Au/WO3 nanocomposite based photocatalyst for enhanced solar photocatalytic activity

Gold nanoparticles (AuNPs) were loaded on tungsten trioxide (WO3) platelet-like support by a simple impreg-nation deposition technique at room temperature. Textural, structural and electrical properties were charac-terized for the as prepared material. The SEM/TEM investigations revealed that formed AuNPs possess a mean diameter of 7 nm and a preferential deposition on the (0 2 0) planes of the orthorhombic WO3 structure. The photodegradation efficiency was evaluated under solar light irradiation using dye pollutant solutions such as rhodamine B (RhB), methylene blue (MB) and methyl orange (MO). According to the affinity between the organic pollutant and the catalyst support, the adsorption/photocatalysis yield and the degradation pathway differ. It was observed that MB created strong electrostatic bonds with the catalyst support while RhB and MO did not adsorb on Au/WO3 hybrid sample. Photocatalytic tests revealed a high performance of Au/WO3 photocatalyst with a complete degradation in 90 min for a cationic dye mainly due to the oxidation by the hydroxyl reactive oxidant species. LC-MS analyses confirmed a higher decomposition with gold compared to bare WO3 on the MB pollutant and results permit to propose a degradation pathway.