Stabilization of oxidation state in ZnO decorated-CeO2 for enhanced formation of CO in CO2 electroreduction

Abstract

Electrochemical CO2 reduction (ECR) is regarded as a potential approach to generate renewable fuel and realize carbon cycling. Zn-based materials have been considered as effective catalysts to reduce CO2 into CO. Unfortunately, low selectivity for CO and Zn metallization impede the development of Zn-based materials. Herein, we propose a strategy in utilizing the changeable valence state of Ce ions to stabilize oxidation state of ZnO, in which the Zn-O-Ce model is constructed by CeO2-modified ZnO nanofibers through electrospinning technique. The effective stabilization of ZnO oxidation state during electroreduction has been verified via operando Raman spectra and other characterizations. Besides, we also find that the introduction of trace amount of inactive CeO2 can not only suppress the hydrogen evolution reaction (HER), but also greatly enlarge active sites. The catalyst with optimized molar ratio of CeO2 to ZnO exhibits high Faradaic efficiency (FE) of 90.00 % for CO at −0.69 V vs reversible hydrogen electrode (RHE) in a flow cell. This work suggests stabilization of oxidation state via introduction of secondary metal-oxide by strong interactions between atoms can be improved.