Enhancing Green Product Generation of Photocatalytic NO Oxidation: A Case of WO₃ Nanoplate/g-C₃N₄ S-Scheme Heterojunction

Abstract

Nitric oxide (NO) removal by photocatalytic oxidation over g-C₃N₄ has achieved more efficient results. However, there is a concern about the high NO-to-NO₂ conversion yield of products, which is not suitable for the photocatalytic NO reaction. In this study, we modify g-C₃N₄ by WO₃ nanoplates for the first time for photocatalytic NO oxidation over a WO₃/g-C₃N₄ composite to enhance the green product selectivity under atmospheric conditions. The results indicate that the photocatalytic efficiency for NO removal by the WO₃/g-C₃N₄ composite is drastically improved and achieves 52.5%, which is approximately 2.1 times higher than that of pure g-C₃N₄. Significantly, the green product (NO₃^-) selectivity of the WO₃/g-C₃N₄ composite is 8.7 times higher than that of pure g-C₃N₄, and the selectivity remained high even after five cycles of photocatalytic tests. We also conclude that the enhanced green product selectivity of photocatalytic NO oxidation by the WO₃/g-C₃N₄ composite is due to the separation and acceleration of the photogenerated charges of the WO₃/g-C₃N₄ S-scheme heterojunction.