Review of the progress in preparing nano TiO2: An important environmental engineering material

TiO₂ nanomaterial is promising with its high potential and outstanding performance in photocatalytic environmental applications, such as CO₂ conversion, water treatment, and air quality control. For many of these applications, the particle size, crystal structure and phase, porosity, and surface area influence the activity of TiO₂ dramatically. TiO₂ nanomaterialswith special structures and morphologies, such as nanospheres, nanowires, nanotubes, nanorods, and nanoflowers are thus synthesized due to their desired characteristics.With an emphasis on the different morphologies of TiO₂ and the influence factors in the synthesis, this review summarizes fourteen TiO₂ preparation methods, such as the sol-gel method, solvothermal method, and reverse micelle method. The TiO₂ formation mechanisms, the advantages and disadvantages of the preparationmethods, and the photocatalytic environmental application examples are proposed as well.