Nanometric NaYF as an Unconventional Support for Gold Catalysts for Oxidation Reactions.

The metal-support interaction plays an important role in gold catalysis. We employ here crystalline cubic (α-) and hexagonal (β-) phases of heterometallic fluoride NaYF nanoparticles (NPs), obtained by the decomposition of a single source precursor [NaY(TFA)(diglyme)] (TFA = trifluoroacetate), as nonoxide supports for gold catalysts. Using an isostructural gadolinium analogue, we also obtained doped α-NaYF:Gd and β-NaYF:Gd NPs.

Atmosphere-dependent stability and mobility of catalytic Pt single atoms and clusters on γ-AlO.

Atomically dispersed metals promise the ultimate catalytic efficiency, but their stabilization onto suitable supports remains challenging owing to their aggregation tendency. Focusing on the industrially-relevant Pt/γ-Al2O3 catalyst, in situ X-ray absorption spectroscopy and environmental scanning transmission electron microscopy allow us to monitor the stabilization of Pt single atoms under O2 atmosphere, as well as their aggregation into mobile reduced subnanometric clusters under H2. Density functional theory calculations reveal that oxygen from the gas phase directly contributes to metal-support adhesion, maximal for single Pt atoms, whereas hydrogen only adsorbs on Pt, and thereby leads to Pt clustering.

Ultimate size control of encapsulated gold nanoparticles.

We report an original and scalable synthesis pathway to produce encapsulated gold nanoparticles. Precise control of the gold particles is achieved in the range of 1-10 nm through the impregnation of silicalite-1 with a controlled concentration of gold solution, followed by dissolution-recrystallization of the zeolite.

Accumulation and transport of microbial-size particles in a pressure protected model burn unit: CFD simulations and experimental evidence.

Background: Controlling airborne contamination is of major importance in burn units because of the high susceptibility of burned patients to infections and the unique environmental conditions that can accentuate the infection risk. In particular the required elevated temperatures in the patient room can create thermal convection flows which can transport airborne contaminates throughout the unit. In order to estimate this risk and optimize the design of an intensive care room intended to host severely burned patients, we have relied on a computational fluid dynamic methodology (CFD).

Structures and associated catalytic properties of well-defined nanoparticles produced by laser vaporisation of alloy rods.

Bimetallic clusters, all containing gold, have been produced by laser vaporisation of bulk alloys followed by deposition of the formed clusters onto Al2O3 and TiO2 powders or flat silica supports. This technique allows a narrow size distribution of highly dispersed gold-based nanoparticles on powders and nanocrystalline structured thin films on 2D supports to be obtained. The catalytic performances of the as-obtained AuFe, AuNi, AuTi powdery catalysts have been studied in the PROX reaction and compared with those obtained in the oxidation of CO in the temperature range 25-300 degrees C.

Stereoselective stilbene epoxidation over supported gold-based catalysts.

The gold reference catalyst Au/TiO(2) exhibits high activity in the stereoselective epoxidation of trans-stilbene in methylcyclohexane in the presence of 5 mol% TBHP, by taking part in a chain reaction involving the activation of molecular oxygen by a radical produced from methylcyclohexane.

Preferential oxidation of CO in H2 over highly loaded Au/ZrO2 catalysts obtained by direct oxidation of bulk alloy.

The intimate mixture of a skeletal gold structure with ZrO2 nanoparticles obtained simply by oxidation of Au(0.5)Zr(0.5) alloy at room temperature turns out to be an efficient catalyst for the selective oxidation of CO in the presence of hydrogen.