Metal Defect-Mediated Adsorption-Catalytic Platform Drives Efficient Electrochemiluminescence Sensing

The rational design of highly active catalytic interfaces is of crucial importance for the construction of sensitive and reliable electrochemiluminescence (ECL) biosensors. In this study, a metal defect-mediated adsorption-catalytic interface, specifically La-deficient LaCoO₃ (LCO-VLa), was rationally constructed via a cation vacancy engineering strategy. The introduction of La vacancy (VLa) significantly enhanced the adsorption capacity for the coreactant (K₂S₂O₈) and concurrently exposed more Co-rich active surfaces. The multivalent redox reversible reaction of Co facilitated an increase in the bond length of the O-O bond in S₂O₈²⁻ from 1.48 to 1.54 Å, which made the O-O bond easier to break, thus significantly improving the interfacial catalytic activity. The dual ligands endowed the framework with excellent electroluminescent properties and chemical stability. The porphyrin groups coordinated at the center of the framework extended the π-conjugation length, which in turn enhanced the charge mobility and ECL efficiency of the emitter. Herein, the synergistic effect between the metal defect-mediated adsorption-catalytic interface and the dual-ligand framework structure enhanced the ECL signal, enabling the highly sensitive detection of microcystin-LR (MC-LR). The sensing strategy provides a reliable analytical tool for the quantitative analysis and online monitoring of ultratrace pollutants in complex environmental matrices.