Effect of Potassium Ions on the Formation of Mixed-Valence Manganese Oxide/Graphene Nanocomposites.

One-pot synthesis of mixed-valence manganese oxide (MnO _x )/potassium ion-doped reduced graphene oxide (rGO) composites for efficient electrochemical supercapacitors is introduced. Using manganese nitrate and potassium permanganate as co-precursors for the MnO _x and by directly annealing the rGO without tedious purification steps, as described herein, MnO _x /rGO composites with a high specific capacitance of 1955.6 F g ^-1 at a current density of 1 A g ^-1 are achieved. It is found that the presence of potassium ions helps in the development of mixed-valence MnO _x on the surface of the rGO.