A Simple and Ligand-Free Synthesis of Light and Durable Metal-TiO2 Polymer Films with Enhanced Photocatalytic Properties

The photocatalytic efficiency of TiO2 can be increased by using co-catalysts, such as metal NPs, which act as electron sinks that suppress the recombination of photogenerated electron-hole pairs. The main challenge in preparing such systems is to create intimate contact between the metal and the TiO2 surface while still maintaining control over the morphology and distribution of the metal nanoparticles (NPs) in the TiO2 matrix. Here lightweight TiO2 films were prepared by assembling a layer of TiO2 NPs onto a thin polymer support, followed by physical vapor deposition of metal NPs onto the TiO2 surface. Importantly the fabrication does not involve any chemical modifications on the surface of NPs, which allows spontaneous formation of strong chemical bonds between deposited metal NPs and TiO2 NPs. Systematic optimization of this process gave materials 6× more catalytically active than the parent TiO2 films and up to 18× more catalytically active than commercial photoactive TiO2 glass. Moreover, the transparent, flexible and robust polymer support enabled the product metal-TiO2 films to be easily used for repeated photocatalytic reactions. Since the whole fabrication process is scalable, highly reproducible, this approach provides new opportunities for controlled synthesis of a new family of practical high-performance metal-semiconductor hybrid photocatalysts.