A5015760920- Catalytic Processes in Materials Science
- Copper-based nanomaterials and applications
- Gold and Silver Nanoparticles Synthesis and Applications
- Catalysis and Oxidation Reactions
- Advanced Photocatalysis Techniques
- Electron and X-Ray Spectroscopy Techniques
- Nanomaterials for catalytic reactions
- Advanced Electron Microscopy Techniques and Applications
- Quantum Dots Synthesis And Properties
- Magnetic properties of thin films
- nanoparticles nucleation surface interactions
- Advancements in Battery Materials
- Electrocatalysts for Energy Conversion
- Electronic and Structural Properties of Oxides
- Optical Coherence Tomography Applications
- ZnO doping and properties
- Catalysts for Methane Reforming
- Transition Metal Oxide Nanomaterials
- Characterization and Applications of Magnetic Nanoparticles
- Semiconductor materials and devices
- Semiconductor materials and interfaces
- Advancements in Solid Oxide Fuel Cells
- Nanocluster Synthesis and Applications
- Catalysis and Hydrodesulfurization Studies
- Advanced Nanomaterials in Catalysis
National Institute of Standards and Technology
2016-2025
Material Measurement Laboratory
2016-2025
North Carolina State University
2009-2022
Brookhaven National Laboratory
2013-2020
Upton Hospital
2020
National Institute of Standards
2017-2018
Nanomaterials Research (United States)
2013-2015
Center for Functional Nanomaterials
2013-2015
RIKEN BNL Research Center
2014
Massachusetts Institute of Technology
2013
Ideal solar-to-fuel photocatalysts must effectively harvest sunlight to generate significant quantities of long-lived charge carriers necessary for chemical reactions. Here we demonstrate the merits augmenting traditional photoelectrochemical cells with plasmonic nanoparticles satisfy these daunting photocatalytic requirements. Electrochemical techniques were employed elucidate mechanics plasmon-mediated electron transfer within Au/TiO2 heterostructures under visible-light (λ>515 nm)...
Water reduction under two different visible-light ranges (λ > 400 nm and λ 435 nm) was investigated in gold-loaded titanium dioxide (Au-TiO2) heterostructures with sizes of Au nanoparticles (NPs). Our study clearly demonstrates the essential role played by NP size plasmon-driven H2O reveals distinct mechanisms to clarify photocatalytic activity excitation conditions. The governs efficiency plasmon-mediated electron transfer plays a critical determining potentials electrons transferred TiO2...
The transformation of Ni nanoparticles (NPs) different sizes (average diameters 9, 26, and 96 nm) during oxidation to hollow (single void) or porous (multiple voids) NiO through the nanoscale Kirkendall effect was observed by transmission electron microscopy. Samples treated for 1−4 h at 200−500 °C show that structures completely oxidized NPs do not depend on temperature, but proceeds more quickly elevated temperatures. For Ni/NiO system, after formation an initial shell (of thickness ∼3...
The steam reforming of ethanol on a Ni-based CeO2-supported catalyst was studied using in situ X-ray diffraction (XRD), operando diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and mass (MS) with focus the structural characterization catalysts, chemical identification reaction pathway, understanding interaction between Ni CeO2 support. Ethoxy, acetate, carbonate, hydroxyl species are identified by DRIFTS as surface intermediates that appear during process. oxidation...
Going with the grain Changes in surface structure can make metal nanoparticles supported on oxides more active for certain catalytic reactions. Huang et al . show that steam pretreatment of palladium alumina led to a high density twin boundaries, unlike other oxidation and reduction pretreatments. The these stable boundaries at correlated higher methane rates lower temperatures initiation reaction. introduction additional defect sites through laser ablation created even catalysts. —PDS
Conversion of unary metal nanoparticles (NPs) upon exposure to oxygen, sulfur, selenium, and phophorus precursors usually produces hollow oxide, sulfide, selenide, or phosphide NPs through the Kirkendall effect. Here, nanostructural control mixed-phase Ni2P/Ni12P5 (represented as NixPy) prepared thermolysis nickel acetylacetonate using trioctylphosphine (TOP) a ligand phosphorus precursor is reported. The P:Ni molar ratio controls NP size key factor in determining nanostructure. For ratios...
A size series of ligand-stabilized Ni nanoparticles (NPs) with diameters between 8-24 nm was prepared by solution chemistry, followed solution-phase oxidation atmospheric oxygen at 200 degrees C to form Ni(core)/NiO(shell) NPs shell thicknesses 2-3 nm. In comparison the Fe and Co NPs, require higher temperatures for significant conversion NiO. Transmission electron microscopy diffraction show polycrystalline cores predominantly amorphous shells. SQUID magnetometry measurements were performed...
A detailed <italic>in operando</italic> study of the morphological effects nanostructured ceria supports on activity and stability CuO/CeO<sub>2</sub> catalysts for water-gas shift reaction.
