Enhanced visible light photocatalytic properties of TiO2 thin films on the textured multicrystalline silicon wafers

TiO2 thin films were grown on solar-grade (SoG) multicrystalline silicon (mc-Si) wafers with different multiscale structures by using a liquid phase deposition (LPD) method. It was found that due to the carrier injection from mc-Si wafers, the photocatalytic activity of the TiO2 films could be expanded from the ultraviolet to the visible light region. In addition, further enhanced visible light photocatalytic properties could be achieved by introducing a nano-texture and p–n junction into the mc-Si wafer, which was ascribed to the excellent light trapping and strong carrier separating properties. Our results suggest that density-graded nanostructures applied to the TiO2 photocatalyst can enhance optical absorption, benefit carrier separation, and improve photocatalytic activity.