CVD Growth of Carbon Nanotube Forest with Selective Wall-Number from Fe-Cu Catalyst

We reported herein the chemical vapor deposition (CVD) growth of vertically aligned carbon nanotubes (CNTs) with selective wall-number using binary Fe-Cu catalysts. High quality single-walled carbon nanotube (SWNT) and double-walled carbon nanotube (DWNT) forests were predominantly produced with selectivity of similar to 92% and similar to 85%, respectively. Formation of small catalyst nanoparticles with high areal density and fully reduced state was found key for efficient SWNT growth. Characterization of the catalysts by atomic force microanalysis (AFM) and high resolution transmission electron microscope (HRTEM) showed that the introduction of the proper amount of Cu into the Fe/Al2O3 catalyzing system inhibited diffusion of Fe NPs and facilitated the full reduction of Fe catalyst, thus facilitating the selective growth of SWNTs. DWNTs were also obtained by introducing a thick layer of Cu catalyst onto Fe/Al2O3. Our work provides a rational way for selective growth of vertically aligned SWNTs and DWNTs, whose remarkable electronic and mechanical properties enable their promising application in nanoelectronics devices.