Highly efficient electrosynthesis of H2O2 in acidic electrolyte on metal-free heteroatoms co-doped carbon nanosheets and simultaneously promoting Fenton process

Abstract

Recently electrochemical synthesis of H2O2 through oxygen reduction reaction (ORR) via 2e− pathway is considered as a green and on-site route. However, it still remains a big challenge for fabricating novel metal-free catalysts under acidic solutions, since it suffers from high overpotential due to the intrinsically week *OOH adsorption. Herein, a co-doped carbon nanosheet (O/NC) catalyst toward regulating O and N content was synthesized for improving the selectivity and activity of H2O2 electrosynthesis process. The O/NC exhibits outstanding 2e− ORR performance with low onset potential of 0.4 V (vs. RHE) and a selectivity of 92.4% in 0.1 mol/L HClO4 solutions. The in situ electrochemical impedance spectroscopy (EIS) tests reveals that the N incorporation contributes to the fast ORR kinetics. The density functional theory (DFT) calculations demonstrate that the binding strength of *OOH was optimized by the co-doping of oxygen and nitrogen at certain content, and the O/NCCOOH site exhibits a lower theoretical overpotential for H2O2 formation than OCCOOH site. Furthermore, the promoted kinetics for typical organic dye degradation in simultaneous electron-Fenton process on O/NC catalyst was demonstrated particularly for broadening its environmental application.