Change in photocatalytic NO removal mechanisms of ultrathin BiOBr/BiOI via NO3– adsorption

Improved photocatalytic NO removal of photocatalysts requires enhanced carrier photocatalysis for more reactive species generation. Ultrathin structural BiOBr/BiOI (BiOBr/BiOI-U) photocatalyst was in-situ prepared and it showed enhanced photocatalytic efficiency for NO removal. The underlying photocatalytic process is divided into two steps: in the first step, NO3– was produced in a nonselective oxidation process. The increased NO3– concentration induces NO3– adsorption on the surface oxygen vacancies of the photocatalyst in the second step, which changed the surface environment of the ultrathin BiOBr/BiOI photocatalyst. During this process, the nonselective oxidation process turned into a selective oxidation process with NO2 as the main product. In addition, the main photogenerated reactive oxygen species contributed to NO removal. Furthermore, the photocatalytic mechanism of BiOBr/BiOI-U was explored.