Alkoxide structure effect on size and size distribution of Ag, Au and Ag@Au nanoparticles, prepared via alkoxide mild reduction in water

Abstract

Gold and silver nanoparticles were synthesized via mild alkoxide reduction of Ag+ and AuCl4- in water, under alkaline conditions. Three non-toxic polyols (glycerin, β-cyclodextrin (βCD), and a polymer (of β-cyclodextrin)) were employed in each case as reducing and capping agent. TEM analysis revealed larger nanoparticles when glycerin was used, followed by β-cyclodextrin, and finally by the polymer. Different numbers of population maxima in nanoparticles size distribution from one alkoxide to another were observed and such variation was dependent on alkoxide’s structure complexity. In UV–Vis spectra the typical bands for gold and silver nanoparticles were detected. ζ-potential measurements showed more electrostatically stable capping layer for glycerin and βCD. For the polymer, the stability of the layer should be a result of bulk effects.On the other hand, Ag-Au bi-metallic nanoparticles with core–shell structure were obtained using glycerin and β-cyclodextrin, whereas a mixture of gold and silver nanoparticles was the result with the polymer. The latter was corroborated via TEM images, EDX, UV–Vis, ζ-potential, and DLS measurements. A systematic study was carried out to elucidate the influence of the different alkoxide molecules on the properties of the resulting nanoparticles.