives for the high-cost and low-abundance noble metal cocatalysts. Special emphasis has been placed on the design principle, modification strategies for further enhancing the activity and stability of Ni-based cocatalysts, and identification of the exact active sites and surface reaction mechanisms. Particularly, four types of modification strategies based on increased light harvesting, enhanced charge separation, strengthened interface interaction, and improved electrocatalytic activity have been thoroughly discussed and compared in detail. This review may open a new avenue for designing highly active and durable Ni-based cocatalysts for photocatalytic H2 generation.Graphical abstractThe fundamentals of photocatalysis and electrocatalysis, roles and challenges, active sites and reaction pathways, and different design strategies are summarized to offer a conceptual basis for designing and developing highly efficient Ni-based photocatalytic H2-evolution cocatalysts.Graphical abstract for this article
       
  • Preface to Special Issue for Chinese Symposium on Photocatalytic Materials
           (CSPM)
    • Abstract: Publication date: March 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 3Author(s): Jiaguo Yu, Xin Li, Zhaohui LiGraphical abstractGraphical abstract for this article
       
  • Synergism of Pt nanoparticles and iron oxide support for chemoselective
           hydrogenation of nitroarenes under mild conditions
    • Abstract: Publication date: February 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 2Author(s): Pei Jing, Tao Gan, Hui Qi, Bin Zheng, Xuefeng Chu, Guiyang Yu, Wenfu Yan, Yongcun Zou, Wenxiang Zhang, Gang LiuAn efficient and low-cost supported Pt catalyst for hydrogenation of niroarenes was prepared with colloid Pt precursors and α-Fe2O3 as a support. The catalyst with Pt content as low as 0.2 wt% exhibits high activities, chemoselectivities and stability in the hydrogenation of nitrobenzene and a variety of niroarenes. The conversion of nitrobenzene can reach 3170 molconv h−1 molPt−1 under mild conditions (30 °C, 5 bar), which is much higher than that of commercial Pt/C catalyst and many reported catalysts under similar reaction conditions. The spatial separation of the active sites for H2 dissociation and hydrogenation should be responsible for the high chemoselectivity, which decreases the contact possibility between the reducible groups of nitroarenes and Pt nanoparticles. The unique surface properties of α-Fe2O3 play an important role in the reaction process. It provides active sites for hydrogen spillover and reactant adsorption, and ultimately completes the hydrogenation of the nitro group on the catalyst surface.Graphical abstractPt/α-Fe2O3 with ultralow Pt loading amount could spatially separate the active sites for H2 dissociation and hydrogenation, leading to a high chemoselectivity for hydrogenation of nitroarenes under mild reaction conditions.Graphical abstract for this article
       
  • Interface-controlled synthesis of CeO2(111) and CeO2(100) and their
           structural transition on Pt(111)
    • Abstract: Publication date: February 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 2Author(s): Yi Zhang, Wei Feng, Fan Yang, Xinhe BaoCeria-based catalytic materials are known for their crystal-face-dependent catalytic properties. To obtain a molecular-level understanding of their surface chemistry, controlled synthesis of ceria with well-defined surface structures is required. We have thus studied the growth of CeOx nanostructures (NSs) and thin films on Pt(111). The strong metal-oxide interaction has often been invoked to explain catalytic processes over the Pt/CeOx catalysts. However, the Pt-CeOx interaction has not been understood at the atomic level. We show here that the interfacial interaction between Pt and ceria could indeed affect the surface structures of ceria, which could subsequently determine their catalytic chemistry. While ceria on Pt(111) typically exposes the CeO2(111) surface, we found that the structures of ceria layers with a thickness of three layers or less are highly dynamic and dependent on the annealing temperatures, owing to the electronic interaction between Pt and CeOx. A two-step kinetically limited growth procedure was used to prepare the ceria film that fully covers the Pt(111) substrate. For a ceria film of ~3–4 monolayer (ML) thickness on Pt(111), annealing in ultrahigh vacuum (UHV) at 1000 K results in a surface of CeO2 (100), stabilized by a c-Ce2O3(100) buffer layer. Further oxidation at 900 K transforms the surface of the CeO2(100) thin film into a hexagonal CeO2(111) surface.Graphical abstractUltrathin ceria films on Pt(111) usually exhibit the CeO2(111) surface under oxidative conditions, but could form the CeO2(100) surface upon UHV annealing at 1000 K owing to the strong interaction between ceria and Pt.Graphical abstract for this article
       
