Interfacial configuration and mechanism insights of an all-solid-state Z-scheme BaTiO₃/Bi/Bi₂O₃ heterojunctions for rapid removal of tetracycline antibiotics

Photocatalytic technology based on efficient-economic heterojunction catalysts has been considered a promising approach to remove the discharged tetracycline (TC) antibiotic residues in contaminated water. However, unveiling an effective interface configuration with a clear mechanism is still the toughest challenge for heterojunction photocatalysts. Through a facile route of hydrothermal and heat treatment for the first time, herein, we reported an all-solid-state Z-scheme heterojunction of BaTiO₃/Bi/Bi₂O₃ (BT/Bi/BO) with a conspicuous light response and efficient photo-excited carrier kinetics (high separation and redox ability). It performed a stable and ultrahigh photocatalytic activity toward removing TC, which can be quickly degraded in a few minutes. Density functional theory calculation on heterogeneous interface confirmed that the metallic Bi at the interlayer played a critical role in the excellent photocatalytic performance. The interlayer Bi not only promoted the adhesion between BT and BO to enhance the structural stability, but also had a strong interaction with O atoms of BT to reduce the band gaps to improve the light response. Moreover, its p band located in the band gaps can assist the Z-scheme transfer of photo-excited carriers under an interfacial built-in electronic field of the heterojunction. Therefore, this work provides a new perspective and deep understanding of the configuration and interfacial mechanism of Z-scheme heterogeneous photocatalysts for the removal of antibiotics.