Anion-Exchange-Membrane-Free Electrolyzers via Interfacial Microenvironment Engineering for Stable Oxygen Reduction to Hydrogen Peroxide

Porous solid electrolyte (PSE) reactors have shown great promise for directly producing electrolyte-free products; however, the use of anion-exchange membranes (AEMs) may introduce cost and stability challenges. Here, we demonstrate an alternative AEM-free PSE reactor design that enables extended electrolysis stability and high product concentrations. By integrating a thin layer of anion-exchange resin wafer to maintain interfacial alkalinity and redesigning the gas-flow pattern in the PSE reactor to prevent cathode flooding, we achieved one-month continuous and stable electrosynthesis of hydrogen peroxide under a high current density of 200 mA cm –2, while continuously delivering a product concentration of 3.7 wt %. This AEM-free PSE reactor concept was further validated in other electrocatalytic systems, including CO 2 reduction to formic acid.