Spatially Confined Co-N4 Sites on N-Doped Carbon Nanotube for Efficient Salt-Free Neutral H2O2 Electrosynthesis

Two-electron oxygen reduction reaction (2e−-ORR) represents a sustainable and energy-efficient approach for decentralized hydrogen peroxide (H2O2) production compared with the conventional anthraquinone process. Among various electrocatalysts, metal–nitrogen–carbon (M–N–C) materials have attracted extensive attention owing to their tunable electronic structures and favorable *OOH adsorption behavior. However, the uncontrolled pyrolysis process generally leads to structurally heterogeneous and ill-defined coordination environments, making it difficult to precisely regulate active sites and understand catalytic mechanisms. Herein, we report a single-atom catalyst (CoN@OCNT) featuring spatially confined pyridinic-N-coordinated Co single sites, synthesized by anchoring a well-defined hexapod terpyridine Co-precursor onto oxidized carbon nanotubes (OCNTs) to suppress metal aggregation during pyrolysis. Benefiting from the optimized coordination environment and enhanced mass/electron transfer, the CoN@OCNT catalyst exhibits nearly 100% H2O2 selectivity over a wide potential window from −1.0 to 0.66 V versus RHE in neutral electrolyte. In situ FT-IR and Raman spectroscopy reveal a rapid *OOH-mediated reaction pathway during the 2e−-ORR process. Furthermore, membrane electrode assembly (MEA) testing demonstrates an H2O2 production rate of 21.8 mol h−1 gcat−1 with stable operation over 80 h at 60 mA cm−2. Remarkably, at an industrially relevant current density of 300 mA cm−2, the catalyst achieves a record H2O2 production rate of 70.3 mol h−1 gcat−1 and a salt-free H2O2 concentration of 9.4 mM, highlighting its great potential for practical large-scale H2O2 electrosynthesis in neutral media.