The effect of Fe and Ni catalysts on the growth of multiwalled carbon nanotubes using chemical vapor deposition

TL;DR

This study compares how Fe and Ni catalysts influence the growth, structure, and properties of multiwalled carbon nanotubes synthesized via atmospheric pressure chemical vapor deposition, revealing distinct morphologies and degrees of graphitization.

Contribution

It provides new insights into the effects of Fe and Ni catalysts on CNT morphology, structure, and growth mechanisms during APCVD synthesis.

Findings

Ni catalyst produces bamboo-like CNTs with radial breathing modes.

Fe catalyst results in iron-filled straight CNTs with higher graphitization.

Both catalysts yield graphitic CNTs without carbide phases.

Abstract

The effect of Fe and Ni catalysts on the synthesis of carbon nanotubes (CNTs) using atmospheric pressure chemical vapor deposition (APCVD) was investigated. Field emission scanning electron microscopy (FESEM) analysis suggests that the samples grow through a tip growth mechanism. High-resolution transmission electron microscopy (HRTEM) measurements show multiwalled carbon nanotubes (MWCNTs) with bamboo structure for Ni catalyst while iron filled straight tubes were obtained with the Fe catalyst. The X-ray diffraction (XRD) pattern indicates that nanotubes are graphitic in nature and there is no trace of carbide phases in both the cases. Low frequency Raman analysis of the bamboo-like and filled CNTs confirms the presence of radial breathing modes (RBM). The degree of graphitization of CNTs synthesized from Fe catalyst is higher than that from Ni catalyst as demonstrated by the high frequency Raman analysis. Simple models for the growth of bamboo-like and tubular catalyst filled nanotubes are proposed.