In Situ Oxygen-Vacancy Engineering for Enhancing CO₂ Reduction Activity

Bulk metallic oxides with abundant surface oxygen vacancies are promising for the electrocatalytic carbon dioxide reduction reaction (CO2RR). However, the obscure quantification of oxygen-release behavior has hindered the development of highly active and robust electrocatalysts. Herein, based on theoretical guidance, graphene confined SnOx nanodots (rGO@SnOx ND) holding the capacity for in situ formation of reaction-induced oxygen vacancies were prepared and taken as the model catalyst. Operando X-ray absorption fine structure (XAFS) quantitatively analyzed the reversible oxygen-released behavior, promoting the SnOx lattice modulation of the adsorption of *OCHO intermediate. These structure changes further facilitate the exceptional performance, yielding a peak jformate of 567 mA cm–2, a selectivity of 92.5% and a 50 h long-term stability of rGO@SnOx ND. The findings significantly advance the comprehensive understanding of the quantitative relationship between controllable oxygen vacancies and reaction activity, highlighting the capabilities of operando spectroscopy toward much wider metallic oxide-based electrochemical systems.