Covalent synthesis and optical characterization of double-walled carbon nanotube-nanocrystal heterostructures

The unique electronic structure and optical properties of double-walled carbon nanotubes (DWNTs) have made them a key focus material of research in recent years. However, the incorporation of DWNTs with quantum dots (QDs) into nanocomposites via a covalent chemical approach as well as the optical properties of the composites have rarely been explored. In particular, we have been interested in this model system to investigate whether nanomaterial heterostructures can provide efficient pathways for charge separation relative to loss mechanisms such as recombination. In this specific work, the synthesis of DWNT-CdSe QD heterostructures obtained by using a conventional covalent protocol has been demonstrated. CdSe QDs with terminal amino groups have been conjugated onto the surfaces of oxidized DWNTs by the formation of amide bonds. The observed trap emission of CdSe is thought to arise from the presence of 2-aminoethanethiol capping ligands and is effectively quenched upon conjugation with the DWNT surface because of the charge transfer from CdSe to DWNTs.