The Effect of Cadmium Ion Adsorption on the Growth of CdS Nanoparticles at Colloidal Silica Particle Interfaces in Binary Liquids

Influence of an adsorption layer and its evolvement on the formation of Ag

The formation mechanism of Ag in an adsorption layer and the influence of temperature on the generation of Ag particles were studied. Two reaction systems were designed to explore the different reduction mechanisms of Ag+ in an adsorption layer and in bulk. A UV-vis adsorption spectrometer was employed to monitor the reaction process of Ag+ in two reaction systems. The results indicated that the formation mechanism of silver in an adsorption layer was largely different from that in alcohol bulk, which led to various morphologies of Ag particles in the two systems. Temperature experiments suggested that the induction time and morphology of Ag particles both changed greatly when temperature increased to 40 degrees C. The disappearance of physical-adsorption and the reaction occurring in alcohol bulk was the primary cause.

Cadmium Ion Adsorption Controls the Growth of CdS Nanoparticles on Layered Montmorillonite and Calumit Surfaces

Adsorption isotherms have been determined for the intercalation of cadmium ions (Cd2+) into layered hydrophobized montmorillonite (HDP-M) and calumit (DBS-C) sheets dispersed in ethanol (1)-cyclohexane (2) mixtures. The amount of Cd2+ adsorbed depended strongly on the composition of the binary liquid; at an ethanol mole fraction of 0.05 (x1 = 0.05), 95% of the added Cd2+ is located in the ethanolic nanoreactor at the HDP-M (or DBS-C) surface. CdS nanoparticles have been generated in situ in ethanolic nanoreactors at the HDP-M and DBS-C surfaces. Absorption spectrophotometric measurements provided information on the number of CdS nanoparticles formed and on their absorption edges, bandgaps, and mean diameters. Good correlations have been obtained between the adsorption isotherms and the size (and the amount) of the CdS formed. X-ray diffractometry established that CdS nanoparticles stretched the HDP-M and DBS-C lamellas unevenly upon intercalation. Copyright 1999 Academic Press.