Synthesis And Performance Of Sulfur Compounds And Their Composites For Hydrogen Evolution Reaction

Electrocatalytic hydrogen reaction?HER?holds tremendous primise as an effient and clean solution.Although excellent HER performance has been reached for platinum and other precious metals,reaplacing the expensive and rare catalysts with earth-abundant material still attraction toward making the hydrogen production more economic and competive.Sulfur compounds have poor electrical conductivity and less active edge exposure,hindering the electrocatalytic hydrogen evolution activity.In this paper,according to the characteristics and defects of sulfur compounds,MoS₂ and MoS₂carbon nanotube composites,MoSe₂ and MoSe₂ carbon nanotube composites,NiSe and NiSe-MoSe₂ composites were prepared by solvothermal and hydrothermal methods.The specific research content is as follows:1 MoS₂ was successfully loaded onto the surface of acidified carbon nanotubes using a mild solvothermal method,in which sodiummolybdate and thioacetamide were used as precursors,DMF and deionized water were used as mixed solvents.The results of electrochemical hydrogen evolution test showed that the morphology and structure of the product changed with composited carbon nanotubes,which increased the specific surface area,increased the electrochemical surface area,and improved the conductivity of the catalyst.This catalyst showed the excellent HER catalytic activities with a low initial peak potential 69 mV,a low overpotential?j=10 mA/cm² at?=151 mV?,a small tafel slope of 71 mV/dec and excellent cycling stability in acid electrolytes.2 With selenium-hydrazine hydrate and molybdic acid amine as precursors,cetyltrimethylammonium bromide?CTAB?as surface active agent,we got lamellar structure MoSe₂ with rough surface by using a mild solvothermal method at 200?for12 h.The results show that the particle size couble be decreased,the roughness could be increased,the specific surface area could be increased,the hydrogen evolution performance could be increased with increasing the amount of hydrazine hydrate.Compared with MoSe₂,the MoSe₂ and carbon nanotube composites exhibited better electrocatalytic hydrogen evolution properties with a small starting overpotential of 72mV,a low overpotential of 149 mV at a current density of 10 mA/cm²,and a small tafel slope of 30 mV/dec,and good cycle stability.3 With selenium-hydrazine hydrate and nickel acetate tetrahydrate as precursors,we got NiSe with different morphology at different hydrothermal temperatures.The morphologies of NiSe were transformed from agglomerated nanoparticles to more dispersed nanorodsand,the hydrogen evolution performances were enhanced,with the hydrothermal temperature rising from 160°C to 200°C.After being doped with MoSe₂,the NiSe-MoSe₂ composites with decreased crystallinity,decreased size and increased agglomeration couble be observed.The catalytic hydrogen evolution activity of the NiSe-MoSe₂ composites were improved compared with before,with a small starting overpotential of 72 mV,a low overpotential of 183 mV at a current density of 10 mA/cm²,and a small tafel slope of 40 mV/dec,showing good hydrogen evolution performance.