Enhanced Electrochemical Synthesis of Hydrogen Peroxide via Two-Electron Oxygen Reduction at Highly Active -SH Edge Sites

Abstract

Electrochemical generation of hydrogen peroxide (H₂O₂) through the two-electron oxygen reduction reaction (2e^– ORR) represents a sustainable development strategy for bulk H₂O₂ manufacturing, yet crafting efficient catalysts remains a substantial challenge. Carbon materials are particularly appealing as electrochemical catalysts, owing to their diverse nanostructures and adjustable electrochemical attributes. Nonetheless, the lack of structure–property understanding has hindered the progression of metal-free carbon electrocatalysts. In this study, we fabricated porous carbon with abundant edge sulfhydryl groups (−SH) and determined that the 2e^– ORR performance is roughly proportional to the edge −SH content, outperforming reported ORR catalysts in aspects such as H₂O₂ selectivity (90–98% over a broad potential of 0.30–0.70 V vs RHE) and stability (maintaining over 90% performance during 12 h testing) as measured in alkaline solution in a rotating ring-disk electrode setup. Furthermore, in a flow cell setup, both the H₂O₂ production rate (2910 mmol g_catalyst^–1 h^–1) and Faraday efficiency (over 80%) surpass most reported carbon- and metal-based electrocatalysts. Consequently, this research illuminates a straightforward pathway to design specific sulfur configurations in carbon-based catalysts for high-selectivity H₂O₂ production.