Properties Of Pd Nanoparticles Research Articles

Influence of hydrogenation on the mechanical properties of Pd nanoparticles.

Atomic simulations are conducted to investigate the influence of hydrogenation on the mechanical properties of Pd nanoparticles. It is found that with an increase in the H atom content both the elastic modulus and the yield stress decrease approximately linearly. Moreover, the H atom content evidently alters the atomic deformation mechanisms in Pd nanoparticles. When the H atom content is in the range of 0–0.3, yield initiates from dislocation nucleating beneath surface steps and then a pyramid hillock is formed. Subsequently, dislocation nucleation and exhaustion at the surface will govern the plastic deformation. However, when the H atom content is in the range of 0.3–0.4, massive initial defects are introduced by hydrogenation, which partially suppress the dislocation nucleation around the surface steps, and no pyramid dislocation hillock is formed. Dislocation multiplication will dominate the subsequent plastic deformation. Moreover, as the H atom content increases to 0.4–0.5, the recoverable phase transition plays a key role in the plastic deformation. This study enriches our understanding of the impact of hydrogenation on the mechanical properties and deformation mechanisms of Pd nanoparticles.

One-Pot Synthesis of Single-Crystal Palladium Nanoparticles with Controllable Sizes for Applications in Catalysis and Biomedicine

Palladium (Pd) nanoparticles are of particular interest to various fundamental studies and emerging areas of technology. The properties of Pd nanoparticles have a strong dependence on particle size...

PVA‐encapsulated Palladium Nanoparticles: Eco‐friendly and Highly Selective Catalyst for Hydrogenation of Nitrobenzene in Aqueous Medium

In aqueous medium without any other additives, palladium (Pd) nanoparticles with water-soluble polyvinyl alcohol (PVA) as stabilizer were synthesized for the catalytic hydrogenation of nitrobenzene. Under the optimum experimental conditions, the nitrobenzene conversion and the selectivity for aniline were 99.3 % and 100 %, respectively. Comprehensive characterization methods, including TEM, UV/Vis, confocal laser scanning microscopy (CLSM), XRD and XPS allowed a better understanding of the role of PVA aggregates and the properties of Pd nanoparticles. The nitrobenzene conversion exceeded 80 % even after 6 cycles without any treatment of the catalyst. A mechanism about the hydrogenation of nitrobenzene catalyzed by Pd/PVA system was proposed. The Pd/PVA catalyst also exhibited excellent activity and selectivity, particularly to ortho-fluoronitrobenzene and ortho-nitrotoluene. This research can provide a reference for the environmentally friendly catalysis for hydrogenation of nitrobenzene and other substituted nitrobenzene compounds.

Morphology and oxidation state of ALD-grown Pd nanoparticles on TiO2- and SrO-terminated SrTiO3 nanocuboids

We employ SrTiO3 nanocuboid single crystals with well-defined (001) surfaces that are synthesized to have either a TiO2- or SrO-terminated surface to investigate the influence of surface termination on the morphology and the chemical property of supported metallic nanoparticles. Using such monodispersed STO nanocuboids allows for practical catalytic reaction studies as well as surface studies comparable to a single crystal model catalyst. Pd nanoparticles were grown by atomic layer deposition, which is able to control the effective coverage, chemical state, and the size of the Pd nanoparticles. The properties of Pd nanoparticles were examined by transmission electron microscopy, X-ray absorption spectroscopy, and X-ray photoemission spectroscopy. The morphology and growth pattern for the Pd nanoparticles supported on the SrTiO3 nanocuboids are shown to depend on the surface termination.

Determination of Nanoparticle Size by Measuring the Metal–Metal Bond Length: The Case of Palladium Hydride

Formation and properties of Pd nanoparticles have been investigated in situ in the temperature range between 186 and 483 K by X-ray absorption fine structure (XAFS) spectroscopy and by ex situ electron microscopy. Results of the experiments conducted under hydrogen and helium atmospheres were compared, in order to illuminate and explain the changes in bond length of Pd particles as a result of hydride formation. By contrasting the data obtained at these two atmospheres we were able to isolate the effects of both the finite particle size and hydrogen absorption on Pd–Pd bond length, obtain hydrogen intake values, and, as a result, estimate the particle size. The calculated average particle size agreed with the electron microscopy data. These results open up new opportunities for in situ size investigations by XAFS of catalytic Pd particles in reaction conditions, when catalyst fragmentation, shape change, and/or coarsening may occur.