Hydroxyl Regulatory Pyridinic N−C Active Sites Boost Neutral H2O2 Electrosynthesis by Tuning Proton-Coupled Electron Transfer

Abstract Hindered by sluggish kinetics and limited proton supply, the electrochemical 2-electron oxygen reduction reaction (2e− ORR) in neutral conditions suffers from low hydrogen peroxide (H2O2) yields and large voltages for scalable production. Herein, hydroxyl-group-modified pyridinic N−C active sites are designed in a porous carbon catalyst (CNO) through a pyrolysis−acidification process. The CNO catalyst achieves a H2O2 selectivity of ∼95% in diluted 0.05 M Na2SO4. In a flow-cell setup, it exhibits a H2O2 production rate of 6.17 mol gcat−1 h−1, while maintaining stable operation for over 120 h at 200 mA current. Experimental analyses combined with density functional theory calculations elucidate that manipulated pyridinic N−C−OH sites contribute to proton supply and facilitate the formation of *OOH intermediates. Pyridinic N activates nearby carbon atoms, which not only stabilize vulnerable C−OH groups but also lower the energy barrier of 2e− ORR by regulating rate-determining steps. Furthermore, by coupling the cathodic 2e− ORR with the anodic phenol electro-oxidation reaction, the H2O2 production is further enhanced to 9.9 mol gcat−1 h−1 with a production-per-energy of 948.55 mgH2O2 kWh−1. Complete inactivation tests of Escherichia coli are eventually demonstrated using the on-site-generated H2O2 in the established neutral system, validating its potential for disinfection.