Synthesis Of Transition-metal Compounds-based Electrocatalysts For Hydrogen Evolution Reaction

As a kind of clean,abundant and high efficient energy carrier,hydrogen has been considered as a possible alternative to petroleum fuel.The generation of hydrogen by water electrolysis via a cathodic hydrogen evolution half reaction is regarded as the most attractive avenue.The prerequisite for hydrogen evolution reaction?HER?is to find efficient catalysts to reduce the energy consumption in water splitting systems,achieving large cathodic current densities at low overpotential.Until now,Pt-group metals are the most active HER electrocatalyst,while the rarity and high-cost restrict its practical applications.Searching for high efficiency and low cost HER catalysts is significant and urgent.Transition metal compound catalysts have been extensively developed for the hydrogen evolution reaction due to its naturally abundant and high electrochemical catalytic activity.This paper gives some practical strategies on how to improve the catalytic activity of transition metal compounds,such as selenide and phosphide,including provide simple methods to synthesize MoO₂/MoSe₂,CNFs/CoSe₂ and CoP/Ni as HER catalysts and investigated them by physical characterizations and electrochemical measurements,such as the following:?1?MoO₂/MoSe₂ hybrid,which loosely stacked MoSe₂ layer were formed on the conductive MoO₂ surface,was synthesized successfully by a facile hydrothermal approach followed by selenylation treatment.The supported catalyst was systematicallyoptimizedwithrespecttoselenylationtimeand the experimental result indicated that 1 h was the best selenylation time.As expected,TheMoO₂/MoSe₂hybridexhibitedexcellentHERactivity,which may be attributed to abundant active sites,good conductivity and outstanding stability.?2?Based on the 3D network structure of bacterial cellulose,CoSe₂/CNFs hybrids,which the CNFs was used as template and CoSe₂ nanoparticles evenly coated on CNFs had been successfully prepared via a one-step low-cost solvothermal method.Electrochemical results showed the obvious improvement of HER activity in the CoSe₂/CNFs hybrids comparing to bare CoSe₂ nanoparticles.Benefiting from especial3D network structure of CNFs,CoSe₂ nanoparticles were free from agglomeration and stacking to expose more active sites,leading to improvement of catalytic performance.?3?Two-dimensional sheet CoP directly grown on Ni foam was prepared by the facilehydrothermalmethodfollowedbyphosphorizationinvolving Co?CH₃COO?₂·4H₂O as the Co source and sodium hypophosphite as the P source?CoP/Ni?.CoP dense films were uniformly grown on the surface of Ni foam.The catalyst was not only avoided the use of binder,but also appeared many pores of different sizes,which would in favor of soaking and penetrating of the electrolyte.The electrochemical performance tests demonstrated the CoP/Ni catalyst exhibited excellent performance of hydrogen evolution reaction.