Evaluation of structure-activity relationship for nitrogen-doped carbon-based metal-free electrocatalysts using electrochemiluminescence.

Nitrogen doping enhances the catalytic performance of carbon-based metal-free electrocatalysts (C-MFECs) by modifying their chemical environment. Understanding the structure-catalytic activity relationship of nitrogen-doped (N-doped) C-MFECs is crucial for elucidating catalytic mechanisms and designing efficient electrocatalysts, but it remains challenging. Recently, reactive oxygen species (ROS)-triggered electrochemiluminescence (ECL) has shown great potential for uncovering these mechanisms due to its simple setup, low background signal, wide dynamic range, and high sensitivity. In this study, four types of N-doped C-MFECs with varying nitrogen dopant types (denoted as N-C, where x represents the annealing temperature) towards the electrochemical reduction of HO are evaluated by monitoring the cathodic ECL of the luminol-HO system in the low negative-potential region. Among these, N-C, contains a higher content of graphitic nitrogen exhibits superior catalytic performance in activating HO to generate significant amounts of ROS, as evidenced by its markedly enhanced ECL emission. The increased incorporation of graphitic nitrogen into the carbon plane likely improved HO adsorption and its capacity to generate ROS. A sensitive antioxidant-mediated ECL platform was successfully developed for detecting antioxidant levels in orange juice, demonstrating potential for evaluating antioxidant capacity. This study not only provides insights into the catalytic mechanisms of N-doped C-MFECs but also highlights the potential of ECL as a versatile tool for studying and designing electrocatalysts.