Developing non-expensive, highly active and highly stable electrocatalysts for hydrogen evolution has aroused extensive attention, owing to the necessity of novel clean and sustainable energy carriers. In this paper, ...Developing non-expensive, highly active and highly stable electrocatalysts for hydrogen evolution has aroused extensive attention, owing to the necessity of novel clean and sustainable energy carriers. In this paper, we report a synthesis of free-standing three-dimensional hierarchical MoS_2/CoS_2 heterostructure arrays through a convenient process. The investigation of electrocatalytic HER performance suggests that the MoS_2/CoS_2 hybrid catalyst exhibits significant enhancement in HER(onsetpotential and potential at a current density of 100 mA cm^(-2) are 20 mV and125 mV, respectively) and superior durability(no shift of current density is observed after a continuous scanning of 3000 times) compared with individual CoS_2 and MoS_2. The superior HER performance was attributed to the formation of the interface between CoS_2 and MoS_2 through the electrochemical characterization, Raman, XPS analysis, and the control experiment. The lower onsetpotential, higher current density, excellent durability, and the free-standing structure of the three-dimensional hierarchical MoS_2/CoS_2 heterostructure array make it a promising cathode catalyst suitable for widespread application.展开更多
The influences of the catalysts of CoS2 and MoB2 nano-particles on microstructure and hydrogen stor-age behaviors of as-milled SmsMg41 alloy have been compared in this work. The SmsMg41 ＋ 5 wt.% M （M = COS2, MoS2） ...The influences of the catalysts of CoS2 and MoB2 nano-particles on microstructure and hydrogen stor-age behaviors of as-milled SmsMg41 alloy have been compared in this work. The SmsMg41 ＋ 5 wt.% M （M = COS2, MoS2） alloys were prepared by milling the mechanical ground as-cast SmsMg41 alloy powders （particle size ≤75 μm） with 5 wt.% CoS2 or MoS2 nano-particles （particle size ≤ 30 nm）, respectively. The results demonstrate that the CoS2 and MoS2 nanoparticles are embedded into the alloy surface, which is nanostructure containing some crystal defects, such as dislocation, grain boundary and twin etc. Those microstructures play a beneficial role in reducing the total potential barrier that the hydrogen absorption or desorption reactions must overcome, hence improving the hydrogen storage kinetics of the alloys. The as-milled alloys are composed of SmsMg41 and SmMg3 phases, and ball milling refines their crys-tal grains. The MgH2 and Sm3H7 phases appear after hydrogenation, while Mg and Sm3H7 phases exist after dehydrogenation. The dehydriding activation energy of M = CoS2 and MoS2 alloys are 101.67 and 68.25 kJ/mol H2 respectively. The initial hydrogen desorption of M = CoS2 and MoS2 alloys are 252.9 ℃ and 247.8 ℃.The hydrogenation and dehydrogenation enthalpy changes of M = MoS2 alloy are a little smaller than that of MzCoS2 alloy. Therefore, the catalyst MoS2 can improve the as-milled SmsMg41 alloy in hydrogen storage property more effectively than C0S2.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.:51503062, 51402100, 21573063 and 21573066)the Youth 1000 Talent Program of China+1 种基金the Fundamental Research Funds for the Central UniversitiesInter-discipline Research Program of Hunan University
文摘Developing non-expensive, highly active and highly stable electrocatalysts for hydrogen evolution has aroused extensive attention, owing to the necessity of novel clean and sustainable energy carriers. In this paper, we report a synthesis of free-standing three-dimensional hierarchical MoS_2/CoS_2 heterostructure arrays through a convenient process. The investigation of electrocatalytic HER performance suggests that the MoS_2/CoS_2 hybrid catalyst exhibits significant enhancement in HER(onsetpotential and potential at a current density of 100 mA cm^(-2) are 20 mV and125 mV, respectively) and superior durability(no shift of current density is observed after a continuous scanning of 3000 times) compared with individual CoS_2 and MoS_2. The superior HER performance was attributed to the formation of the interface between CoS_2 and MoS_2 through the electrochemical characterization, Raman, XPS analysis, and the control experiment. The lower onsetpotential, higher current density, excellent durability, and the free-standing structure of the three-dimensional hierarchical MoS_2/CoS_2 heterostructure array make it a promising cathode catalyst suitable for widespread application.
基金financially supported by the National Natural Science Foundations of China(51471054,51761032 and51371094)Natural Science Foundation of Inner Mongolia,China(2015MS0558)
文摘The influences of the catalysts of CoS2 and MoB2 nano-particles on microstructure and hydrogen stor-age behaviors of as-milled SmsMg41 alloy have been compared in this work. The SmsMg41 ＋ 5 wt.% M （M = COS2, MoS2） alloys were prepared by milling the mechanical ground as-cast SmsMg41 alloy powders （particle size ≤75 μm） with 5 wt.% CoS2 or MoS2 nano-particles （particle size ≤ 30 nm）, respectively. The results demonstrate that the CoS2 and MoS2 nanoparticles are embedded into the alloy surface, which is nanostructure containing some crystal defects, such as dislocation, grain boundary and twin etc. Those microstructures play a beneficial role in reducing the total potential barrier that the hydrogen absorption or desorption reactions must overcome, hence improving the hydrogen storage kinetics of the alloys. The as-milled alloys are composed of SmsMg41 and SmMg3 phases, and ball milling refines their crys-tal grains. The MgH2 and Sm3H7 phases appear after hydrogenation, while Mg and Sm3H7 phases exist after dehydrogenation. The dehydriding activation energy of M = CoS2 and MoS2 alloys are 101.67 and 68.25 kJ/mol H2 respectively. The initial hydrogen desorption of M = CoS2 and MoS2 alloys are 252.9 ℃ and 247.8 ℃.The hydrogenation and dehydrogenation enthalpy changes of M = MoS2 alloy are a little smaller than that of MzCoS2 alloy. Therefore, the catalyst MoS2 can improve the as-milled SmsMg41 alloy in hydrogen storage property more effectively than C0S2.
