Optimizing nitrogen dopants in carbon for effective and selective two-electron water oxidation to H₂O₂

Hydrogen peroxide (H₂O₂) is a sustainable oxidant with wide applications in energy and environmental technologies, yet its current anthraquinone-based synthesis is energy-intensive and environmentally hazardous. Electrochemical two-electron water oxidation (2e^- WOR) offers a green alternative, but its efficiency is hampered by competition from the four-electron oxygen evolution reaction (OER). Here, we employ first-principles calculations and microkinetic simulations to unravel the catalytic behavior of carbon nitrides in the 2e^- WOR. We show that pyridinic nitrogen has little impact on selectivity, whereas graphitic nitrogen substantially enhances 2e^- WOR activity and selectivity in a concentration-dependent manner. Excessive nitrogen promotes the OER, while insufficient doping favors one-electron side reactions. Microkinetic analysis identifies an optimal graphitic nitrogen concentration of ∼5-10%, enabling near-unity faradaic efficiency and a low potential of 2.2 V_RHE at 10 mA cm^-2 for the 2e^- WOR. These findings provide mechanistic insights and quantitative design principles for tailoring carbon-based catalysts, offering a pathway toward sustainable and scalable H₂O₂ electrosynthesis.