The increased public concern with wastewater effluents from industrial or domestic sources and these environmental pollutants has prompted the need to develop novel treatment methods. Titanium dioxide (TiO2) can be used for various application like hydrogen production, electricity generation via dye-sensitized solar cells, photokilling and self-cleaning effect, photo-oxidation of organic pollutant, wastewater management, and organic synthesis etc. The aim of this paper is to give an overview of the current applications of research into the use of TiO2 nanoparticles as photocatalysts with different preparation method have been reviewed. The incorporation of CeO2 in TiO2 and preparation in the ionic liquid decreased the crystalline size, increased the surface area and retarded anatase–rutile phase transformation. Among CT–carbon nanocomposites, CT–GR nanocomposite shows highest photocatalytic activity and COD removal. Despite drawbacks of titania photocatalysis many organic compounds have been successfully investigated largely from the viewpoint of air and water purification.