H2O2 generation via an electrochemical two-electron oxygen reduction (2e- ORR) is a potential candidate to replace the industrial anthraquinone process. In this study, porous carbon catalysts co-doped by nitrogen and oxygen are successfully synthesized by the pyrolysis and oxidation of a ZIF-67 precursor. The catalyst exhibits a selectivity of ~83.1% for 2e- ORR, with the electron-transferring number approaching 2.33, and generation rate of 2909.79 mmol g-1 h-1 at 0.36 V (vs. RHE) in KOH solution (0.1 M). The results prove that graphitic N and -COOH functional groups act as the catalytic centers for this reaction, and the two functional groups work together to greatly enhance the performance of 2e- ORR. In addition, the introduction of the -COOH functional group increases the hydrophilicity and the zeta potential of the carbon materials, which also promotes the 2e- ORR. The study provides a new understanding of the production of H2O2 by electrocatalytic oxygen reduction with MOF-derived carbon catalysts.
Keywords: electrocatalyst; hydrogen peroxide; porous carbon; two-electron reduction of oxygen.