ABSTRACT
A key challenge in the fabrication of ferromagnetically filled carbon nano-onions (CNOs) is the control of their thickness, dimensions and electric properties. Up to now literature works have mainly focused on the encapsulation of different types of ferromagnetic materials including α-Fe, Fe3C, Co, FeCo, FePd3 and others within CNOs. However, no report has yet shown a suitable method for controlling both the number of shells, diameter and electric properties of the produced CNOs. Here, we demonstrate an advanced chemical vapour deposition approach in which the use of small quantities of sulfur during the pyrolysis of ferrocene allows for the control of (i) the diameter of the CNOs, (ii) the number of shells and (iii) the electric properties. We demonstrate the morphological, structural, electric and magnetic properties of these new types of CNOs by using SEM, XRD, TEM, HRTEM, EIS and VSM techniques.
ABSTRACT
In this work we demonstrate an advanced chemical vapour synthesis approach in which the synthesis of Cu-filled carbon nano-onions (CNOs) is achieved by direct sublimation and pyrolysis of a not previously used precursor, namely chloro(1,5-cyclooctadiene)copper(i) dimer. The cross-sectional morphology and filling-ratio of the as grown CNOs were characterized by detailed transmission electron microscopy (TEM), high resolution TEM analyses, Fourier transform and lattice profile analyses. The structural graphitic arrangement and electronic properties of the CNOs were then investigated by means of X-ray diffraction and absorption spectroscopy. The electrochemical impedance spectroscopy and cyclic voltammetry of presented structures were also investigated and reveal a high electrical resistance. Finally the electrochemical performances of this type of CNOs were compared with those of another type of CNOs filled with different metal-carbide materials.