The effect of alcohols and solvents on the synthesis of CdS nanoparticles in reverse micellar media

Abstract

Colloidal nanoparticles of the photo-semiconductor CdS have been prepared in reverse micelles of water/sodium bis(2-ethylhexyl) sulfosuccinate (known as AOT)/n-heptane. Particle sizes were calculated from the UV-visible absorbance threshold. The effect of alcohol additives on Cds nanoparticle size and stability was investigated. Short chain alcohols (methanol, ethanol and propanol) enhanced the CdS growth rate and size; even aggregates were observed at high concentration. Addition of alcohol and water to already equilibrated CdS nanoparticles resulted in detectable increase in the size of the nanoparticles leading to flocculation in the presence of enough additive. This is due to a decrease in the rigidity of the microemulsion interface by the alcohol additives which in turn enhances the exchange processes between reverse miscelles. On the other hand, small amounts of benzyl alcohol and long chain alcohol additives such as octan-1 -ol and dodecan-1 -ol result in smaller CdS nanoparticles than in their absence. However, these alcohols too were found to increase the size of the particles slightly at higher concentrations.