Synthesis and Spectroscopic Analysis of Au-Ag Alloy Nanoparticles with Different Composition of Au and Ag

Au-Ag bimetallic alloy nanoparticles, having an average size from 35 to 25 nm, were successfully synthesized (using chemical reduction process) from AuCl3 and AgNO3. Ethylene glycol was used as a solvent and polyaniline (PANI) as a capping agent. Au-Ag alloy nanoparticles, with different proportions among Au and Ag, were synthesized and characterized by various spectroscopic techniques. The steady-state fluorescence spectroscopy, X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM) data revealed the formation of alloy nanoparticles of various compositions, which agrees with the absorption data obtained by UV-Visible spectroscopy. Ag was found to be acting as a quencher for emission radiations, as evidenced by fluorescence spectroscopy. XRD data pointed out the crystalline structure of alloy nanoparticles. Variation in Au and Ag's atomic composition in Au-Ag was confirmed by energy dispersive spectroscopy (EDS). Scanning Electron Microscopy (SEM) was applied to study the morphology of the bimetallic alloy nanoparticles. Interestingly, the size of nanoparticles decreases with a decrease in Au's composition in Au-Ag alloy nanoparticles. Maximum values of molar absorptivity were recorded by Au-Ag alloy nanoparticles with ratio 1:3, which indicates that at ratio 1:3 of Au and Ag in Au-Ag alloy nanoparticles, the size of the nanoparticles is minimum with maximum surface area.