The silver ultrafine particles with diameters less than 10 nm were prepared by the sodium borohydride reduction of aqueous silver nitrate within AOT reverse micelles at 25°C. By the analyses of high-resolution electron microscope, electron diffraction pattern and XRD, the resulting particles have been found to be pure fcc silver. The results indicated that the sizes of silver ultrafine particles increased with the increase of the molar ratio of water to AOT (ω(0)) and with the increase of silver nitrate and sodium borohydride concentrations due to the increases in the number of nuclei formed. However, when sodium borohydride was largely in excess, the aqueous solution became basic after mixing and silver oxide was formed. The increase of AOT concentration only resulted in the increase of the number of silver ultrafine particles formed but had no significant influence on their particle size. Using an alkane with higher carbon-number as the solvent, it was found that the silver ultrafine particles formed were larger because of the higher intermicellar potential and exchange rate of reverse micelles. Furthermore, blue-shift phenomenon was observed from the investigation on the UV-VIS absorption spectra of the reverse micellar solutions containing silver ultrafine particles. At 400 nm, a linear relationship between the particle size and the molar absorbance could be correlated.
|Number of pages||8|
|Journal||Journal of the Chinese Institute of Chemical Engineers|
|Publication status||Published - 2000 May 1|
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)