High-quality Prussian blue/reduced graphene oxide (PB/rGO) nanohybrids were synthesized via a simple polyvinylpyrrolidone (PVP)-assisted polyol reduction method under mild conditions. The structure and composition of PB/rGO were confirmed by means of X-ray diffraction (XRD), electron microscopes (SEM and transmission electron microscopy (TEM)), Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). These results indicate that ratios of starting materials allow a good control on loading and morphology of PB/graphene hybrids, and at ratio of K3Fe(CN)6/GO of 1:2, PB nanocubes get completely embedded into the defect of porous graphene matrices. Electrochemcial characterization of the PB/rGO nanocomposites with different PB/rGO weight ratios was carried out by cyclic voltammograms and galvanostatic charge–discharge in 1.0 M KNO3 electrolyte. The PB/rGO nanocomposites exhibit much higher specific capacitances than either bare PB nanocrystals or pure rGO sheets. PB/rGO (1:2) exhibits the highest specific capacitance of 251.6 F g−1 at a scan rate of 10 mV s−1 and an excellent cycling stability along with 92 % specific capacitance retained after 1000 cycle tests. The significant enhancement in electrochemical performance over PB/rGO nanocomposites can be attributed to a positive synergetic effect that the PB nanocube interlocked dispersion of rGO sheets superimposes pseudocapacitance from PB on double-layer capacitance from rGO sheets.
