The hydrogen evolution reaction(HER) is a half-cell reaction in water electrolysis for producing hydrogen gas. In industrial water electrolysis, the HER is often conducted in alkaline media to achieve higher stability...The hydrogen evolution reaction(HER) is a half-cell reaction in water electrolysis for producing hydrogen gas. In industrial water electrolysis, the HER is often conducted in alkaline media to achieve higher stability of the electrode materials. However, the kinetics of the HER in alkaline medium is slow relative to that in acid because of the low concentration of protons in the former.Under the latter conditions, the entire HER process will require additional effort to obtain protons by water dissociation near or on the catalyst surface. Heterostructured catalysts, with fascinating synergistic effects derived from their heterogeneous interfaces, can provide multiple functional sites for the overall reaction process. At present, the activity of the most active known heterostructured catalysts surpasses(platinum-based heterostructures) or approaches (noble-metal-free heterostructures) that of the commercial Pt/C catalyst under alkaline conditions, demonstrating an infusive potential to break through the bottlenecks. This review summarizes the most representative and recent heterostructured HER catalysts for alkaline medium. The basics and principles of the HER under alkaline conditions are first introduced, followed by a discussion of the latest advances in heterostructured catalysts with/without noblemetal-based heterostructures. Special focus is placed on approaches for enhancing the reaction rate by accelerating the Volmer step. This review aims to provide an overview of the current developments in alkaline HER catalysts, as well as the design principles for the future development of heterostructured nano-or micro-sized electrocatalysts.展开更多
Electrochemical water splitting is a sustainable and feasible strategy for hydrogen production but is hampered by the sluggish anodic oxygen evolution reaction(OER).Herein,an effective approach is introduced to signif...Electrochemical water splitting is a sustainable and feasible strategy for hydrogen production but is hampered by the sluggish anodic oxygen evolution reaction(OER).Herein,an effective approach is introduced to significantly decrease the cell voltage by replacing the anodic OER with a urea oxidation reaction(UOR).A Ni_(2)P/NiMoP nanosheet catalyst with a hierarchical architecture is uniformly grown on a nickel foam(NF)substrate through a simple hydrothermal and phosphorization method.The Ni_(2)P/NiMoP achieves impressive HER activity,with a low overpotential of only 22 mV at 10 mA cm^(-2)and a low Tafel slope of 34.5 mV dec^(−1).In addition,the oxidation voltage is significantly reduced from 1.49 V to 1.33 V after the introduction of 0.33 M urea.Notably,a two-electrode electrolyzer employing Ni_(2)P/NiMoP as a bifunctional catalyst exhibits a current density of 10 mA cm^(-2)at a cell voltage of 1.35 V and excellent long-term durability after 80 h.展开更多
Silicon carbide （SIC） has been considered a promising metal-free photocatalyst due to its unique photoelectrical properties and thermal/chemical stability. However, its performance suffers from the fast recombinatio...Silicon carbide （SIC） has been considered a promising metal-free photocatalyst due to its unique photoelectrical properties and thermal/chemical stability. However, its performance suffers from the fast recombination of charge carriers. Herein, we report mesoporous SiC nanofibers with in situ embedded graphitic carbon （SiC NFs-Cx） synthesized via a one-step carbothermal reduction between electrospun carbon nanofibers and Si powders. In the absence of a noble metal co-catalyst, the hydrogen evolution efficiency of SiC NFs-Cx is significantly improved under both simulated solar light （180.2 μmol.g-1.h-1） and visible light irradiation （31.0 ~amol-g-l-h-~） in high-pH solution. The efficient simultaneous separation of charge carriers plays a critical role in the high photocatalytic activity. The embedded carbon can swiftly transfer the photogenerated electrons and improve light absorption, whereas the additional hydroxyl anions （OH-） in high- pH solution can accelerate the trapping of holes. Our results demonstrate that the production of SiC NFs-Cx, which contains exclusively earth-abundant elements, scaled up, and is environmentally friendly, has great potential for practical applications. This work may provide a new pathway for designing stable, low- cost, high efficiency, and co-catalyst-free photocatalysts.展开更多
基金financial support provided by National Natural Science Foundation of China (Nos.61301026 and 51802073)the supports from the Talent Introduction Foundation (No.ZRC2014448)+1 种基金the Key Discipline Foundation (No.AKZDXK2015A01) of Anhui Science and Technology Universitythe financial support by the Singapore National Research Foundation under its Campus for Research Excellence And Technological Enterprise (CREATE) program through the Cambridge Center for Carbon Reduction in Chemical Technology (C4T) and eCO2EP programs
文摘The hydrogen evolution reaction(HER) is a half-cell reaction in water electrolysis for producing hydrogen gas. In industrial water electrolysis, the HER is often conducted in alkaline media to achieve higher stability of the electrode materials. However, the kinetics of the HER in alkaline medium is slow relative to that in acid because of the low concentration of protons in the former.Under the latter conditions, the entire HER process will require additional effort to obtain protons by water dissociation near or on the catalyst surface. Heterostructured catalysts, with fascinating synergistic effects derived from their heterogeneous interfaces, can provide multiple functional sites for the overall reaction process. At present, the activity of the most active known heterostructured catalysts surpasses(platinum-based heterostructures) or approaches (noble-metal-free heterostructures) that of the commercial Pt/C catalyst under alkaline conditions, demonstrating an infusive potential to break through the bottlenecks. This review summarizes the most representative and recent heterostructured HER catalysts for alkaline medium. The basics and principles of the HER under alkaline conditions are first introduced, followed by a discussion of the latest advances in heterostructured catalysts with/without noblemetal-based heterostructures. Special focus is placed on approaches for enhancing the reaction rate by accelerating the Volmer step. This review aims to provide an overview of the current developments in alkaline HER catalysts, as well as the design principles for the future development of heterostructured nano-or micro-sized electrocatalysts.
