Mixed oxide/sulfide systems for photocatalysis

Mixed WO₃/WS₂ and ZnO/ZnS powders have been prepared by sulfidation of H₂WO₄ or ZnO. Photocatalytic degradation of phenol has been employed to test the photoactivity of the samples. The results indicated that the coupling of the two tungsten chalcogenides enhanced the rate of disappearance of the organic substrate. Unlikely, the ZnO/ZnS systems exhibited lower photocatalytic activitiy than pure ZnO. The different photocatalytic behaviour of the two mixed oxide/sulfide systems can be explained by a simultaneous displacement of electrons and holes between two different semiconductors.