Interstitial Boron Atoms in the Palladium Lattice of an Industrial Type of Nanocatalyst: Properties and Structural Modifications.

It is well-established that the inclusion of small atomic species such as boron (B) in powder metal catalysts can subtly modify catalytic properties, and the associated changes in the metal lattice imply that the B atoms are located in the interstitial sites. However, there is no compelling evidence for the occurrence of interstitial B atoms, and there is a concomitant lack of detailed structural information describing the nature of this occupancy and its effects on the metal host. In this work, we use an innovative combination of high-resolution B magic-angle-spinning (MAS) and Pd static solid-state NMR nuclear magnetic resonance (NMR), synchrotron X-ray diffraction (SXRD), in situ X-ray pair distribution function (XPDF), scanning transmission electron microscopy-annular dark field imaging (STEM-ADF), electron ptychography, and electron energy loss spectroscopy (EELS) to investigate the B atom positions, properties, and structural modifications to the palladium lattice of an industrial type interstitial boron doped palladium nanoparticle catalyst system (Pd-B/C NPs).

Crystal Chemistry and Antibacterial Properties of Cupriferous Hydroxyapatite.

Copper-doped hydroxyapatite (HA) of nominal composition Ca(PO)[Cu(OH)O] (0.0 ≤ x ≤ 0.8) was prepared by solid-state and wet chemical processing to explore the impact of the synthesis route and mode of crystal chemical incorporation of copper on the antibacterial efficacy against () and () strains.

Direct solid state NMR observation of the Pd nucleus in inorganic compounds and palladium metal systems.

The ability to clearly relate local structure to function is desirable for many catalytically relevant Pd-containing systems. This report represents the first direct Pd solid state NMR measurements of diamagnetic inorganic (KPd(iv)Cl, (NH)Pd(iv)Cl and KPd(iv)Br) complexes, and micron- and nano-sized Pd metal particles at room temperature, thereby introducing effective Pd chemical shift and Knight shift ranges in the solid state. The very large Pd quadrupole moment (Q) makes the quadrupole parameters (C, η) extremely sensitive to small structural distortions.

Performance of Preformed Au/Cu Nanoclusters Deposited on MgO Powders in the Catalytic Reduction of 4-Nitrophenol in Solution.

The deposition of preformed nanocluster beams onto suitable supports represents a new paradigm for the precise preparation of heterogeneous catalysts. The performance of the new materials must be validated in model catalytic reactions. It is shown that gold/copper (Au/Cu) nanoalloy clusters (nanoparticles) of variable composition, created by sputtering and gas phase condensation before deposition onto magnesium oxide powders, are highly active for the catalytic reduction of 4-nitrophenol in solution at room temperature.

The cluster beam route to model catalysts and beyond.

The generation of beams of atomic clusters in the gas phase and their subsequent deposition (in vacuum) onto suitable catalyst supports, possibly after an intermediate mass filtering step, represents a new and attractive approach for the preparation of model catalyst particles. Compared with the colloidal route to the production of pre-formed catalytic nanoparticles, the nanocluster beam approach offers several advantages: the clusters produced in the beam have no ligands, their size can be selected to arbitrarily high precision by the mass filter, and metal particles containing challenging combinations of metals can be readily produced. However, until now the cluster approach has been held back by the extremely low rates of metal particle production, of the order of 1 microgram per hour.

Atomic Resolution Observation of a Size-Dependent Change in the Ripening Modes of Mass-Selected Au Nanoclusters Involved in CO Oxidation.

Identifying the ripening modes of supported metal nanoparticles used in heterogeneous catalysis can provide important insights into the mechanisms that lead to sintering. We report the observation of a crossover from Smoluchowski to Ostwald ripening, under realistic reaction conditions, for monomodal populations of precisely defined gold particles in the nanometer size range, as a function of decreasing particle size. We study the effects of the CO oxidation reaction on the size distributions and atomic structures of mass-selected Au(561±13), Au(923±20) and Au(2057±45) clusters supported on amorphous carbon films.

Interstitial modification of palladium nanoparticles with boron atoms as a green catalyst for selective hydrogenation.

Lindlar catalysts comprising of palladium/calcium carbonate modified with lead acetate and quinoline are widely employed industrially for the partial hydrogenation of alkynes. However, their use is restricted, particularly for food, cosmetic and drug manufacture, due to the extremely toxic nature of lead, and the risk of its leaching from catalyst surface. In addition, the catalysts also exhibit poor selectivities in a number of cases.

The effects of 1-pentyne hydrogenation on the atomic structures of size-selected Au(N) and Pd(N) (N = 923 and 2057) nanoclusters.

We report an investigation into the effects of the vapour-phase hydrogenation of 1-pentyne on the atomic structures of size-selected Au and Pd nanoclusters supported on amorphous carbon films. We use aberration-corrected high-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) to image populations of the nanoclusters at atomic resolution, both before and after the reaction, and we assign their atomic structures by comparison with multi-slice image simulations over a full range of cluster orientations. Gold nanoclusters consisting of 923 ± 20 and 2057 ± 45 atoms are found to be robust, exhibiting high structural stability.

Synthesis, alignment, and magnetic properties of monodisperse nickel nanocubes.

This Communication describes the synthesis of highly monodispersed 12 nm nickel nanocubes. The cubic shape was achieved by using trioctylphosphine and hexadecylamine surfactants under a reducing hydrogen atmosphere to favor thermodynamic growth and the stabilization of {100} facets. Varying the metal precursor to trioctylphosphine ratio was found to alter the nanoparticle size and shape from 5 nm spherical nanoparticles to 12 nm nanocubes.

Ultrafast growth of highly branched palladium nanostructures for catalysis.

Palladium is widely used as a catalyst in pharmaceutical and chemical syntheses as well as in the reduction of harmful exhaust emissions. Therefore, the development of high performance palladium catalysts is an area of major concern. In this paper, we present the synthesis of highly branched palladium nanostructures in a simple solution phase reaction at room temperature.

Substituent dependence of the reactions of [RuCl2(PPh3)3] with bulky aromatic thiols.

2,4,6-trialkylbenzenethiols react with [RuCl2(PPh3)3] to give Ru products with the alkyl substituents forming M-C sigma bonds, carbene, carbene with a S alpha-heteroatom, agostic hydrogen interaction or a simple tetrahedral Ru(II) species, depending on the substituent.