Influence of Carbon Matrix Type on the Morphology and Electrochemical Properties of Co3O4/C Nanocomposites
YU. A. ZAKHAROV1, T. A. LARICHEV1,2, N. M. FEDOROV2, V. M. PUGACHEV1,2, V. G. DODONOV1, G. YU. SIMENYUK1, T. O. TROSNYANSKAYA1, YU. N. DUDNIKOVA1
1Federal Research Center of Coal and Coal Chemistry, Siberian Branch of the Russian Academy of Sciences, Kemerovo, Russia
2Kemerovo State University, Kemerovo, Russia
Keywords: nanostructured composites, CoO nanoparticles, single-walled carbon nanotubes, highly porous carbon matrices, electrode materials, supercapacitors
Pages: 475-486
Abstract
Nanostructured composites obtained by forming a filler (Co3O4 nanoparticles) during thermal decomposition of two kinds of precursors (Co(N3)2 and Co(OH)2) in the air on the surface of carbon matrices with significantly different morphology (single-walled carbon nanotubes and highly porous material from raw coal) are characterized, and the influence of matrix type on composite properties is considered. It is established that the characteristics holding the greatest significance for electrode materials, that is, the distribution of filler particles over composites, their sizes, matrix stability against oxidation, and, most importantly, the electrical capacitance characteristics of composites, are determined first of all by matrix morphology. This relationship manifests itself in the regularities of matrix oxidation during the formation of Co3O4 nanoparticles within its volume, acting as a catalyst for this process. Highly porous matrix is most prone to oxidation, and for this reason an increase in filler content and oxygen concentration is observed in the subsurface layers, which leads to a substantial decrease in electrical capacitance. In composites based on almost non-oxidized multiwall C-tubes, a noticeable increase in capacitance occurs due to the contribution of Red-Ox electrode processes involving Co3O4 particles. Composites based on single-walled C-tubes coalesced into dense “ropes” occupy an intermediate position.
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