Preparation of nanotubes-clay hybrid systems by iron-catalyzed isobutane decomposition

Evaluation of crystalline perfection degree of multi‐walled carbon nanotubes: correlations between thermal kinetic analysis and micro‐Raman spectroscopy

“…The widths of the D band (40-60 cm −1 ) and the G band (28-42 cm −1 ) measured in MWCNT spectra are compatible with those reported for crystalline graphite-like allotropes, [16] which allows ruling out the presence of amorphous phases that give rise to quite broad bands (>100 cm −1 ). Different from the case in which different carbonaceous phases coexist within the same sample, [18] the G band has a single peak; moreover, except for a few of samples (A1, M3 and C1), it is detected at positions (1575-1580 cm −1 ) always lower than in the aspurchased graphite sample (1582 cm −1 ), where a smaller line width (17 cm −1 ) is further measured. Besides, as expected, [5] in MWCNT samples the G band position is down-shifted with respect to sample G1 (∼2700 cm −1 against a centre position of Table 1. ∼2720 cm −1 , respectively), thus demonstrating the absence of graphite as a by-product.…”

“…1). [15,18,19] In SWCNTs, the D band shifts towards lower wavenumbers with respect to MWCNTs (1345 cm −1 in place of 1350 cm −1 , for 2.41 eV excitation). [5] In MWCNTs, the D band further appears (around 1610 cm −1 at 2.41 eV) as a weak shoulder to the G band.…”

“…The synthesis conditions of laboratory-prepared MWCNTs are reported in Table S1 (supporting information). A detailed description of catalyst preparation, synthesis experiments and subsequent sample purification can be found elsewhere, [18,32,33] together with an extensive discussion concerning growth mechanism and influence of CCVD parameters on the resulting CNT specifics. The nominal outer diameters of commercially available CNTs are reported in Table 1.…”

“…[8,13 -15] In the study of graphitic carbons, the use of single-wavelength RS is often coupled with complementary characterisation techniques, [9,12,16] such as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). This offers the possibility of correlating the results obtained by the different techniques, finally achieving a more [19] (e) nano-crystalline graphite [18] and (f) amorphous carbon. [15] In spectrum (b), RBM is clearly visible in the lower wavenumber region (100-500 cm −1 ).…”

Crystalline Quality Evaluation of Carbon Nanotubes by Kinetic Analysis in Quasi‐Isothermal Conditions

“…The former, coded "A" or "K" depending on the support material (alumina or K10-montmorillonite, respectively) of the Fe-catalyst, were synthesised by isobutane CCVD by using the conditions reported in Table 1. A detailed description of catalyst preparation, synthesis experiments and subsequent sample purification can be found elsewhere, [7,20] together with an extensive discussion concerning growth mechanisms and the influence of CCVD parameters on the resulting CNT specifics. The latter, coded "C" and characterised by different nominal outer diameters (Table 2), were purchased from Bayer (C1) and Helix Material Solutions Inc. (C2-C4).…”