Effect of Addition of Surfactant to the Surface Hydrophilicity and Photocatalytic Activity of Immobilized Nano-TiO<sub>2</sub> Thin Films

Abstract

We study the effect of adding cetrimonium bromide (CTAB) as a surfactant to titanium dioxide (TiO2) solution for immobilizing TiO2 on glass substrates. The thin films are deposited by the dip-coating technique. After dipping into the TiO2 sol, the films are calcined and a pure anatase crystal phase is obtained. The thickness of the thin film is changed by varying the number of the dip-and-calcine cycles. The prepared films are characterized using FE-SEM, TG-DTA, and XRD, and samples’ photocatalytic performances are tested with regard to the degradation of methylene blue dye. Aside from the photocatalytic performance, the photoinduced hydrophilicity of thin TiO2 films surface is also studied.Characterization results show that the addition of surfactant gives rise to characteristic patterns on the surface of the TiO2 thin film, which also affects the photocatalytic activity. The addition of CTAB to the TiO2 dipping solution has a negative effect because the calcination temperature is not sufficiently high to burn all the surfactants off. As for surface wettability, the addition of surfactant has a positive effect on the photoinduced surface hydrophilicity of the TiO2 films under UV light.