La-doped Bi₄Ti₃O₁₂ nanosheets: Ferroelectric polarization-enhanced carrier dynamics for efficient tetracycline photodegradation

The development of high-performance photocatalysts is crucial for the efficient photodegradation of antibiotics. A key challenge in photocatalysis is charge recombination, which occurs both within the bulk and at the surface of semiconductor catalysts. In this study, charge recombination was suppressed by enhancing carrier dynamics through ferroelectric polarization in Bi₄Ti₃O₁₂ (BTO)-based materials, leading to a significant improvement in tetracycline (TC) degradation performance. Our results demonstrate that La doping strengthens ferroelectric polarization, improving charge carrier dynamics and emphasizing the critical role of polarization in photocatalysis. Differences in polarization led to varying effects on charge carrier dynamics, which directly influenced the photocatalytic degradation of TC. La-doped BTO (La-BTO) exhibited the highest photocurrent density, the lowest charge transfer resistance, and a reduced photoluminescence (PL) lifetime when compared with both pristine and depolarized BTO. Photocatalytic tests revealed that La-BTO achieved nearly complete TC degradation within 30 min under light irradiation, with ∙O₂⁻ and ∙OH radicals identified as the primary oxidative species. Specifically, La-BTO achieved a 94.6% degradation rate, which is significantly higher than that of undoped BTO (70.7%) and depolarized BTO (40.7%). These findings demonstrate that polarization-driven carrier dynamics are crucial for optimizing photocatalytic antibiotic degradation, offering new insights into the rational design of high-performance photocatalysts for water purification.