News & Scientific Highlights

The activation and conversion of hydrocarbons is one of the most important challenges in chemistry. This work shows that isolated Co(II) sites are catalysts for a number of hydrocarbon conversion reactions, such as the dehydrogenation of propane, the hydrogenation of propene, and the trimerization of terminal alkynes. The data are consistent with all of these reactions occurring by a common mechanism, involving heterolytic C–H or H–H activation via a 1,2 addition across a Co–O bond.

The kinetics involved in novel ambient-temperature mechanism for the catalytic oxidation of carbon monoxide by oxygen over a Pt/Al2O3 catalyst is evaluated within a periodic redox operation paradigm using combined mass spectrometry (MS), diffuse reflectance infrared spectroscopy (DRIFTS), and time-resolved Pt L3-edge XAFS. A high-wavenumber (ca. 1690 cm-1) carbonate species are shown to be associated with a room-temperature redox process occurring in a fraction of the Pt atoms present in the catalyst.

A simple and scalable method for preparation of well-defined chlorine–free iridium oxide nanoparticles active for oxygen evolution reaction (OER) was developed. Operando X-ray absorption spectroscopy and X-ray photoelectron spectroscopy indicate that OER activity is strongly related to the presence of iridium hydroxo (Ir–OH) species on the surface of iridium oxide nanoparticles.

Industrial alkene metathesis processes rely on silica-supported tungsten oxide catalysts, which operate at high temperatures (>350 °C) due to the difficulty in generating active sites (carbenes or metallacyclobutanes). We report here a low temperature activation process of well-defined metal oxo surface species using organosilicon reductants, which generate a large amount of active species at only 70 °C (0.6 active sites/W).

Using an assembly of colloidal nanocrystals a Ag-PbS nanocomposite was produced with increased thermoelectic figures of merit up to 1.7K at 850 K. EXAFS spectroscopy at the Ag K-edge was essential to show that Ag does not dissolve in PbS nanoparticles but preserved the individual nanodomains. This reduces the PbS intergrain energy barriers for charge transport