Au(core)/Ag(shell) and AuAg alloy nanoparticles are synthesized with stoichiometric control through digestive ripening, a potentially general approach for synthesizing core/shell nanoparticles. obtained by annealing These bimetal have tunable surface plasmon resonance absorbance of interest use in catalysis as taggants security applications. Detailed facts importance to specialist readers published ”Supporting Information”. Such documents peer-reviewed, but not copy-edited or typeset. They...
The redox chemistry and CO oxidation (2CO + O2 → 2CO2) activity of catalysts generated by the dispersion CuO on CeO2 nanorods were investigated using a multitechnique approach. Combined measurements time-resolved X-ray absorption near-edge spectroscopy (XANES) diffuse reflectance infrared Fourier transform (DRIFTS) in one setup made possible with development novel reaction cell which fluorescence mode detection was applied to collect XANES spectra. This is first reported example similar...
Use of bulky ligands (BLs) in the synthesis metal nanoparticles (NPs) gives smaller core sizes, sharpens size distribution, and alters discrete sizes. For BLs, highly curved surface small NPs may facilitate growth, but as increases flattens, NP growth terminate when ligand monolayer blocks BLs from transporting atoms to core. Batches thiolate-stabilized Au were synthesized using equimolar amounts 1-adamantanethiol (AdSH), cyclohexanethiol (CySH), or n-hexanethiol (C6SH). The CyS-...
The ceria–titania mixed metal oxide is an important component of catalysts active for the production hydrogen through water–gas shift reaction (CO + H2O → H2 CO2) and photocatalytic splitting water (H2O hv 0.5O2). We have found that prepared wet chemical methods a unique hierarchal architecture. Atomic resolution imaging by high-angle annular dark field scanning transmission electron microscopy (HAADF STEM) reveals ceria supported on titania exhibits range morphologies. One can clearly...
Cerium oxide nanomaterials (nanoceria, CNMs) are receiving increased attention from the research community due to their unique chemical properties, most prominent of which is ability alternate between Ce3+ and Ce4+ oxidation states. While many analytical techniques methods have been employed characterize amounts present (Ce3+/Ce4+ ratio) within nanoceria materials, to-date no studies used multiple complementary tools (orthogonal analysis) with technique-independent state controls for...
Catechol stabilizes photo-generated holes on metal nanoparticles to create a new multi-hole reaction pathway for oxidizing water under visible light.
Light-driven synthesis of plasmonic metal nanostructures has garnered broad scientific interests. Although it been widely accepted that surface plasmon resonance (SPR)-generated energetic electrons play an essential role in this photochemical process, the exact function plasmon-generated hot holes regulating morphology not fully explored. Herein, we discover those work with adsorbates collectively to control anisotropic growth gold (Au) nanostructures. Specifically, is found stabilized by...
Mixed oxide interfaces are critical for delivering active components of demanding catalytic processes such as the photocatalytic splitting water. We have studied CeOx–TiO2 catalysts with low ceria loadings 1, 3, and 6 wt % that were prepared wet impregnation methods to favor a strong interaction between CeOx TiO2. In these materials been sequentially loaded (1%, 3%, 6%), without Pt (0.5 %). The structure properties characterized using several X-ray electron based techniques including XRD,...
The water-gas shift reaction (WGS, CO + H2O → H2 CO2) was studied over a series of W–Ce, Ni–Ce, and Ni–W–Ce mixed-metal oxide catalysts. structure the catalysts WGS intermediates were characterized using in situ techniques including X-ray diffraction (XRD), absorption near edge (XANES), scanning transmission electron microscopy (STEM), diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS). XANES showed existence Ni2+ W6+ inside ceria lattices. coexistence Ni W led to large...
We demonstrate depth-resolved viscosity measurements within a single object using polarized optical scattering from ensembles of freely tumbling plasmon resonant gold nanorods (GNRs) monitored with polarization-sensitive coherence tomography. The rotational diffusion coefficient the GNRs is shown to correlate in molecular fluids according Stokes-Einstein relation. and highly anisotropic properties are favorable for microrheological studies nanoscale properties.
Supported metal nanoparticles are essential components of high-performing catalysts, and their structures intensely researched. In comparison, nanoparticle spatial distribution in powder catalysts is conventionally not quantified, the influence this collective property on catalyst performance remains poorly investigated. Here, we demonstrate a general colloidal self-assembly method to control uniformity common industrial supports. We quantify distributions nanoscale using image statistics...
Abstract Additive manufacturing (AM) technologies offer unprecedented design flexibility but are limited by a lack of understanding the material microstructure formed under their extreme and transient processing conditions its subsequent transformation during post-build processing. As part 2022 AM Bench Challenge, sponsored National Institute Standards Technology, this study focuses on phase composition evolution nickel alloy 718, nickel-based superalloy, to provide benchmark data essential...