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−), hole, and hydroxyl radicals (OH−) 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.