Seawater Electrosynthesis of Hydrogen Peroxide at Industrial-level Current Densities Enabled by Pentagonal Defect-Rich Nanocarbon with Chlorine Doping.

The electrosynthesis of hydrogen peroxide (H2O2) via two-electron oxygen reduction reaction (2e- ORR) in seawater shows great prospects. However, designing an electrocatalyst with high activity and selectivity, resistance to seawater corrosion, and even stable operation at industrial currents (≥300 mA cm-2), remains a critical challenge. In this work, we report a pentagonal defect-rich nanocarbon with chlorine-doping (Cl-PDC) by tailoring fullerene (C60) precursors via the molten salt method. The as-prepared Cl-PDC catalyst achieves a record H2O2 yield of 74.61 mol gcat -1 h-1 at a current density of 800 mA cm-2 with a nearly 100% Faradaic efficiency, outperforming among all previously reported catalysts in simulated seawater or neutral environments. Remarkably, the Cl-PDC-based electrode maintains operational stability over 400 h in simulated seawater, and enables rapid disinfection and pollutant degradation. Theoretical calculations and experimental analysis reveal that the synergy between the intrinsic pentagonal defects and Cl doping modulates the electronic structure of the carbon framework, optimizing *OOH intermediate adsorption, and introduces the localized negative charge to suppress Cl- poisoning at active sites. This work paves the way for sustainable seawater H2O2 production and marine environmental protection.