Fabrication of a vertically aligned carbon nanotube electrode and its modification by nanostructured MnO<sub>2</sub> for supercapacitors

Zhang, Wei-De; Chen, Jin

doi:10.1351/PAC-CON-08-11-25

Pure Appl. Chem., 2009, Vol. 81, No. 12, pp. 2317-2325

http://dx.doi.org/10.1351/PAC-CON-08-11-25

Published online 2009-11-16

Fabrication of a vertically aligned carbon nanotube electrode and its modification by nanostructured MnO₂ for supercapacitors

Wei-De Zhang* and Jin Chen

Nano Science Research Center, School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640, China

Abstract: Strongly bonded arrays of vertically aligned, multi-walled carbon nanotubes (MWNTs) have been successfully grown on Ta foils, and provide a convenient basis for fabricating electrodes with high conductivity and stability. The MWNT arrays were further coated by nanostructured MnO₂ through reacting with KMnO₄ solution at room temperature. The morphology of the MnO₂/MWNT nanocomposite was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that the MnO₂ is a beehive-like nanostructure that is homogeneously and densely coated on the surface of the MWNTs. The capacitance of the MWNT electrode was significantly increased from 0.14 to 6.81 mF cm^–2 after being modified with nanostructured MnO₂, that is, the mass-specific capacitance of the bare and MnO₂-modified MWNTs was about 33 and 446 F g^–1, respectively. The MnO₂/MWNT nanocomposite on Ta foils could be potential for developing a supercapacitor.