Generation of hydrophilic, bamboo-shaped multiwalled carbon nanotubes by solid-state pyrolysis and its electrochemical studies

A simple, efficient, and novel method was developed for the direct preparation of hydrophilic, bamboo-shaped carbon nanotubes by the pyrolysis of ruthenium(III) acetylacetonate in a Swagelock cell is reported. The obtained product exhibits mostly bamboo-shaped, straight, periodic twisted, multiwalled carbon nanotubes possessing diameters of 50-80 nm and lengths of around 10 mu m. The pyrolyzed product was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM), Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), micro-Raman, and cyclic voltammetric techniques. HRTEM studies showed that the walls of bamboo-shaped carbon nanotubes consisted of oblique grapheme planes with respect to the tube axis. The interlayer spacing between two graphitic layers was found to be 0.342 nm. XPS measurements have suggested that as-prepared carbon nanotubes consist the surface functional groups on the surface of carbon nanotubes. The electrochemical properties of synthesized carbon nanotubes have been evaluated. Thermogravimetric analysis (TGA), IR, and cyclic voltammetric studies showed the presence of oxygen functionalities. Raman studies revealed the presence of disorder in the graphitic carbon and the presence of exposed edge plane defects in the generated carbon nanotubes for influencing the surface behavior and electrochemical properties. The electrochemical behavior of electrodes made of bamboo-shaped carbon nanotubes served for an oxygen reduction reaction.