Interfacial Engineering of a Z-Scheme BiOS/NiTiO Heterojunction Photoanode for the Degradation of Sulfamethoxazole in Water.

To develop a semiconductor interface with enhanced spatial separation of carriers under visible light irradiation for the photoelectrochemical (PEC) oxidation process, we explored the fabrication of a BiOS/NiTiO heterojunction photoanode for the removal of sulfamethoxazole in water. The BiOS/NiTiO photoanode was synthesized via an in situ hydrothermal process, and it exhibited better light absorption and charge separation, as well as a reduced rate of recombination of photoexcited charge species compared to pristine BiOS and NiTiO The improved photoelectrocatalytic performance was attributed to the synergistic interaction between BiOS and NiTiO and the presence of an S-O bond at the heterojunction interface, thus resulting in Z-scheme heterojunction formation. Various characterization methods such as XPS, UV-DRS, electrochemical impedance spectroscopy, photoluminescence, FESEM, TEM, and photocurrent response measurements were explored to explain the optical and electrochemical properties of the semiconductor heterojunction. The PEC degradation process was optimized, demonstrating a degradation efficiency removal of 80% for 5 mg/L sulfamethoxazole in water, with a TOC removal of 45.5%. A Z-scheme heterojunction formation mechanism was proposed to explain the enhanced photoelectrocatalytic activity of the photoanode. This work generally contributes to the development of efficient and sustainable photoanodes for environmental remediation.