Synthesis Of Transition Bimetallic Sulfide And Their Performances For Electrocatalytic Hydrogen Production

As the foundation of social development,the importance of energy is self-evident.At present,fossil energy is gradually exhausted and its combustion brings about environmental pollution.This is an important factor hindering sustainable development.As a clean and renewable energy carrier,hydrogen energy is regarded as the ultimate clean energy for human beings.The traditional highly active catalysts for electrolysis of Hydrogen evolution are noble metals such as platinum.However,these noble metals are expensive,scarce and unstable for a long time.Therefore,it is very important to develop efficient and cheap electrocatalytic catalysts for hydrogen evolution.In this paper,the catalyst of transition bimetal sulfide is studied,the electrocatalytic hydrogen evolution performance of the material can be improved by increasing the surface area of the catalyst（increasing the number of active sites）or by adjusting the intrinsic electronic structure of the active sites（increasing the activity）.Many kinds of transition bimetallic sulfide catalysts were synthesized by hydrothermal/solvent-thermal method.The catalysts were characterized by SEM,XRD,XPS,Raman,ICP and N₂ adsorption-desorption and hydrogen evolution performance of the catalysts were evaluated by electrochemical workstation.This thesis mainly includes three parts:（1）A series of hierarchical Co-Mo-S nanoarchitectures catalysts were synthesized from Co（NO₃）₂·6H₂O as cobalt source and Na₂MoO₄·2H₂O as molybdenum source.in a water-ethylene glycol mixed solvent system.Such as-synthesized bimetallic sulfide nanostructures as an electrocatalyst exhibits good performance for HER in phosphate buffer solution（1M PBS）,especially Co-Mo_0.4-S nanocomposite exhibits the highest activity for HER.Co-Mo_0.4-S only requires an overpotential of 213 mV to reach 10 mA cm^-2 with 94 mV dec^-1 of Tafel slope,which outperforms those of Co-S and Mo-S.The excellent HER performance of Co-Mo_0.4-S electrocatalyst can be attributed to the strong electronic interactions of Co-S and Mo-S and the high specific surface.（2）Ni-Mo-S/MoO_x material was synthesized by adding Na₂MoO₄·2H₂O into thioacetamide aqueous solution and directly on the foamed nickel substrate.This avoids the use of polymer templates,and the solvent is only aqueous,making the synthesis process easier.Great catalytic activity was obtained by electrocatalytic hydrogen evolution in 1 M KOH alkaline medium.The as-obtained sample requires an overpotential of only 180 mV to attain the current density of 50mA cm^-2.The stability of the catalyst was tested for 50 h,and the current density did not decrease obviously.The experimental results show that three-dimensional self-supporting catalyst on nickel foam substrate can improve the catalytic performance.（3）V-doped Ni₃S₂/NF self-supporting electrode was prepared by using NH₄VO₃ as vanadium source and adding F127 in a water-ethylene glycol mixed solvent system.V⁵⁺is observed by X-ray photoelectron spectroscopy（XPS）.The electrocatalytic properties for HER are investigated in alkaline media（1M KOH）,and the results show that V-doped Ni₃S₂/NF electrode has a low overpotential of 206 mV at 50 mA cm^-2,which is lower than that of the Ni₃S₂/NF（226 mV）at the same current density.It is shown that the doping of metal V regulates the electronic structure of the catalyst and thus improves the electrocatalytic hydrogen evolution performance of Ni₃S₂/NF self-supporting electrode.