Investigating the Outskirts of Fe and Co Catalyst Particles in Alumina-Supported Catalytic CVD Carbon Nanotube Growth

Abstract

Using thermal CVD, the synthesis of multi-walled carbon nanotubes exhibiting roots anchored directly onto ␣-alumina supports, rather than the catalyst particle, is reported. At such roots, the alignment of the graphitic planes with the support lattice fringes depends on the support crystal structure and orientation.Surface defects may alter the reactivity of the surface or control the anchoring of supported atoms or nanoparticles.We argue this surface defect is provided by the catalyst particle's edge interaction with the support, in other words its circumference. The development of oxide-based catalysts is attractive in that they potentially provide an appropriate solution to directly integrate the synthesis of carbon nanotubes and graphene into silicon-based technology.

Synthesis of carbon nanotubes with and without catalyst particles

“…Whilst the studies showed a good correlation between the initial catalyst size and the CNT outer diameter, after synthesis the catalyst particles are found to lie within the core of the CNT and are elongated [42]. In addition, the roots of the graphitic walls do not terminate on the metal particle but rather on the oxide support as shown in Figure 5[43]. This highlights the diversity with which carbon nanotubes can grow, in that some base growth modes show the CNT is rooted at the metal catalyst particle [44] much like tip growth grown CNT [45] or in other cases from the oxide support [42,43].…”

“…The right micrograph is a copy of the middle image with lines added to highlight the alignment of the graphitic planes with the rhombohedral (110) lattice fringes of the corundum support. Reprinted from Rümmeli et al [43]. …”

Structural and magnetic characterization of batch-fabricated nickel encapsulated multi-walled carbon nanotubes

“…AAO templates can also function as catalysts for CNT deposition [17]. Therefore, metal-filled CNTs can be grown within the template, either before or after the deposition of ferromagnetic material inside the pores.…”

Morphological and Interfacial Studies of Fe Clusters on SrTiO₃(001) Surfaces

“…Nano-sized clusters and particles are attracting much attention for both fundamentally and technologically due to their unique properties [1][2][3][4][5]. Metal clusters on oxide substrates are of particular interest due to their applicability in nanomagnetism, catalysis, and so on.…”