Preparation Of Nickel-based Catalysts Towards Alkaline Water Electrolysis By Electrodeposition

Hydrogen energy has become the most potential new energy because of its high efficiency,renewable and pollution-free advantages.Among them,alkaline water electrolysis technology is an important means to achieve large-scale hydrogen production.At present,the overpotential of the cathodic hydrogen evolution reaction of alkaline water electrolysis is still very high,which makes the industrial power consumption too high,and the core of reducing the overpotential of the cathodic reaction is to improve the catalytic efficiency of the cathodic material.Nickel-based catalysts have attracted wide attention due to their excellent catalytic performance,but their stability is poor.Especially under the conditions of high temperature and high alkalinity of industrial alkaline water electrolysis,the catalyst is easily damaged.Therefore,the preparation of nickel-based catalysts with excellent catalytic performance and excellent stability is the key to the field of alkaline water electrolysis.In this paper,Ni Mo/Co Mn/Ni cathodic catalysts were prepared by a combination of multi-layered electrodeposition and dehydrogenation treatment.The multi-layered structure can not only expose more active sites,and improve the HER performance,but also improve the stability of the catalysts.The dehydrogenation treatment mainly aims at the hydrogen embrittlement phenomenon in the process of electrodeposition preparation and solves the problem of poor stability caused by hydrogen embrittlement.The specific research contents are as follows:（1）Ni Mo/Co Mn/Ni cathodic catalysts were prepared by the multi-layered electrodeposition method.The multi-layered structure includes nickel mesh substrate,Co Mn nanoparticles at the bottom,and cauliflower-like Ni Mo nanoparticles at the top.In the three-electrode system,the overpotentials of Ni Mo/Co Mn/Ni cathodic catalysts at current densities of 10m A/cm²and 500 m A/cm²are only 28.7 m V and 259.1 m V,respectively.The overpotential rise rates of the catalysts were 4.42 m V/h and 8.74 m V/h after the 12 h constant current test at the current density of 200 m A/cm²and 500m A/cm²,respectively.The overpotential rise rate of the catalysts after 1000cycles was 1.9 m V/h.According to the Tafel extrapolation polarization curve,the corrosion potential(E_corr)and corrosion current density(I_corr)were-0.3267V and 1.954（?）10^-5A/cm²,respectively.The charge transfer resistance was small during the hydrogen evolution reaction,indicating its excellent corrosion resistance.The current density of the catalysts was 121.6 m A/cm²at1.8 V in the test of the alkaline electrolytic cell,and the voltage remained stable after 50 h of the intermittent test.The free energy of hydrogen adsorption calculated by density functional theory is-0.8876 e V,which is closer to zero than that of monolayer catalysts,indicating that its surface has a stronger adsorption effect on hydrogen atoms.（2）The hydrogen embrittlement problem was solved by introducing nitrogen and sintering dehydrogenation during the electrodeposition process,thereby improving the stability and corrosion resistance of the catalysts.In the three-electrode system,the voltage rise rate of Ni Mo/Co Mn/Ni cathodic catalysts（after dehydrogenation）is only 1.64 m V/h after the 12 h test at a current density of 500 m A/cm².The voltage rise rate of the catalysts was only1.29 m V/h after 1000 cycles of cyclic voltammetry.The corrosion resistance of Ni Mo/Co Mn/Ni cathodic catalysts（after dehydrogenation）was enhanced.The corrosion potential was-0.2434 V and the corrosion current density was2.636（?）10^-7A/cm².With the increase of dehydrogenation degree,the current density and stability of Ni Mo/Co Mn/Ni cathodic catalysts at 1.8 V in the system were improved.In addition,the dehydrogenation treatment method is universal for Ni Mo/NiIn summary,the Ni Mo/Co Mn/Ni cathodic catalysts prepared in this paper have excellent HER performance and stability,and the simulation results obtained by model simulation are consistent with the experimental results.This paper is expected to provide new research ideas for the preparation of industrial nickel-based catalysts for alkaline water electrolysis.