Enhanced Potential-Resolved Luminol Electrochemiluminescence by the Catalyzing Oxygen Reduction Reaction on Carbonized Polydopamine Nanospheres

The efficient activation of molecular oxygen to generate reactive oxygen species (ROS) offers great promise for achieving potential-resolved electrochemiluminescence (ECL) in the luminol/O₂ system, though it typically relies on sophisticated catalysts. In this work, we demonstrate that carbonized polydopamine nanospheres (C-PDANSs) serve as an effective metal-free electrocatalyst to enhance the oxygen reduction reaction (ORR), thereby enabling the potential-resolved ECL of luminol. Mechanistic studies indicate that the ORR catalyzed by C-PDANSs proceeds via a two-electron pathway, yielding both superoxide radicals (O₂^-•) and hydrogen peroxide (H₂O₂). This ORR behavior facilitates the generation of sufficient ROS, which significantly boosts both cathodic and anodic luminol ECL, leading to 11.6-fold and 5.1-fold intensity enhancements, respectively. Based on the dual-potential ECL response, a ratiometric sensing platform was constructed for the detection of alkaline phosphatase (ALP). This study not only presents a different electrocatalyst for regulating dual-potential luminol ECL but also opens the avenue for designing biosensing schemes.