Morphology and electrochemical properties of composites based on multi-wall carbon nanotubes filled with gold and manganese oxides nanoparticles

The morphology and electrochemical characteristics of multi-wall carbon nanotubes (MWCNT)-based nanostructured composites filled with Au or MnxOy nanoparticles have been studied. It is determined that during the both nanocomposites types preparation by the reduction of aqueous HAuCl4, KMnO4 solutions, fillers nanoparticles formed in MWCNTs channels or on its external surface. The maximum electric capacitances of the nanostructured composites with optimal filler content are in 1.3 times (for the 4 wt.%Au composites) and 2.9 times (for the 5 wt.% MnxOy composites) more than initial MWCNT capacitance. The nature of anodic and cathodic peaks determining the pseudocapacitance on cyclic voltammetry curves for the composites filled with MnxOy and corresponding to transformations in Mn oxides has been defined. Electrochemical impedance spectra for the nanocomposites reflect the occurrence of these reactions, as well as Red-Ox processes with the participation of functional groups on the C-matrixes surface, in addition to the formation of an electric double layer. Electrochemical properties of MWCNTs and nanocomposite electrodes are described with proposed equivalent scheme with the satisfactory accuracy in the frequency range of 0.1 Hz - 100 kHz.