A DFT study of the ORR on M-N-3 (M = Mn, Fe, Co, Ni, or Cu) co-doped graphene with moiety-patched defects

摘要

Graphene-based nanomaterials have potential as electrocatalysts for the oxygen reduction reaction (ORR) due to their unique physical and chemical properties. In this study, the mechanism of the ORR on M-N-3 (M = Mn, Fe, Co, Ni, Cu) co-doped graphene with defects is investigated using dispersion-corrected density functional theory (DFT) computations. The results show that Mn-N-3-Gra, Co-N-3-Gra, and Ni-N-3-Gra are more thermodynamically stable than Fe-N-3-Gra and Cu-N-3-Gra. Only Mn-N-3-Gra exhibits some catalytic activity at pH < 11.327 while M-N-3-Gra (M = Fe, Co, Ni, and Cu) are not suitable ORR catalysts. Under acidic conditions at pH = 0, the overpotentials of the optimal 4e(-) catalytic path are 0.56 V, 0.849 V, and 0.381 V for Mn-N-3-Gra, Co-N-3-Gra, and Ni-N-3-Gra, respectively. These values are consistent with experimental results. These results indicate that Ni-N-3-Gra, the optimal catalyst in this study, is comparable with Pt. The M-N-3-Gra (M = Fe, Cu) catalysts cannot promote ORR under acid conditions.