CeO2–TiO2 mixed oxide thin films with enhanced photocatalytic degradation of organic pollutants

Abstract

A series of CeO2–TiO2 mixed oxides were prepared by the peroxo sol–gel method. X-ray diffraction, transmission electron microscopy, ultraviolet–visible spectroscopy, atomic force microscopy, and X-ray photoelectron spectroscopy were used to investigate the characteristics of CeO2–TiO2 sols and thin films in order to determine the influence of adding CeO2 to TiO2 on the photocatalytic degradation of methylene blue aqueous solution under both ultraviolet and visible light irradiation. The pH values of the as-prepared CeO2–TiO2 sols were neutral; the as-prepared sols contained nanocrystals in colloidal suspensions, and there was no subsequent calcination process. It was observed that the highest photocatalytic degradation activities with respect to methylene blue under both UV and visible light irradiation were exhibited for an optimum CeO2–TiO2 weight ratio of 0.05. The high photocatalytic activity was because of changes in the spectral absorption of material, which was attributed to the heterojunction formed by TiO2 and CeO2 networks via Ti–O–Ce bonds after addition of CeO2. Thus, the presence of CeO2 in TiO2 significantly enhanced the photocatalytic activity.