Coating of TiO2 Thin Films on the Surface of SiO2 Microspheres: Toward Industrial Photocatalysis

A core/shell SiO2/TiO2 photocatalyst was prepared using a liquid-phase deposition (LPD) method. Zeta- potential measurement showed that deposition of a layer of polyelectrolyte on the surface of SiO2 microspheres was a prerequisite for subsequent deposition of the TiO2 shell with a controllable and uniform thickness. The photocatalytic activity of the core/shell SiO2/TiO2 catalyst for decomposition of Orange II in liquid phase was observed to be comparable with that of P25 (a commercial TiO2 product of Degussa). Experimental data also showed that the SiO2/TiO2 core/shell nanostructured photocatalyst can be easily separated from the reaction medium by sedimentation, and the solid can be recycled and reused. Thus, the photocatalyst described in this work represents a new catalyst system with a high potential for practical applications in treating wastewater.