Controllable synthesis of water-soluble luminescent CdxZn1−xS nanocrystals

Multicolored luminescent CdxZn1−xS nanocrystals in aqueous solution have been controllably synthesized with thioglycollic acid (TGA) as a surface modifier. The CdxZn1−xS nanocrystals were characterized by X-ray diffraction (XRD) patterns, transmission electron microscope (TEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FT-IR) spectrum, ultraviolet–visible (UV–vis) spectra, and photoluminescence (PL) spectra. From a combination of TEM data and computing methods according to UV–vis spectra and XRD patterns, the particle size of CdS nanocrystal was found to be about 4 nm. Homogeneous CdxZn1−xS nanocrystals have the same well-crystallized cubic lattice structure. FT-IR spectrum indicates that the carboxyl group of TGA is coated on the surface of nanocrystals successfully. The composition dependent UV–vis and PL spectra reveal that the series CdxZn1−xS nanocrystals exhibit good optical properties, which can be modulated by changing the cation molar ratio of Zn:Cd in the reactants. The green and yellow luminescence of CdxZn1−xS nanocrystals is brightly eye-viewable under UV irradiation.