Topic
Platinum
About: Platinum is a research topic. Over the lifetime, 49675 publications have been published within this topic receiving 1150035 citations. The topic is also known as: Pt & element 78.
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TL;DR: In this article, it was shown that the beneficial effects on catalyst selectivity and stability which are brought about by adding widely different catalyst modifiers (gold, tin, sulfur, carbon) to platinum catalysts are largely due to one common cause, namely, the division of the platinum surface into very small ensembles of platinum atoms.
269 citations
TL;DR: Results of single-particle X-ray energy dispersive spectroscopy (EDS) and catalysis experiments indicate that the hydrogenation rate of allyl alcohol is enhanced in the presence of the bimetallic nanoparticles compared to DECs containing only platinum or only palladium nanoparticles.
Abstract: We report the synthesis, characterization, and catalytic activity of bimetallic palladium−platinum dendrimer-encapsulated catalysts (DECs). These materials are prepared by co-complexation of different ratios of palladium and platinum salts to the interior tertiary amines of fourth-generation, hydroxyl-terminated poly(amidoamine) (PAMAM) dendrimers. Chemical reduction of these composites yields stable, fairly monodisperse, water-soluble bimetallic DECs having sizes on the order of 1.9 ± 0.4 nm. Evidence that these nanoparticles are bimetallic comes from single-particle X-ray energy dispersive spectroscopy (EDS) and catalysis experiments. The latter indicate that the hydrogenation rate of allyl alcohol is enhanced in the presence of the bimetallic nanoparticles compared to DECs containing only platinum or only palladium nanoparticles. EDS results indicate that the percentage composition of the bimetallics is reflected by the percentage of metal salts initially complexed with the dendrimer.
269 citations
TL;DR: In this article, the surface species formed by adsorption of atomic hydrogen on alumina has been characterized by a desorption peak at 480 °C in the temperature-programmed desorptions.
269 citations
TL;DR: In this article, Holton et al. present a review of the performance of Proton Exchange Membrane Fuel Cells (PEMFCs) using P Pt and its alloys.
Abstract: Johnson Matthey, Orchard Road, Royston, Hertfordshire SG8 5HE, UK Email: *oliver.holton@matthey.com; **joe.stevenson@matthey.com Proton exchange membrane fuel cells (PEMFCs) dominate the transportation fuel cell market and platinum (Pt) is the catalyst material used for both anode and cathode. This review sets out the fundamentals of activity, selectivity, stability and poisoning resistance which make Pt or its alloys the best available materials to use in this application. It is clear that Pt is the only element which can meet the requirements for performance while avoiding slow reaction kinetics, proton exchange membrane (PEM) system degradation due to hydrogen peroxide (H2O2) formation and catalyst degradation due to metal leaching. Some of the means by which the performance of Pt can be enhanced are also discussed.
267 citations
TL;DR: In this article, carbon-supported catalysts were held at elevated temperatures under dry air conditions, and the carbon support was evaluated with a first-order kinetic model to describe the results.
267 citations