A5056692673- Catalytic Processes in Materials Science
- Catalysis and Oxidation Reactions
- Fuel Cells and Related Materials
- Ionic liquids properties and applications
- Surfactants and Colloidal Systems
- Membrane-based Ion Separation Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Nanocluster Synthesis and Applications
- Lipid Membrane Structure and Behavior
- nanoparticles nucleation surface interactions
- Gold and Silver Nanoparticles Synthesis and Applications
- Mesoporous Materials and Catalysis
- Polymer crystallization and properties
- Copper-based nanomaterials and applications
- Diamond and Carbon-based Materials Research
- Quantum Dots Synthesis And Properties
- Catalysts for Methane Reforming
- Electrocatalysts for Energy Conversion
- Electron and X-Ray Spectroscopy Techniques
- Advanced Chemical Physics Studies
- Supramolecular Self-Assembly in Materials
- Polymer Nanocomposites and Properties
- Enzyme Structure and Function
- Fiber-reinforced polymer composites
- Porphyrin and Phthalocyanine Chemistry
Argonne National Laboratory
2016-2025
Advanced Photonix (United States)
2012-2025
Advanced Photon Source
2008-2025
Alex's Lemonade Stand Foundation
2017-2020
Center for NanoScience
2016
Northwestern University
2010
Yale University
2010
Center for Nanoscale Materials
2009
Universität Hamburg
1995-2000
Institut für Technische und Angewandte Physik (Germany)
1995
The activation of CO2 and its hydrogenation to methanol are much interest as a way utilize captured CO2. Here, we investigate the use size-selected Cu4 clusters supported on Al2O3 thin films for reduction in presence hydrogen. catalytic activity was measured under near-atmospheric reaction conditions with low partial pressure, oxidation state investigated by situ grazing incidence X-ray absorption spectroscopy. results indicate that most active low-pressure catalyst conversion CH3OH. Density...
Hematite photoanodes were coated with an ultrathin cobalt oxide layer by atomic deposition (ALD). The optimal coating-1 ALD cycle, which amounts to <1 monolayer of Co(OH)2/Co3O4-resulted in significantly enhanced photoelectrochemical water oxidation performance. A stable, 100-200 mV cathodic shift the photocurrent onset potential was observed that is correlated order magnitude reduction resistance charge transfer at Fe2O3/H2O interface. Furthermore, optical transparency Co(OH)2/Co3O4 coating...
Epoxidation made easy: Subnanometer gold clusters immobilized on amorphous alumina result in a highly active and selective catalyst for propene epoxidation. The highest selectivity is found gas mixtures involving oxygen water, thus avoiding the use of hydrogen. Ab initio DFT calculations are used to identify key reaction intermediates pathways. results confirm high activity owing formation oxide metallacycles. Al green, Au yellow, O red, C gray.
Addition of water to 1-decyl-3-methylimidazolium bromide is shown result in its spontaneous self-organization and the concomitant formation a liquid-crystalline gel, thus providing simple means preparing supramolecular assembly comprising room-temperature ionic liquid.
Size-selected Cun catalysts (n = 3, 4, 20) were synthesized on Al2O3 thin films using mass-selected cluster deposition. A systematic study of size and support effects was carried out for CO2 hydrogenation at atmospheric pressure a combination in situ grazing incidence X-ray absorption spectroscopy, catalytic activity measurement, first-principles calculations. The methanol synthesis is found to strongly vary as function the size; Cu4/Al2O3 catalyst shows highest turnover rate CH3OH...
Water oxidation is a key catalytic step for electrical fuel generation. Recently, significant progress has been made in synthesizing electrocatalytic materials with reduced overpotentials and increased turnover rates, both parameters enabling commercial use electrolysis or solar to fuels applications. The complexity of the water reaction makes understanding site critical improving process. Here we study alkaline conditions using size-selected clusters Pd probe relationship between cluster...
The oxidative dehydrogenation of cyclohexane by cobalt oxide nanoparticles was studied via temperature programmed reaction combined with in situ grazing incidence X-ray absorption spectroscopy and small-angle scattering theoretical calculations on model Co3O4 substrates. Both 6 12 nm were made through a surfactant-free preparation dispersed an Al2O3 surface formed atomic layer deposition. Under conditions the retained their oxidation state did not sinter. They instead underwent...
Understanding the origins of enhanced reactivity supported, subnanometer in size, metal oxide clusters is challenging due to scarcity methods capable extract atomic-level information from experimental data. Due both sensitivity X-ray absorption near edge structure (XANES) spectroscopy local geometry around ions and reliability theoretical codes for modeling XANES spectra, supervised machine learning approach has become a powerful tool extracting structural spectra. Here, we present...
The solvation structure of water-in-salt electrolytes was thoroughly studied, and two competing structures─anion solvated anion network─were well-defined in recent publications. To further reveal the those highly concentrated electrolytes, particularly influence solvent, methanol chosen as solvent for this proposed study. In work, small-angle X-ray scattering, neutron Fourier-transform infrared spectroscopy, Raman spectroscopy were utilized to obtain global local structural information. With...
The relationship between molecular architecture and the nature of interactions with lipid bilayers has been studied for a series poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO−PPO−PEO) triblock copolymers using small-angle X-ray scattering (SAXS) thermal analysis (differential scanning calorimetry, DSC). number repeat units in hydrophobic poly(propylene oxide), PPO, block found to be critical determinant copolymer−lipid bilayer association. For...
