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Single-walled carbon nanotubes (SWCNT) manufactured with Nano-C’s unique combustion technology are currently available in three grades:
- Nano-CAPT: as-produced material (25% SWCNTs)
- Nano-CPPT: pre-purified material (70% SWCNTs)
- Nano-CPT: purified material (97% SWCNTs)
The characteristics of each type are described below. For further details on our 3 SWCNT products, please see our product guide.
nano-cAPT
As-produced single-walled carbon nanotubes
Fig. 1 Raman spectrum of as-produced combustion-generated material.
Setpoints: 785 nm, laser power: »0.18 mW, exposure time: 4 s, 5 accumulations.
Fig. 2 Scanning electron microscopy (SEM) of as-produced material.
Fig. 3 Transmission electron microscopy (TEM) of as-produced material.
Material generated in the combustion process has been characterized by means of Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Raman spectroscopy confirms the presence of significant amounts of single-walled carbon nanotubes (Fig. 1). The G-band occurring in the 1500-1605 cm-1 range corresponding to tangential vibrations indicates an abundance of conducting nanotubes vs. semi-conducting SWCNT. The radial breathing mode (RBM) reflecting the diameter of the detected SWCNT shows combustion generated material to have a narrow diameter distribution. The peak seen in Fig. 1 at a wave number of 220 cm-1 corresponds to a tube diameter of approximately 1.1 nm. The weakness of the peak near 1350 cm-1 (D-band) indicates only low level of impurities or other symmetry-breaking defects. Details about Raman spectroscopy of single-walled carbon nanotubes can be found in Dresselhaus et al., Carbon 40 (2002) 2043-2061. Scanning electron microscopy (SEM) has been conducted in the Center of Materials Science and Engineering of the Massachusetts Institute of Technology (MIT) using a JEOL 6320 instrument. Figs. 2a and b show two different locations of a randomly selected sample of as-produced material. As confirmed by transmission electron microscopy (TEM), the observed strands correspond to rafts of individual SWCNT (Fig. 3). Different degrees of ordering, partially aligned in Fig. 2a and rather randomly oriented in Fig. 2b can be observed. Bright spots, observed in both images, are thought to be remaining catalyst particles or their reaction products. Transmission electron microscopy (TEM) images of as-produced material are given in Fig. 3a and b. Fig. 3b represents a magnified partial view showing unambiguously the presence of rafts of individual single-walled carbon nanotubes. Images have been taken, also at MIT, with a JEOL 2010 instrument.
As-produced material is proposed to be used by customers who are not concerned about the presence of metal particles. Easily removable metal particles may represent > 50 weight% of the as-produced material. As-produced material is also the best choice for customers who worry about effects of purification on the materials composition and/or having developed own purification methods adapted to their application.
nano-cPPT
Pre-purified single-walled carbon nanotubes
Fig. 4 Scanning electron microscopy (SEM) of pre-purified material
Fig. 5 Transmission electron microscopy (TEM) of pre-purified material
Most of the remaining catalyst particles have been removed by treatment with a non-oxidative acid. While some metal particles usually remain, the use of a non-oxidative acid allows minimizing the effect of purification on the characteristics of individual nanotubes. Scanning electron microscopy images of pre-purified material are given in Fig. 4 showing sheets of entangled rafts of carbon nanotubes (Fig. 4a) and regions of increased alignment (Fig. 4b). Pre-purified material is proposed to customers who are interested in higher degrees of purity but who want to minimize the effect of the purification process on the characteristics of single-walled carbon nanotubes. TEM images are presented in Figure 5a and 5b.
nano-cPT
Purified single-walled carbon nanotubesTreatment with an oxidative acid leads to nearly quantitative removal of metal contaminations. A network of single-walled carbon nanotubes is formed (Fig. 6). In Figure 7 is a typical TGA analysis. Purified material is suggested for customers with applications that allow for direct use of high-purity single-walled carbon nanotube material. Figure 8a and 8b present selected TEM images.
Fig. 6 Scanning electron microscopy (SEM) of purified material; Fig. 7. Thermogravimetric analysis of purified SWCNT.
Fig. 8 Transmission electron microscopy (TEM) of purified material.