A compressor-free dry-cathode PEM electrolyzer for efficient on-site hydrogen peroxide production from air

This study reports a self-engineered dry-cathode proton exchange membrane electrolyzer (DC-PEM-H₂O₂) for sustainable hydrogen peroxide production using a waste biomass-derived carbon catalyst. The device features an initially dry, air-exposed cathode in a membrane-based configuration. Using carbon cloth with 10% wet proofing as cathode support, 100% faradaic efficiency was achieved at 50 mA·cm −2 with an electrochemical specific energy consumption (ESEC) of 4.2 kWh·kg −1 H₂O₂, producing droplets exceeding 6 wt% H₂O₂ (>60,000 mg·L −1 ). Increasing hydrophobicity to 60% wet proofing enabled operation at 100 mA·cm −2 , reaching 45 mg·cm −2 ·h −1 with ~70% faradaic efficiency and ~8.4 kWh·kg −1 H₂O₂. This simultaneous achievement of high concentration, competitive production rate and moderate energy demand positions the reactor among the most balanced electrochemical configurations reported to date. Long-term tests demonstrated stable operation for >100 h without catalyst degradation; performance losses at high current density were reversible and associated with temporary cathode wetting. A system-level energy assessment was introduced by separating electrochemical (ESEC) and non-electrochemical (NESEC) contributions to determine total specific energy consumption (TSEC). Remarkably, ESEC accounted for only 5–14% of total energy demand, whereas auxiliary devices dominated overall consumption. These results demonstrate that reporting electrochemical energy alone substantially underestimates real process requirements and highlight the importance of holistic energy evaluation for reactor design and scale-up of electrochemical H₂O₂ production.