Synergistic effect between Mn single atoms and oxygen vacancies in Mn/Ov-BiOBr with boosted ozonation assisted photocatalytic N2 oxidation

Ozonation assisted photocatalytic (OPC) nitrogen oxidation provides a new sustainable strategy for nitrate production, yet the inefficient activation of N 2 and the rapid recombination of photogenerated carrier remains a challenge. Herein, the BiOBr-based catalysts with Mn single atoms and oxygen vacancies is designed for the OPC N 2 oxidation. Under optimal conditions, the yield of NO 3 − over Mn 0.035 /O v -BiOBr is as high as 151.3 μmol g −1  h −1 , which are 7.63 times that over BiOBr (19.8 μmol g −1  h −1 ). Detailed experimental analysis reveals a synergistic effect between Mn single atoms and oxygen vacancies, where Mn single atoms act the active site for N 2 adsorption and reaction, and oxygen vacancies for O 3 activation and transformation. Theoretical calculations further demonstrate that the synergistic effect between Mn single atoms and oxygen vacancies not only enhance the dipole moment along the [001] direction (i.e. the interlayers), but also induce a dipole moment within the [Bi 2 O 2 ] 2+ layer, both of which are advantageous for chare separation and the subsequent transformation of O 3 to reactive oxygen species (ROS). Meanwhile, a variety of active species act cooperatively to sped up the N 2 oxidation process. This work provides a new method for efficient N 2 oxidation to NO 3 − , namely photocatalytic ozonation, and also provides a deep understanding for the modulation of the internal electric field (IEF) effect of BiOBr via both single atoms and oxygen vacancies to improve charge separation.