Electrolyte‐Free Electrosynthesis of Pure H ₂ O ₂ via Triple‐Phase Interface Engineering

Electrosynthesis of pure H 2 O 2 through proton exchange membrane electrolyzers offers a promising route for decentralized, on‐demand production. However, conventional approaches face critical challenges in balancing O 2 supply and H 2 O 2 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 O 2 transport, while shear‐driven convection accelerates directional H 2 O 2 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 cm 2 electrode), and tunable H 2 O 2 concentrations (153.6–2443.7 mg L −1 ), rendering a robust platform for sustainable, on‐demand chemical electrosynthesis.