Selective electrochemical oxygen reduction (ORR) toward a two-electron (2e À ) pathway is an eco-friendly alternative method for H 2 O 2 synthesis to replace the energy-intensive anthraquinone oxidation process. Carbon-based electrocatalysts (CBEs) show great potential for practical H 2 O 2 synthesis. However, their complex structures make it challenging to determine the nature of active sites and to precisely control them. Herein, we show that precise modulation of the chemistry and structures of holey graphene with edge sites enriched by oxygen-containing functional groups can facilitate 2e À ORR. These combined functionalities could improve ORR performance under various pH conditions, for example, resulting in an average of 95% H 2 O 2 selectivity, ~97% Faraday efficiency, high productivity of 2360 mol kg cat À1 h À1 in alkaline media. Density functional theory calculations on the oxygen functional groups at the edge sites revealed the most active site for 2e À ORR is a synergy between ether (C O C) and carbonyl (C O) functional groups with nearly zero overpotential.

Nitrogen (N) and oxygen (O) doping for carbon-based electrocatalysts is one of the most effective methods for improving the oxygen reduction reaction (ORR). Despite its significance, fundamental studies remain needed to determine the effects of atomic configuration on the two-electron (2e − ) oxygen reduction. In this study, we investigate the coupling effects between pyrrolic N and the O functional groups, including ether (O−C−O) and carbonyl (CO), on 2e − ORR. The results suggest that the 2e − ORR performance depends on the CO/O−C−O ratio. Among several atomic configurations, the coupling of pyrrolic N with carbonyl O is the most favorable type for the 2e − reaction, with 98.3% H 2 O 2 selectivity at 0.0 V (vs the reversible hydrogen electrode) in the alkaline electrolyte. Additionally, this combination exhibits considerably stable performance during long-term (12 h) durability test, demonstrating approximately 100% current retention. The experimental results were further supported by theoretical calculation, exhibiting optimal adsorption free energy of OOH* for the couple of pyrrolic N and carbonyl O.