  • Effective production of γ-valerolactone from biomass-derived methyl
           levulinate over CuO x -CaCO3 catalyst
    • Abstract: Publication date: February 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 2Author(s): Xuejuan Cao, Huai Liu, Junnan Wei, Xing Tang, Xianhai Zeng, Yong Sun, Tingzhou Lei, Geng Zhao, Lu LinThe production of γ-valerolactone (GVL) from lignocellulosic biomass has become a focus of research owing to its potential applications in fuels and chemicals. In this study, (n)CuOx-CaCO3 (where n is the molar ratio of Cu to Ca) compounds were prepared for the first time and shown to function as efficient bifunctional catalysts for the conversion of biomass-derived methyl levulinate (ML) into GVL, using methanol as the in-situ hydrogen source. Among the catalysts with varied Cu/Ca molar ratios, (3/2)CuOx-CaCO3 provided the highest GVL yield of 95.6% from ML. The incorporation of CaCO3 with CuO resulted in the formation of Cu+ species in a CuOx-CaCO3 catalyst, which greatly facilitated the hydrogenation of ML. Notably, CuOx-CaCO3 also displayed excellent catalytic performance in the methanolysis products of cellulose, even in the presence of humins. Therefore, a facile two-step strategy for the production of GVL from cellulose could be developed over this robust and inexpensive catalyst, through the integration of cellulose methanolysis catalyzed by sulfuric acid, methanol reforming, and ML hydrogenation in methanol medium.Graphical abstractIncorporation of CaCO3 greatly stabilized Cu+ species. The robust and stable CuOx-CaCO3 catalyst could contribute to the development of a facile two-step strategy for the production of GVL from cellulose with methanol as the in-situ hydrogen source.Graphical abstract for this article
       
  • Rod-shaped porous alumina-supported Cr2O3 catalyst with low acidity for
           propane dehydrogenation
    • Abstract: Publication date: February 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 2Author(s): Xin-Qian Gao, Wen-Duo Lu, Shou-Zhao Hu, Wen-Cui Li, An-Hui LuDirect catalytic propane dehydrogenation (PDH) to obtain propylene is a more economical and environmentally friendly route for propylene production. In particular, alumina-supported Cr2O3 catalysts can have better potential applications if the acidic properties could be tuned. Herein, a series of rod-shaped porous alumina were prepared through a hydrothermal route, followed by calcination. It was found that the acidity of the synthesized alumina was generally lower than that of the commercial alumina and could be adjusted well by varying the calcination temperature. Such alumina materials were used as supports for active Cr2O3, and the obtained catalysts could enhance the resistance to coke formation associated with similar activity in PDH reaction compared to the commercial alumina. The amount of coke deposited on a self-made catalyst (Cr-Al-800) was 3.6%, which was much lower than that deposited on the reference catalyst (15.7%). The lower acidity of the catalyst inhibited the side reactions and coke formation during the PDH process, which was beneficial for its high activity and superior anti-coking properties.Graphical abstractRod-shaped porous alumina supported chromium oxide exhibited high activity and superior anti-coking ability in propane dehydrogenation process because of the low total acidity of alumina surface.Graphical abstract for this article
       
  • Synthesis of spiropyrrolidine oxindoles through Rh(II)-catalyzed
           olefination/cyclization of diazooxindoles and vinyl azides
    • Abstract: Publication date: February 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 2Author(s): Ruxia Yi, Leilei Qian, Boshun WanA simple and efficient process involving the Rh(II)-catalyzed [1+1+3] annulation of diazooxindoles and vinyl azides has been developed for the synthesis of spiropyrrolidine oxindoles with potential biological activity and significant synthetic applications. This process involves a novel rhodium-catalyzed olefination of diazo compounds, followed by annulation with vinyl azides. This method is compatible with a broad range of substrates and affords moderate to good yields under mild reaction conditions.Graphical abstractAn efficient [1+1+3] annulation process of 3-diazooxindoles and vinyl azides has been developed using dirhodium carboxylate as catalyst, providing access to potential bioactive spiropyrrolidine oxindoles in moderate to good yields and with a broad substrate scope.Graphical abstract for this article
       
