The Study On The Preparation And Water Oxidation Properties Of Stainless Steel Based Electrodes

Energy shortage and environmental pollution are prompting people to seek clean and renewable energy resources to replace the fossil fuels that are running out.Hydrogen,as a kind of clean energy,is carbon neutral,high efficiency and harmless to the environment.Electrolysis of water is an effective means of hydrogen production,but the anodic oxygen evolution process is a four-proton coupled electron transfer process,and its reaction energy barrier is high.Therefore,it is necessary to develop efficient oxygen evolution catalysts.Although precious metals Ru O₂and Ir O₂are highly active OER catalysts,their high cost,low reserves,and weak stability limit the practical application.Traditional NiFe-based bimetallic compounds are widely used as excellent OER electrocatalysts due to their low price,abundant reserves,and strong intrinsic activity.However,the complex preparation process and the insufficient contact between the active center and the base material caused by the polymer binder lead to the unsatisfactory OER performance and long-term electrolytic stability.To solve the above question,stainless steel material is used as the substrate,and simple surface in-situ modification technology is used to prepare efficient and stable OER catalysts in this paper.The main research contents and conclusions are as follows:1.By introducing less electronegative Mn element into cheap stainless steel,the electron-rich structure is formed around NiFe element,thus increasing OER activity.Specifically,a three-metal catalyst（NiFeMn-SSP）composed of NiFe oxide/oxyhydroxide and Mn O_xwas successfully prepared by one-step hydrothermal method by using KMn O₄as the etchant and Mn source,and 304 stainless steel as the substrate.The nanosheet array structure on NiFeMn-SSP exposes more active sites,which makes it have excellent stability and OER performance.At current densities of 10 m A cm^-2,the overpotentials are only 232 m V,with low Tafel slope(37.6 m V dec^-1)and high TOF value(2.27 s^-1).In 5.4 M KOH electrolyte,it can be electrolyzed stably for 100 h with a current density of 500 m A cm^-2.The experimental results show that the prepared NiFeMn trimetal electrode has excellent stability and OER performance,and also provides ideas for the preparation of trimetal oxygen evolution catalysts.2.Stainless steel felt is a kind of three-dimensional porous material,which has high porosity and larger specific surface area.The NiFe bimetallic catalyst was successfully prepared by in-situ etching using 316 stainless steel felt as substrate and NaNO₃and NaOH mixed solution as corrosive agent.The presence of NaNO₃not only promotes the formation of NiFe₂O₄octahedral particles,but also eliminates the presence of surface Cr elements.The overpotential of the prepared electrode is only 223 m V at the current density of 10 m A cm^-2,The slope of Tafel is 40.4 m V dec^-1.In the long-time electrolysis at the current density is 10 and 100 m A cm^-2,the curve fluctuation of overpotential is unchanged.The experimental results show that the in-situ etched NiFe₂O₄octahedral particles have excellent OER performance and stability.3.In order to eliminate the problems of the Cr precipitation in the process of stainless steel hydrothermal treatment.Using Cr-free permalloy1J79 as the base material and alkaline（NH₄）₂S₂O₈as the etchant,a one-step hydrothermal method was used to prepare an OER catalyst with a tower-like nanocone morphology.At the current density of 10 m A cm^-2,the overpotentials are 237 m V,and the Tafel slope is only 37.3 m V dec^-1.In addition,this electrode has good stability,when electrolyzed for a long time at the current density of 10 m A cm^-2.The experimental results show that the OER catalyst prepared using Cr-free materials not only has little pollution to the environment,but also has excellent water oxidation performance.