Promoting the Electrochemical Water Oxidation Reaction to H₂O₂ via Bubbles on the Electrode

Surface bubbles on electrodes generated via gas evolution reaction are generally considered harmful to the desired electrochemical reaction as they reduce the electrochemically active area and increase energy consumption. However, it is shown herein that surface bubbles on the electrode can significantly improve the electrosynthesis of hydrogen peroxide (H₂O₂) by a two-electron water oxidation reaction (2e-WOR) due to the high concentration of OH^– accumulated by the corona of the bubbles. Inspired by this understanding, aerophilic PVDF-coated CFP electrodes were designed to prolong the residence time of the in situ generated surface bubbles to improve their 2e-WOR selectivity from 16.3 to 62.5%, and the H₂O₂ generation rate was as high as 28.4 μmol min^–1 cm^–2. This study subverts long-held assumptions about the effect of the bubbles on the electrode toward electrochemical reaction and provides a theoretical guideline for designing 2-WOR catalysts.