Tailoring Pyridinic Nitrogen Functionalities in Nitrogen and Fluorine Co-Modified Porous Carbon for Selective...

Developing earth-abundant, selective, and durable catalysts for electrochemical hydrogen peroxide (H2O2) production is essential. Herein, we report nitrogen and fluorine co-modified porous carbon (NF-PC) as an interface-engineered, metal-free electrocatalyst for the selective two-electron oxygen reduction reaction (2e- ORR). Unlike conventional N-doped carbons, in which pyridinic nitrogen (N6) can promote O2 activation but also accelerate parasitic H2O2 reduction, NF-PC was designed to regulate the local chemical environment of exposed N6 sites. Fluorine modification was used to partially passivate exposed pyridinic nitrogen, mitigating the inner sphere electron transfer pathway and suppressing H2O2 decomposition. This interfacial regulation produced a nearly three-fold improvement in the H2O2 formation-to-decomposition ratio (Kf/Kd = 6.75) compared with pristine N-doped porous carbon, while increasing H2O2 selectivity and Faradaic efficiency to approximately 93 and 92.41%, respectively. NF-PC also maintained enhanced H2O2 production over a broad pH window (pH 3-13), indicating that the modified carbon interface retained ORR activity under diverse electrolyte conditions. Rotating ring-disk electrode analysis further supported a dominant two-electron pathway, whereas open-circuit potential measurements and H2O2 reduction tests supported the inhibited interaction between H2O2 and fluorine-modified carbon surfaces. Density functional theory calculations revealed that fluorine-induced electronic redistribution near N6 optimized the binding strength of the *OOH intermediate and decreased the predicted overpotential for 2e- ORR. These results establish N6 passivation as a practical strategy for suppressing peroxide-consuming pathways in doped carbon electrocatalysts and for designing selective, metal-free cathodes for on-site H2O2 electrosynthesis.