Fig. 1

a Schematic illustration of the synthesis of MnO samples. b Structural evolution schematics of MnOx. c XRD patterns of MnO-T samples (T = 400, 500, 600 °C)

a Schematic illustration of the synthesis of MnO samples. b Structural evolution schematics of MnOx. c XRD patterns of MnO-T samples (T = 400, 500, 600 °C)