A breakthrough electrochemical reactor for the simultaneous production of hydrogen peroxide and ozone via solid electrolyte and gas diffusion electrode technologies

Abstract

This work reports the development of an innovative electrochemical reactor for the simultaneous on-site production of hydrogen peroxide (H₂O₂) and ozone (O₃) in a salt-free aqueous medium, based on a multilayer membrane–resin–electrode assembly (MMREA). The system employs a Printex L6 gas diffusion electrode as the cathode and a mesh boron-doped diamond anode, coupled through a compacted Nafion 117 membrane and Amberlite IR-120H⁺ resin layer to enable proton transport without supporting electrolytes. Under optimized conditions, the reactor achieved maximum current efficiencies of 19% for H₂O₂ and 4% for O₃, corresponding to production yields comparable to those reported for early stages laboratory-scale on-site electrochemical systems, while eliminating electrolyte-related downstream separation and corrosion issues. Hydrogen peroxide generation was favored at lower current densities and catholyte flow rates of 0.5–1.0 mL min⁻¹ (19.6 cm² electrode area), whereas ozone production increased with higher current densities, with stable current efficiencies over the evaluated range. The reactor exhibited stable performance under both continuous and discontinuous operation, indicating robustness for decentralized and intermittent operation scenarios. Although the current efficiencies remain lower than those of mature single-oxidant generators, the simultaneous and electrolyte-free production of H₂O₂ and O₃ enables direct in situ peroxone formation with reduced process complexity and chemical footprint. Additionally, the yields are sufficiently high to demonstrate the feasibility of the approach and the need for additional studies, given the high application potential. The applicability of this approach was demonstrated through the effective treatment of real pharmaceutical wastewater, highlighting its potential for decentralized advanced oxidation processes powered by renewable electricity.