Direct Fabrication of Au/Pd(II) Colloidal Core-Shell Nanoparticles by Pulsed Laser Ablation of Gold in PdCl₂ Solution

In this study, Au/Pd(II) core-shell colloidal nanoparticles (NPs) were prepared by pulsed laser (Nd:YAG, λ = 1064 nm) ablation synthesis in solution (LASiS) of gold target in PdCl2 solution of different concentrations. From X-ray diffraction, metallic Au, PdO, or PdCl2 crystal phases were obtained in this process. Surface plasmon resonance investigations, by means of UV–vis spectrophotometer, revealed damping of Au peak by increasing PdCl2 concentration. Transmission electron microscope showed the bimetallic particles are spherical core Au NPs covered by a Pd(II) shell whose thickness is dependent on PdCl2 concentration. X-ray photoelectron spectroscopy was used for surface chemical analysis. On the basis of the results from the previously described measurements, a mechanism for Au/Pd(II) core-shell formation was given.