The results of Raman analysis on multi-walled carbon nanotubes, prepared by catalysed chemical vapour deposition, are used as a guide for the calibration of the growth parameters, directed to improve crystalline quality and resulting thermal stability of nanotubes. Under selective growth conditions, the resistance to oxidation in air, as assessed by thermogravimetry measurements, is found to increase with the establishment of the long-range graphitic order in radial tube direction, as signalled by the Raman G'/G intensity ratio enhancement. In the range of parameters explored (synthesis temperature: 500-700 A degrees C; growth atmosphere: 120 cc/min i-C4H10-H-2-He mixture with He at 0-25%; i-C4H10/H-2 flow ratio: 1-3; metal load and reduction temperature of Fe/Al2O3 catalysts: 17-40 wt%, and 500 and 700 A degrees C, respectively), the best crystalline quality and the highest oxidative resistance are achieved by carrying out the synthesis reaction at 700 A degrees C in 1:1:0 i-C4H10-H-2-He atmosphere over 29 wt% Fe catalysts reduced at 700 A degrees C. An additional relevant finding is the strong correlation evidenced between results of thermogravimetry and Raman analyses, suggesting the use of Raman spectroscopy for non-destructively evaluating the thermal stability of any graphitically ordered carbon species.

Calibration of reaction parameters for the improvement of thermal stability and crystalline quality of MWCNTs

PISTONE, Alessandro;MILONE, Candida
2010

Abstract

The results of Raman analysis on multi-walled carbon nanotubes, prepared by catalysed chemical vapour deposition, are used as a guide for the calibration of the growth parameters, directed to improve crystalline quality and resulting thermal stability of nanotubes. Under selective growth conditions, the resistance to oxidation in air, as assessed by thermogravimetry measurements, is found to increase with the establishment of the long-range graphitic order in radial tube direction, as signalled by the Raman G'/G intensity ratio enhancement. In the range of parameters explored (synthesis temperature: 500-700 A degrees C; growth atmosphere: 120 cc/min i-C4H10-H-2-He mixture with He at 0-25%; i-C4H10/H-2 flow ratio: 1-3; metal load and reduction temperature of Fe/Al2O3 catalysts: 17-40 wt%, and 500 and 700 A degrees C, respectively), the best crystalline quality and the highest oxidative resistance are achieved by carrying out the synthesis reaction at 700 A degrees C in 1:1:0 i-C4H10-H-2-He atmosphere over 29 wt% Fe catalysts reduced at 700 A degrees C. An additional relevant finding is the strong correlation evidenced between results of thermogravimetry and Raman analyses, suggesting the use of Raman spectroscopy for non-destructively evaluating the thermal stability of any graphitically ordered carbon species.
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

Caricamento pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11570/1901120
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 15
  • ???jsp.display-item.citation.isi??? 11
social impact