Nanocomposites of multi-walled carbon nanotubes with encapsulated cobalt

Abstract

A new nanocomposite material involving multi-walled carbon nanotubes (MWCNTs) was synthesized using the traditional chemical vapor deposition (CVD) method. The objective of this investigation was to embed and encapsulate metal (cobalt) nanoparticles inside the MWCNTs in a one-step CVD process. The morphological and structural characterization of MWCNTs-based nanocomposites was performed using scanning electron micrscopy (SEM), high resolution transmission electron microscopy (HRTEM), thermal gravimetry analysis (TGA), Brunauer, Emmett and Teller theroy (BET surface area), and Raman spectroscopy. HRTEM confirmed the formation of Co encapsulated MWCNTs (Co@MWCNTs), whose average diameter was 27 nm. Surface area of the nanocomposites was determined by the BET method, which was found to be 40 m2 g−1 for the MWCNTs and 120 m2 g−1 for the Co@MWCNTs nanocomposite, respectively. The crystallinity of the MWCNTs and Co@MWCNTs was analyzed using Raman spectra, where the ratio of intensities of D and G band for the MWCNTs was 0.94 and 0.80 for the Co@MWCNTs, respectively. Electrochemical evaluation of the Co@MWCNTs nanocomposite was performed by cyclic voltammetry in 5 M KOH solution. The Co@MWCNTs nanocomposite displayed oxidation in alkaline media with onset potential at 0.55 V vs. SHE. This new approach of synthesizing nanocomposites where metal particles are encapsulated between the walls of MWCNTs could lead to the development of new, efficient and interesting electrocatalysts.