Pt−Ru is the favored anode catalyst for the oxidation of methanol in direct methanol fuel cells (DMFCs). The nanoscale Pt−Ru blacks are accepted to be bimetallic alloys as based on their X-ray diffraction patterns. Our bulk and surface analyses show that although practical Pt−Ru blacks have diffraction patterns consistent with an alloy assignment, they are primarily a mix of Pt metal and Ru oxides plus some Pt oxides and only small amounts of Ru metal. Thermogravimetric analysis and X-ray photoelectron spectroscopy of as-received Pt−Ru electrocatalysts indicate that DMFC materials contain substantial amounts of hydrous ruthenium oxide (RuOxHy). A potential misidentification of nanoscale Pt−Ru blacks arises because RuOxHy is amorphous and cannot be discerned by X-ray diffraction. Hydrous ruthenium oxide is a mixed proton and electron conductor and innately expresses Ru−OH speciation. These properties are of key importance in the mechanism of methanol oxidation, in particular, Ru−OH is a critical component ...

Role of hydrous ruthenium oxide in Pt-Ru direct methanol fuel cell anode electrocatalysts: The importance of mixed electron/proton conductivity

The electrocatalytic activities of a wide range of ordered intermetallic phases toward a variety of potential fuels have been studied, and results have been compared to those of a pure polycrystalline platinum (Ptpc) electrode. A significant number of the ordered intermetallic phases exhibited enhanced electrocatalytic activity when compared to that of Pt, in terms of both oxidation onset potential and current density. The PtBi, PtIn, and PtPb ordered intermetallic phases appeared to be the most promising electrocatalysts tested thus far for fuel cell applications. PtPb, in particular, showed an onset potential that was 100 mV less positive and a peak current density ∼40 times higher than those observed for Pt in the case of methanol oxidation. The ability to control the geometric and electronic structures of the electrocatalytic material by using ordered intermetallic phases has been shown to be a promising direction of inquiry in the search for superior electrocatalysts for fuel cell applications.

Electrocatalytic Activity of Ordered Intermetallic Phases for Fuel Cell Applications

Three periods of Pt–Ru research are considered step-by-step: the initial period after discovery (1963–1970); observation and classification of basic tendencies (like the effects of composition, segregation, structural features on the activity; up to 1990); nanostructural studies and molecular level consideration of electrocatalytic phenomena in combination with advanced applied studies of materials, mechanistic, and applied aspects (after 1990). The main idea of this review is to balance various aspects of Pt–Ru electrochemistry related to material science and electrocatalysis as well as to remember the early basic results being of importance for future understanding of Pt–Ru functional properties.

Pt–Ru electrocatalysts for fuel cells: a representative review

Minimally invasive transcatheter embolization is a common nonsurgical procedure in interventional radiology used for the deliberate occlusion of blood vessels for the treatment of diseased or injured vasculature. A wide variety of embolic agents including metallic coils, calibrated microspheres, and liquids are available for clinical practice. Additionally, advances in biomaterials, such as shape-memory foams, biodegradable polymers, and in situ gelling solutions have led to the development of novel preclinical embolic agents. The aim here is to provide a comprehensive overview of current and emerging technologies in endovascular embolization with respect to devices, materials, mechanisms, and design guidelines. Limitations and challenges in embolic materials are also discussed to promote advancement in the field.

Advances in Biomaterials and Technologies for Vascular Embolization

Intermetallic compounds PtPb and PtBi have been prepared in nanoparticle form by dissolving Pt and Pb or Bi precursors in anhydrous methanol and coreducing the metal precursors with sodium borohydride. The average domain size determined from pXRD is 10 nm. The particles have been characterized by pXRD, SEM, STEM, EDX, and CBED. SEM and STEM images show the particles to be aggregated, forming clusters and chains. The BET surface area of the nanoparticles was measured using Kr as the adsorbing gas. The electrocatalytic oxidation of formic acid and methanol by the as-prepared PtPb and PtBi nanoparticles has been studied by rotating disk voltammetry for potential fuel-cell applications. The PtPb and PtBi nanoparticles displayed enhanced electrochemical activity toward formic acid and methanol oxidation when compared to commercially available Pt and PtRu nanoparticles. The electrocatalytic activity of the PtPb nanoparticles was studied as a function of sonication time of the catalyst ink, and morphology change...

Synthesis, Characterization, and Electrocatalytic Activity of PtBi and PtPb Nanoparticles Prepared by Borohydride Reduction in Methanol

Introduction
This study evaluated the safety, effectiveness, and biodegradation of a new embolic agent, Occlusin™ 503 Artificial Embolization Device (OCL 503). The agent consists of biodegradable poly-lactic-co-glycolic acid microspheres (150–212 μm) coated with type I bovine collagen and was compared with Embosphere® Microspheres (300–500 μm) in this controlled study of uterine artery embolization (UAE) in sheep.

A Preclinical Study of the Safety and Efficacy of Occlusin™ 500 Artificial Embolization Device in Sheep

Black Pt effected the hydrogenation of Ru(COD)(η3-C3H5)2 (1; COD is 1,5-cyclooctadiene) by dihydrogen gas (pressure ∼1 atm) at −10 °C in hexanes. The hydrogenation resulted in adsorption of Ru adatoms by the surface of Pt with concomitant formation of propane, cyclooctane, and small amounts of cis-bicyclo[3.3.0]octane and n-octane. Compound 1 did not react with dihydrogen gas under these conditions in the absence of Pt. The total amount of cyclooctane, bicyclo[3.3.0]octane, and n-octane in solution was equal to the amount of 1 consumed at all stages of the hydrogenation. The lifetimes of the organic fragments on the surface were short on the time scale of the hydrogenation. It was therefore possible to observe in real time both the stoichiometry and the activity of the evolving Ru−Pt surface by monitoring the concentrations of either 1 or the C8 product hydrocarbons in solution. There was a kinetic burst during the initial stages of the hydrogenation that ended after deposition of 0.2−0.5 equiv of Ru vers...

Hydrogenation of Ru(1,5-cyclooctadiene)(η3-C3H5)2 over Black Platinum. A Low-Temperature Reactive Deposition of Submonolayer Quantities of Ruthenium Atoms on Platinum with Real Time Control over Surface Stoichiometry

The present invention relates generally to methods and compositions for targeting and delivering solid-phase platelet-dependent vascular occlusion agents. In particular, particles or coils or stents coated with platelet binding agents are directed to target vasculature, such as the vasculature of solid tumor masses or AV-malformations or aneurysms or endoleaks; the solid-phase agent then binds and activates platelets, which in turn bind and activate other platelets. This process results in the rapid formation of a platelet-mediated thrombus about the solid-phase agent causing vessel occlusion.

Compositions and methods for producing vascular occlusion using a solid-phase platelet binding agent

The present invention relates to a method, and the product thereof, of reducing one or more metal centres of one or more organometallic precursors in the presence of a metal surface to deposit sub-monolayer, monolayer or multilayer quantities of the metal centres thereon. Further, the invention relates to a method, and the product thereof, of hydrogenating an organometallic precursor over a metal surface to deposit sub-monolayer, monolayer or multilayer quantities of the metal centre of the precursor thereon. Preferably, the method permits real time control over surface stoichiometry of the evolving surface resulting from the reaction. Finally, the present invention relates to a method of manufacturing electrodes having bimetallic or polymetallic clusters or surfaces for use in fuel cells.

Method of deposition of a metal on a metal surface and the product thereof

Optimizing nitrogen fertilization for hybrid canola (Brassica napus L.) production across Canada

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