Sandwich-like photocatalyst MIL-101@TiO2@PDVB with water resistance for efficient oxidation of toluene

The coordination of H2O with the metal nodes of MOFs destroys the framework of MOFs, which severely inhibits the application of MOFs in the actual environment. In this work, sandwich-like MIL-101@TiO2@PDVB composite was synthesized by in-situ hydrothermal and thermal deposition methods and used for the photocatalytic oxidation of toluene under high humidity. The result showed that the composite material had outstanding hydrophobic property with a water contact angle of 142.5°. When relative humidity (RH) was 60%, MIL-101@TiO2@PDVB and MIL-101@TiO2 exhibited an excellent photocatalytic activity for toluene degradation. When RH was 90%, the photocatalytic activity of MIL-101@TiO2 was severely inhibited, while MIL-101@TiO2@PDVB showed high resistance to water. The semi-encapsulated form of PDVB effectively resisted the erosion of H2O while providing enough ·OH, and ensured the effective contact between the composites and toluene molecules. MIL-101@TiO2@PDVB also exhibited remarkable adsorption-photocatalytic performance in the degradation of liquid phase organic pollutant. MIL-101@TiO2@PDVB maintained high stability in long-term alkali resistance experiment and cyclic reaction test. This work provided new insights for the preparation of hydrophobic MOFs based functional materials and their applications for photocatalytic purification of VOCs.