Tuning Oxygen Vacancies of Oxides to Promote Electrocatalytic Reduction of Carbon Dioxide

Abstract

Tin oxide (SnOx) has emerged as a promising metal oxide catalyst for the CO2 reduction reaction (CO2RR) into value-added chemicals such as formic acid/formate. However, the improvement of SnOx catalytic performance is hindered by its complex surface structures and limited knowledge about the nature of the active sites. This Letter describes the critical role of oxygen vacancies (Ov) in partially reduced SnO2(110) for CO2RR selectivity by combined theoretical and experimental studies. The SnOx with moderate content of Ov is the most active surface and can suppress the undesirable hydrogen evolution reaction simultaneously. This is also confirmed by the electrochemical experiments that also demonstrate that the selectivity of HCOOH changes with varied content of Ov. Further electronic structure analysis reveals that the bond strength and charge transfer between HCOO* and the active site can be regulated by varying the content of Ov, so that the adsorption strength of HCOO* can be tuned.