Preparation, Characterization and Application of Multi-walled CNTs by means of Phthalocyanine Pyrolysis

In order to investigate the catalytic activity of high temperature treated CoPc toward oxygen reduction, and find the active site of the catalyst, using cobalt (Ⅱ) phthalocyanine (CoPc) as raw material, through thermal chemical vapor deposition method at 850℃ under a current of Ar/H2, two layer well-aligned multiwalled carbon nanotubes (CNTs) were made. The diameters of the well-aligned carbon nanotubes were distributed in the range of 60～120 nm and the length was about 40 μm. The Co particle with 10 nm in diameter was encapsulated in the CNTs compartment. The products were observed by field emission scanning electron microscope (SEM), and transmission electron microscope (TEM). The well-aligned carbon nanotubes were characteriszed by Raman scattering spectrum and X-ray diffraction (XRD). The cyclic voltammetric measurement demonstrates that the CNTs have some effect to prevent the metal nanoparticle encapsulated from eroding rapidly. It is assumed that the small amount of the N element in the CNTs is very necessary for the bamboo-like morphology and the protected action for metal particles against dissolution in the acid medium. The radian of the winding wall should be affected by the amount of the N and the interaction between the N in the carbon network and the metal cluster. In addition, the CNTs greater electrochemically active surface area is a great advantage for any electrocatalytic application.