Regulating Spin Polarization through Cationic Vacancy Defects in Bi₄ Ti₃ O₁₂ for Enhanced Molecular Oxygen Activation

Molecular oxygen (O₂ ) activation technology is of great significance in environmental purification due to its eco-friendly operation and cost-effective nature. However, the activation of O₂ is limited by spin-forbidden transitions, and efficient molecular oxygen activation depends on electronic behavior and surface adsorption. Herein, we prepared cationic defect-rich Bi₄ Ti₃ O₁₂ (BTO-MV2) catalysts containing Ti vacancies (V_Ti ) for O₂ 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 O₂ and extracting electrons, effectively generating ⋅OH, O₂ ⋅^- and ¹ O₂ . 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.