Tailored cutting of carbon nanotubes and controlled dispersion of metal nanoparticles inside their channels

A novel method has been developed for homogeneous dispersion of metal nanoparticles inside short carbon nanotubes (CNTs) with an inner diameter smaller than 10 nm. The process involves controlled cutting of pristine long nanotubes via oxidation catalyzed by Ag or Fe and introduction of metal nanoparticles inside the CNT channels using a wet chemistry method aided by ultrasonic treatment and extended stirring. The resulting metal particles are very uniform with sizes in the range of 2-4 nm. In addition, selective dispersion of such nanoparticles on the exterior surfaces of open CNTs has been achieved by temporary blocking of the channels with an organic solvent while decorating the CNT exterior surfaces with aqueous solution of the metal salt. The trick is the choice of this organic solvent, which is immiscible with, and has a higher boiling point than, water.