A generic process of growing aligned carbon nanotube arrays on metals and metalalloys

Abstract

Aligned carbon nanotube (CNT) arrays are integral towards the development of severalapplications such as field emission, interconnects in silicon technology, and chemicaland biological sensing. Even though the synthesis of CNTs has been describedextensively in the literature, there has not been significant success in growing uniform,well-aligned CNT arrays on pure metal surfaces other than metals that catalyseCNT growth themselves. In this paper, we describe a method of growing alignedCNT arrays on a variety of pure metals, metal alloys, and conductive ceramicsusing a bimetallic iron/alumina composite catalyst at low temperatures (550 to700 °C). We believe that the addition of alumina to the iron catalyst significantly reducescatalyst–metal underlayer interactions that have traditionally proven to be a barrier for thegrowth of CNTs on metals. The alumina also minimizes surface diffusion of iron and allowsthe formation of a high density of uniformly dispersed catalyst nanoparticles to act asnucleation sites for well-aligned CNT arrays. Despite the presence of non-conductingalumina from the catalyst, the contact resistance between the CNTs and the metalunderlayer was observed to be quite low, emphasizing the usefulness of this approach topractical applications. Our process was successful in growing aligned CNTs even oncommercial steel plates and may be applicable for substrates of any shape orsize.