Preparation and characterization of water-soluble CdS nanocrystals by surface modification of ethylene diamine

Abstract The water-soluble CdS nanoparticles were obtained by hydrogen bond between the cadmium-thiolate complex on the surface of CdS nanoparticles and ethylene diamine (anhydrous). The modified CdS nanoparticles enhanced its solubility in H2O and alcohol. The ethylene diamine-capped CdS nanoparticles were characterized by Fourier Transform Infrared Spectroscopy (FTIR), photoluminescence (PL) and Ultraviolet–Visible absorption spectrum (UV–Vis spectrum). The absorption peak at 262 nm was observed, which belonged to ethylene diamine-modificated Cd-thiolate complex at the surface of as-grown CdS nanoparticles. The results of the PL spectra indicated that the modification of CdS nanoparticles reduced effectively the local surface-trap states. Based on the above results, a possible mechanism for the formation of the water-soluble CdS nanoparticles was discussed.