Abstract The design, synthesis, and characterization of a hierarchically ordered composite whose structure optical properties can be reversibly switched by adjustment solvent conditions are described. Solvent‐induced swelling de‐swelling is shown to provide control over the internal packing arrangement hence, in situ synthesized metal nanoparticles. Specifically, gold‐nanoparticle‐containing ionic‐liquid‐derived polymer single step UV irradiation metal‐ion‐precursor‐doped, self‐assembled...
Subnanometer Ag aggregates on alumina supports have been found to be active toward direct propylene epoxidation oxide by molecular oxygen at low temperatures, with a negligible amount of carbon dioxide formation (Science 2010, 328, 224, ). In this work, we computationally and experimentally investigate the origin high reactivity subnanometer aggregates. Computationally, study O2 dissociation unsupported Ag19 Ag20 clusters, as well alumina-supported Ag19. The apparent barriers interface...
Block copolymers of polystyrene‐ b ‐poly(vinyl benzyl trimethylammonium tetrafluoroborate) (PS‐ ‐[PVBTMA][BF 4 ]) were synthesized by sequential monomer addition using atom transfer radical polymerization. Membranes the block prepared drop casting from dimethylformamide. Initial evaluation microphase separation in these PS‐ ] materials via SAXS revealed formation spherical, cylindrical, and lamellar morphologies. hydroxide) ‐[PVBTMA][OH]) as polymeric alkaline anion exchange membranes ion...
Bridging the support gap in heterogeneous ultrananocatalysis.
Abstract The discovery of more efficient, economical, and selective catalysts for oxidative dehydrogenation is immense economic importance. However, the temperatures required this reaction are typically high, often exceeding 400 °C. Herein, we report subnanometer sized cobalt oxide clusters cyclohexane that active at lower than reported catalysts, while they can also eliminate combustion channel. These results found two cluster sizes suggest other size (CoO) x will be low temperatures. high...
Subnanometer copper tetramer–zirconia catalysts turn out to be highly efficient for CO2 hydrogenation and its conversion methane. The cluster size substrate morphology are controlled optimize the catalytic performance. two types of zirconia supports investigated prepared by atomic layer deposition (∼3 nm thick film) supersonic beam (nanostructured film, ∼100 thick). plays a crucial role in determining activity catalyst as well cyclability over repeated thermal ramps. A temperature-programmed...
The SAXS instrument on the high brilliance undulator beam line (ID12, BESSRC-CAT) at APS has been designed to produce high-resolution scattering patterns in millisecond time domain. This is equipped with a 18 cm x position sensitive gas detector and 15 CCD mosaic detector. A photodiode mounted 3.7 mm diameter stop permits quick alignment of as well precise measurement transmitted intensity. exposure varies from 0.1 10 seconds depending cross-section samples. Techniques interface ancillary...
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTIn Situ Small-Angle X-ray Scattering Observation of Pt Catalyst Particle Growth During Potential CyclingMatt C. Smith†, James A. Gilbert†, Jennifer R. Mawdsley†, Sönke Seifert‡, and Deborah J. Myers†View Author Information Chemical Sciences Engineering Division, Advanced Photon Source, 9700 South Cass Avenue, Argonne, Illinois 60439[email protected]†Chemical Division.‡Advanced Source.Cite this: Am. Chem. Soc. 2008, 130, 26,...
Size and support effects in the oxidative decomposition of methanol on amorphous alumina supported subnanometer palladium clusters were studied under realistic reaction conditions pressure temperature. The smaller Pd8−12 found to promote channel CO hydrogen, however with mediocre activity due poisoning. larger Pd15−18 preferentially produce dimethyl ether formaldehyde, without signs posioning. A thin titania overcoat applied improves sintering-resistance catalyst. Accompanying density...
Nanometer-sized liquid droplets formed at temperatures below the bulk melting point become supercooled as they grow through Ostwald ripening or coalescence and can be exploited to nanowires without any catalyst. We used this simple approach synthesize a number of highly crystalline metal oxide in chemical physical vapor deposition apparatus. Examples made way include VO2, V2O5, RuO2, MoO2, MoO3, Fe3O4, some which have not been previously reported. Direct evidence new mechanism nanowire...
An extensive SAXS investigation of the 3M perfluorinated sulfonic acid ionomer was performed to investigate morphological changes that occur during and after annealing at temperatures above Tα. The effect film thickness in range studied, 11–45 μm, found be negligible. These properties were studied as a function equivalent weight from 700 1100 correlated with water uptake measured by dynamic vapor sorption. Isoscattering points observed experiments unboiled annealed films q = 0.023, 0.096...
Abstract A combined experimental and theoretical investigation of Ag‐Pt sub‐nanometer clusters as heterogeneous catalysts in the CO→CO 2 reaction (COox) is presented. Ag 9 Pt 3 are size‐selected gas phase, deposited on an ultrathin amorphous alumina support, tested experimentally under realistic conditions by first‐principles simulations at coverage. In situ GISAXS/TPRx demonstrates that do not sinter or deactivate even after prolonged exposure to reactants high temperature, present...
Accurate determination of molecular distances is fundamental to understanding the structure, dynamics, and conformational ensembles biological macromolecules. Here we present a method determine full distance distribution between small (∼7 Å radius) gold labels attached macromolecules with very high-precision (≤1 Å) on an absolute scale. Our uses anomalous small-angle X-ray scattering close absorption edge separate gold–gold interference pattern from other contributions. Results for 10–30 bp...
Propylene oxide, a key commodity of the chemical industry for wide range consumer products, is synthesized through sequential propane dehydrogenation and epoxidation reactions. However, lack direct catalytic route from to propylene oxide reduces efficiency represents major challenge catalysis science. Herein, we report discovery highly active selective catalyst, made alumina-supported subnanometer copper clusters, which can directly convert at temperatures as low 150 °C. Moreover, higher...