Enhanced electrochemical properties of MnO2/PPy nanocomposites by miniemulsion polymerization

In this study, manganese/polypyrrole (MnO2/PPy) nanocomposites were facilely synthesized by an in situ miniemulsion polymerization method, and their morphologies and structures were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction and thermogravimetric analysis. The results showed that these MnO2/PPy nanocomposites were quasi-spherical with a mean particle size of similar to 50 nm. The electrochemical performances were evaluated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge measurements with a three-electrode cell system filled with 0.5 mol L-1 Na2SO4 solution. The results indicate that the specific capacitance of MnO2/PPy nanocomposites was as high as 625 F g(-1) at a current density of 0.5 A g(-1) when the molar ratio of Py to KMnO4 was 10:1. In addition, these MnO2/PPy nanocomposites also show better long-term cycling stability and electrochemical reversibility than that prepared by traditional chemical methods. Thus, in situ miniemulsion polymerization can be a promising method for the preparation of MnO2/PPy nanocomposites for supercapacitors, and MnO2 and PPy can have a synergistic effect in improving the electrochemical properties of nanocomposites.