2D Conjugated Polymer Nanosheets: A New Choice for Boosting Electrochemiluminescence

The application of 2D conjugated polymers (2D CPs) in electrochemiluminescence (ECL) has been hindered due to their inherent flaws. Meanwhile, the weak ECL emission at the cathode is often ignored due to the poor conversion efficiency of O₂ to reactive oxygen species (ROS). To overcome these dilemmas, novel 2D conjugated polymer nanosheets (2D CPNs) are synthesized via a liquid-liquid polymerization strategy to enhance ECL. The 2D CPNs exhibit effective catalytic active sites to facilitate the oxygen reduction reaction (ORR) performance, which are employed as a co-reaction accelerator to promote the cathodic ECL in the luminol-dissolved O₂ system. Importantly, the ECL signal is significantly amplified ≈50-fold. It is found that the four-electron (4e⁻) pathway dominates the ORR process in an extremely narrow cathodic potential range. The ROS can participate in the chemical oxidization of luminol, which is confirmed by density functional theory calculations and in situ Raman tests. Moreover, a novel ECL sensor is designed for the ultra-sensitive detection of the antioxidant catechol (CC) and would successfully distinguish with the isomers of CC. This work discovers the application of 2D conjugated polymers in the cathodic ECL of luminol and provides a new option to boost ECL for diverse requirements in practice.