Preparation Of MOF-derived CoP Catalysts And Electrocatalytic Hydrogen Evolution Performance

With the growth of global population and the rapid development of industry,the problem of energy has become more and more prominent.We have to seek sustainable energy to replace fossil fuels.Hydrogen energy is regarded as the most promising green fuel.And the hydrogen production from electrolytic water is now considered to be the most environmentally friendly and pollution-free method.Therefore,it is of great significance to search for catalysts with low cost,high activity and good stability for water electrolysis.Currently,transition metal phosphides have attracted wide attention.However,it faces many problems such as low stability and active sites with insufficient exposing.Therefore,in this paper,graphdiyne doped nano-CoP with N,P,and C layers was prepared by adding different carbon materials during the preparation of Co-MOF and improved its electrocatalytic performance of hydrogen evolution.Metal organic frameworks（MOFs）are porous,which the porosity of MOFs can improve the exposure of active sites and electron/mass transfer.The organic linkers can serve as the source of N-doping which facilitates to maximize conductivity of carbon matrix.The specific research process includes the following parts:（1）The CoP catalyst was obtained by oil bath,refluxing,stirring,calcining and phosphating.It was found that CoP showed good electrocatalytic activity.The active site was increased with P filled the oxygen vacancy.The electronic structure and adsorption characteristics of CoP catalyst was improved.The electrocatalytic hydrogen evolution performance was also improved.Electrochemical tests showed that the CoP catalyst needed only 155 m V to reach 10 m A·cm^-2 and the Tafel slope was 64 m V/decade when the oil bath temperature was 350 ^oC and the oil bath time was 1 h.（2）A proper amount of Vulcan XC-72R was added during the synthesis of ZIF-67,and the CoP-C catalyst was obtained by oil bath,calcining and phosphating.It is found that the addition of Vulcan XC-72R is beneficial to increase the electrical conductivity,capacitance and electrochemical active area.When the calcination temperature is 350^oC,MOF derived CoP-C doped with Vulcan XC-72R has the best electrocatalytic performance for hydrogen evolution.Electrochemical tests showed that the CoP-C catalyst needed only 134 m V to achieve 10 m A·cm^-2,with Tafel slope of 57 m V/decade.（3）Vulcan XC-72R and graphdyine（GDY）were added in the synthesis process of Co-MOFs.It was obtained to CoP@NPC catalyst by phosphating.The results showed that Vulcan XC-72R and graphdyine（molar ratio=15:2）had a synergistic effect on the electrocatalytic hydrogen evolution activity of CoP@NPC.CoP@NPC requires only144 m V to achieve 10 m A·cm^-2.The Tafel slope was 67 m V/decade.