Ultraviolet Light‐Modulated Defects on BiOBr to Improve the Photocatalytic Fixation of Nitrogen to Ammonia

Defect engineering has been considered as a feasible approach to improve the photocatalytic activity in nitrogen fixation. However, as the main determinants of photocatalytic properties, the type of vacancy and controllable preparation methods remain elusive. Herein, a controllable method for defect fabrication on BiOBr is achieved by ultraviolet (UV) light illumination. With extending the UV light illumination time, the type of defects is switched from oxygen vacancies to triple‐vacancy associates (V Bi ‴V O •• V Bi ‴). Notably, V Bi ‴V O •• V Bi ‴ is much more stable compared with oxygen vacancies on the surfaces of BiOBr, resulting in higher photocatalytic activity in nitrogen fixation. The reaction mechanism of photocatalytic reduction of N 2 to ammonia in different defects‐modified BiOBr is also proposed along with the testing results. Herein, a controllable method to fabricate vacancies on BiOBr induced by UV light is provided, and the reaction pathways of photocatalytic fixation of N 2 on different defects‐modified BiOBr are demonstrated.