Photocatalytic water treatment over WO3 under visible light irradiation combined with ozonation

► Photocatalytic water treatment over bare WO3 under visible light irradiation combined with ozonation exhibited a much higher total organic carbon removal than ozonation alone. ► Bare WO3 was found to function as an active visible-light-responsive photocatalyst for decomposition of organic compounds in the presence of ozone, which readily reacts with photoexcited electrons in the conduction band of WO3. ► In the photocatalytic water treatment under visible light irradiation combined with ozonation, WO3 was superior to commercial N-doped TiO2, which is the well-known as an active visible-light-responsive photocatalyst.