Engineering Localized Alkalinity and Oxygen Enrichment for Efficient Acidic O-to-HO Electroreduction via Carbon-Based Triphase Interfaces.

The sustainable production of hydrogen peroxide (HO) via the two-electron oxygen reduction reaction (2e⁻ ORR) on carbon-based catalysts offers a compelling alternative to the energy-intensive anthraquinone process. However, the slow kinetics of the 2e⁻ ORR in acidic media limits its efficiency. Herein, a novel strategy is introduced to overcome this limitation by engineering a needle-shaped hydrophobic carbon felt embedded with hard carbon as a natural air diffusion electrode (ADE). In situ and ex situ characterization show this design creates an oxygen-enriched, locally alkaline microenvironment at the triphase interface, which accelerates 2e⁻ ORR kinetics by confining oxygen enrichment within the hard carbon layer. Quantitatively, this oxygen-enriched hydrothermal carbon electrocatalyst achieves a remarkable HO selectivity of 95.47% at near-zero overpotential and a high production rate of 487.82 mg L h at 200 mA cm. Furthermore, density functional theory calculations reveal that the carboxyl and ether functional groups in hydrothermal hard carbon optimize O and OOH adsorption, promoting the desired 2e⁻ pathway. Importantly, this ADE design not only exhibits exceptional performance and long-term stability but also demonstrates a significantly reduced global warming potential compared to conventional methods, highlighting its potential to revolutionize industrial-scale HO electrosynthesis by replacing commercial carbon black-based cathodes.