Dependence of calcination temperature on wettability and photocatalytic performance of SnO2-TiO2 composite thin films

In the present work, we report the effectiveness of calcination temperature on the photocatalytic activity of SnO2-TiO2 composite thin films. SnO2-TiO2 films calcined at various temperatures (300 degrees C, 400 degrees C and 500 degrees C) were tailored with stearic acid (SA) and octadecyltrichlorosilane (ODTS). SnO2-TiO2 films calcined at 500 degrees C attain superhydrophobic state with water contact angle as high as 150 degrees after tailoring. SA tailored surfaces turned hydrophilic whereas ODTS tailored surfaces are highly stable under UV exposure. The hydrophilic conversion rate of SA modified SnO2-TiO2 films calcined at 500 degrees C is better and of the order of 2.21 x 10(-3)deg.(-1)min(-1). The versatility of the films was further accessed by the degradation of Rhodamine B. SnO2-TiO2 films calcined at 500 degrees C shows superior photocatalytic activity with 82% efficiency. The maximum photocatalytic efficiency is due to better crystallinity, roughness and effective charge separation.