The Journal of Physical Chemistry B · 1997 · 79 citations · 32 references
Natural SciencesChemistryMaterials ScienceInorganic ChemistryMaterials ChemistryPhysical ChemistryCluster ChemistryColloid ChemistryNanomaterial CharacterizationSupported CatalystsSurface PhysicsX-ray DiffractionCo OxidationColloid CharacterizationColloidal NanoparticlesMetallic CharacterNanoparticle CatalystsOxidationParticle GrowthParticle Growth Kinetics
In situ XRD has been used to study both unsupported and silica-supported clusters PtRu[N(Oct) 4 Cl] 5 (Pt:Ru ≈ 1:1). Structural information has been gained by Debye function analysis. For the unsupported clusters, the best fit simulation gives a 50/50 mixture of colloid particles with fcc symmetry and multiply twinned decahedral particles. The narrow size distribution centers around 12 Å. The near-neighbor distance is found to be 0.9% smaller than for the bulk PtRu. XANES data provide evidence for the metallic character of the Pt component. The silica-supported colloid particles oxidize rapidly in air to form an amorphous state but can be rereduced in hydrogen at room temperature. An “open-slit” XRD technique was used to study the particle growth in H 2 and He. Particles annealed to 700 °C in He show a twinned fcc symmetry with an average size of 23 Å. The CO oxidation of this catalyst was studied by in situ XRD. At 280 °C surface oxide species are formed that slowly coalesce to RuO 2 particles. After rereduction the catalyst consists of a pure hcp ruthenium phase and larger alloy particles enriched in platinum.
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Robert L. Whetten, Joseph T. Khoury, Marcos M. Alvarez et al. · Advanced Materials · 1996 · 1.2K citations