Surface-Adsorbed Oxygen-Triggered Luminescence-Guided Defect Engineering of Oxygen Vacancy

Oxygen vacancies (Ov) in metal oxide-based materials can regulate their surface chemical and electronic properties, and thus the amount of Ov is crucial to exert their photo-, electro-, and thermocatalytic performances. Defect engineering has been introduced to prepare metal oxide-based materials with sufficient Ov. However, the current efforts have been hampered due to the failure to quantify the absolute values of Ov in metal oxide-based materials. In this work, we have prepared ZnFe oxides with varied Ov through the calcination of a ZnFe hydroxide precursor under the guidance of reaction-triggered luminescence induced by Ov. Hydrogen sulfide (H₂S), with the dual functionality of specific affinity toward metal oxides and low-temperature reducibility, has been utilized to react with Ov and interpret the Ov contents in ZnFe oxides. A stoichiometric relationship has been established between H₂S and surface-adsorbed oxygen (Oad), leveraging the reversible interconversion between Oad and Ov. Accordingly, the Ov contents in ZnFe oxides have been regulated, guided by the total luminescence integral areas of H₂S oxidation. The universality of the proposed luminescence strategy was verified by other metal oxide-based materials, such as ZnCo and MgFe oxides. Our work demonstrates a simple and rapid strategy to quantify the Ov contents in metal oxide-based materials, providing guidance for the precise modulation of Ov in metal oxide-based materials with a high catalytic performance.