Correlation between Photoactivity and STM Topographic Parameters of TiO2 Polycrystalline Film

Titanium dioxide is rising growing interest because of its photocatalytic and photoelectrochemical properties. Under UV irradiation, photogenerated charge carriers can migrate to the surface and drive several redox reactions, from water splitting in hydrogen and oxygen to the photocatalytic decomposition of organic pollutants. Potential applications of TiO2 thin films range from self cleaning and superhydrophilic surfaces to photocatalytic air and water detoxification. One of the approaches to improve material performance involves transition metal doping of anatase thin films and colloids. The doping could affect not only the optical band gap, but also surface and morphology of nanocristalline thin films. In this work was explored the effect of Sn doping on anatase polycrystalline TiO2 films. Scanning Tunneling Microscopy (STM) was used to image the sample surfaces. Good STM images were obtained by TiO2 film deposition on conductive substrates (SnO2 coated glass). A statistical analysis of the roughness parameters from the images has been made, showing a correlation between photocatalytic activity and exposed surface area of the samples.