SYNTHESIS AND FUNCTIONALIZATION OF CARBON NANOTUBES FOR SUPERCAPACITOR ELECTRODES

Abstract

Carbon nanotubes (CNTs) have been synthesized using catalysts of the Ni/Mg, Fe-Co/Al2O and Co-Mo/Al2O3-MgO composition with different component ratios by gas-phase chemical deposition. They differ in geometric parameters, the nature of the inclusion of metal oxide catalyst impurities, and morphological features. To form oxygen-containing functional groups on the surface, CNTS were oxidized with ozone-oxygen mixture (1 vol.% O3) at room temperature for 5 h. Initial and functionalized CNT samples were characterized by scanning and transmission electron microscopy, Raman and IR spectroscopy. It is shown that as a result of oxidation, the amorphous phase is removed from the material, and oxygen-containing groups-OH, >C=O and –O–C–O–are formed on the CNT surface. Also, during functionalization, there is a slight decrease in the specific surface area of the studied nanotube samples. The electrochemical behavior of initial and functionalized carbon nanotubes in an alkaline electrolyte was studied using cyclic voltammetry. It is shown that based on the analysis of CVA curves, CNTS can be divided into two groups-with the Faraday and non-Faraday character of the current electrode processes. The contribution of the non-Faraday component prevails when carbon nanotubes synthesized on Ni/Mg and Co-Mo/Al2O3-MgO catalysts are used as electrode materials. Oxidative functionalization of CNTs of this type is appropriate and contributes to the improvement and stabilization of capacitance properties during cycling. The positive influence of metal oxide catalyst admixtures on the properties of electrode materials was also noted. Therefore, ozone oxidation is a promising way to functionalize CNTs for their subsequent use as electrode materials for electrochemical capacitors.