A Brief Review of the Current Scenario on the Synthesis and Application of TIO₂ Nanoparticles

TiO2 nanomaterials can be synthesized in various types of structures, such as nano-powder, nano-films, nano-rods, nano-crystals, etc., by various methods such as biological, precipitation, hydrothermal, electrochemical, solvothermal, spray pyrolysis, co-precipitation, micro-emulsion, solution-combustion, and sol-gel, etc. Each method has unique importance, merits, and demerits. Such as biological method is an ecofriendly method and avoids toxic chemicals in the preparation of TiO2 -based nanomaterials. The co-precipitation technique is very convenient and easy, but its control over size distribution is not good, which results in coarser particles instead of nanoparticles. The micro-emulsion method facilitates good control over the particle size by the ratio of surfactant to water, low reaction temperature, and short processing time. The sol-gel method has high homogeneity in crystals, better tuning over the shape and size of the crystals with reasonable preparation cost. The hydrothermal and solvothermal processes have good chemical uniformity and a higher probability of synthesizing unique metastable structures at minimum reaction temperatures but nanomaterials synthesized via these methods are not stable for application at the higher temperature. The electrochemical technique facilitates a multifaceted and minimum temperature method to synthesize TiO2 nanoparticles with good control over crystallite size, better yield, and negligible environmental effect. To synthesize the nanostructures of TiO2 , liquid phase processing is the most convenient method since it gives better homogeneity in the product with good control over shape and size. In this chapter, short literature regarding the synthesis of TiO2 nanostructure by various methods and its applications are discussed. Moreover, the regeneration of used TiO2 -based nanoparticles is also reported.