Electrochemical reduction of carbon dioxide on the oxide-containing electrocatalysts

Abstract

Electrochemical reduction of carbon dioxide (CO2 RR) is one of the promising approaches to mitigate the climate-change effects through a negative CO2 emission technology while producing value-added products. Significant advances in CO2 RR have been achieved on various metal electrocatalysts to produce a variety of products in gas, liquid, or even solid forms. The frequently used metals such as Ag, Au, Bi, Cu, Sn, and Zn may contain oxide species that were either intentionally or unintentionally formed during the syntheses. For the oxide-derived catalysts, the oxides are pre-catalyst active forms, which are reduced under the CO2 RR environment and thus affected the physical/chemical properties of the final catalysts. On the other hand, oxide species (MOx, M+, or O2 /O-) can directly enhance CO2 activation, C-C coupling, dimerization, and/or modify the surface electronic states of the active species for CO2 RR. In this review, we provide the latest progress towards understanding the roles of oxide-containing electrocatalysts in CO2 RR. The nature of oxides on various groups of metal electrocatalysts as categorized by their major products [e.g., CO, CH4, HCOOH, CH3 OH, C2 H5 OH, C2 H4, and C (solid)] and their roles in the direct and in-direct effects for improving the CO2 RR performances has been emphasized.