Enhanced Photocatalytic Activity and Stability of Bi₂WO₆ – TiO₂-N Nanocomposites in the Oxidation of Volatile Pollutants

The development of active and stable photocatalysts for the degradation of volatile organic compounds under visible light is important for efficient light utilization and environmental protection. Titanium dioxide doped with nitrogen is known to have a high activity but it exhibits a relatively low stability due to a gradual degradation of nitrogen species under highly powerful radiation. In this paper, we show that the combination of N-doped TiO2 with bismuth tungstate prevents its degradation during the photocatalytic process and results in a very stable composite photocatalyst. The synthesis of Bi2WO6–TiO2-N composites is preformed through the hydrothermal treatment of an aqueous medium containing nanocrystalline N-doped TiO2, as well as bismuth (III) nitrate and sodium tungstate followed by drying in air. The effect of the molar ratio between the components on their characteristics and photocatalytic activity is discussed. In addition to an enhanced stability, the composite photocatalysts with a low content of Bi2WO6 also exhibit an enhanced activity that is substantially higher than the activity of individual TiO2-N and Bi2WO6 materials. Thus, the Bi2WO6–TiO2-N composite has the potential as an active and stable photocatalyst for efficient purification of air