Novel incomplete phase transition from α-Bi₂O₃ to γ-Bi₂O₃ constructing dual interfaces contacts with BaTiO₃ for highly efficient degradation of antibiotics

Incomplete lattice transition in heterojunction preparation can generate another crystal phase to provide a new transfer channel of electrons and holes for enhancing photocatalytic activity. In this paper, the hydrothermal synthesis of BaTiO₃ and α-Bi₂O₃ composite induced a part of α-Bi₂O₃ to γ-Bi₂O₃ lattice transition. Except for α-Bi₂O₃/BaTiO₃ interface, a new BaTiO₃/γ-Bi₂O₃ contact was formed to realize another transfer channel of the charge carriers. The removal efficiencies of norfloxacin and lomefloxacin using the optimal α-Bi₂O₃/BaTiO₃/γ-Bi₂O₃ sample reached 93% and 95%, much higher than those of the pure phases and the diphasic heterojunction samples. After five times of cycle tests, the photodegradation efficiencies of these two antibiotics were above 90% and 91%, respectively, while the crystal structure of the sample unchanged to exhibit good structure stability. The superoxide radical (O₂^[rad]−), hole, and hydroxyl radicals (OH^−[rad]) were the main active substances upon the antibiotics degradation. The photocatalytic enhancement mechanism was originated from the formation of a new Z-type energy band according to the surface and interface calculation. Finally, the analysis of mass spectrometry revealed the degradation processes of these two pollutants. These results provided a simple way to obtain efficient double interfaces heterojunction photocatalysts for removing antibiotic pollutants.