Interfacial Engineering of a Z-Scheme Bi2O2S/NiTiO3 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 Bi2O2S/NiTiO3 heterojunction photoanode for the removal of sulfamethoxazole in water. The Bi2O2S/NiTiO3 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 Bi2O2S and NiTiO3. The improved photoelectrocatalytic performance was attributed to the synergistic interaction between Bi2O2S and NiTiO3 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.