Facile synthesis of mesoporous MnO2/C spheres for supercapacitor electrodes

• Mesoporous MnO2/C spheres are prepared by a reaction of KMnO4 and carbon spheres.
• The MnO2/C spheres have high efficient MnO2 loading and large specific surface area.
• The porous MnO2/C composite shows good performance as supercapacitor electrodes.

A mesoporous MnO2/C composite with spherical morphology and large surface area of 324 m2/g has been successfully prepared at room temperature by a redox process between KMnO4 and carbon spheres which were hydrothermally synthesized and used without any previous activation treatment. The composition, morphology and structure of the obtained material are examined by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and nitrogen adsorption–desorption. Supercapacitive performance of the MnO2/C samples as active electrode materials has been evaluated by cyclic voltammetry (CV) and galvanostatic charge–discharge. The results of electrochemical tests indicate that the mesoporous MnO2/C composite with 72.86 wt% of MnO2 exhibits a high specific capacitance of 383 F/g at 2 mV/s and demonstrates a superior long-term cyclic stability, with specific capacitance retention about 82.2% of the initial value after 1000 cycles.