Study On Electrocatalytic Performance Of Porous FeCoNiCuTi(Ga) High Entropy Alloy

Fossil energy has always been the main source of energy needed for human survival,but its extraction,transportation and combustion processes generate many environmental problems,and hydrogen energy as a clean energy source has started to enter people’s view,making electrolytic water to hydrogen technology attracts much attention in the development and utilization of new energy sources.Hydrogen production from electrolytic water generally uses precious metal catalysts such as platinum,but it is difficult to achieve large-scale hydrogen production due to its expensive price.Therefore,there is an urgent need to develop economical,efficient and stable non-precious metal catalysts.In this thesis,FeCoNiCuTi（Ga）high entropy alloy catalyst with different micromorphology was prepared by dealloying method and its electrochemical performance was studied.The mechanism of water electrolytic reaction of catalyst was explored by combining DFT theory calculation and simulation.The main research conclusions are as follows:（1）FeCoNiCuTi high entropy alloy ingot was prepared by vacuum arc melting,and metal strips were prepared by vacuum solution ultra-cooling system.Then dealloying was carried out in 5.0 M HCl at different times.According to characterization and testing,FeCoNiCuTi with dealloying time of 15h has the best performance.When the current density is 10 m A cm^-2,the overpotential of FeCoNiCuTi is 64.9 m V,the Tafel slope is 36.81 m V dec^-1,the double layer capacitance is 34.1 m F cm^-2,and has high stability.The adsorption energy of some sites in FeCoNiCuTi was lower than that of Pt（111）.（2）Ga was added into FeCoNiCuTi alloy to form（FeCoNiCuTi）_100-xGa_x（x=1,2,3,5,10,16.67）high entropy alloy.The strips were prepared by vacuum arc melting and vacuum solution ultra-cooling system.Then dealloying was carried out in 5.0 M HCl for 15h.Through characterization and testing,it is found that（FeCoNiCuTi）₉₈Ga₂ has better performance.At the current density of 10 m A cm^-2,the overpotential is only 47.4m V,the Tafel slope is 35.75 m V dec^-1,and the double layer capacitance can reach 36.8m F cm^-2,showing excellent stability.The DFT theoretical simulation results show that the addition of Ga can make the d-band center shift negatively,reduce the adsorption free energy of H,and improve the catalytic activity.（3）The catalytic activity of FeCoNiCuTi and（FeCoNiCuTi）₉₈Ga₂ dealloyed strips in OER was investigated.The overpotential of FeCoNiCuTi and（FeCoNiCuTi）₉₈Ga₂are 370 m V and 356 m V at the current density of 10 m A cm^-2.The Tafel slopes were69.62 m V dec^-1 and 44.25 m V dec^-1,respectively.And it still maintains high stability after 6h stability test.The overpotential of Feconicuti-O and（FeCoNiCuTi）₉₈Ga₂-O is0.338 e V and 0.300 e V respectively,and the addition of Ga increases the d-band central energy level and the adsorption capacity of（FeCoNiCuTi）₉₈Ga₂-O.The results showed that the addition of Ga further improved the OER electrocatalytic performance of FeCoNiCuTi.