Scanning tunnelling microscope studies of angstrom-scale Co3O4 nanowires

We report the bottom-up assembly of an atomic-scale building block, which consists of four Co(3+) cations, two Co(2+) cations, and eight O(2-) anions, for generating one-dimensional Co(3)O(4) nanostructures with diameters ranging from 0.5 to 3 nm. Controlled experiments were carried out and the growth mechanism of the Co(3)O(4) nanowires was investigated. The effects of a single cation defect on the epitaxial growth of the one-dimensional nanostructures were investigated. We proposed a self-rectifying growth mechanism on the basis of direct experimental observations. This mechanism will help us to understand synthesized crystals usually exhibiting homogeneous composition and uniform morphology, though the existence of defects is inevitable in the growth process.