Formation of conjugated polymer/TiO2(B) S-scheme heterojunctions by functional group regulation for efficient natural light-driven inactivation of super-resistant bacteria

S-scheme heterojunctions hold potential applications in enhancing the photocatalytic activity of composites by effectively segregating photogenerated electrons and holes. In this study, we synthesized an organic–inorganic S-scheme heterojunction material by incorporating a carboxyl-modified polythiophene-based linear conjugated polymer (PB-C) with TiO2(B) nanotubes through morphology modification. This composite facilitates accelerated charge separation and migration, as well as optimized redox potential due to the closely coupled heterointerface and strong internal electric field. Under full-band white light irradiation for 20 min, the PB-C/TiO2(B) S-Scheme heterojunction material exhibited remarkable antibacterial performance, eliminating 3.86 × 107 cfu mL−1 methicillin-resistant Staphylococcus aureus (MRSA). Moreover, it demonstrated good antibacterial efficacy under both sunlight and indoor light irradiation. Density functional theory (DFT) calculations and in situ X-ray photoelectron spectroscopy (XPS) analyses revealed that excellent photocatalytic performance can be attributed to the formation of efficient electron transfer channels facilitated by interfacial Ti–O bonds. This research provides valuable insights into designing and preparing high-performance organic-inorganic S-scheme heterojunction photocatalysts for antimicrobial applications.