Supercritical synthesis and characterization of SWNT-based one dimensional nanomaterials

Abstract

The present study developed a novel, fast and efficient method to synthesize one dimensional nanotube-based materials via supercritical reactions and supercritical fluids. It was proved that supercritical organic fluids were good media to take materials into the nanocavity, not only as solvents but also as reaction agents. Different kinds of metals (Ni, Cu, Ag) and fullerenes (C(60), C(70), C(78), C(84), Gd@C(82), Er@C(82), Ho@C(82), Y@C(82)) were successfully inserted into nanotubes with small diameters by this technique, with various supercritical fluids such as C(2)H(5)OH, CH(3)OH or C(6)H(5)CH(3). The filling rates were proved to be more than 90%. The high filling efficiency and the properties of the as-generated materials were characterized by TEM, Raman, EDS and XPS. In principle, this technique can be applied to construct new types of nanomaterials, if we choose the appropriate supercritical reaction and fluid in the CNTs.

Spin-state-dependent electrical conductivity in single-walled carbon nanotubes encapsulating spin-crossover molecules

“…The SWCNTs characteristic Raman bands are also shifted. The radial breathing modes RBMs are blue shifted in both SCO1@SWCNT and SCO2@SWCNT for those tubes excited with 532 and 633 nm, an alteration previously described for several different encapsulations 30,31 . This effect is not so obvious with the 785 nm laser owing to the excitation of wider SWCNTs, less strained upon encapsulation.…”

“…9). This shift could be associated with a small charge transfer between SCO molecule and SWCNT, strain, or aggregation effects 13,[31][32][33] . A detailed voltammetry study 34 to disentangle the charge transfer contribution and subtle differences between SCO molecules will be the subject of a further study.…”

The importance of an extensive elemental analysis of single-walled carbon nanotube soot

“…The disadvantage of using these surface sensitive techniques for the analysis of a heterogeneous powder stems from their high spatial resolution. Specifically, XPS has a depth resolution of <100 Å and a lateral resolution of 10 μm – 2 mm [19, 21–23], and EDS systems associated with electron microscopes have a depth resolution of 0.3 – 5 μm and a lateral resolution of 0.5 μm [24–26]. It is therefore prohibitively expensive and time consuming to obtain enough discrete XPS or EM-EDS spectra to accurately represent the bulk properties of a SWCNT soot sample.…”

Modifications of mechanical, thermal, and electrical characteristics of epoxy through dispersion of multi-walled carbon nanotubes in supercritical carbon dioxide

“…The importance of supercritical fluids, particularly supercritical carbon dioxide (SCC), as a green friendly alternative to organic solvents for environmentally benign processing of carbon nanomaterials has recently been recognized [1][2][3].They have been adopted either to develop new technologies or to replace traditional technologies based on the use of organic solvents. The advantages of using SCC over conventional methods for processing of carbon nanomaterials are not only environmental but also chemical and economical.…”

“…The advantages of using SCC over conventional methods for processing of carbon nanomaterials are not only environmental but also chemical and economical. Due to its unique inexpensive, non-toxic, and non-flammable properties and excellent recyclability without energy expenditures, SCC has been used for processing of one dimensional carbon nanostructures [1], synthesis of carbon nanotubes (CNTs) [2,3], patterning of carbon nanomaterials [4], growth of CNTs [5] and carbon nanocages [6], purification of sing-walled CNTs (SWCNTs) [7,8], coating of inorganic nanoparticles [9] and polymers over carbon nanostructured surfaces [10], non-covalent functionalization of CNTs with molecular anchors [11], and preparation of endohedral derivatives of CNTs [12] and CNT/polymer composites [13][14][15].…”