Unlocking flooded domains in air-breathing cathodes with edge-located asymmetric CoN2O2 sites for robust H2O2 electrosynthesis

Abstract

Air-breathing gas-diffusion electrodes (GDEs) eliminating energy-intensive aeration hold great promise for industrial-scale hydrogen peroxide electrosynthesis. However, this configuration suffers from limited O2 mass transport and easy flooding. Herein, the active region of GDEs was extended beyond the three-phase boundary into the flooded domain by designing an alveolate carbon-supported Co single-atom electrocatalyst featuring abundant edge-located asymmetric CoN2O2 sites (eCoN2O2) to modulate the catalytic layer. The porous framework facilitates O2 mass transport, while the eCoN2O2 sites enable efficient O2 activation, sustaining fast ORR thanks to rational electrode design across the scales. Moreover, the superior O2 enrichment capability of eCoN2O2 allows efficient utilization of dissolved O2. Notably, the eCoN2O2-based GDE delivers a high H2O2 yield of 738.5 mg L−1 after 6 h at 25 mA cm−2, showing a 3.8-fold increase over basal-plane CoN4 moiety and even outperforming many aeration-driven systems. This work paves the way for integrated design of electrocatalysts and GDE architectures.