Photocatalytic performance of TiO2/Bi2WO6 photocatalysts with trace Fe3+ dopant for gaseous toluene decomposition

As one of the typical volatile organic compounds, toluene is harmful to human health and challenging to decompose effectively with traditional photocatalysts, such as TiO2 or ZnO. Here, a trace Fe3+ doped TiO2/Bi2WO6 composite photocatalyst with abundant oxygen vacancies was successfully synthesized via a hydrothermal method and subsequently impregnation treatment. The Fe3+ doped TiO2/Bi2WO6 were optimized by adjusting the molar ration of TiO2 and Bi2WO6, and the optimal molar ratio was found to be TiO2:Bi2WO6 = 1:2. The obtained Fe(0.1)-TB2 with only 0.1 wt% Fe3+ dopant exhibited superior photocatalytic activity with over 90% toluene removal efficiency after 180 min under visible light irradiation. A series of characterizations reveal that the improved photocatalytic activity of Fe3+ doped TiO2/Bi2WO6 can be attributed to synergistic effects between the extension of photogenerated carrier lifetime and the increase of visible light absorption range by narrowing the energy bandgap (shortened about 0.32 eV) and the formation of oxygen vacancies. Furthermore, hydroxyl radicals and holes as the key reactive oxygen species (ROS) in the photodegradation reaction were confirmed by electron spin resonance (ESR) experiments. Therefore, introducing Fe-ions into TiO2/Bi2WO6 photocatalysts is an effective way to enhance the photocatalytic activities, and the modified catalysts can be considered as a promising material for decomposing toluene and other VOCs.