Efficient oxygen reduction electrocatalysis on Mn3O4 nanoparticles decorated N-doped carbon with hierarchical porosity and abundant active sites

Transition metal on nitrogen-doped carbons (M-N-C, M = Fe, Co, Mn, etc.) are a group of promising sustainable electrocatalysts toward oxygen reduction reaction (ORR). Compared to its Fe, Co analogues, Mn-N-C possesses the advantage of being inert for catalyzing Fenton reaction, and thus is expected to offer higher durability, but its ORR activity needs essential improvement. Herein, an efficient Mn-N-C ORR catalyst composed of Mn3O4 nanoparticles supported on nitrogen-doped carbon was successfully synthesized by pyrolysis of cyanamide/Mn-incorporated polydopamine (PDA) film coated carbon black (CB), where the presence of N-rich cyanamide confers abundant Mn-N-x active sites and rich micropore/mesopores to the catalyst. In an alkaline medium, as synthesized Mn-N-C electrocatalyst outperforms commercial Pt/C catalyst in terms of onset potential (0.98 V, vs. RHE), half-wave potential (0.868 V, vs. RHE), and limiting current density. Meanwhile, it exhibits excellent durability and resistance to methanol. In a Zinc-air primary battery, it demonstrates better performance as a cathodic catalyst than Pt/C. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.