Synergistic Defect and Interface Engineering in PANI-Bridged CeO ₂ /BiOI Dual Z-Scheme Heterojunction for Efficient Antibiotic Photoremediation

Tetracycline antibiotics pose persistent ecological risks, underscoring the urgent need for sustainable remediation strategies. Bismuth oxyiodide (BiOI) is attractive for photocatalysis owing to its visible-light responsiveness, yet its narrow band gap (1.8 eV) and rapid charge recombination hinder efficiency. Here, a ternary CeO 2 /BiOI/PANI heterostructure was fabricated via hydrothermal synthesis and in situ polymerization. The design exploits Ce 3+ /Ce 4+ redox cycling to generate oxygen vacancies, establishes a dual Z-scheme heterojunction among CeO 2, BiOI, and PANI to preserve high redox potentials, and leverages PANI’s π-conjugated framework to accelerate interfacial electron transfer. These synergistic effects narrow the band gap to 1.30 eV, suppress photoluminescence by 75%, and markedly reduce interfacial resistance, thereby enhancing charge separation and migration. The optimized composite achieved 92% tetracycline degradation within 120 min under visible light─approximately double that of pristine BiOI─and retained 79% activity after five cycles, demonstrating excellent stability. Radical quenching and band structure analyses confirmed a dual Z-scheme charge transfer pathway. This work provides a robust strategy for constructing organic–inorganic heterostructures toward efficient photocatalytic degradation of antibiotics and other recalcitrant pollutants.