Identifying a Key Factor Determining Interfacial Electron Transfer in CO2 Reduction to Formate: Potential of Zero Charge

Abstract

Listen

Translate article

Electron transfer at the metal–solution interface is crucial to an electrocatalytic reaction, which is generally recognized as a rate-determining step. So far, there is still lack of a universal experimental electrochemical quantity strongly correlated with the interfacial electron transfer rate for different kinds of catalysts, limiting the design of superior electrocatalysts for a given electrocatalytic reaction. Here, we propose that the potential of zero charge (PZC) is theoretically and experimentally correlated with the interfacial electron transfer rate and thus profoundly affects the activity and selectivity of CO2 electroreduction to formate for Bi, In, Sn, and Pb. PZC takes into account the contributions from both the work function of catalysts and the change in the electron overlapping distribution at the catalyst surface induced by the solvent dipoles. The higher the PZC, the faster the interfacial electron transfer rate of CO2·– formation in the process of CO2 electrochemical reduction to formate. Thus, the promotion by accelerating the interfacial electron transfer leads to higher electrocatalytic activity and selectivity for yielding formate. This study demonstrates the relationships between PZC and activity and selectivity, and further lays a theoretical foundation for in-depth insight into the electrocatalytic mechanism of different kinds of metals on highly yielding the same product.