The Effect of Cadmium Ion Adsorption on the Growth of CdS Nanoparticles at Colloidal Silica Particle Interfaces in Binary Liquids
✍ Scribed by Imre Dékány; László Turi; Gábor Galbács; Janos H. Fendler
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 390 KB
- Volume
- 195
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
sors (Cd 2/ for CdS or Zn 2/ for ZnS) into the nanoreactors Adsorption isotherms have been determined for the binding of and on the extent of Cd 2/ (or Zn 2/ ) adsorption at the silica Cd 2/ onto the surfaces of hydrophilic A200 SiO 2 and hydrophobic particle interfaces. We have determined, therefore, the ad-R972 SiO 2 particles dispersed in ethanol (1) -cyclohexane (2) mixsorption of Cd 2/ onto hydrophilic A200 and hydrophobic tures at ethanol mole fractions of x 1 Å 0.05, 0.10, 0.20, and 0.40. R972 SiO 2 particles in ethanol-cyclohexane binary liquids.
CdS nanoparticles have been generated in situ within the ethanolic
The obtained adsorption isotherms permitted the calculation nanoreactors at surfaces of SiO 2 particles in the different ethanolof the density of cadmium ions on the SiO 2 surface in the cyclohexane binary liquids by the addition of hydrogen sulfide. different binary liquids. Optical absorption edges (and hence Absorption spectra of the CdS particles provided information on band gaps) of the CdS nanoparticles, generated in situ by their quantity, absorption edges, optical band gaps, and mean diameters. Good correlations have been obtained between the ad-H 2 S injection, have also been determined by absorption specsorption isotherms and size of the CdS particles as well as between trophotometry (6-9). Sizes of the incipient CdS nanoparthe adsorption isotherms and the amount of CdS formed. The ticles were found to be profoundly dependent on the adsorpsmallest CdS particles (ca. 6 nm diameter) have been obtained on tion isotherms of the Cd 2/ ions. the surfaces of SiO 2 particles dispersed in ethanol (1) -cyclohexane (2) mixtures at ethanol mole fractions of x 1 Å 0.05. More CdS EXPERIMENTAL particles have been observed to coat the hydrophilic A200 SiO 2 than the hydrophobic R972 particles. In the x 1 Å 0.10 ethanol (1) -cyclohexane (2) liquid mixtures up to 10% of the SiO 2 surface 1. Materials can be covered by CdS nanoparticles. Immersion wetting enthalpy Two colloidal silica (SiO 2 ) particles, hydrophilic A200 measurements in methanol established the surface of the SiO 2 and hydrophobic R972, were obtained from Degussa AG particles to be hydrophilic, which became partially hydrophobic (Germany). The specific surface areas of the A200 and R972 upon and the binding of cadmium ions and hence upon the subsequent formation of CdS.