  • Highly enhanced visible-light photocatalytic hydrogen evolution on g-C3N4
           decorated with vopc through π-π interaction
    • Abstract: Publication date: February 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 2Author(s): Yanan Liu, Liubo Ma, Congcong Shen, Xin Wang, Xiao Zhou, Zhiwei Zhao, Anwu XuPhotocatalytic H2 evolution reactions on pristine graphitic carbon nitrides (g-C3N4), as a promising approach for converting solar energy to fuel, are attractive for tackling global energy concerns but still suffer from low efficiencies. In this article, we report a tractable approach to modifying g-C3N4 with vanadyl phthalocyanine (VOPc/CN) for efficient visible-light-driven hydrogen production. A non-covalent VOPc/CN hybrid photocatalyst formed via π-π stacking interactions between the two components, as confirmed by analysis of UV-vis absorption spectra. The VOPc/CN hybrid photocatalyst shows excellent visible-light-driven photocatalytic performance and good stability. Under optimal conditions, the corresponding H2 evolution rate is nearly 6 times higher than that of pure g-C3N4. The role of VOPc in promoting hydrogen evolution activity was to extend the visible light absorption range and prevent the recombination of photoexcited electron-hole pairs effectively. It is expected that this facile modification method could be a new inspiration for the rational design and exploration of g-C3N4-based hybrid systems with strong light absorption and high-efficiency carrier separation.Graphical abstractThis work describes a novel system of molecule-grafted g-C3N4 through π-π interactions between VOPc and g-C3N4 aromatic frameworks. The introduction of VOPc can extend the spectral response region to longer than 460 nm and retard charge recombination, thus resulting in significantly improved photoactivity for H2 production.Graphical abstract for this article
       
  • Integrating non-precious-metal cocatalyst Ni3N with g-C3N4 for enhanced
           photocatalytic H2 production in water under visible-light irradiation
    • Abstract: Publication date: February 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 2Author(s): Jianhua Ge, Yujie Liu, Daochuan Jiang, Lei Zhang, Pingwu DuPhotocatalytic H2 production via water splitting in a noble-metal-free photocatalytic system has attracted much attention in recent years. In this study, noble-metal-free Ni3N was used as an active cocatalyst to enhance the activity of g-C3N4 for photocatalytic H2 production under visible-light irradiation (λ> 420 nm). The characterization results indicated that Ni3N nanoparticles were successfully loaded onto the g-C3N4, which accelerated the separation and transfer of photogenerated electrons and resulted in enhanced photocatalytic H2 evolution under visible-light irradiation. The hydrogen evolution rate reached ∼305.4 μmol h−1 g−1, which is about three times higher than that of pristine g-C3N4, and the apparent quantum yield (AQY) was ∼0.45% at λ = 420. Furthermore, the Ni3N/g-C3N4 photocatalyst showed no obvious decrease in the hydrogen production rate, even after five cycles under visible-light irradiation. Finally, a possible photocatalytic hydrogen evolution mechanism for the Ni3N/g-C3N4 system is proposed.Graphical Noble-metal-free Ni3N was used as an active cocatalyst to accelerate the separation and transfer of photogenerated charges. The resultant catalyst exhibited enhanced photocatalytic H2 evolution, which was about three times higher than that of pristine g-C3N4.Graphical abstract for this article
       
