Ultrasensitive Electrochemiluminescence Platform Based on Self-Photocatalysis-Induced Continuous Generation of H ₂ O ₂ for Synchronous Monitoring and Degradation of Enrofloxacin

Luminol, as a classic electrochemiluminescence (ECL) emitter, often suffers from signal instability due to the rapid decomposition of its common coreactant H₂O₂. In this study, a self-photocatalysis strategy was developed to generate the coreactant in situ for luminol and enhance the stability of its ECL stability, and the underlying mechanism was systematically investigated. The proposed sensor enabled the sensitive and accurate detection of enrofloxacin (ENR) in natural water samples. Specifically, the photocatalyst NH₂-MIL-125 (TiM) was incorporated into the sensing platform. The light energy emitted by luminol (hv = 2.89 eV) exceeded the bandgap energy of TiM (Ebg = 2.50 eV), thereby activating TiM to catalyze the production of H₂O₂, which ensured a continuous supply of the coreactant and significantly improved the ECL signal stability. Furthermore, a stable and antifouling sensing interface was constructed by the codeposition of a zwitterionic polymer and in situ reduction of silver nanoparticles (Ag NPs), which ensures reliable sensing performance in complex aqueous environments and supports the practical applicability of the proposed dual-function platform. In the presence of ENR, H₂O₂ was consumed through a degradation process that converted ENR into nontoxic and harmless small molecules, resulting in a corresponding decrease of the luminol ECL signal. This dual-function strategy enabled the simultaneous detection and degradation of the antibiotic. The sensor exhibits a wide linear range (100 fM-1 μM) and a low detection limit (42.8 fM, S/N = 3), demonstrating great potential for rapid and accurate monitoring of antibiotic contaminants in environmental water.