Photocatalytic NO removal on BiOI surface: The change from nonselective oxidation to selective oxidation

Abstract Numerous publications have investigated nitric oxide (NO) removal through semiconductor photocatalytic technology. However, few reports are available on the products and mechanisms of the photocatalytic NO removal process. In this study, BiOI hollow microspheres are synthesized for the photocatalytic removal of NO under the visible light irradiation. Results show that NO removal product and NO removal mechanism could interfere with each other. NO removal process could be changed from nonselective oxidation to selective oxidation as the irradiation time increases. Meanwhile, the product of NO removal could be changed from nitrate (NO 3 − ) to nitrogen dioxide (NO 2 ). These interesting changes were attributed to the generated NO 3 − , which was produced from the reactions between NO and OH. The generated NO 3 − could inhibit OH generation, thus leading to a change in the NO removal products and NO removal mechanism. This study can improve our understanding of NO removal on the photocatalyst surface and serve as a guide in using photocatalysts for NO removal.