One-pot synthesis of MnO2/graphene/carbon nanotube hybrid by chemical method

A branched hybrid of MnO2/graphene/carbon nanotube (CNT) is generated in a one-pot reaction process by chemical method. Some ultrathin MnO2/graphene nanosheets, around 5 nm in thickness, are randomly distributed on the CNT surface. Morphology, phase structure, microstructure and vibrational properties of the hybrid were characterized by field emission scanning electron microscope, X-ray diffractometer, high resolution transmission electron microscope and Raman spectrometer. Elemental distribution of the hybrid was determined by energy dispersive X-ray mapping performed in scanning transmission electron microscope mode. The key factor of the formation mechanism is associated with both redox and oxidation-intercalation reactions. Graphene flakes are partly exfoliated from the surface layers of the CNTs, and the redox reaction between KMnO4 and hydroxyl groups occurs on both sides of these flakes, resulting in the formation of a MnO2/graphene/CNT hybrid. Brunauer-Emmett-Teller surface area measurements indicate that the hybrid has over four times the specific surface area of the pristine CNTs. (C) 2011 Elsevier Ltd. All rights reserved.