Turning on Low-Temperature Catalytic Conversion of Biomass Derivatives through Teaming Pd and Mo Single-Atom Sites.

On-purpose atomic scale design of catalytic sites, specifically active and selective at low temperature for a target reaction, is a key challenge. Here, we report teamed Pd and Mo single-atom sites that exhibit high activity and selectivity for anisole hydrodeoxygenation to benzene at low temperatures, 100-150 °C, where a Pd metal nanoparticle catalyst or a MoO nanoparticle catalyst is individually inactive. The catalysts built from Pd or Mo single-atom sites alone are much less effective, although the catalyst with Pd sites shows some activity but low selectivity.

Elucidating the active phases of CoO films on Au(111) in the CO oxidation reaction.

Noble metals supported on reducible oxides, like CoO and TiO, exhibit superior activity in many chemical reactions, but the origin of the increased activity is not well understood. To answer this question we studied thin films of CoO supported on an Au(111) single crystal surface as a model for the CO oxidation reaction. We show that three reaction regimes exist in response to chemical and topographic restructuring of the CoO catalyst as a function of reactant gas phase CO/O stoichiometry and temperature.

Toward more accurate surface properties of ceria using many-body perturbation theory.

Despite the wide applications, the ab initio modeling of the ceria based catalyst is challenging. The partial occupation in the 4f orbitals creates a fundamental challenge for commonly used density functional theory (DFT) methods, including semilocal functionals with Hubbard U correction to force localization and hybrid functionals. In this work, we benchmark the random phase approximation (RPA) for ceria surface properties, including surface energy and hydrogenation energy, compared to the results utilizing the DFT + U approach or hybrid functionals.

Mechanistic and Electronic Insights into a Working NiAu Single-Atom Alloy Ethanol Dehydrogenation Catalyst.

Elucidation of reaction mechanisms and the geometric and electronic structure of the active sites themselves is a challenging, yet essential task in the design of new heterogeneous catalysts. Such investigations are best implemented via a multipronged approach that comprises ambient pressure catalysis, surface science, and theory. Herein, we employ this strategy to understand the workings of NiAu single-atom alloy (SAA) catalysts for the selective nonoxidative dehydrogenation of ethanol to acetaldehyde and hydrogen.

CO Oxidation Mechanisms on CoO-Pt Thin Films.

The reaction of CO and O with submonolayer and multilayer CoO films on Pt(111), to produce CO, was investigated at room temperature in the mTorr pressure regime. Using operando ambient pressure X-ray photoelectron spectroscopy and high pressure scanning tunneling microscopy, as well as density functional theory calculations, we found that the presence of oxygen vacancies in partially oxidized CoO films significantly enhances the CO oxidation activity to form CO upon exposure to mTorr pressures of CO at room temperature. In contrast, CoO films without O-vacancies are much less active for CO formation at RT, and CO only adsorbed in the form of carbonate species that are stable up to 260 °C.

Water on Oxide Surfaces: A Triaqua Surface Coordination Complex on CoO(111).

The interaction of water with metal oxides controls their activity and stability in heterogeneous catalysis and electrocatalysis. In this work, we combine density functional theory calculations and infrared reflection absorption spectroscopy (IRAS) to identify the structural motifs formed upon interaction of water with an atomically defined CoO(111) surface. Three principal structures are observed: (i) strongly bound isolated OD, (ii) extended hydrogen-bonded OD/DO structures, and (iii) a third structure which has not been reported to our knowledge.

Small-seeded Hakea species tolerate cotyledon loss better than large-seeded congeners.

Six Hakea species varying greatly in seed size were selected for cotyledon damage experiments. The growth of seedlings with cotyledons partially or completely removed was monitored over 90 days. All seedlings perished by the fifth week when both cotyledons were removed irrespective of seed size.

Characterization of the sdw1 semi-dwarf gene in barley.

Background: The dwarfing gene sdw1 has been widely used throughout the world to develop commercial barley varieties. There are at least four different alleles at the sdw1 locus.

Results: Mutations in the gibberellin 20-oxidase gene (HvGA20ox2) resulted in multiple alleles at the sdw1 locus.