Facile synthesis of monodisperse CdS nanospheres capped with allyl thiourea

Highly monodisperse CdS nanospheres capped with allyl thiourea were synthesised via a facile hydrothermal method without any surfactant. The products were characterised by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, photoluminescence and Fourier transform infrared spectra. The results show that CdS nanospheres have the diameters of about 300 nm and are composed of nanoplates. The reaction parameters, such as the concentration of the reagent, the ratio of sulphide to cadmium source and the cadmium salt type that affected the CdS morphology, were investigated systematically. Based on the experiments, the possible formation mechanism for the nanospheres is ascribed to anisotropic growth of the nanoparticles and self-assembly caused by the lowest surface tension. The photoluminescence spectrum of the nanospheres shows about 60 nm blue shift compared with that of bulk CdS.