Selective and controlled self-assembly of zinc oxide hollow spheres on bundles of single-walled carbon nanotube templates

The possibility of selectively assembling three-dimensional structures along bundles of sinule-walled carbon nanOtLibes (SWCNTs) will pave the way to using SWCNTs as nanoconducting templates that can spontaneously integrate into a conductive probe or pathway in a nano device. In the past 2 years, ZnO microcages have attracted interest due to their potential application in the remote coupling of electromagnetic signals into nanoscale machines or devices. We report here, for the first time, highly selective self-assembly of ZnO cages on bundles of conducting SWCNT templates. For the selective Zn nucleation we use electrostatic coordination of carboxyl groups on the SWCNTs to Zn atoms. Bundles of SWCNTs perform a dual function as templates for growth and as scaffolds providing structural integrity to the hollow ZnO spheres (20 nm wall thickness).