Proton-Shielding Interface Engineering for Efficient Acid H ₂ O ₂ Electrosynthesis

Electrochemical synthesis of H2O2 through the two-electron oxygen reduction reaction (2e– ORR) in acidic media faces inherent limitations due to uncontrolled proton accumulation at catalytic interfaces, which drives undesirable side reactions and diminishes product selectivity. To address this challenge, we develop a cation-engineered electrocatalytic system featuring a proton-modulated interface microenvironment. By anchoring the high-density cationic ionomer PiperION onto graphene oxide (GO) through electrostatic interactions, a proton-shielding catalytic interface is constructed. The optimized PiperION-GO catalyst exhibits high performance in acidic flow cell reactors, demonstrating >90% faradaic efficiency (FE) across an exceptionally broad current density window while maintaining remarkable operational stability. Through comprehensive characterization techniques, the mechanism by which the cationic interface regulates proton flux and local microenvironment to selectively promote 2e– ORR is elucidated. Impressively, this design strategy extends effectively to pure water systems, achieving >85% efficiency with a record production rate of 8.0 mol gcat h–1, providing a promising route for green H2O2 production.