Size Control of Palladium Nanoparticles and Their Crystal Structures

Abstract

The mean diameter of monodispersed Pd nanoparticles could be controlled from 17 to 30 Å in a one-step reaction by changing the amount of protective polymer, poly(N-vinyl-2-pyrrolidone) (PVP) and the kind and/or the concentration of alcohol in the solvent. Although increasing the amount of protective polymer made the size of Pd nanoparticles smaller, the particle size appeared to have a lower limit determined by the kind of alcohol. On the other hand, monodispersed Pd nanoparticles of smaller diameter were obtained in the order methanol > ethanol > 1-propanol, indicating that a faster reduction rate of [PdCl4]2- ions is an important factor to produce the smaller particles. The particle diameter showed a minimum at around 40 vol % of alcohol in solvent. Once the monodispersed Pd nanoparticles were obtained, the larger particles with a narrow size distribution could be easily synthesized by using the stepwise growth reaction. The Pd nanoparticles obtained here had fcc structures like that of bulk Pd, although the lattice constant increased with a decrease in the particle size.

Dielectric relaxation behavior of colloidal suspensions of palladium nanoparticle chains dispersed in PVP/EG solution

“…This is not surprising taking into account the following fact. On one hand, the Pd NP is surrounded by PVP molecules, which are absorbed by the surface via the coordination of the PVP carbonyl group to the Pd atoms, 38,39 therefore the diffusion of the ions within the double layer is blocked by PVP molecules and is slower than in bulk solution. On the other hand, since tangential counterion diffusion around the particle is forbidden as previously discussed, the volume diffusion mechanism proposed by Dukhin and Shilov 16 is preferable to account for the present dielectric relaxation, that is, the relaxation arises from the diffusion of ions in the bulk solution adjoining the EDL due to a concentration gradient, and D C is comparable to that in bulk solution.…”

Total oxidation of naphthalene using palladium nanoparticles supported on BETA, ZSM-5, SAPO-5 and alumina powders

“…Their preparation, structure, characterization and applications are issues of great current interest [19], with particular attention paid to the importance of their size and structure. Focusing on Pd nanoparticles, Teranishi et al [20] dealt with the fundamental aspects of monometallic palladium nanoparticles, their synthesis and structural control, and the system has played an important role as a catalyst in numerous organic reactions. Within this field, unsupported Pd based nanoparticles have been used successfully in our group in the semi-hydrogenation of phenylacetylene [21] or supported on carbon [22] or inorganic materials [23].…”

Synthesis of Micronsized Gold Nanoplates at Low Precursor Concentration Using Ionic Liquid as Novel Subphase Solvent

“…We think that the rates of the nucleation and growth are the key factors. As has been reported, rapid nanoparticle nucleation affords small, aggregated nanoparticles, whereas slow growth at low temperature leads to thermodynamic stabile nanostructures [23]. The theory of DLA (diffusion-limited aggregation) has been widely applied to the interpretation of the phenomenon of growth and assembly related to a variety of fractal structures [24].…”