Improvement of gaseous pollutant photocatalysis with WO3/TiO2 heterojunctional-electrical layered system

Since the photogenerated holes play a much more important role than electrons in gas-phase photocatalysis, it is better to enrich the holes in the surface of a material system. Here, a novel [interdigital electrode/WO3/TiO2] heterojunctional-electrical layered (HEL) system is proposed to realize this attempt. The HEL system consists of interdigital electrode, WO3 layer and TiO2 layer, and they are orderly printed onto the alumina substrate from bottom to top using the technology of screen printing. It is surprise that the synergistic effect of layered heterojunction and external low bias can strengthen the separation of electron-hole pairs in both TiO2 and WO3, and enrich the TiO2 surface layer with photogenerated holes to degrade the gaseous pollutants. In comparison with the pure TiO2 film, a 6-fold enhancement in photocatalytic activity was observed using the HEL system by applying a very low bias of 0.2 V. Furthermore, the results also showed that the remarkable improvement could not be obtained when either the WO3 layer or the low external bias was absent. (C) 2011 Elsevier B.V. All rights reserved.