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. Graphical Abstract: [InlineMediaObject not available: see fulltext.]