Cu ion doping α-MnO2 nanowire electrocatalysts for Mg-air battery

Copper-doped α-MnO2 (Cu-α-MnO2) nanowires were synthesized with various amounts of Cu2+ via a hydrothermal method. Based on the XRD and XPS data, the substitution of larger Cu2+ ions in place of Mn3+ (0.645 Å) or Mn4+ ions (0.530 Å) result in the expansion in the lattice and increase of the amount of Mn3+. The electrocatalytic results indicate that the Cu-α-MnO2 shows superior ORR activity than that of the pristine α-MnO2 due to the decreases in the charge transfer resistance and enhance the kinetic rate. In addition, the Mg-air battery using Cu-α-MnO2 (Cu: Mn = 1:4) displays a maximal peak power density of 73.4 mW cm−2 and high discharge voltage. This finding provides an effective and cheap method to improve electrocatalyst for Mg-air batteries.