Synthesis and electrochemical properties of graphene/MnO₂ composites

Accordion-like MnO₂-coated graphene composites were successfully prepared by a facile hydrothermal method at 160℃. The as-products were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray dif-fraction, energy dispersive spectrometry, BET and Raman spectroscopy. The high capacitance of 138 F·g^-1 at 0.2 A·g^-1 is achieved with MnO₂/graphene composites as a supercapacitor electrode, much higher than that of a single MnO₂ or graphene electrode. The ex-cellent electrochemical performance is attributed to the uniform MnO₂ nanosheet morphology, large surface area of graphene and stable chemical bonding of MnO₂ on the graphene substrate.