Electrochemically synthesized H2O2 at industrial-level current densities enabled by in situ fabricated few-layer boron nanosheets.

Abstract

Carbon nanomaterials show outstanding promise as electrocatalysts for hydrogen peroxide (H₂O₂) synthesis via the two-electron oxygen reduction reaction. However, carbon-based electrocatalysts that are capable of generating H₂O₂ at industrial-level current densities (>300 mA cm^-2) with high selectivity and long-term stability remain to be discovered. Herein, few-layer boron nanosheets are in-situ introduced into a porous carbon matrix, creating a metal-free electrocatalyst (B_n-C) with H₂O₂ production rates of industrial relevance in neutral or alkaline media. B_n-C maintained > 95% Faradaic efficiency during a 140-hour test at 300 mA cm^-2 and 0.1 V vs. RHE, and delivered a mass activity of 25.1 mol g_catalyst^-1 h^-1 in 1.0 M Na₂SO₄ using a flow cell. Theoretical simulations and experimental studies demonstrate that the superior catalytic performance originates from B atoms with adsorbed O atoms in the boron nanosheets. B_n-C outperforms all metal-based and metal-free carbon catalysts reported to date for H₂O₂ synthesis at industrial-level current densities.