Optical response enhancement and Z-scheme charge migration in plasmonic Bi0-BiVO4/polypyrrole photocatalysts for antibiotic mineralization

Antibiotic contamination in aquatic environments has become an increasingly serious issue, creating an urgent need for efficient and environmentally friendly remediation technologies. Herein, a Bi 0 -BiVO 4 /PPy composite photocatalyst was prepared through a combined hydrothermal, in situ reduction, and oxidative polymerization strategy for visible-light-driven tetracycline (TC) removal. Under optimized reaction conditions, Bi 0 -BiVO 4 /PPy-3 achieved 85.4% TC removal within 60 min and exhibited a significantly improved reaction rate compared with pristine BiVO 4 . The composite also showed good recyclability after regeneration, satisfactory salt tolerance, and stable activity in different water matrices. Moreover, a preliminary wheat-growth assay suggested that the treated solution had lower phytotoxicity than the original TC solution. The enhanced photocatalytic activity is associated with the synergistic effects of Bi 0 introduction and PPy coupling, including improved visible-light absorption and more efficient interfacial charge separation. THz Time-Domain Spectroscopy (THz-TDS) further revealed enhanced terahertz absorption and a modulated refractive response in Bi 0 -BiVO 4 /PPy-3, providing additional evidence for strengthened interfacial coupling and charge transport. Radical trapping experiments and EPR analysis indicate that h + and •O 2 − are the dominant reactive species in the TC degradation process. Based on the available experimental and DFT calculations, a possible Z-scheme like charge transfer pathway and several tentative degradation routes of TC were proposed. Overall, this work suggests that Bi 0 -BiVO 4 /PPy is a promising visible-light-responsive photocatalyst for antibiotic removal from water.