Sum frequency generation vibrational spectroscopy of 1,3-butadiene hydrogenation on 4 nm Pt@SiO2, Pd@SiO2, and Rh@SiO2 core-shell catalysts.

1,3-Butadiene (1,3-BD) hydrogenation was performed on 4 nm Pt, Pd, and Rh nanoparticles (NPs) encapsulated in SiO2 shells at 20, 60, and 100 °C. The core-shells were grown around polyvinylpyrrolidone (PVP) coated NPs (Stöber encapsulation) prepared by colloidal synthesis. Sum frequency generation (SFG) vibrational spectroscopy was performed to correlate surface intermediates observed in situ with reaction selectivity.

Dramatically different kinetics and mechanism at solid/liquid and solid/gas interfaces for catalytic isopropanol oxidation over size-controlled platinum nanoparticles.

We synthesize platinum nanoparticles with controlled average sizes of 2, 4, 6, and 8 nm and use them as model catalysts to study isopropanol oxidation to acetone in both the liquid and gas phases at 60 °C. The reaction at the solid/liquid interface is 2 orders of magnitude slower than that at the solid/gas interface, while catalytic activity increases with the size of platinum nanoparticles for both the liquid-phase and gas-phase reactions. The activation energy of the gas-phase reaction decreases with the platinum nanoparticle size and is in general much higher than that of the liquid-phase reaction which is largely insensitive to the size of catalyst nanoparticles.

ZnS nanocrystal cytotoxicity is influenced by capping agent chemical structure and duration of time in suspension.

As a result of their characteristic physical and optical properties, including their size, intense fluorescence, broad excitation, narrow emission and resistance to photobleaching, semiconductor nanocrystals are potentially useful for a variety of biological applications including molecular imaging, live-cell labeling, photodynamic therapy and targeted drug delivery. In this study, zinc sulfide (ZnS) semiconductor nanocrystals were synthesized in the 3 to 4 nm size range with selected capping agents intended to protect the nanocrystal core and increase its biological compatibility. We show that the biocompatibility of ZnS nanocrystals with primary murine splenocytes is influenced by the chemical structure of the outer capping agent on the nanocrystal.

Synthesis, characterization, and reaction studies of a PVP-capped platinum nanocatalyst immobilized on silica.

An immobilized platinum nanocatalyst was prepared by first functionalizing the surface of activated silica with poly(vinylpyrrolidone) (PVP) and then reducing encapsulated platinum ions in the presence of these functionalized supports to form nanoparticles. Surface functionalization was monitored by infrared spectroscopy and surface area measurements, and the resulting nanocatalyst was characterized using transmission electron microscopy (TEM) and X-ray diffraction (XRD). Platinum nanoparticle size was determined to be approximately 5 nm based on TEM and XRD measurements.