Effect of the deposition conditions on the properties of photocatalytic WO3 thin films prepared by mid-frequency magnetron sputtering

WO3 is a widely considered photocatalytic material for water purification. In this paper, nanocrystalline WO3 films were deposited on a glass slide by the mid-frequency reactive magnetron sputtering method. The aim is to determine the photocatalytic activities of the films, which are controlled by the process parameters (oxygen flow and substrate bias). The annealed films reveal a hexagonal structure and have some absorptivity in the visible region. The field emission scanning electron microscopy pattern shows that the films exhibit a uniform, smooth surface. The photocatalytic properties of the prepared films were evaluated by the photodecolorization of methylene blue. The films exhibit the best activity at an oxygen flow rate of 30 sccm and a substrate bias of −50 V. The reason is that this film can create more electron-hole pairs as a result of the greater absorption of visible light, which enhances the photocatalytic performance. Based on the results, a possible photocatalytic mechanism has been proposed.