Investigation of New Methods to Improve the Photocatalytic Activity of TiO2 Nanoparticles

The wide band gap, high recombination ratio of photo-induced hole–electron pairs and thermal instability of anatase, reduced the photocatalytic activity of TiO2 nanoparticles. In this review study in addition to introducing the characteristics and limitations of TiO2, some of the new methods to improve the performance of photocatalytic TiO2 are presented. Cation or anion doping, semiconductor composites and semiconductor alloys has been extensively investigated for enhancing the visible-light response of wide band-gap TiO2. The photocatalytic activity and thermal stability of SiO2 coated TiO2 nanoparticles can be enhanced efficiently than pure TiO2 powder. Recently, addition of graphene can narrow the band gap of TiO2, lower the electron– hole recombination rate, and enhances electron transport between TiO2 and graphene.