Synthesis Of Self-supported Nickel-based Electrode For Electrochemical Properties

Electrochemical water splitting is an attractive hydrogen generation technology with advantages including zero carbon emission,high‐purity product,and the ability to store intermittent renewable energy（i.e.,wind and solar energy）.The theoretical voltage of electrolyzed water is 1.23 V,and the voltage required in the actual electrolysis process is 1.8-2.0 V,which is much larger than the theoretical voltage.In order to effectively improve the slow dynamics of OER and reduce the overpotential,we must choose efficient electrocatalyst.Up to date,the most efficient OER electrocatalysts are generally considered to be Ru or Ir based catalysts and their oxides.But their scarce reserves and high costs hinder their widespread use.For this reason,scientists are committed to the development of non-precious metal catalysts.However,the activity and durability of most non-precious metal electrocatalytic materials are still far from satisfactory,and it is of great interest to develop an inexpensive,efficient,and durable catalyst.In this paper,a catalytic electrode with porous structure was prepared by powder metallurgy method,and the formation of its phase was regulated by adjusting its composition ratio,and the effects of these variables on its OER performance were studied.Through electrochemical performance tests,such as linear volt-ampere curve,cyclic volt-ampere curve,electric double layer capacitance calculation,impedance map,etc.,combined with the above-mentioned structure and phase test,the chemical properties were analyzed,and the rules were summarized.Ni₈Fe₂ porous alloy was found.Shows efficient OER and electrolyzed water performance.For OER,the Tafel slope is 42.5 m V dec^-1,and the current potential is only 269 m V when the current density reaches 10 m A cm^-2.At the same time,the chronopotentiometry results show that it has good catalytic stability.In addition,the composition in the Ni-Fe alloy can be adjusted by adjusting the Ni/Fe ratio to further adjust the OER performance.In addition,the electrolytic cell with the Ni₈Fe₂ porous alloy as the anode and the cathode has a total water-splitting voltage of only 1.65 V at a current density of 10 m A cm^-2,and the Faraday efficiency is close to 100%.The highly efficient electrochemical performance of the Ni₈Fe₂ porous alloy is due to its large surface area,which can expose more active sites,and the metal matrix can achieve rapid charge transfer.In addition,a NiFeTi porous alloy electrode（dealloyed-Ni Fe Ti）with a nickel hydroxide nanosheet array on the surface was prepared by de-alloying treatment,and its OER performance under alkaline conditions was investigated.The dealloyed-Ni Fe Ti sample has a low Tafel slope(45.1 m V dec^-1)and good OER performance.When the current density reaches 10 m A cm^-2,the overpotential is only 250 m V and excellent catalytic stability for OER reactions in alkaline solutions.The dealloyed-Ni Fe Ti has good OER performance due to its multi-stage pore structure.This is because the multi-stage pore structure can provide a large exposed surface area and can achieve efficient mass transfer and gas evolution between the electrolyte and the electrode,facilitating the OER reaction.