Aid of Raman spectroscopy in diagnostics of MWCNTs synthesised by catalytic CVD

This work shows that a set of quality indicators (QI), able to reliably monitor the basic characteristics of carbon nanotubes (CNT) grown by of Fe-catalysed chemical vapour deposition (CVD), can be derived from Raman spectroscopy (RS) measurements. Multi-walled nanotubes, prepared at 750 °C in C2H6+H2 mixture over 20þ/SiO2 catalyst, are demonstratively considered. By quantitatively analysing the spectra measured in the 100-3100 cm-1 range, information is obtained on level of defectiveness and degree of smoothness of C deposits, as well as, on relative amount of Fe-nanoparticles incorporated. The effect of the growth atmosphere composition on the quality of synthesis products is investigated. Indications provided by RS are confirmed by the results of scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analyses. Raman QI agreeably correlate with the average growth rate of the carbonaceous species.