Photocatalytic activity of metal-decorated SiO2@TiO2 hybrid photocatalysts under water splitting

We report the fabrication of a metal-decorated hybrid nanocomposite with TiO2 encapsulation (Metal/ SiO2@TiO2, Metal=Pt or Ru) using a simple surface-modification chemical process. Metal nanoparticles capped with polyvinylpyrrolidone were successfully assembled on functionalized SiO2 via electrostatic interactions, after which a thin layer of TiO2 was coated on the surface by the sol-gel process to avoid agglomeration of the coated silica spheres. Transmission electron microscopy studies confirmed that the metal nanoparticles were uniformly distributed throughout the surface of the SiO2 with a thin layer of TiO2. In addition, X-ray diffraction was employed to ensure the crystal structure of the uniformly coated thin TiO2 layer. Even after calcination at 500 oC, the structure remained intact, confirming high thermal stability. The photocatalytic activity of the metal-decorated SiO2/TiO2 nanocomposites was evaluated using the H2 evolution reaction. The Metal/SiO2@TiO2 catalysts show the photocatalytic water splitting efficiency for H2 generation (i.e., 0.14% for Pt/SiO2@TiO2 and 0.12% for Ru/SiO2@TiO2), while there is no generation of H2 on the Metal/SiO2 without a coating layer. These results indicate that the anatase crystalline coating layer has good thermal and chemical stability and plays a significant role in photocatalytic H2 production. (c) Copyright by The Korean Institute of Chemical Engineers.5