Preparation Of Three-dimensional Transition Bimetallic Compound Electrode And Study On Its Electrocatalytic Water Oxidation Performance

Increasing use of fossil fuels has caused major social and environmental problems.Therefore,it is very important to seek and develop sustainable and clean energy.In recent years,as an effective means of clean energy production,electrochemical hydrogen production has attracted widespread attention.Compared with the electrocatalytic water splitting hydrogen reaction of the cathode,the slow oxygen evolution reaction（OER）at the anode has prevented the large-scale application of water splitting devices.Therefore,the design and development of high-performance and high-stability OER electrocatalyst is beneficial to promote the development of electrolysis water hydrogen production process.Among them,Ni-Fe-based bimetallic compounds have been widely studied as an excellent OER electrocatalyst due to their low price,abundant reserves,and high intrinsic activity.Two three-dimensional（3D）composite Ni-Fe catalysts,NiFe OOH/NF and NiSe₂/NiFe₂Se₄@NiFe,have been studied.And the electrocatalytic properties of oxygen evolution and water decomposition in an alkaline electrolyte have been investigated.1.A 3D transitional bimetallic hydroxide composite electrode（NiFe OOH/NF）grown in situ on the Nickle foam（NF）is successfully constructed by impregnation chemical method.The NiFe OOH/NF electrode is composed of crystalline Ni（OH）₂ and amorphous Fe OOH evenly grown on the NF surface.Profiting from the synergistic effect of crystalline Ni（OH）₂ and amorphous Fe OOH,the NiFe OOH/NF electrode requires potentials as small as 1.46 and 1.51 V to achieve super-high catalytic current densities of 100 and 500 mA cm^-2,respectively.The NiFe OOH/NF electrode own outperforming catalytic activity,surpassing all Ni-Fe based electrocatalysts reported thus far,as well as the commercial Ir/C catalyst.In situ electrochemical Raman spectroscopy demonstrated the Fe OOH and NiOOH species produced by NiFe OOH/NF in the OER process are the real active phases.Importantly,the NiFe OOH/NF electrode delivered an outstanding overall water splitting performance under challenging industrial conditions in a 10.0 M KOH electrolyte at 80 ^oC,requiring potentials of 1.65 and 1.89 V to achieve 100 and 500 mA cm^-2,respectively.2.A 3D transition bimetallic selenide compositeelectrode（NiSe₂/NiFe₂Se₄@NiFe）was grown in situ on the surface of NiFe alloy by thermal selenization.The NiSe₂/NiFe₂Se₄@NiFe composite electrode is composed of crystalline NiSe₂and NiFe₂Se₄.The material has special superaerophobic nanowrinkles characteristics.In this heterostructure structure,numerous nanowrinkles of NiSe₂/NiFe₂Se₄hybrid with a thickness of～100 nm wasgrown on NiFe alloy in a uniform manner.Profiting by the large active surface area and high electronic conductivity,the superaerophobic NiSe₂/NiFe₂Se₄@NiFe heterostructure exhibits excellent electrocatalytic activity and durability towards OER in alkaline media,outputting the low potentials of 1.53 and 1.54 V to achieve ultra-high current densities of 500 and 1,000 mA cm^-2,respectively.The NiSe₂/NiFe₂Se₄@NiFe is currently the most active Ni/Fe-based selenide OER catalyst,and is even superior to the commercial Ir/C catalyst.In situ Raman experiment results show that in-situ derived Fe OOH and NiOOH species from OER process are the real active sites.