Facile Hydrothermal Synthesis of Manganese Dioxide/Nitrogen-Doped Graphene Composites as Electrode Material for Supercapacitors

We report a simple and efficient approach for the in-situ decoration of manganese dioxide (MnO2) nanoparticles onto nitrogen-doped graphene (NG) using polyvinylpyrrolidone (PVP) as the dispersing agent and stabilizer. The morphology and microstructure of the as-prepared MnO2/NG composites were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The results show that a uniform dispersion of MnO2 nanoparticles with a mean size of about 10-20 nm was successfully anchored on the NG surfaces. Furthermore, the electrochemical capacitive behaviors of the MnO2/NG hybrid materials were investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). The MnO2/NG composites delivered a high specific capacitance of 302 F/g at 1 A/g in 1 M Na2SO4 electrolyte; they also showed good cycling stability with 88.9% retention rate of specific capacitance after 1000 cycles of charge and discharge. This study provides a rational device for designing high-performance MnO2-based supercapacitors.