Optimizing Nitrogen Dopants in Carbon for Effective and Selective Two-Electron Water Oxidation to H2O2

Abstract

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 VRHE at 10 mA/cm2 for 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.