Anionic Surfactant‐Modulated Electrode–Electrolyte Interface Promotes H2O2 Electrosynthesis

Abstract Conventional strategies for highly selective and active hydrogen peroxide (H 2 O 2 ) electrosynthesis primarily focus on catalyst design. Electrocatalytic reactions take place at the electrified electrode–electrolyte interface. Well‐designed electrolytes, when combined with commercial catalysts, can be directly applied to high‐efficiency H 2 O 2 electrosynthesis. However, the role of electrolyte components is equally crucial but is significantly under‐researched. In this study, anionic surfactant n ‐tetradecylphosphonic acid (TDPA) and its analogs are used as electrolyte additives to enhance the selectivity of the two‐electron oxygen reduction reaction. Mechanistic studies reveal that TDPA assembled over the electrode–electrolyte interface modulates the electrical double‐layer structure, which repels interfacial water and weakens the hydrogen‐bond network for proton transfer. Additionally, the hydrophilic phosphonate moiety affects the coordination of water molecules in the solvation shell, thereby directly influencing the proton‐coupled kinetics at the interface. The TDPA‐containing catalytic system achieves a Faradaic efficiency of H 2 O 2 production close to 100% at a current density of 200 mA cm −2 using commercial carbon black catalysts. This research provides a simple strategy to enhance H 2 O 2 electrosynthesis by adjusting the interfacial microenvironment through electrolyte design.