Assembling Carbon Nanotube Architectures

Well-defined multiwalled carbon nanotube structures are generated on stainless steel AISI 304 (EN AW 1.4301) by chemical vapor deposition. Pulsed laser-induced dewetting (PLiD) of the surface, by 532 nm nanosecond laser pulses, is utilized for the preparation of metal oxide nanoparticle fields with a defined particle number per area. The reduction of the precursor particles is achieved in an Ar/H₂ (10% H₂) atmosphere at 750 °C, thereby generating catalytic nanoparticles (c-NPs) for carbon nanotube (CNT) growth. Ethylene is used as a precursor gas for CNT growth. CNT lengths and morphology are directly related to the c-NP aerial density, which is dependent on the number of dewetting cycles during the PLiD process. Within a narrow window of c-NP per area, vertically aligned carbon nanotubes of great lengths are obtained. For more intense laser treatments, three-dimensional dewetting occurs and results in the formation of cauliflower-like structures. The laser process enables the creation of all kinds of CNT morphologies nearby on the microscale.