Low-Temperature Growth of Carbon Nanotubes on Bi- and Tri-metallic Catalyst Templates

摘要

Low temperature growth process of carbon nanotubes (CNTs) over bi-metallic (Co-Fe) and tri-metallic (Ni-Co-Fe) catalysts on Si/Al/Al2O3 substrates is carried out from acetylene precursor using hydrogen, ammonia or nitrogen as a carrier in a low pressure chemical vapor deposition system. Using the tri-metallic Ni-Co-Fe catalyst template, vertically aligned CNTs of ~700 run length could be grown already at 450 °C within 10 min using ammonia as a carrier. Within the same period of time, on bi-metallic Co-Fe catalyst templates, ~250 nm long aligned nanotubes emerged already at 400 °C in nitrogen carrier. At low temperatures most of the catalyst materials were elevated from the support by the grown nanotubes indicating tip growth mechanism. The structure of catalyst layers and nanotube films was studied using scanning and transmission electron microscopy and atomic force microscopy.