Single-Atomic\nMn–N–C\nCatalyst with Hierarchical\nPores for Anion Exchange Membrane Fuel Cells: A Mn Confinement Strategy

Metal-\nand nitrogen-doped carbon (M–N-C) catalysts\nare effective\nalternatives to oxygen reduction reaction (ORR) catalysts, such as\nplatinum-based systems, in fuel cell technology. Among various transition\nmetals, Mn is an abundant metal; in biological systems, enzymes including\nMn effectively catalyze oxygen-evolving reactions at low potentials.\nHerein, a hollow and single-atom Mn–N–C catalyst was\nsynthesized by using a pseudomorphic replication strategy. This approach\nis an efficient way to synthesize single-atom Mn catalysts without\nsegregating Mn species. The prepared Mn–N–C hollow spheres\nexhibited high ORR activity with a half-wave potential of 0.877 V\nand an onset potential of 1.01 V vs reversible hydrogen electrode.\nWhen applied as a cathode in an anion exchange membrane fuel cell,\nMn–N–C hollow spheres exhibited a maximum power density\nof 617 mW/cm<sup>2</sup> and a current density of 785 mA/cm<sup>2</sup> at 0.6 V.