Single-Atomic Mn-N-C Catalyst with Hierarchical Pores for Anion Exchange Membrane Fuel Cells: A Mn Confinement Strategy

Abstract

Metal- and nitrogen-doped carbon (M-N-C) catalysts are effective alternatives to oxygen reduction reaction (ORR) catalysts, such as platinum-based systems, in fuel cell technology. Among various transition metals, Mn is an abundant metal; in biological systems, enzymes including Mn effectively catalyze oxygen-evolving reactions at low potentials. Herein, a hollow and single-atom Mn-N-C catalyst was synthesized by using a pseudomorphic replication strategy. This approach is an efficient way to synthesize single-atom Mn catalysts without segregating Mn species. The prepared Mn-N-C hollow spheres exhibited high ORR activity with a half-wave potential of 0.877 V and an onset potential of 1.01 V vs reversible hydrogen electrode. When applied as a cathode in an anion exchange membrane fuel cell, Mn-N-C hollow spheres exhibited a maximum power density of 617 mW/cm2 and a current density of 785 mA/cm2 at 0.6 V.