Continuous deposition of carbon nanotubes on a moving substrate by open-air laser-induced chemical vapor deposition

Continuous deposition of carbon nanotubes under open-air conditions on a moving fused quartz substrate is achieved by pyrolytic laser-induced chemical vapor deposition. A CO₂ laser is used to heat a traversing fused quartz rod covered with bimetallic nanoparticles. Pyrolysis of hydrocarbon precursor gas occurs and subsequently gives rise to rapid growth of a multi-wall carbon nanotube forest on the substrate surface. A “mushroom-like” nanotube pillar is observed, where a random orientation of carbon nanotubes is located at the top of the pillars while the growth is more aligned near the base. The typical carbon nanotube deposition rate achieved in this study is approximately 50 μm/s. At high power laser irradiation, various carbon microstructures are formed as a result of excessive formation of amorphous carbon on the substrate. High-resolution transmission and scanning electron microscopy, and X-ray energy-dispersive spectrometry are used to investigate the deposition rate, microstructure, and chemical composition of the deposited carbon nanotubes.