Sulfur vacancy-mediated self-photocatalysis-boosted electrochemiluminescence sensing via molecular oxygen activation for sensitive detection of isocarbophos.

The luminol-dissolved oxygen electrochemiluminescence (ECL) system is fundamentally limited by the poor redox activity of oxygen, which fails to generate sufficient reactive oxygen species (ROS) for efficient luminol excitation, restricting the performances of sensors. Herein, a high-performance ECL sensor was fabricated for sensitive detection of isocarbophos (ICP) by utilizing sulfur vacancy-engineered ZnIn2S4 (Sv-ZIS) as a novel photocatalytic co-reaction accelerator with superior molecular oxygen activation. The introduction of sulfur vacancies not only effectively enhanced visible-light harvesting but also accelerated interfacial electron transfer while maintaining a sufficient thermodynamic driving force for O2 reduction, generating abundant ROS for the luminol ECL reaction, thus remarkably boosting the ECL signal intensity and luminescence stability of the system. By integrating with the specific target recognition capability of aptamers, the as-fabricated aptasensor achieved highly sensitive and specific detection of the organophosphorus pesticide ICP, with a linear range of 0.1-50 ng mL-1, an ultralow limit of detection (LOD) of 32.63 pg mL-1 at a signal-to-noise (S/N) ratio of 3, and excellent detection stability. This proposed sensing platform can be successfully applied to the quantitative determination of ICP in real samples, providing a reliable strategy for pesticide residue monitoring and a new avenue for sensitive detection of hazardous small molecules in environmental and food analyses.