Engineering Oxygen-Vacancy-Rich S-Scheme CeSnO₃/Bi₂S₃ Perovskite-Based Heterojunction with Dynamic Ce³⁺/Ce⁴⁺ Redox Recycling: Efficient Photoactivation of Peroxymonosulfate towards Lindane Degradation, Antimicrobial Activity and Sustainable H₂ Production

Abstract

In this work, a series of highly porous and multifunctional CeSnO₃/Bi₂S₃ perovskite-based heterojunctions (CBX) were successfully synthesized via a two-step mixing approach. Among them, the optimized CB30 heterojunction exhibited outstanding textural and electronic properties, featuring a high specific surface area (~85 m² g⁻¹) that enables efficient light harvesting and enhanced charge carrier separation. Consequently, CB30 degraded 70.7% of LN (600 µg/L) in aqueous media under solar light irradiation for 100 min. The incorporation of peroxymonosulfate (PMS) into the reaction medium synergistically enhanced the photocatalytic efficiency of CB30 heterojunction by achieving 93.2% degradation of LN in 100 min. The outstanding performance of CB30 in conjunction with PMS is primarily attributed to successful activation of PMS by oxygen vacancies rich CeSnO 3 /Bi 2 S 3 heterojunction and the continuous redox recycling of Ce³⁺/Ce⁴⁺ species in the heterojunction. Furthermore, radical quenching experiments revealed • OH, SO 4 •⁻ and O 2 •⁻ as the dominant species responsible for the photocatalytic degradation of LN in aqueous media. In addition to LN degradation, the antimicrobial activity analysis test confirmed the excellent performance of CB30 with an average zone of inhibition (ZOI) value of 21.5 mm and 20 mm against E.coli and C.albicansrespectively. The electrochemical studies showed that the CB30 heterojunction yielded a specific capacitance of 316.5 F g -1 , energy density of 10.99 Wh kg -1 and power density of 500 W kg -1 at a current density of 2 A g -1 . Furthermore, CB30 exhibited outstanding hydrogen evolution performances of 12.2, 22.2 and 37.7 mmol g -1 of H₂ with EQE values of 34.4, 41.9 and 50.5% upon simulated solar irradiations for 6, 9 and 12 hrs of reaction time, respectively. The superior photocatalytic and photo-electrochemical activities are primarily governed by the synergistic integration of S-scheme charge transfer, oxygen vacancies (34.91%) and Ce³⁺/Ce⁴⁺ redox cycling, establishing CB30 as a robust and multifunctional platform for persistent pollutant degradation, antimicrobial disinfection and sustainable hydrogen production.