Observation of hybrid carbon nanostructures as intermediates in the transformation from hydrocarbon nanotubes and nano-onions to carbon nanotubes and nano-onions via sonolysis on silicon nanowires and nanodots, respectively

It was found that hydrocarbon nanotubes (HCNTs) and nano-onions (HCNOs) (hereafter collectively referred to as HCNT(O)s) can be converted to carbon nanotubes (CNTs) and nanoonions (CNOs) (hereafter collectively referred to as CNT(O)s) upon prolonged sonication via hybrid CNT⊂HCNT and CNO⊂HCNO nanostructures as intermediates, respectively. These intermediate hybrid carbon nanostructures may thus be considered as snapshots in the transformation process. The morphologies and the characteristic properties of these carbon nanostructures are reported. The formation of HCNT(O)s, and their subsequent transformation from HCNT(O)s to the hybrid CNT(O)⊂HCNT(O) nanostructures, and ultimately to the conventional CNT(O)s, have been elucidated by recording the HRTEM images of the products as a function of sonication time and in different solvents. On the basis of these experimental results, detailed formation mechanism and transformation pathways of these carbon nanomaterials, as well as their interrelationships, are proposed. Structural models of the HCNTs and HCNOs are also proposed. Other peculiar phenomena and transformation processes of these nanomaterials are also described.©2010 American Chemical Society.