Characterization of water/AOT/benzene microemulsions during photoreduction to produce silver particles

Colloidal dispersions of silver (Ag) particles were prepared by the photoreduction of silver perchlorate (AgClO4) in water/AOT/benzene water-in-oil (w/o) microemulsions consisting of sodium bis(2-ethylhexyl) sulfosuccinate (AOT), water and benzene. Formation mechanisms of Ag particles prepared in the presence of benzoin by photoreduction from Ag+-containing w/o microemulsions were investigated by UV–vis, transmission electron microscopy (TEM), extended X-ray absorption fine structure (EXAFS) and small-angle X-ray scattering (SAXS) measurements. By a combination of TEM and EXAFS results, Ag particles show a metallic nature after the photoreduction and the diameter of Ag particles ranges between 5 and 30 nm. In situ time-resolved SAXS measurements show that the integrated rate equation can be applied in the reduction process of Ag+ ions to Ag0 atoms, and the autocatalytic Ag particle growth proceeds in the association process of Ag0 atoms during the photoreduction of Ag+-containing w/o microemulsions. The nanometer-sized water droplets microemulsified by AOT in benzene continuous-phase regulated the size of Ag particles, and the size and shape of water droplets were retained during the Ag particle formation.

Time evolution of the SAXS profiles and the representative TEM image for the Ag colloidal dispersions prepared by the photoreduction in the water/AOT/benzene water-in-oil (w/o) microemulsions.Figure optionsDownload high-quality image (120 K)Download as PowerPoint slide