Surface Modification Of CdS Ultrafine Particles And Their Photoelectric Properties

Cadmium sulfide is the tipical transition metal compound of the II-VI Group Elements.As fluorescent semiconductor materials, CdS ultrafine particle has unique photoelectric properties, which can be used as bioluminescence markers materials.In this paper, a new synthesis method of preparing functional CdS ultrafine particles in aqueous phase was proposed respectively using cadmium nitrate and thioacetamide as the source of Cd and S and using thioglycolic acide as surface-modifying agent. The effects of molar ratio of cadmium nitrate and thioglycolic acide, molar ratio of cadmium nitrate and thioacetamide, initial pH value of solution, temperature, reaction time, reactant concentration and additives on structure and morphologies and photoelectric properties of products were experimentally investigated. The structure, morphology, particle size and its distribution, surface groups and spectral properties of the products were characterized by XRD, SEM, FT-IR, Uv-Vis and PL analysis, individually.The results indicate that adding thioglycolic acide can slower reaction rate of Cd²⁺ and S^2-, inhibit agglomeration of CdS particles, decrease their grain sizes, improve their surface structures and fluorescence properties, and make them exhibit good solubility in water. The CdS particles prepared in optimum conditions have smaller particle sizes and more narrow size distribution, higher fluorescence intensity from bandgap emission, abrupt absorption edge, obvious surface group characteristic peaks, and their solution has been stable for six months.The preparation method for CdS has such advantages as simple operation, integration between preparation and surface modification, and the functional CdS ultrafine particles exhibit stable structure,, controllable particle size, good water-soluble and stability.