Synthesis and Characterization of Flower-Shaped Porous Au−Pd Alloy Nanoparticles

Abstract

A facile synthesis of flower-shaped porous Au−Pd alloy nanoparticles with ascorbic acid as a reductant and PVP as a stabilizing agent is presented. The alloy nanoparticles were prepared from the aqueous solutions of HAuCl4/K2PdCl4 mixtures in molar ratios of 3:1, 1:1, and 1:3. The size, structure, optical properties, and composition distribution of the synthesized Au−Pd alloy nanoparticles were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy, UV−vis spectroscopy, and X-ray diffraction. The experimental results for the bimetallic systems and the physical mixtures of individual monometallic nanoparticles revealed that unstable small nanoparticles aggregate into the three-dimensional flower-shaped nanoparticles and the prepared nanoparticles are Au−Pd alloys. The surfaces of Au−Pd alloy nanoparticles were characterized by cyclic voltammetry measurement in 0.1 M HClO4 and surface-enhanced Raman scattering spectra of 1,4-phenylene diisocyanide adsorbed thereon. All alloy nanoparticles have a Pd-enriched surface.