Controlled Synthesis of Hierarchical Pd Nanodendrites and Their Electrocatalytic Properties.

Well-defined hierarchical Pd nanodendrites with (111) surface were successfully synthesized with Pd(acac)2 as a precursor, polyvinylpyrrolidone (PVP) as a stabilizer, CO as a reducing agent in the presence of appropriate amounts of NaAc and oleylamide (OAm) at 100 °C for 3 h under atmospheric pressure. OAm played an important role in controlling the growth of the hierarchical dendritic nanostructures of the final products. The formation of the hierarchical Pd dendrites was ascribed to the OAm-confined growth from the tips along 〈111〉 axis directions. This kind of hierarchical Pd nanodendrites exhibited an enhanced electrocatalytic activity for the electro-oxidation of formic acid compared with Pd black.

Morphological control and evolution of octahedral and truncated trisoctahedral Pt-Au alloy nanocrystals under microwave irradiation.

Uniform and well-defined truncated trisoctahedral and octahedral Pt-Au alloy nanocrystals were fabricated by co-reducing H(2)PtC(l6)-HAuC(l4) with tetraethylene glycol (TEG) under microwave irradiation for only 140 s. Iodide ions were critical to the morphological control and evolution of Pt-Au alloy nanostructures. The as-prepared Pt-Au alloy nanocrystals exhibited efficient electrocatalytic activities.

Synthesis of PVP-stabilized ruthenium colloids with low boiling point alcohols.

A route to the preparation of poly(N-vinyl-2-pyrrolidone) (PVP)-stabilized ruthenium colloids by refluxing ruthenium(III) chloride in low boiling point alcohols was developed. Deep purple colloids with shuttle-like ruthenium particles were also synthesized. XPS measurement verified the nanoparticles were in the metallic state. The morphology of metal nanoparticles was characterized by UV-visible absorption spectrophotometry, TEM and XRD.

Size control synthesis of polymer-stabilized water-soluble platinum oxide nanoparticles.

A series of narrowly distributed nanoparticles with different sizes of platinum oxide stabilized by polyvinylpyrrolidone (PVP) were synthesized by hydrolytic decomposition of platinum chloride. The as-synthesized nanoparticles were characterized by UV-vis, TEM, and XPS examination. Studies on the parameters influencing the size of the as-synthesized platinum oxide nanoparticles were carried out. The pH of the solution was demonstrated to be the main factor affecting the particle diameter. The particles size also decreased with the increasing molar ratio of stabilizer (PVP):PtCl(4). The influence of the concentration of sodium acetate on the rate of hydrolytic decomposition and the condensation reaction was studied. It was found that increasing the concentration of sodium acetate increased the rate of the condensation reaction nearly linearly.

Preparation of platinum nanoparticles using star-block copolymer with a carboxylic core.

Well-defined star polymers containing a functionalized core supply a molecular nanocavity and may be used to control formation of inorganic nanoparticles. Herein, platinum (Pt) nanoparticles of 2-4 nm were prepared by using (poly(acrylic acid)-b-polystyrene)6 (PAA-b-PS)6 amphiphilic star block copolymer as a novel single molecular stabilizer. This PAA core functionalized star polymer was obtained by hydrolysis of (poly(tert-butyl acrylate)-b-polystyrene)6 (PtBA-b-PS)6, which was synthesized by sequential atom transfer radical polymerization (ATRP) of tert-butyl acrylate and styrene with an initiator bearing six 2-bromoisobutyloxyl groups. Pt(IV) ions were loaded by ion exchange to the core of the star polymer and Pt nanoparticle stabilized by single star polymer was produced by a reduction with NaBH4.

Synthesis of solvent-stabilized colloidal nanoparticles of platinum, rhodium, and ruthenium by microwave-polyol process.

Solvent-stabilized Pt, Rh, and Ru colloidal nanoparticles were synthesized by a microwave-polyol process. They were characterized by TEM and XPS, XRD, and UV-vis examination. These colloids have small particle sizes with narrow size distribution, and they were stable in glycol upon storage under ambient condition for months. Separation and XPS characterization of the intermediate colloids demonstrated the two-step mechanism for the formation of solvent-stabilized metal colloids via hydrolysis.

Unexpected effects of trace impurities on the properties of polymer-stabilized ruthenium colloids from different sources of ruthenium(III) chloride hydrate.

The stability and the catalytic performances of polyvinylpyrrolidone-stabilized ruthenium colloids (PVP-Ru) prepared by using RuCl(3).xH(2)O of different sources have been investigated. The trace impurity content of platinum and palladium in RuCl(3).xH(2)O was demonstrated to be the main factors affecting the properties of PVP-Ru colloids.