Adsorbed oxygen dynamics at forced convection interface in the oxygen evolution reaction

The oxygen evolution reaction is a prevalent anodic reaction in electrocatalytic processes. Modulation of adsorbed oxygen (*O) at the electrochemical interface is an effective means to reduce the overpotential of the oxygen evolution reaction. However, the contribution of various *O conversions to the overpotential remains unclear. Herein, the development of a multi-component forced convection electrochemical mass spectrometry constructs *O-labeled electrochemical interfaces with specific coverages to track the *O conversions. The relationships between the Faradic contributions and the specific *O conversion pathways are established by considering the anomalous fractionation of molecule oxygen. Our experiments confirm that *O coupling contributes up to 48% with a specific overpotential on full coverage platinum. Distinguishing the *O conversion contributions with various coverages reveals that balancing the *O formation and conversions, especially *O coupling enables further minimization of the overpotential of the oxygen evolution reaction. Thus, tracking the intermediate conversions has implications for designing high-performance electrocatalytic interfaces. The oxygen evolution reaction is central to electrochemistry, yet how its intermediates contribute to overpotential is unclear. Here, the authors use a multi-component forced-convection mass-spectrometry system to label adsorbed oxygen and reveal its conversion through product fractionation.