Influence of the Fe-based catalyst incorporation method on the carbon nanotube structure of hybrid composites synthesized by CCVD method using methane and without hydrogen reduction step

Abstract

Nanostructured silica (n-SiO2) synthesized by sol-gel method was used in this work as a support for multi-walled carbon nanotubes (MWCNTs) synthesis by catalytic chemical vapor deposition (CCVD) process. The syntheses were performed using methane as carbon feedstock and without previous catalyst reduction with hydrogen. Three different methods to incorporate the iron-based catalyst on the silica support have been studied to identify its influence on the structural characteristics of the synthesized MWCNTs. Such study aims to develop the production of an advanced hybrid composite with better structural properties to be applied as a strengthener additive in different material matrices. The synthesized hybrid composites were characterized to analyze the MWCNTs quality in terms of morphology, graphitization degree, and thermal stability. Regarding the silica support containing the catalyst, Infrared (FTIR) and X-ray (XRD) analyses showed that no significant differences in terms of chemical composition and crystalline phases have been observed between the analyzed samples regardless of the catalyst incorporation method used. Concerning the hybrid composite, Raman spectroscopy, electron microscopies, and thermal analyses suggested modifications in terms of graphitization degree, morphology, and thermal stability of the MWCNTs. Indeed, the catalyst incorporation method would influence the catalyst/support interaction promoting the deposition of different carbon structures, and the quality of the MWCNTs grown in the hybrid material.