Atomically dispersed manganese-based catalysts for efficient catalysis of oxygen reduction reaction

Abstract

Rational design and preparation of earth-abundant materials with high-efficiency oxygen reduction reaction (ORR) performance is pivotal for fuel cells. Here, an atomically dispersed Mn- and nitrogen-codoped graphene material (Mn@NG) is developed by a facile high-temperature annealing and subsequent acid-leaching strategy. The atomically dispersion of manganese in Mn@NG is confirmed by aberration-corrected electron microscopy with atomic resolution and the main structure of MnN4 moiety is resolved by X-ray absorption spectroscopy. The Mn@NG catalyst shows an onset potential and half-wave potential of 0.95 and 0.82 V vs RHE in 0.1 M KOH solution, respectively. Theoretical calculations manifest that MnN4 moiety embedded into graphene is the active center for efficient ORR, on which the theoretical overpotential is 0.63 V, lower than that on graphitic-N (1.18 V), pyridinic-N (1.58 V), MnN3-G (1.48 V), MnN3O-G (2.33 V), and Mn3O4 (001) surface (0.86 V).