Photocatalyst of TiO2/ZnO nano composite film: Preparation, characterization, and photodegradation activity of methyl orange

The TiO2/ZnO nano composite film with atomic ratios of Ti/(Ti + Zn) of 100%, 75%, 50%, 25%, and 0% was successfully prepared via sol–gel process from directly mixing TiO2/ZnO sol followed by heat treatment at 500 °C for 2 h in air. The SEM observation and the XRD measurement revealed that the microstructural morphology and the crystallization behavior of the composite film were essentially related to the atomic ratio of Ti/(Ti + Zn). The UV irradiated degradation of MO solution using the composite film as catalyst showed a linear tendency of the photocatalytic activity of the film against the value of Ti/(Ti + Zn). An exception to photocatalytic activity was observed for the film with Ti/(Ti + Zn) of 75%, which has been attributed to the poor crystallization of the film. Heat treatment with 5 h was applied to the film and better crystallization was achieved for the film. Consequently, a substantial improvement of the photocatalytic activity for the film was finally achieved.