Regulating Spin Polarization through Cationic Vacancy Defects in Bi 4 Ti 3 O 12 for Enhanced Molecular Oxygen Activation.

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.
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