Controlled transformation of aqueous CdTe quantum dots → Te-rich CdTe nanorods → second CdTe QDs

Abstract

The transformation of existing inorganic nanomaterials from one structure into another represents a straightforward, versatile and effective approach for the synthesis of nanomaterials. Hence, in this paper, we focus on the controlled transformation of water-soluble CdTe quantum dots (QDs) → Te-rich CdTe nanaorods (NRs) → second CdTe QDs. It was found that in the presence of L-cysteine (L-cys), aqueous thiolglycolic acid (TGA)-stabilized CdTe QDs might spontaneously assemble and recrystallize into luminescent Te-rich CdTe nanorods under ambient conditions. However, increasing the temperature of the nanorod dispersion to 90 °C or adding a specific amount of TGA into the dispersion of NRs might effectively induce the transformation of Te-rich CdTe NRs → second CdTe QDs. These unique transformation processes that involve simultaneous complicated changes in the chemical compositions, structures and morphologies of nanocrystals were systematically characterized by optical techniques, transmission electron microscopy (TEM) and powder X-ray diffractometry (XRD).