A new wet chemical method to fill in Carbon Nanotubes (CNTs) with nanoclusters of various materials

Profil Titel	A new wet chemical method to fill in Carbon Nanotubes (CNTs) with nanoclusters of various materials
Referenz	05 IT LADA 0DPT
Herkunftsland	Italy
Kooperationsart	Angebot
Eintrag/Änderung	2005-11-16 / 2007-05-23
Status	Dieses Profil ist abgelaufen! Falls Sie denoch Interesse haben, kontaktieren Sie uns. (2007-12-15)

Kurzfassung

An Italian research centre developed a new wet chemical method that allows the filling of CNTs with nanoclusters of various materials, without causing any external material growth. This method implies low-cost technologies, using a multi-step synthesis and controlling carefully the dimension of the filling material. License agreements with companies interested in the electronic, energetic and material application of the technology are expected.

Details

Since the discovery of Carbon Nanotubes in 1991, the use of this new material in many scientific and technological fields has become more and more important. Some unique properties of CNTs, such as the possibility of tailoring the electrical conductivity, the mechanical resistance together with the small dimensions and high aspect ratio, enable the development of nanotechnology in various fields. Moreover, the encapsulation of materials inside the CNTs cavity has attracted great interest for a fine tailoring of the physical properties (optical, electrical and magnetic) at the nanometric scale. The filling of CNTs can be performed using various methods, such as vapour deposition, molten salts or solutions, electrochemical deposition and using supercritical fluids.
An Italian research group has developed a new wet chemical method that allowed the filling of CNTs with nanoclusters of various materials, without causing any external material growth. Using a multi-step synthesis and controlling carefully the dimension of the filling material, it is possible to use low cost technologies. The filling material can be both organic and inorganic. The procedure is split in two main steps. It starts with the filling of the CNTs with a solution of starting material (i.e. CdCl2 in water), then followed by freezing of the mixture and by the evaporation of the solid solvent. It is possible to find a couple of solvents adapted to every filling material. After that filling it is possible to perform chemical synthesis inside the cavity. In fact the researchers contacted the filled tubes with hydrogen sulphide gas, transforming CdCl2 in CdS. High resolution transmission electron microscopy analysis permitted to establish the crystalline properties of the CdS nanoclusters and to observe their regularly spacing along the CNTs interiors, as shown in the figure. AFM (Atomic Force Microscopy) and STM-UHV (Scanning Tunnelling Microscopy - Ultra High Vacuum) measurements give further information on the morphology and could indicate changes in the electrical local properties on passing from the CdS-filled areas to the empty areas of the nanotube itself.

Innovative Aspects:
The new method allows filling in the CNTs with nanoclusters of various materials, without causing any external material growth. Only low-cost technologies are requested, and further chemical synthesis inside the cavity can be performed. This method allows obtaining an ordered filling of the hollow structure, choosing which part of the hollow structure to fill up, choosing all the synthesis parameters, and using a low-cost procedure.