Tin dioxide nanomaterial-based photocatalysts for nitrogen oxide oxidation: a review

Recent progresses on single-atom catalysts for the removal of air pollutants

The booming industrialization has aggravated emission of air pollutants, inflicting serious harm on environment and human health. Supported noble-metals are one of the most popular catalysts for the oxidation removal of air pollutants. Unfortunately, the high price and large consumption restrict their development and practical application. Single-atom catalysts (SACs) emerge and offer an optimizing approach to address this issue. Due to maximal atom utilization, tunable coordination and electron environment and strong metal-support interaction, SACs have shown remarkable catalytic performance on many reactions. Over the last decade, great potential of SACs has been witnessed in the elimination of air pollutants. In this review, we first briefly summarize the synthesis methods and modulation strategies together with the characterization techniques of SACs. Next, we highlight the application of SACs in the abatement of air pollutants including CO, volatile organic compounds (VOCs) and NOx, unveiling the related catalytic mechanism of SACs. Finally, we propose the remaining challenges and future perspectives of SACs in fundamental research and practical application in the field of air pollutant removal.

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

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.