Understanding Reactive Oxygen Species in Potential-Resolved Electrochemiluminescence of Luminol-Dissolved O2

Electrochemiluminescence (ECL) of the luminol-dissolved O2 system has been applied in many fields, but the role of reactive oxygen species (ROS) in potential-resolved ECL of luminol-dissolved O2 remains ambiguous due to the complexity of the ROS production and the difficulty in detecting ROS. In this work, the function of ROS in potential-dependent luminol-O2 ECL was investigated in detail. Interestingly, the four ECL peaks were observed in the potential-resolved ECL profiles, including a cathodic ECL peak at −0.5 V (ECL-1), two anodic ECL peaks at 0.45 V (ECL-2) and 1.3 V (ECL-3), and a broad and flat peak starting from 1.11 V and ending at 0.35 V (ECL-4, a secondary peak) on the reverse scan backward from upper potentials. The impact of ROS on the different ECL channels was investigated. It was found that superoxide radical (O2•–) could promote all of the above four ECL peaks, while hydroxyl radical (HO•) could only facilitate ECL-1, ECL-3, and ECL-4. Additionally, pathways of all ECL peaks were proposed. The investigation on the role of ROS in potential-resolved ECL of luminol-dissolved O2 will guide the rational regulation and potential applications of luminol ECL in various fields.