Catalytic CVD Growth of Millimeter-Tall, Single-Wall Carbon Nanotube Carpets Using Industrial Gaseous Waste As a Feedstock

We have utilized a gaseous product mixture from Fischer-Tropsch synthesis (FTS-GP) as an efficient feedstock for growth of high-quality, well-aligned, single-wall carbon nanotube (SWCNT) carpets of millimeter-scale heights on Fe and (sub) millimeter-scale heights on Co catalysts via chemical vapor deposition (CVD). Growth conducted at optimal temperatures for Co (850°C) and Fe (750°C) yielded predominantly SWCNTs that are straight and clean, with sidewalls largely free of amorphous carbon. Growth on Fe is characterized by a relatively high growth rate (~50 μm/min) and long catalyst lifetime (> 90 min), with the catalyst showing no decay of activity, while growth on a Co catalyst shows a lifetime of ~60 min, with a slower growth rate of ~7μm/min. Resulting area densities of SWCNT carpets grown on Fe and Co catalysts, determined by the weight-gain method, were 1.0 × 10¹² and 6.0 × 10¹² cm^-2, respectively — among the highest achieved for SWCNT carpets on standard catalysts. Unlike SWCNT carpet growth involving conventional feedstocks, growth rate and density of SWCNTs on Fe are less sensitive to the FTS-GP fraction and thus allow for relatively easy optimization and scale-up.