Interfacial Engineering\nof a Z‑Scheme Bi<sub>2</sub>O<sub>2</sub>S/NiTiO<sub>3</sub> Heterojunction Photoanode\nfor the Degradation of Sulfamethoxazole in Water

To develop a semiconductor interface with enhanced spatial\nseparation\nof carriers under visible light irradiation for the photoelectrochemical\n(PEC) oxidation process, we explored the fabrication of a Bi<sub>2</sub>O<sub>2</sub>S/NiTiO<sub>3</sub> heterojunction photoanode for the\nremoval of sulfamethoxazole in water. The Bi<sub>2</sub>O<sub>2</sub>S/NiTiO<sub>3</sub> photoanode was synthesized via an in situ hydrothermal\nprocess, and it exhibited better light absorption and charge separation,\nas well as a reduced rate of recombination of photoexcited charge\nspecies compared to pristine Bi<sub>2</sub>O<sub>2</sub>S and NiTiO<sub>3.</sub> The improved photoelectrocatalytic performance was attributed\nto the synergistic interaction between Bi<sub>2</sub>O<sub>2</sub>S and NiTiO<sub>3</sub> and the presence of an S–O bond at\nthe heterojunction interface, thus resulting in Z-scheme heterojunction\nformation. Various characterization methods such as XPS, UV-DRS, electrochemical\nimpedance spectroscopy, photoluminescence, FESEM, TEM, and photocurrent\nresponse measurements were explored to explain the optical and electrochemical\nproperties of the semiconductor heterojunction. The PEC degradation\nprocess was optimized, demonstrating a degradation efficiency removal\nof 80% for 5 mg/L sulfamethoxazole in water, with a TOC removal of\n45.5%. A Z-scheme heterojunction formation mechanism was proposed\nto explain the enhanced photoelectrocatalytic activity of the photoanode.\nThis work generally contributes to the development of efficient and\nsustainable photoanodes for environmental remediation.