Directed/localized growth of multiwalled carbon nanotubes catalyzed by cobalt nanoclusters

Tip based lithography was used to print arbitrary patterns of cobalt oxide nanoclusters from single features to large repeatable arrays over square millimeter areas. Cobalt ions were mixed with a P2VP-PEO block-copolymer and were delivered in sub-micron sized droplets to a surface. These droplets were heat treated at 360 degrees C, which removed the organic polymer and formed Co3O4 nanoclusters. The deposited material was used as a catalyst to grow multiwalled carbon nanotubes (MCNTs) at each printed location. AFM and SEM imaging were used to examine the morphology of the cobalt oxide nanoclusters and multiwalled carbon nanotubes. Powder X-ray diffraction was used to identify the catalytic material, while Raman spectroscopy was used to interrogate the resulting carbon structures. This directed multiwalled carbon nanotube growth method can be applied directly for sensor fabrication.