1D Flower-like Morphologies of Palladium Nanoparticles Using Strongly Hydrophobic Surfactants

Flower-like crystalline morphologies of palladium (Pd) nanoparticles (NPs) were synthesized in the aqueous phase at room temperature by using strongly hydrophobic surfactants as capping/stabilizing agents following the seed-growth method. Small Pd seeds were synthesized first and then used as nucleating centers for the growth of large NPs. The NPs were interconnected with each other through small polyhedral Pd NPs in a typical pearl-necklace arrangement. When the reactions were performed at 70 degrees C, the number of flower-like NPs drastically reduced and short Pd nanowires appeared. The results were discussed on the basis of kinetic controlled nucleation, which got accelerated at 70 degrees C. Similarly, gold (Au)-Pd bimetallic NPs were also synthesized by using Au seeds at room temperature. It was observed that Au seeds were completely capped with a thick coating of Pd and no detection of Au was observed in Au-Pd bimetallic NPs. Oxidative corrosion of these particles lead to the formation of holes in the NPs which in turn became UV-visible active due to surface plasmon resonance. TEM, XRD, XPS, and UV-visible studies were used to characterize the shape, structure, and surface composition of these particles.