Preparation And Electrocatalytic Properties Of Non-noble Metal Catalyst With Hierarchical Structure

With the increasing demand of industry and people's livelihood,searching for new energy to replace the position of coal in the energy structure has become a spotlight with broad prospects.Hydrogen energy,featured as a clean and energy,are of promising foreground and stands out in many new energy sources.Further,its discounted and wide existence also lays a good foundation for the development of hydrogen energy.As one of the simplest and controllable methods to obtain hydrogen resource,hydrogen production by electrolysis has received extensive attention.To reduce energy consumption during the hydrogen production,exploration of the cheap electrode materials has been a key point and bottleneck for the application of electrolysis.First of all,foamed nickel(NF)and the precursors containing Ni,Co or Fe were used to fabricate M1M2(OH)x/NF and M1M2Px/NF through a hydrothermal and phosphorization method.The influence of different metal and phosphorization process on electrocatalytic activity and structure have been discussed.FeM2Px/NF has a compact nanosheet(thickness?20nm)structure which enable itself to interconnect and support each other to build pores.TheOER was operated in 1M KOH and the results shows that the FeM2(OH)x/NF and FeM2Px/NF have excellent OER performance.At the overpotential of 350mV,them can delivers 100mA·cm-2.The CoNiPx/NF with nanowires structure possesses the best hydrogen evolution performance(HER)and overpotential at current densities of-100mA·cm-2 is 210 mV,which was improved by 303 mV than CoNi(OH)x/NF.Phosphating treatment could highly improve HER performance of electrode materials,and has little impact on OER performance.And the enhancement of HER is mainly due to the high electron conduction efficiency of phosphide and the low hydrogen adsorption energy.According to HRTEM,the CoNiPx/NF nanowires composed of nanoparticles have abundant micropores and more crystal defects to expose more active sites.Replacing OER with HzOR on the anode offers a viable strategy to further reduce the energy consumption in the process of hydrogen production.Based on CoNiP/NF and additional electrodeposition method,the composite structure,NiCoPx@NiCo(OH)x/NF electrode was fabricated.The results shows that the material structure is composed of three layers which is foam nickel on the bottom,NiCoPx nanowire in the middle and NiCo(OH)x nanosheet on the top.With the multiple layers,NiCoPx@NiCo(OH)x-30s/NF possesses larger specific surface area and greater electrical conductivity.Consequently,the electrode come as a highly efficient bifunctional electrocatalyst which exhibits excellent HzOR and HER properties.Especially in HzOR(3M KOH with 0.1M N2H4),the onset potential is around-1.19V.When the current density delivers 200 mA·cm-2,the voltage is-1.08V,and the Tafel slope of NiCoPx@NiCo(OH)x-30s/NF is only 13.2mV·dec-1.Finally,the cell couple constitute of NiCoPx@NiCo(OH)x-30s/NF requires almost 0.22V to deliver 100mA·cm-2.The goal of reducing energy consumption of hydrogen production by electrolysis is achieved.