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

Abstract

Hydrogen peroxide (H₂O₂) 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 H₂O₂ 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 H₂O₂. 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 H₂O₂ generation, and mechanistic details are confirmed by trapping different radical intermediates. This study demonstrates an efficient and sustainable alternative for H₂O₂ production, advancing interface-driven and catalyst-free chemistry.