Effect of catalyst support layers on emissivity of carbon nanotubes grown via floating catalyst chemical vapor deposition

Abstract

We propose an efficient method of growing carbon nanotube (CNT) arrays on a variety of metals using chemical vapor deposition (CVD) assisted by a simple surface treatment of the substrate materials. The main feature of this method is the application of shot blasting with fine alumina shot to create the catalyst support layer that is required for the effective growth of CNTs on the various conductive materials, including the ultrahard metal tungsten. Energy dispersive X-ray spectroscopy shows that the shot blasting forms a noncontinuous layer where alumina nanoparticles are embedded as residue from the blasting media on the treated surfaces. Such a noncontinuous alumina layer can behave as the catalyst support layer, which is normally prepared via sputtering or a vacuum evaporation coating process. The influence of shot size on the characteristics of the nonuniform alumina buffer layer as well as the resultant multiwalled CNT arrays grown via CVD in conjunction with a floating iron catalyst are investigated. The results show that the morphology, crystallinity, and spectral emissivity of CNTs depend on the size of alumina shot used in the shot blasting treatment. The characteristics of the CNTs grown on various metal substrates with a discontinuous and continuous alumina buffer layers are compared with each other. These comparisons indicate that the degrees of hardness and the redox property of the substrates moderately affect the characteristics of CNTs on the discontinuous layer in contrast to the continuous layer.