One-Step Hydrothermal Synthesis of Nitrogen-Doped Reduced Graphene Oxide/Hausmannite Manganese Oxide for Symmetric and Asymmetric Pseudocapacitors.

In this paper, the pseudocapacitive performance of nitrogen-doped and undoped reduced graphene oxide/tetragonal hausmannite nanohybrids (N-rGO/Mn3O4 and rGO/Mn3O4) synthesized using a one-pot hydrothermal method is reported. The nanohybrid electrode materials displayed exceptional electrochemical performance relative to their respective individual precursors (i.e., reduced graphene oxide (rGO), nitrogen-doped reduced graphene oxide (N-rGO), and tetragonal hausmannite (Mn3O4)) for symmetric pseudocapacitors. Among the two nanohybrids, N-rGO/Mn3O4 displayed greater performance with a high specific capacitance of 345 F g-1 at a current density of 0.1 A g-1, excellent specific energy of 12.0 Wh kg-1 (0.1 A g-1), and a high power density of 22.5 kW kg-1 (10.0 A g-1), while rGO/Mn3O4 demonstrated a high specific capacitance of 264 F g-1 (0.1 A g-1) with specific energy and power densities of 9.2 Wh kg-1 (0.1 A g-1) and 23.6 kW kg-1 (10.0 A g-1), respectively. Furthermore, the N-rGO/Mn3O4 nanohybrid exhibited an impressive pseudocapacitive performance when fabricated in an asymmetric configuration, having a stable potential window of 2.0 V in 1.0 M Na2SO4 electrolyte. The nanohybrid showed excellent specific energy and power densities of 34.6 Wh kg-1 (0.1 A g-1) and 14.01 kW kg-1 (10.0 A g-1), respectively. These promising results provide a good substance for developing novel carbon-based metal oxide electrode materials in pseudocapacitor applications.