Fabrication and characterization of ZnxCd1−xS nanoparticles in chitosan alginate nanocomposite films

ZnxCd1−xS nanoparticles were formed in chitosan alginate nanocomposite films using spin-coating technique. Crystal structure and size, optical properties and surface morphology were characterized by X-ray diffraction (XRD), ultraviolet–visible (UV–vis), photoluminescence (PL) spectra, transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The ZnxCd1−xS nanoparticles have a cubic structure with an average crystal size of ~2 nm. With increasing Zn/Cd molar ratio, the UV–vis absorption peaks shift to low-wavelength side with a slight intensity decrease. The relative emission intensity of the film may be changed regularly by variation of the ZnxCd1−xS nanoparticles composition. Surface morphology of the films containing ZnxCd1−xS nanoparticles changes with various Zn/Cd molar ratios. The film morphology goes from rough to smooth with increasing Zn/Cd, and the phase goes from bump-like shape to particle-like shape with a more uniform distribution due to the radius difference between Zn and Cd ions.