Electrode Fouling by Gas Bubbles Enables Catalyst-Free Hydrogen Peroxide Synthesis.

Hydrogen peroxide (HO) is an essential chemical for environmental remediation, chemical synthesis, and energy storage, yet conventional synthetic methods are energy-intensive and environmentally taxing. Herein, we report a catalyst-free strategy for HO synthesis by exploiting the gas-liquid-solid triple phase boundary formed at bubble-pinned porous carbon electrodes. The process involves three key mechanisms: (i) hydroxide anions enrichment in the electric double layer reduces the energy barrier for their oxidation to hydroxyl radicals, (ii) the hydrophobic bubble interface suppresses overoxidation, favoring the two-electron water oxidation pathway, and (iii) oxygen molecules capture electrons from previous steps to form HO. Density functional theory calculations indicate a 30% reduction in work function at the bubble-pinned interface compared to bubble-free counterparts, which thermodynamically promotes the electrochemical oxidation of hydroxide anions. Experiments verify that both water and oxygen are involved in HO generation, and mechanistic details are confirmed by trapping different radical intermediates. This study demonstrates an efficient and sustainable alternative for HO production, advancing interface-driven and catalyst-free chemistry.