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

Oxygen vacancies (O v ) in metal oxide-based materials can regulate their surface chemical and electronic properties, and thus the amount of O v is crucial to exert their photo-, electro-, and thermocatalytic performances. Defect engineering has been introduced to prepare metal oxide-based materials with sufficient O v . However, the current efforts have been hampered due to the failure to quantify the absolute values of O v in metal oxide-based materials. In this work, we have prepared ZnFe oxides with varied O v through the calcination of a ZnFe hydroxide precursor under the guidance of reaction-triggered luminescence induced by O v . Hydrogen sulfide (H 2 S), with the dual functionality of specific affinity toward metal oxides and low-temperature reducibility, has been utilized to react with O v and interpret the O v contents in ZnFe oxides. A stoichiometric relationship has been established between H 2 S and surface-adsorbed oxygen (O ad ), leveraging the reversible interconversion between O ad and O v . Accordingly, the O v contents in ZnFe oxides have been regulated, guided by the total luminescence integral areas of H 2 S 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 O v contents in metal oxide-based materials, providing guidance for the precise modulation of O v in metal oxide-based materials with a high catalytic performance.