Engineering Durable Superhydrophobic Photocatalyst for Oil-Water Separation and Degradation of Chemical Pollutants

Wastewater treatment, especially for those containing insoluble oils and soluble chemical pollutants, has been a major concern in the field of environmental protection. Materials integrating both hydrophobicity and photocatalytic activity are good candidates in terms of separating insoluble oils from water and photodegrading soluble chemical pollutants. However, the wide application of such materials is curtailed by their susceptible photodecomposition issue. In this paper, we report the design of a durable yet efficient hydrophobic photocatalyst by immobilizing photocatalytic titanium dioxide (TiO2) on a carbonized melamine foam (CMF) for a three-dimensional (3D) porous structure, and subsequently coating a hydrophobic polydimethylsiloxane (PDMS) layer on TiO2 surface (CMF-TiO2-PDMS). The key feature of the design is that the PDMS layer could re-graft on the TiO2 surface via forming chemical bonds with TiO2 under UV illumination, granting the resulting CMF-TiO2-PDMS stable hydrophobicity to durably resist photocatalytic oxidation. As expected, the as-designed CMF-TiO2-PDMS photocatalyst shows excellent durability in removing insoluble organic solvents and photodegrading soluble chemical pollutants under UV illumination. This study is interesting not only because it provides a paradigm in designing durable yet efficient hydrophobic photocatalyst for wastewater treatment, but also shed lights on the design of other multifunctional materials.