Photooxidative properties of various BiVO4/TiO2 layered composite films and study of their photocatalytic mechanism in pollutant degradation

The pollution of the natural environment by organic pollutants has become a great issue since several decades. As a result, the removal of compounds by using photocatalytic processes under sunlight irradiation attracts a growing interest. In the present work, BiVO4/TiO2 photocatalysts were prepared in the form of films by simple wet chemical methods Various layered configurations of BiVO4/TiO2 film were studied and it was found that the best photocatalyst was composed of top-coated TiO2 layer onto a BiVO4 layer. Such composite exhibited better photodegradation ability toward organic pollutants than single components or top-coated BiVO4 onto TiO2 film. Indeed, the photooxidative mechanism involved oxidative radical species. Therefore the mechanism of photooxidative degradation depended on the layered configuration of the composite film. All the photocatalytic films were characterized by XRD, SEM, UV-vis spectroscopy and XPS in order to study the composition, the surface, and the energy band gap of the photocatalyst. The mechanism of photodegradation was investigated indirectly by using different charge scavengers in order to determine the main oxidative species.