Modification of tungsten trioxide with ionic liquid for enhanced photocatalytic performance

Abstract

To develop WO₃, a narrow band gap semiconductor with a deep valence band, into an efficient visible light photocatalyst, we modified WO₃ with an ionic liquid [Bmim]I through a facile impregnation method in this study. Upon visible light irradiation, the [Bmim]I-modified WO₃ has been shown to have significantly higher photocatalytic activity than its unmodified counterparts for the degradation of RhB in aqueous solution. The effects of ionic liquid modification on the physicochemical properties of WO₃ and its enhanced photocatalysis were investigated in detail using various characterization methods and analysis of photogenerated hydroxyl radicals. It was revealed that the ionic liquid is bound to the surface of WO₃ after the modification. The presence of a surface-bound imidazolium ring was demonstrated to effectively suppress the recombination of photoexcited electron–hole pairs, resulting in enhanced photocatalysis compared to [Bmim]I-modified WO₃. Furthermore, the [Bmim]I-modified WO₃ exhibited sufficient stability and recyclability with respect to photocatalytic activity, which could make it a promising photocatalyst for practical applications.