Porous Membrane Electrode Assembly for Electrosynthesis of High-Purity and High-Concentration Hydrogen Peroxide

Abstract

Hydrogen peroxide (H₂O₂) is an environmentally benign oxidant with broad applications in chemical synthesis, environmental remediation, and disinfection. Electrochemical production via the two-electron oxygen reduction reaction (2e⁻ ORR) offers a sustainable alternative to the traditional energy-intensive process. However, achieving high concentrations under electrolyte-free conditions remains challenging due to limited selectivity, mass-transport constraints, and high operating voltages. Here, we report a porous proton exchange membrane (PEM)–based electrochemical cell (5 cm × 5 cm) that enables efficient and durable H₂O₂ production. Among various porous substrates, glass-fiber filters retained dimensional stability after Nafion ionomer loading and provided uniform proton-conduction pathways, balancing proton conductivity and oxygen gas permeability in the porous PEM. Acid-treated Co single-atom catalysts dispersed in hydrophilic SiO₂ particles enhanced intrinsic 2e⁻ ORR selectivity and catalyst-layer wettability, resulting in a H₂O₂ Faradaic efficiency above 75% at 100 mA cm⁻² at a cell voltage of ∼2.3 V. The porous PEM-based cell produced electrolyte-free H₂O₂ solutions up to 12 wt.% (3.6 mol L⁻¹) and operated stably for over 100 h, demonstrating its potential as a platform for practical H₂O₂ electrosynthesis.