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

Abstract

Electrochemiluminescence (ECL) of the luminoldissolved O 2 system has been applied in many fields, but the role of reactive oxygen species (ROS) in potential-resolved ECL of luminol-dissolved O 2 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-O 2 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 (O 2 •−) 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 O 2 will guide the rational regulation and potential applications of luminol ECL in various fields.