Probing the activity of transition metal M and heteroatom N co-doped in vacancy fullerene (M-N-C, M = Fe, Co, and Ni) towards the oxygen reduction reaction by density functional theory.

In this study, a novel type oxygen reduction reaction (ORR) electrocatalyst is explored using density functional theory (DFT); the catalyst consists of transition metal M and heteroatom N co-doped in vacancy fullerene (M-N-C, M = Fe, Co, and Ni). Mulliken charge analysis shows that the metal center is the reaction site of ORR. PDOS analysis indicates that in M-N-C, the interaction between Fe-N-C and the adsorbate is the strongest, followed by Co-N-C and Ni-N-C. This is consistent with the calculated adsorption energies. By analyzing and comparing the adsorption energies of ORR intermediates and activation energies and reaction energies of all elemental reactions in M-N-C (M = Fe, Co, and Ni), two favorable ORR electrocatalysts, Fe-N-C and Co-N-C, are selected. Both exhibited conduction through the more efficient 4e reduction pathway. Moreover, PES diagrams indicate that the whole reaction energy variation in the favorable ORR pathways of Fe-N-C and Co-N-C is degressive, which is conducive to positive-going reactions. This study offers worthwhile information for the improvement of cathode materials for fuel cells.