Oxygen Vacancies in ZnO Nanosheets Enhance CO₂ Electrochemical Reduction to CO

Abstract

As electron transfer to CO₂ is generally considered to be the critical step during the activation of CO₂ , it is important to develop approaches to engineer the electronic properties of catalysts to improve their performance in CO₂ electrochemical reduction. Herein, we developed an efficient strategy to facilitate CO₂ activation by introducing oxygen vacancies into electrocatalysts with electronic-rich surface. ZnO nanosheets rich in oxygen vacancies exhibited a current density of -16.1 mA cm^-2 with a Faradaic efficiency of 83 % for CO production. Based on density functional theory (DFT) calculations, the introduction of oxygen vacancies increased the charge density of ZnO around the valence band maximum, resulting in the enhanced activation of CO₂ . Mechanistic studies further revealed that the enhancement of CO production by introducing oxygen vacancies into ZnO nanosheets originated from the increased binding strength of CO₂ and the eased CO₂ activation.