Aggregation-Induced Electrochemiluminescence Probe for Real-Time Quantification of CO₂ Intermediates in Urea...

Real-time monitoring of fleeting reaction intermediates is essential for elucidating electrocatalytic mechanisms but is often hindered by a lack of sensitive and selective analytical tools. Here, we develop an aggregation-induced electrochemiluminescence (AIECL) probe, N-(pyren-1-yl) benzamide (NPB), which enables the real-time quantification of CO₂ dynamics indirectly via CO₃^2- during the urea oxidation reaction (UOR). The probe exhibits exceptional sensitivity with a detection limit of 1.0 nM for CO₃^2- (the hydrolysis product of CO₂) and outstanding selectivity against other UOR-related species, allowing for precise kinetic tracking. By integrating this probe with a series of LiNiO₂ catalysts (LNO-x) featuring systematically modulated lattice oxygen content, we establish an indirect quantitative correlation between lattice oxygen abundance and the kinetics of CO₂ intermediate formation. Time-resolved AIECL analysis, supported by in situ spectroscopy and density functional theory (DFT) calculations, reveals that lattice-oxygen-rich surfaces lower the energy barriers for CO oxidation and CO₂ desorption, accelerating the reaction via a lattice oxygen mechanism (LOM). Kinetic analysis confirms quasi-first-order behavior, with the highest rate constant (0.95 min^-1) observed for the catalyst with the highest lattice oxygen content. This work introduces a powerful analytical tool for intermediate tracking and establishes a generalizable "structure-intermediate-performance" paradigm for electrocatalyst design.