Structural Regulation Of Indium-based Catalysts And Performance Of Electrocatalytic CO₂ Reduction

Electrocatalytic CO₂ reduction reactions（CO₂RR）is a method of converting greenhouse gas carbon dioxide into high value-added products through a catalytic process,such as hydrocarbons such as formic acid,carbon monoxide,methanol,methane and so on.It is hoped that the excess carbon dioxide emitted by industry will be converted into high-value-added fuels.Compared with other energy-driven catalytic processes（such as photocatalysis and thermal catalysis）,electrocatalysis has become one of the research hotspots in environment,energy,materials and other related fields due to its advantages of mild reaction conditions,no high temperature and high pressure,high energy efficiency,and easy control of reaction rate and product selection by changing the electrode potential.However,there are still many challenges in the selectivity of reaction products and catalyst stability in electrocatalytic CO₂reduction reactions.As a low-toxicity p-block metal,indium metal（Indium,In）has the characteristics of high overpotential of hydrogen evolution reaction（HER）and low competitive reactivity,which can selectively convert CO₂ into high value-added products,and has become a hot catalyst in the field of electrocatalytic CO₂RR catalysis.In this work,a series of CO₂ reduction reaction electrocatalysts with high catalytic activity and selectivity were prepared by regulating the structure of indium-based catalysts,and high selectivity for formate products was achieved at a wide reaction potential.Furthermore,the mechanism of electrocatalytic CO₂ reduction reaction was explored by electrochemical test and DFT calculation.The research is as follows:1.A series of In Zn bimetallic oxide catalysts with different proportions In Zn-0.18,In Zn-0.37 and In Zn-0.56,as well as Zn O and In₂O₃ catalysts,were designed using the bimetal construction strategy.The efficient catalytic conversion of CO₂ into formate products was achieved,with the highest FE of90.3%,and the high selectivity of more than 86%at a wide potential of-0.8～-1.2 V.XRD,XPS and HRTEM test results characterize the structure of the bimetallic oxide and confirm the existence of electron interaction between the two oxides.Electrochemical tests such as Tafel,EIS,and ECSA have clarified that In Zn-0.37 bimetallic oxide has the largest electrochemically active specific surface area,the smallest charge transfer resistance and the smallest Tafel slope.Therefore,In Zn-0.37 bimetallic oxide has the fastest reaction kinetics and exhibits the best electrocatalytic CO₂RR performance.In addition,it was recognized that In Zn-0.37 bimetallic oxide has the strongest adsorption capacity for CO₂*by OH-simulated CO₂*adsorption,which is beneficial to promote subsequent reaction steps,thereby improving the selectivity of formate.2.The crystalline-amorphous In₂O₃-Ce O_x heterostructure was constructed by using the heterostructure strategy.The efficient catalytic conversion of CO₂reduction reaction is realized,the highest FE is 94.8%,and the high selectivity of more than 90%is achieved at a wide potential of-0.8～-1.2 V.And maintain stability for more than 20 hours.XPS,LSV and other tests confirmed the strong electron interaction between In₂O₃-Ce O_x heterostructures.Electrochemical characterization such as Tafel,EIS and ECSA revealed that the crystalline-amorphous In₂O₃-Ce O_x heterostructure enables efficient reaction kinetics.Theoretical calculations elucidate the construction of In₂O₃-Ce O_xheterostructure,which optimizing the electron configuration of active site of In₂O₃,significantly enhance the adsorption of*OCHO intermediates on the catalyst surface,reduce the energy barrier of*OCHO→*HCOOH,and improve the catalytic activity of CO₂RR.