The design and development of novel metal oxide nanocomposites for sunlight driven water cleaning

Photocatalytic degradation of environmental pollutants using a visible light-driven photocatalysts has attracted much attention in order to effectively utilize the majority of the solar energy. Bismuth vanadate (BiVO4) has been one of the semiconducting materials used as visible light driven photocatalysts due to its physical and chemical properties and remarkable photocatalytic performance. However, the individual BiVO4 exhibits low efficiency in photodegradation of organic pollutants. The recombination of photogenerated electron and hole pairs and redox potentials of the generated electron are considered as the factors that affect to its photocatalytic efficiency. In this regard, the primary aims of this work are to synthesis BiVO4 by a simple, cost effective and environmentally friendly method and to improve its photocatalytic efficiency by coupling with selected metal oxides, providing appropriate different band edge positions. To achieve these goals, BiVO4 nanoparticles were prepared by a single-step microwave at the low temperature of 90C (< 300 W) for a short holding time of 1 h. The photocatalytic activity of the BiVO4 was studied through monitoring degradation of Rhodamine B (RhB) and Methylene blue (MB) as model dyes under a simulated solar irradiation. The influence of parameters including film thickness, initial dyes concentration, solar light intensity and reactor volume on the photocatalytic activities of the BiVO4 were investigated. The BiVO4 was modified by coupling with CeO2, TiO2 and WO3 in order to enhance transport of charge carriers that can improve photocatalytic degradation of dyes. Additionally, possible mechanisms of the three composites in photocatalytic degradation of dyes were also investigated by monochromatic light experiments and reactive species quenching study.