Enhanced VOCs degradation performance of TiO₂-OV/NH₂-MIL-125 by synergistic modulation of oxygen vacancy and heterojunction

With the development of industry, large quantities of volatile organic compounds (VOCs) not only cause damage to the ecological environment, but also pose a serious threat to human health. At present, most photocatalysts used for benzene treatment still suffer from problems such as narrow light absorption range, high electron-hole recombination rate, and low charge transfer efficiency. Therefore, the development of high-performance photocatalysts is extremely urgent. The introduction of oxygen vacancies and the construction of heterojunctions can effectively solve the above problems. In this study, a defect-rich photocatalyst was combined with a topology-structured metal-organic framework (MOF) to construct a tightly coupled heterojunction, aiming to address these issues and improve the photocatalytic degradation performance of benzene. By introducing oxygen vacancy-rich TiO₂ nanosheets into NH₂-MIL-125, a tightly coupled Z-scheme heterojunction composite photocatalyst is fabricated. The benzene degradation efficiency of the composite reaches up to 98.5%, which is 1.47 times and 1.27 times that of pure NH₂-MIL-125 and oxygen vacancy-rich TiO₂, respectively, while also exhibiting remarkable stability and high adsorption capacity. Oxygen vacancies act as active sites that strengthen the interfacial electronic interaction of the composite, thereby optimizing the electron transport pathway of the heterojunction and improving the carrier separation efficiency. Under the dual modulation of the heterojunction and oxygen vacancies, the built-in electric field is further intensified, leading to a significant enhancement in the adsorption and catalytic performance of the composite. This study provides an effective design strategy for utilizing oxygen vacancy-driven heterojunctions in catalysts for the efficient abatement of VOCs.