Synthesis, characterization, and manipulation of nitrogen-doped carbon nanotube cups.

Isolated, carbon nanotube cups with diameters of 12-40 nm have been synthesized by chemical vapor deposition through incorporation of nitrogen atoms into graphitic carbon structure and subsequent mechanical separation. Incorporation of nitrogen affords carbon nanotube cups with a unique composition comprising multiwalled, graphitic lattice with nitrogen groups on the exterior rim and hollow interior cavities. These nanostructures demonstrate the ability to participate in hydrogen bonding because of nitrogen functionalities on their open edges. Furthermore, reaction with these nitrogen functionalities results in the coupling of gold nanoparticles (GNPs) to the open rim of carbon nanotube cups. Through atomic force microscopy manipulation and adhesion force measurements, we compare the mobility of these structures on a hydrophilic surface before and after GNP coupling. Understanding of these forces will aid in useful nanostructure assembly for energy and biomedical applications.