Nanoporous Nickel-based Alloy Hybrid Electrocatalysts For Water Splitting

In recent years,due to the large consumption of fossil fuels such as oil and coal,the earth’s resources are becoming increasingly scarce,and environmental pollution is becoming more and more serious.It is urgent to find environmentally-friendly and efficient renewable energy to replace the fossil energy.Hydrogen is a new energy car that can be manufactured artificially and has ultra-high energy density and ultra-high calorific value.It has become the most promising new product to replace fossil fuels.The noble metals Pt,and oxides of Ir or Ru have the highest intrinsic catalytic activity for hydrogen evolution（HER）and oxygen evolution reaction（OER）respectively,but their expensive cost and scarce earth reserves limit their wide application.To reduce the cost of catalytic materials and improve the electrocatalytic performance,the following two works have been carried out in this paper around nanoporous nonnoble intermetallic compounds:（1）NiMoAl precursors were prepared by melting and melt spinning,and then self-supporting nanoporous MoNi₄/Ni electrode was prepared by chemical dealloying.Its dual-mode pore structure can promote the mass transfer of electrolyte and electron transport in the catalytic reaction process,and MoNi₄ intermetallic compound has excellent catalytic activity for intrinsic hydrogen evolution reaction.Therefore,in 1 M KOH electrolyte,the composite electrode only needs an overpotential of 70 mV to reach a current density of 100 mAcm^-2,and the Tafel slope is as low as 40 mVdec^-1,indicating that it has rapid reaction kinetics.In addition,due to the ordered crystal structure and high thermodynamic stability of the intermetallic compound,the intermetallic compound/metal composite electrode material can maintain a constant current density in the stability test of 250 h,which can meet the requirements for the durability of the catalytic material in practical applications.（2）The self-supporting nano porous Cr_1.12Ni_2.88/Ni intermetallic compound/metal composite catalyst was prepared by simple melting,melt spinning,and dealloying.It has a bimodal pore structure,exposing a large number of active sites.The composite has a dual-mode pore structure,which can not only improve the material transport and electron transfer,but also increase the number of active sites and improve the utilization rate of active sites.The electrode material needs an overpotential of 88 mV to reach a hydrogen evolution reaction current density of 100 mAcm^-2 in an alkaline electrolyte of 1 M KOH,with a Tafel slope of 42 mVdec^-1 and excellent stability.In addition,the electrode can also be used as an electrode for oxygen evolution reaction,and has bi-functional characteristics.