Preparation Of Ni-Fe-based Catalytic Electrodes By Soluble Anodic Electrodeposition In Eutectic System For Anion Exchange Membrane Water Electrolysi

With the advantages of high combustion calorific value,environmental friendliness and zero CO₂ emission,hydrogen energy has become one of the most effective ways to control greenhouse gas emissions and reduce global warming in the fields of energy storage,chemical industry,metallurgy and distributed power generation,and has been described as"the ultimate energy source for the 21st century".Compared with other hydrogen production methods,hydrogen production by water electrolysis with renewable energy sources is green,flexible and has high purity,which makes it an ideal production technology to achieve the strategic goal of carbon neutrality.This work proposes the electrochemical preparation of NiFe-based electrode materials in deep eutectic solvent（DES）for hydrogen production from water electrolysis.The effect of deposition conditions on the structure of electrode materials is systematically investigated,focusing on the dynamic transformation mechanism of the surface structure of the electrode during catalytic water electrolysis and the constitutive relationship between the catalytic performance,with the following main results:（1）NiFe thin film catalytic materials grown in situ on copper foam substrates（denoted as:NiFe＿FA＿NC and NiFe＿FA＿NN,respectively）were prepared by electrodeposition from a choline chloride-ethylene glycol（Ch Cl-EG）type deep eutectic solvent（Ethaline）containing NiCl₂ and Ni（NO₃）₂,respectively,using iron plates instead of conventional inert anodes,by tuning the deposition parameters.During the electrodeposition process,the iron plates acting as soluble anodes are electrochemically dissolved by oxidation to provide iron ions,which are electroreduced into the plating layer with nickel to form a NiFe hybrid coating at the cathode.Similarly,with the additional addition of Na H₂PO₃ as a phosphorus source to the electrolyte,NiFe P thin film electrodes（NiFe P＿FA＿NC,NiFe P＿FA＿NN and NiFe P＿GA＿NN）were obtained based on different anion precursors（NiCl₂,Ni（NO₃）₂）and anode materials（Fe,Graphite）,respectively,exhibiting excellent catalytic performance of HER in alkaline systems.（2）Compared to graphite anodes,the deposition device constructed based on iron plate anodes can significantly reduce the required cell voltage for electrodeposition and reduce energy consumption.The samples prepared by the deposition of different anion precursors（Cl^-and NO₃^-）exhibit different microscopic morphologies.In contrast to Cl^-,NO₃^-induced electrodeposition produced NiFe thin film electrodes with a unique NiFe alloy and hydroxide mixture phase,which undergoes in situ surface reconstruction during the subsequent catalytic OER process,transforming from a surface of nanoparticle accumulation to a microstructure of nanosheet assembly.In situ oxygen evolution reaction induces electrochemical oxidation and leaching at the electrode and generates abundant anion and cation vacancies on the NiFe＿FA＿NN surface.Theoretical calculations show that the in-situ generation of anion and cation vacancies on the NiFe＿FA＿NN surface during OER can optimize the adsorption energy of the OER intermediates,thus significantly enhancing the catalytic activity of NiFe＿FA＿NN for the OER process.（3）The electrochemical testing results show that the NiFe＿FA＿NN and NiFe P＿FA＿NN prepared by iron plate anodes and nitrate precursors exhibit excellent catalytic activities for OER and HER,respectively,with overpotentials of 258 m V and 56 m V at a current density of 10 m A cm^-2.The NiFe-based electrode materials prepared under the optimized conditions were loaded into a home-made anion-exchange membrane（AEM）electrolyzer（effective area of 10 cm²）.The device demonstrated excellent loading performance under simulated industrial conditions of 5.0 M KOH at 60℃,requiring only 1.73 V_cell to drive 1000 m A cm^-2and operating stably for 200 h.