Diameter and morphology dependence on experimental conditions of carbon nanotube arrays grown by spray pyrolysis

A systematic study on the controlled growth of large areas of aligned multi-wall carbon nanotube arrays, from ferrocene-benzene precursor, and of nanotube junctions from ferrocene-thiophene precursor, without hydrogen addition, using an injection CVD method easy to scale up for industrial production is reported. A detailed study is presented of how the synthesis parameters such as growth temperature, active solution flow rate, catalyst concentration or sulfur addition can control the properties and morphology of the grown nanotube mat. Nanotube junctions with considerable yield can be grown with our method by adding sulfur to the synthesis process. The sulfur addition also results in growth of carbon nanocones (CNC) in the lower temperature regime of the furnace. Observation of single-wall carbon nanotubes in our STM investigations provides further indication that under properly chosen conditions SWCNTs can be grown with similar continuous processes. (c) 2004 Elsevier Ltd. All rights reserved.