The effect mechanisms of pH, complexant and calcination temperature on the hydrophilicity of TiO2 films prepared by the sol-gel method.

Graphical abstract The effects of pH, complexant and calcination temperature on the hydrophilicity of TiO 2 films were studied from three aspects of surface morphology, TiO 2 crystal structure and chemical nature in this paper. Highlights • This paper systematically studied the influence of the pH of sols, complexing agent and calcination temperature on the hydrophilicity of TiO 2 films, and discussed its influence mechanism. • The optimum process for preparing super hydrophilic TiO 2 films was proposed by orthogonal experiment. • It is concluded from mechanism analysis that super hydrophilicity of TiO 2 films is the combination of TiO 2 particles and the surface morphology that work together. Abstract Nano TiO 2 sols are prepared by the sol-gel method, and hydrophilic TiO 2 films are deposited on stainless steel sheets by spin-coating technology. The effects of pH, complexant and calcination temperature on the hydrophilicity of TiO 2 films are studied in this paper. In summary, they all affect the hydrophilicity of films by changing the hydroxyl content on the films surface. pH has a decisive influence on the size of holes in the film surfaces and also has a marked impact on the hydrolysis rate of Ti(OBu) 4. When pH = 6, the film surfaces are covered with micro-Nano holes. The complexant is the critical factor of the hydrolysis rate of Ti(OBu) 4. Double-complexants makes TiO 2 sols more stability and films more hydrophilic. The calcination temperature determines the size, arrangement and crystal structure of TiO 2 particles. When the temperature is 500 °C, the hydrophilicity of TiO 2 films is the best. It is concluded from mechanism analysis that super hydrophilicity of TiO 2 films is the combination of TiO 2 particles and the surface morphology that work together. [ABSTRACT FROM AUTHOR]