Synthesis of silver-gold alloy nanoparticles by a phase-transfer system

We have studied the preparation of silver-gold alloy nanoparticles based on the phase transfer of metal precursors from aqueous phase to organic solution by a fatty amine at room temperature. Silver-gold nanoparticles were synthesized with different molar ratios (2:1, 1:1, 1:2). Ultraviolet-visible absorption spectra suggested the formation of alloy phases. The elemental Ag:Au ratios in the bimetallic nanoparticles determined by energy dispersive x-ray analysis (EDX) were consistent with the Ag:Au molar ratios used in the feeding solution. Transmission electron microscopy (TEM) revealed the formation of a uniform size distribution of Ag:Au nanoparticles (around 5 nm). X-ray photoelectron spectroscopy (XPS) showed that the composition in the outer part of the Ag:Au nanoparticles was similar to that obtained by EDX analysis, which indicates the formation of homogeneous silver-gold nanoparticles. Silver-gold alloy nanoparticles on a gram scale can be obtained with this method.