The growth of CdSe quantum dots on a single wall carbon nanotubes template without organic solvent and surfactant

A conventional synthesis of Cadmium selenide (CdSe) quantum dots (QDs) usually employs toxic organic solvents, and the synthesized CdSe QDs must be modified for dispersion in an aqueous solution. This modification often limits the application of CdSe QDs in biomedical fields. In this study, a simple method was developed to synthesize CdSe QDs on single wall carbon nanotubes (SWCNTs) employing the SWCNTs as a template to prevent the aggregation of the CdSe QDs in an aqueous solution without the addition of any organic reagent. Our newly developed synthetic procedure included the formation of SWCNTs with carboxyl groups (SWCNT–COOHs) followed by mixing these with the precursors of Cd and Se to obtain SWCNT–CdSe QDs. The resulting SWCNT–CdSe QDs were analyzed using spectrophotometry, transmission electron microscopy (TEM) and X-ray diffraction (XRD). Results showed that CdSe nanocrystals with a zinc blend structure could be synthesized on the SWCNT–COOHs. The average crystal size of the synthesized CdSe QDs was approximately 3 nm. The blue-shift of CdSe QDs powerfully emitted light at 550 nm as compared to the bulk CdSe at 730 nm. These CdSe QDs were synthesized in an aqueous environment without using toxic surfactants and are expected to have great potential as bio-labeling contrast agents in the future.