基金This work was financially supported by the National Natural Science Foundation of China(52025013,51622102)Ministry of Science and Technology of China MOST(2018YFB1502101)+1 种基金the 111 Project(B12015)the Fundamental Research Funds for the Central Uni-versities(63191523,63191746).
文摘Electrochemical water splitting is a sustainable and feasible strategy for hydrogen production but is hampered by the sluggish anodic oxygen evolution reaction(OER).Herein,an effective approach is introduced to significantly decrease the cell voltage by replacing the anodic OER with a urea oxidation reaction(UOR).A Ni_(2)P/NiMoP nanosheet catalyst with a hierarchical architecture is uniformly grown on a nickel foam(NF)substrate through a simple hydrothermal and phosphorization method.The Ni_(2)P/NiMoP achieves impressive HER activity,with a low overpotential of only 22 mV at 10 mA cm^(-2)and a low Tafel slope of 34.5 mV dec^(−1).In addition,the oxidation voltage is significantly reduced from 1.49 V to 1.33 V after the introduction of 0.33 M urea.Notably,a two-electrode electrolyzer employing Ni_(2)P/NiMoP as a bifunctional catalyst exhibits a current density of 10 mA cm^(-2)at a cell voltage of 1.35 V and excellent long-term durability after 80 h.
基金The work was financially supported by National Natural Science Foundation of China （Nos. 51173202 and 51203182）, Hunan Provincial Natural Science Foundation of China （No. 13JJ4009）, State Key Laboratory of Advanced Technology for Materials Synthesis and Processing （Wuhan University of Technology） （No. 2014-KF-10）, the State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology （No. G201501） and Research Project of National University of Defense Technology （No. JC13-01-05）. This work was also supported by Aid program for Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province and Aid Program for Innovative Group of National University of Defense Technology.
文摘Silicon carbide （SIC） has been considered a promising metal-free photocatalyst due to its unique photoelectrical properties and thermal/chemical stability. However, its performance suffers from the fast recombination of charge carriers. Herein, we report mesoporous SiC nanofibers with in situ embedded graphitic carbon （SiC NFs-Cx） synthesized via a one-step carbothermal reduction between electrospun carbon nanofibers and Si powders. In the absence of a noble metal co-catalyst, the hydrogen evolution efficiency of SiC NFs-Cx is significantly improved under both simulated solar light （180.2 μmol.g-1.h-1） and visible light irradiation （31.0 ~amol-g-l-h-~） in high-pH solution. The efficient simultaneous separation of charge carriers plays a critical role in the high photocatalytic activity. The embedded carbon can swiftly transfer the photogenerated electrons and improve light absorption, whereas the additional hydroxyl anions （OH-） in high- pH solution can accelerate the trapping of holes. Our results demonstrate that the production of SiC NFs-Cx, which contains exclusively earth-abundant elements, scaled up, and is environmentally friendly, has great potential for practical applications. This work may provide a new pathway for designing stable, low- cost, high efficiency, and co-catalyst-free photocatalysts.
基金国家自然科学基金项目“Thermochemical redox cycles for high temperature solar energy conversion into fuels and chemicals”(51950410590)河北省自然科学基金“高炉富氧喷吹煤粉燃烧砷析出机理研究”(E2019209516)。
