Influence of catalyst particles on multi-walled carbon nanotubes morphology and structure

ABSTRACT

Multi-walled carbon nanotubes (MWCNTs) have been successfully grown by Chemical Vapor Deposition (CVD) method. Elucidating the key characteristics of catalyst sources that affect carbon nanotubes growth is of great importance for improving and control MWCNTs morphology and structure. In this work we present a systematically study of CVD parameters, such as catalyst source, substrate morphology and temperature and how it affects carbon nanotubes synthesis. The novelty of this work lies on the catalyst composition. Two specific catalyst sources were analyzed: (i) Fe₂Co and (ii) Fe₂Co with ferrocene. Cyclic Voltammetry results confirmed the presence of Fe²⁺ in the Fe₂Co with ferrocene solution. X-Ray Diffraction analysis confirmed the presence of iron particles on the substrate surface after its submission to growth conditions. Raman results suggested an improvement in carbon nanotubes crystalline quality catalyzed by Fe₂Co with ferrocene. For tridimensional substrates such as fibers, the Fe₂Co with ferrocene provided aligned CNTs with lower defects density noticed in Raman spectra and SEM micrographs. Finally, we corroborated the Fe²⁺ encapsulation relation with the growth mechanism and MWCNTs formation.

KEYWORDS:

• Carbon nanotubes
• Catalyst
• Chemical Vapor Deposition
• Ferrocenium

Acknowledgments

The authors would like to thank Anderson de Oliveira Lobo (FAPESP Process n° 2011/17877-7) and Claúdia do Amaral Razzino for Cyclic Voltammetry analysis. FAPESP supported this work (Processes n° 2015/02960-7 and n° 2012/15857-1).

Additional information

Funding

This work was supported by the Funda¸ão de Amparo à Pesquisa do Estado de São Paulo (2012/15857-1,2015/02960-7).