Enhanced oxygen diffusion and catalytic performance of self-breathing CB/CNT cathodes for high-efficiency H₂O₂...

A novel self-breathing gas diffusion electrode was developed by loading carbon nanotubes (CNTs) and carbon black (CB) onto the surface of graphite felt through vacuum filtration. This electrode features a well-structured mesoporous network and a stable three-phase interface, which enable efficient oxygen mass transfer and enhance the self-breathing capability. The incorporation of carbon nanotubes and carbon black significantly boosts the electrode's catalytic performance. In a dual-chamber reactor operating at a current density of 12 mA/cm² and an initial pH of 3, the system achieved an H₂O₂ concentration of 4691 mg/L within 1 h, with an energy consumption of 6.58 kWh/kg H₂O₂ substantially outperforming conventional gas diffusion electrodes. The dynamic pH regulation in the dual-chamber system optimizes the 2e^- ORR pathway, leading to corresponding changes in proton transfer pathways and adsorbed species within the Helmholtz plane. Additionally, the presence of reactive hydrogen (H∗) enhances the chemisorption of O₂ and facilitates its hydrogenation to form the ∗OOH intermediate. The electrode exhibited excellent stability, maintaining H₂O₂ yields above 4000 mg/L over 5 cycles and nearly complete degradation of the simulated contaminants within 30 min in an electro-Fenton system application. These results highlight the electrode's potential for efficient H₂O₂ synthesis and environmental remediation.