Facile synthesis of nitrogen-doped graphene-ultrathin MnO2 sheet composites and their electrochemical performances.

Nitrogen-doped graphene-ultrathin MnO2 sheet composites (NGMCs) were prepared through a one-step hydrothermal method at low temperature (120 °C). Ultrathin MnO2 sheets were well-dispersed and tightly anchored on graphene sheets, which were doped with nitrogen simultaneously. NGMCs electrode exhibited enhanced capacitive performances relative to those of undoped graphene-ultrathin MnO2 sheets composites (GMCs). As the current density increased from 0.2 to 2 A/g, the capacitance of NGMCs still retained ~74.9%, which was considerablely higher than that of GMCs (27%). Moreover, over 94.2% of the original capacitance was maintained after 2000 cycles, indicating a good cycle stability of NGMCs electrode materials.