Plasmonic engineered Bi/CAU-17 photocatalysts for sunlight driven efficient degradation of tetracycline hydrochloride

Antibiotic residues like tetracycline hydrochloride (TCH) in water threaten ecosystems and human health, yet traditional photocatalysts struggle with low visible-light utilization and rapid photogenerated carriers recombination. This study presents a Bi/CAU-17 heterojunction designed as a photo-antenna/reaction center system, where metallic Bi acts as the light-harvesting antenna via the surface plasmon resonance (SPR) effect, and the CAU-17 metal-organic framework serves as the reaction center. The Bi/CAU-17 composite is synthesized via an in-situ reduction method, where Bi is generated on the surface of CAU-17, The research aims to elucidate the mechanisms by which the SPR effect influences the separation of photogenerated electron-hole pairs and improves the degradation efficiency of TCH. Under visible light, the optimized Bi/CAU-17 achieves 99.6 % TCH degradation within 60 min, with the pseudo-first-order rate constant ( k ) constant 9.45 times higher than pristine CAU-17. Mechanistic studies reveal that the SPR-enhanced heterojunction promotes the production of ⋅O₂⁻ as the dominant reactive species. Ecotoxicity assays (fish, daphnid, green algae and rat) confirm mineralization into non-toxic end products. This study also evaluates the ecotoxicity of degradation processes, confirming safe mineralization of intermediates into non-toxic end products. Notably, the practical applicability of the Bi/CAU-17 catalyst in real water sources maintain high degradation efficiency under sunlight irradiation. By integrating the photo-antenna concept with MOF-based reaction centers, this work demonstrates a scalable strategy for developing efficient plasmonic photocatalysts, providing valuable insights into the design of efficient photocatalyst for environmental remediation, particularly in the efficient degradation of antibiotic pollutants.