Al doping effect on the morphological, structural and photocatalytic properties of TiO₂ thin layers

In this study, Al-doped TiO₂ films are deposited by sol-gel dip-coating method. Structure, surface morphology, optical properties and photocatalytic degradation of Methylene blue have been investigated. The films are characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), UV–Visible spectroscopy and scanning electron microscope (SEM) equipped with electron dispersive X-ray (EDX). XRD analysis confirms the formation of single nanocrystalline anatase phase. The crystallite size is in the order of 17 nm and seems not affected by the presence of Al. AFM analysis reveals that the surface topography of TiO₂:Al films is significantly affected by Al content. The optical properties are found not affected and all TiO₂:Al thin films show high visible infrared transmission and high optical gap energy. The phocatalytic efficiency has been improved by Al doping; with the highest degradation rate of methylene blue observed for TiO₂:0.2% Al.