Engineering an 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) was successfully synthesized via a two-step mixing approach. Among them, the optimized 30% CeSnO₃/Bi₂S₃ heterojunction (CB30) exhibited outstanding textural and electronic properties, featuring a high specific surface area (∼85 m² g⁻¹), which enabled efficient light harvesting and enhanced charge carrier separation. Consequently, CB30 degraded 70.7% of lindane (LN; 600 µg L⁻¹) in aqueous media under solar light irradiation within 100 min. The incorporation of peroxymonosulfate (PMS) into the reaction medium synergistically enhanced the photocatalytic efficiency of the CB30 heterojunction, achieving 93.2% degradation of LN in 100 min. The outstanding performance of CB30 in conjunction with PMS is primarily attributed to the successful activation of PMS by the oxygen-vacancy-rich CeSnO₃/Bi₂S₃ heterojunction and the continuous redox recycling of Ce³⁺/Ce⁴⁺ species in the heterojunction. Furthermore, radical quenching experiments revealed hydroxyl, sulphate and superoxide radical ions (˙OH, SO₄˙⁻ and O₂˙⁻) as the dominant species responsible for the photocatalytic degradation of LN in aqueous media. In addition to LN degradation, antimicrobial activity analysis tests confirmed the excellent performance of CB30, with an average zone of inhibition (ZOI) of 21.5 mm and 20 mm against Escherichia coli (E. coli) and Candida albicans (C. albicans), respectively. Furthermore, CB30 exhibited outstanding hydrogen evolution performance of 12.2, 22.2 and 37.7 mmol g⁻¹ of H₂ with external quantum efficiency (EQE) values of 34.4%, 41.9% and 50.5% upon simulated solar irradiation for 6, 9 and 12 h of reaction time, respectively. The superior photocatalytic and photo-electrochemical activities are primarily governed by the synergistic integration of step-scheme (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.