A brief review on the synthesis of TiO2 thin films and its application in dye degradation

Nanocatalyst films provide a large surface to volume ratio which helps for easy and higher adsorption of the target particles. Thin films also have a large specific surface area and high reactivity. Thin films have been extensively used to study the degradation of various dyes in previous research. Titanium dioxide is one of the most widely used photocatalysts catering to its low cost, easy synthesis and availability, high stability and long term photoactivity. This review focuses on the various methods of preparation of both bare and metal-doped TiO 2 thin films and their further application in degradation studies of various dyes. The photoactivity of TiO 2 films depends largely on the method used for synthesizing the films, the type of TiO 2 used, the reaction conditions, and the type of product to be degraded. There have been several methods for synthesizing thin films some of which include sol–gel method, hydrothermal method, plasma chemical vapor deposition, chemical spray pyrolysis and others. Doping also helps in enhancing the degradation efficiency of the photocatalyst. Doping in TiO 2 results in an overlap of the Ti 3d orbitals with the d levels of the metals causing a shift in the absorption spectrum to longer wavelengths which in turn favors the use of visible light to photoactivate the TiO 2, resulting in a higher efficiency in degradation of dyes.