Improving Interfacial Electron Transfer Via Tuning Work Function Of Electrodes For Electrocatalysis

Interfacial electron transfer（IET）at metal-solution interface generally as a rate-determine step determines the overall rate of an electrocatalytic reaction.Although the electrocatalytic performance can be improved by enhancing IET,there is still lack of physical insight into the IET mechanism at metal-solution interface,as well as a physical quantity available in experiment that is linked to the evaluation of IET rate.As a typical electroctalytic reaction,the first step of carbon dioxide reduction CO₂+e^-→CO₂^·-is the rapid control step of the reaction,which involves the electron transfer of electrons at the interface of the metal solution.However,the microscopic mechanism of this process is still unclear and lacks theoretical basis,limiting the development of super catalysts.（1）In this work,we present the physical insight into the nature of IET from a quantum electrochemical perspective,and propose work function of a metal as a key physical quantity to determine the IET rate.We elucidate how the work function influences the IET rate:A decrease in the work function of a metal can dramatically enhance the interface electron transfer.（2）To experimentally verify this theory,three different silver electrodes are prepared for CO₂ electroreduction,the work functions of which are determined by differential capacitance curve and ultraviolet photoelectron spectroscopy.The results of the Tafel slope confirm that the interfacial electron transfer rate of the reaction can be increased by lowering the work function of metal electrode.（3）The Ag catalyst with smaller work function has higher activity and selectivity for CO production.Na BH₄-Ag prepared by oxidative derivatization has the smallest work function,showing a Faradaic efficiently of 97.5%for CO at-0.9 V vs.RHE.This study demonstrates that tuning the work function of the metal catalyst can affect the overlap degree between equal energy levels of the electron in metal and the solvated CO₂,increase the IET rate and thus improve catalytic activity,which provide a promising strategy for predicting catalyst performance and designing super catalysts.