Hydrogel templated CdS quantum dots synthesis and their characterization

This work reports a facile method for preparation of CdS quantum dots (Q-dots), using a crosslinked hydrophilic p(AMPS) hydrogel network by absorption of Cd(II) ions and sequential precipitation with aqueous Na2S within the network at room temperature. The TEM images revealed that prepared CdS Q-dots were distributed throughout the p(AMPS) hydrogel network and their sizes were about 5 nm. The amount of inorganic material inside p(AMPS) hydrogel was determined by TGA measurements to be 16.9% by weight. Additionally, the Cd and S amounts inside the p(AMPS) network were determined by dissolution of particles with HCl (three treatments with 3 M HCl) and by using ICP-AES (for Cd) and an elemental analyzer (for S). From UV-visible absorbance measurements, optical energy gap values of 5.1 +/- 0.1 eV for p(AMPS) and 2.4 +/- 0.05 eV for p(AMPS)-CdS were determined. From the fluorescence spectrum of the p(AMPS)-CdS hydrogel, the peak energy was observed at 2.30 eV. The in situ prepared Q-dots were recovered from hydrogel matrices by placing the p(AMPS)-CdS composite in purified water. (C) 2011 Elsevier B.V. All rights reserved.