Research On High-currentdensity Electrocatalytic Performance Of Self-supported Catalyst Prepared By Corrosion Engineering

Hydrogen energy is a clean and pollution-free energy source with advantages such as high energy density,high calorific value,various forms of utilization,and convenient storage.It is considered the most promising alternative to fossil fuels.Electrochemical complete hydrolysis of water is a green,environmentally friendly,and efficient way to produce hydrogen,involving oxygen evolution（OER）and hydrogen evolution（HER）.Due to the slow reaction dynamics of OER and HER,water electrolysis often requires a higher potential than the theoretical value,which leads to a large energy loss.Currently,Pt,Ir O₂and other precious metals have been shown to be effective electrocatalysts for HER and OER,but the scarcity and high cost of precious metals have prevented their large-scale application.Transition metals are widely used in research due to their high conductivity,abundant reserves and low cost.However,the low catalytic activity and poor cycling stability of transition metals are the main obstacles limiting their application in the field of electrolytic water.Thus,how to improve the activity and stability of transition metal-based catalysts has become a hot topic of research.In this paper,a highly active and stable complete hydrolysate catalyst is grown in-situ on a self-sustaining support using a simple corrosion engineering assisted heat treatment strategy.The particular study is as follows:（1）Ni,Fe,and Mo trimetallic oxide nanoflowers were successfully prepared in situ on Ni Fe foam frame by using chloride ion corrosion-assisted low-temperature annealing engineering.Detailed characterization results indicate the presence of heterogeneous interfaces between metallic oxides and abundant pore structures on the nanoflowers,which provide sufficient active sites for catalytic processes.In 1 M KOH,when the current density is 500 m A cm^-2,HER overpotential is 365 m V,OER overpotential is only 330 m V,and the catalyst can run continuously and stably for more than 150 h.In addition,when the prepared catalyst is used as the bifunctional catalyst of the full hydrolysis pool,the voltage of the 2.58 V battery can reach the current density of 500 m A cm-2,and can run stably for more than 70 h.（2）RuO₂/Ni（OH）₂ ultra-thin nanosheet arrays were successfully synthesized on nickel foam using chloride ion corrosion-assisted thermal annealing engineering.Detailed characterization and analysis showed that the prepared catalyst was a hetero-structure of Ru O₂/Ni（OH）₂nanoflower.The water electrolysis properties and dynamics of the catalyst were analyzed through a series of electrochemical tests.The results show that the unique structure of the catalyst enhances the intrinsic activity,accelerates the ion diffusion rate,and has a low charge transfer resistance.It is important to note that the fully hydrolytic cell assembled using the prepared material as a bifunctional catalyst requires only 1.71 V battery voltage to reach a current density of 100 m A cm^-2and can operate smoothly for 200 h.（3）First,Ru-doped Ni（OH）₂ nanosheets array was vertically grown on nickel foam using corrosion engineering strategy.Then,inspired by thermal shrinkage films,thermal shrinkage engineering is applied to prevent the ultrathin sheet from being damaged by the formation of dense gas far away from the interface.It has been shown that the catalytic properties of the catalyst are excellent due to the close bonding between the charge carriers and the catalyst and the amorphous/crystalline mixing characteristics.Most notably,HER has an excess potential of only 400 m V at a current density of 2000 m A cm^-2and can operate stable for more than 100 h at a high current density of 2000 m A cm^-2.In the 1 M KOH+0.5 M Na Cl medium,the HER activity shows little decay.The assembled full hydrolysis cell requires only 1.53 V battery voltage to achieve a current density of 10 m A cm^-2and can operate smoothly for 130 h.