Ink jet printing of ferritin as method for selective catalyst patterning and growth of multiwalled carbon nanotubes

Ferritin, an iron containing protein was used as catalyst precursor for nanoscopic iron particles from which an iron/iron oxide mixed catalyst can be generated. Multiwall carbon nanotubes can be grown by chemical vapor deposition (CVD) therefrom. When printing the ferritin catalyst precursor via ink jet printing the distribution of the catalyst particles generated from the ferritin precursor on the substrate surface was found to be dependent on the surface wetting of the aqueous ferritin solution. Ink jet printing of the aqueous ferritin solution with a non-ionic sugar based tenside which incorporates the ferritin molecules in a micellar structure allows to form a homogeneous precursor distribution due to a good wetting behaviour on the substrate. Conversion of the ink jet printed solution of the ferritin precursor molecules into the active iron/iron oxide catalyst particles by thermal treatment was followed by a water assisted low pressure CVD growth with ethylene. Multiwall carbon nanotubes in prepatterned areas, e.g. in line or dot shaped morphology on the substrate were obtained.