Preparation Of Ni Fe Electrocatalyst On Foam Ni Fe Substrate And Its Oxygen Evolution Performance

With the development of society,the massive use of fossil fuels has brought many environmental problems,which pushed the development of clean energy.Hydrogen is widely recognized as clean and green energy.Due to the slow reaction kinetics,oxygen evolution reaction（OER）is the bottleneck of water electrolysis that is a promising way to produce green hydrogen.Thus,developing low-cost and efficient electrocatalysts for OER is of great significance for the electrochemical water electrolysis to produce H₂.Transition metals have been widely studied as a promising electrocatalyst,among which nickel-iron-based catalysts have excellent performance.Compared to powder catalysts,free-standing catalysts have many advantages,such as high conductivity and stability.Furthermore,doping and morphology modification are effective ways to enhance the OER performance.Herein,we improved the performance of Ni Fe based free-standing catalysts by using heteroatom doping and designing composite,respectively.This thesis is divided into two main parts as follows:1.The S-doped nickel-iron hydroxyl oxide（S-Ni/Fe OOH）has been synthesized on nickel-iron foam（NFF）using a simple and rapid low-temperature immersion method as the conducting substrate material.The S-Ni/Fe OOH@NFF electrode grown in situ on the NFF substrate exhibited good OER activity.It has a low overpotential of 229 m V at a current density of 10 m A cm^-2and exhibits a durable stability with minor attenuation for at least 150 h at a current density of 100 m A cm^-2.2.In the second work,a Ni（OH）₂/Ni OOH/Fe（OH）₃composite has been synthesized on foam nickel iron by one-step hydrothermal method,named NNF-HO_X.The morphology can be adjusted by NH₄F.Reaction time has been controlled to tune the OER performance,wherein the synthesized NNF-HO_X-4h has the best OER catalytic performance,requiring only 224 m V over potential at a current density of 10m A cm^-2.In addition,NNF-HO_X-4h also has excellent stability,which can be stable for more than 100 h at a large current density of 120 m A cm^-2.