Electrolyte-Free Electrosynthesis of Pure H₂O₂ via Triple-Phase Interface Engineering

Electrosynthesis of pure H₂O₂ through proton exchange membrane electrolyzers offers a promising route for decentralized, on-demand production. However, conventional approaches face critical challenges in balancing O₂ supply and H₂O₂ removal at the gas-liquid-solid interface. In this study, we propose a triple-phase interface engineering strategy by integrating a three-dimensional (3D) hydrophobic grid gas diffusion electrode (GDE) with gas-liquid two-phase flow. This design achieves a peak Faradic efficiency (FE) of 84.6% at -10.0 mA cm^-2 using deionized water as the catholyte. Simulations reveal that bubble wake-induced toroidal vortices enhance O₂ transport, while shear-driven convection accelerates directional H₂O₂ transport. Integrated with a T-junction microfluidic unit, it achieves real-time organic pollutant degradation while maintaining an FE above 60% over 50 h. The system demonstrates high flexibility, scalability (25 cm² electrode), and tunable H₂O₂ concentrations (153.6-2443.7 mg L^-1), rendering a robust platform for sustainable, on-demand chemical electrosynthesis.