Are Nanoparticles Spherical or Quasi-Spherical?

The geometry of quasi-spherical nanoparticles is investigated. The combination of SEM imaging and electrochemical nano-impact experiments is demonstrated to allow sizing and characterization of the geometry of single silver nanoparticles

Factors Governing the Catalytic Reactivity of Metallic Nanoparticles

Uzio, Denis Berhault, GillesSome recent advances in catalysis by metals are reviewed illustrating the versatility of supported nanoparticles and their high potential to be major contributors to solve energetic or environmental issues of the ongoing century. Since the early structure sensitivity concept, progresses have brought new insights and guidelines on structure reactivity relationships such as strain effects, the ring-capture model, the particle surface density effect, or the influence of crystallographic planes. These phenomena are proposed to play a key role in the catalytic cycle. Systematic studies are however still required to estimate their real relevance and their respective contributions according to the type of chemical reactions and of operating conditions

Aromatic Reduction Over Supported Modified Platinum Catalysts Influence of a Second Metal on the Sulfur Resistance of Platinum

Pt-M/Al2O3 bimetallic catalysts with M = Ge, Au or Pd were prepared and characterised by H2-O2 volumetric titration and IR(CO) spectroscopy. The effects of the second metal on the sulfur resistance of platinum were investigated by the hydrogenation of orthoxylene. Compared to platinum monometallic reference catalyst, the bimetallic catalysts ranking in terms of hydrogenation activity was PtPd > PtAu = Pt >> PtGe. Correlation between these catalysis results and electronic properties extracted from IR(CO), or orthoxylene hydrogenation without sulfur, shows that sulfur resistance of platinum can not be exclusively related to an electronic effect and an electrodeficient character of Pt surface atoms. The mechanism of sulfur poisoning is discussed

Detailed characterization of caol-derived liquids from direct coal liquefaction on supported catalysts.

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Preparation of Nickel Phosphide Hydrodesulfurization Catalysts Assisted by Supercritical Carbon Dioxide

New preparation method to obtain silica-supported nickel phosphide nanoparticles assisted by supercritical carbon dioxide and their application to hydrodesulfurization..