  • A theoretical study of electrocatalytic ammonia synthesis on single metal
           atom/MXene
    • Abstract: Publication date: February 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 2Author(s): Yijing Gao, Han Zhuo, Yongyong Cao, Xiang Sun, Guilin Zhuang, Shengwei Deng, Xing Zhong, Zhongzhe Wei, Jianguo WangElectrocatalytic ammonia synthesis under mild conditions is an attractive and challenging process in the earth's nitrogen cycle, which requires efficient and stable catalysts to reduce the overpotential. The N2 activation and reduction overpotential of different Ti3C2O2-supported transition metal (TM) (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Ru, Rh, Pd, Ag, Cd, and Au) single-atom catalysts have been analyzed in terms of the Gibbs free energies calculated using the density functional theory (DFT). The end-on N2 adsorption was more energetically favorable, and the negative free energies represented good N2 activation performance, especially in the presence Fe/Ti3C2O2 (−0.75 eV). The overpotentials of Fe/Ti3C2O2, Co/Ti3C2O2, Ru/Ti3C2O2, and Rh/Ti3C2O2 were 0.92, 0.89, 1.16, and 0.84 eV, respectively. The potential required for ammonia synthesis was different for different TMs and ranged from 0.68 to 2.33 eV. Two possible potential-limiting steps may be involved in the process: (i) hydrogenation of N2 to *NNH and (ii) hydrogenation of *NH2 to ammonia. These catalysts can change the reaction pathway and avoid the traditional N–N bond-breaking barrier. It also simplifies the understanding of the relationship between the Gibbs free energy and overpotential, which is a significant factor in the rational designing and large-scale screening of catalysts for the electrocatalytic ammonia synthesis.Graphical abstractThe overpotential of electrolytic ammonia synthesis is determined by the Gibbs free energies of two potential-limiting steps N2 + H+ → NNH (ΔG1) and NH2 + H+ → NH3 (ΔG2).Graphical abstract for this article
       
  • Highly active and stable porous polymer heterogenous catalysts for
           decomposition of formic acid to produce H2
    • Abstract: Publication date: February 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 2Author(s): Yan Zhang, Yuan Lyu, Yuqing Wang, Cunyao Li, Miao Jiang, Yunjie DingFormic acid (FA) has attracted extensive attention as a hydrogen storage material. Here, we develop two heterogeneous catalysts based on porous organic polymers (POPs). After loading the Ru species, the catalyst bearing the triphenylphosphine ligand showed excellent performance in terms of activity and stability for the decomposition of FA to produce hydrogen.Graphical abstractTwo heterogeneous Ru@POPs catalysts were synthesized for the decomposition of formic acid, and excellent performance was obtained. The properties of the ligands in the polymer framework significantly impact the activity and selectivity of the catalysts.Graphical abstract for this article
       
  • The origin of the extraordinary stability of mercury catalysts on the
           carbon support: the synergy effects between oxygen groups and defects
           revealed from a combined experimental and DFT study
    • Abstract: Publication date: February 2019Source: Chinese Journal of Catalysis, Volume 40, Issue 2Author(s): Jian Li, Jiangtao Fan, Sajjad Ali, Guojun Lan, Haodong Tang, Wenfeng Han, Huazhang Liu, Bo Li, Ying LiThermal stability of HgCl2 has a pivotal importance for the hydrochlorination reaction as the loss of mercuric compounds is toxic and detrimental to environment. Here we report a low-mercury catalyst which has durability over 10000 h for acetylene hydrochlorination under the industrial condition. The stability of the catalyst is carefully analyzed from a combined experimental and density functional theory study. The analysis shows that the extraordinary stability of mercury catalyst is resulted from the synergy effects between surface oxygen groups and defective edge sites. The binding energy of HgCl2 is increased to be higher than 130 kJ/mol when adsorption is at the edge site with a nearby oxygen group. Therefore, the present study revealed that the thermal stability problem of mercury-based catalyst can be solved by simply adjusting the surface chemistry of activated carbon. Furthermore, the reported catalyst has already been successfully applied in the commercialized production of vinyl chloride.Graphical abstractHgCl2/carbon: Thermally unstable! Proper carbon support with more surface defects shows stronger C-HgCl2 interaction, which greatly increases the thermal stability of mercury catalyst.Graphical abstract for this article
       
 
 
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