Bi₂WO₆ quantum dots with oxygen vacancies combined with g-C₃N₄ for NO removal

Semiconductor materials have been used for photocatalytic degradation since they were discovered to be useful for photocatalytic degradation. Many studies have been researched to improve the efficiency of photocatalytic degradation. Among them, the introduction of vacancies to improve the photocatalytic efficiency has been verified to be a more feasible method. In this study, we combined two-dimensional (2D) graphite carbon nitride (g-C₃N₄) nanosheets with oxygen-containing vacancy zero-dimensional (0D) Bi₂WO₆ (BWO-OV) quantum dots to prepare 2D-0D g-C₃N₄/Bi₂WO₆-OV composite catalyst. The use of Bi₂WO₆ containing oxygen vacancies enhanced the absorption of light and increased the generation of photogenerated carriers. In addition, the formation of heterojunction and the vacancy structure of Bi₂WO₆ promote the life of photogenerated carriers and improve the catalytic effect of the catalyst. This structure shows high efficiency in removing low concentration (0.5 ppm) of nitric oxide (NO) at room temperature. The efficiency of the composite catalyst is much higher than g-C₃N₄ or BWO-OV, and better than the composite g-C₃N₄/Bi₂WO₆ without oxygen vacancies. When applied to NO removal, the composite g-C₃N₄/Bi₂WO₆-OV-10 showed the best catalytic activity which was up to 61.2%. At the same time, five cycles of experiments show that the material has excellent stability.