Regulating Spin Polarization through Cationic Vacancy Defects in Bi4Ti3O12 for Enhanced Molecular Oxygen Activation

Abstract Molecular oxygen (O 2 ) activation technology is of great significance in environmental purification due to its eco‐friendly operation and cost‐effective nature. However, the activation of O 2 is limited by spin‐forbidden transitions, and efficient molecular oxygen activation depends on electronic behavior and surface adsorption. Herein, we prepared cationic defect‐rich Bi 4 Ti 3 O 12 (BTO‐MV2) catalysts containing Ti vacancies ( V Ti ) for O 2 activation in water purification. The V Ti on BTO nanosheets can induce electron spin polarization, increasing the number of spin‐down photogenerated electrons and reducing the recombination of electron‐hole pairs. An active surface V Ti is also formed, serving as a center for adsorbing O 2 and extracting electrons, effectively generating ⋅OH, O 2 .− and 1 O 2 . The degradation rate constant of tetracycline achieved by BTO‐MV2 is 3.3 times faster than BTO, indicating a satisfactory prospect for practical application. This work provides an efficient pathway to activate molecular oxygen by constructing new active sites through cationic vacancy modification technology.