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چکیده
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CdS nanocrystals were thermochemically (thermally activated) synthesized thorough the reaction between CdSO4 and Na2S2O3 in an aqueous solution. Thioglycolic Acid (TGA) was used as the capping agent and catalyst of the reaction. The method was based on heat activated dissociation of Na2S2O3 and controllable release of S and free electrons in the solution. CdS NCs were formed by heating the sample solution at 96 °C for 1 h. The results of optical spectroscopy and transmission electron microscopy demonstrated round shape NCs with sizes about 3.0 nm. The nanocrystals were also luminescent and represented a broad emission with a peak located at 515 nm and FWHM of 160 nm. Several samples were prepared and introduced to different solvents i.e ethanol plus water, methanol plus water, acetone plus water and pure water to investigate the nanocrystals dispersion. The results demonstrated that the NCs could not be well re-dispersed in 10 mL ethanol, methanol or acetone plus extra water. Nevertheless they revealed a super hydrophilic property and perfectly re-dispersed in small volume of pure water without any need to ultrasonication. They are also quite stable in water for long times without any agglomerations. Finally we deliver a model based on zeta potential measurements to justify the observation and address the super hydrophilic property of the thermochemically prepared CdS NCs.
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