Effect of the Support on Structure of the Multi-Walled Carbon Nanotubes Grown By CCVD over Nickel Nanoparticles

Abstract

Abstract. Effect of the support and preparation method of the Ni/CaO and Ni/CaCO 3 impregnated catalysts on the morphology, diameters and growth mechanisms of the MWCNTs grown from ethylene by CCVD synthesis were studied. It was found that the interactions between the support and Ni nanoparticles in both cases are mainly weak and the growth mechanism of the majority of the carbon nanotubes is the "tip-growth". The structure of the nanotubes produced using different catalysts was, however, significantly different. Use of the Ni/CaO catalyst results in the formation of two types of the MWCNTs on the basis of the diameters. At the Ni/CaCO 3 , the formation of the MWCNTs and chain-like carbons fibers was observed. The differences in the morphology and diameters related to the distinct chemical transformation of the support and active phase of the catalyst during the catalyst preparation and reduction, as well as during synthesis of the nanotubes.