A5017152024- Nuclear materials and radiation effects
- Radioactive element chemistry and processing
- Iron oxide chemistry and applications
- Electronic and Structural Properties of Oxides
- Nuclear Materials and Properties
- Radioactive contamination and transfer
- Mine drainage and remediation techniques
- Fusion materials and technologies
- Minerals Flotation and Separation Techniques
- Advanced Chemical Physics Studies
- Surface Chemistry and Catalysis
- X-ray Diffraction in Crystallography
- X-ray Spectroscopy and Fluorescence Analysis
- Clay minerals and soil interactions
- Crystallization and Solubility Studies
- Electron and X-Ray Spectroscopy Techniques
- Spectroscopy and Quantum Chemical Studies
- Muon and positron interactions and applications
- Semiconductor materials and devices
- Luminescence Properties of Advanced Materials
- Multiferroics and related materials
- Advanced Condensed Matter Physics
- Advanced Materials Characterization Techniques
- Molecular Junctions and Nanostructures
- Quantum Dots Synthesis And Properties
Pacific Northwest National Laboratory
2016-2025
Physical Sciences (United States)
2020-2024
Battelle
2020
Richland College
2017-2018
Curtin University
2012-2014
Aix-Marseille Université
2010-2011
Centre National de la Recherche Scientifique
2008-2011
Institut des Matériaux, de Microélectronique et des Nanosciences de Provence
2009-2010
Direct air capture (DAC) may be feasible to remove carbon dioxide (CO2) from the atmosphere at gigaton scale, holding promise become a major contributor climate change mitigation. Mineral looping using magnesium oxide (MgO) is potentially an economical, efficient, and sustainable pathway gigaton-scale DAC. The hydroxylation carbonation of MgO determine efficiency process, but their rates mechanisms remain uncertain. In this work, single crystals were reacted in or CO2 varying humidities...
Despite substantial experimental evidence for Fe(II)–Fe(III) oxide electron transfer, computational chemistry calculations suggest that oxidation of sorbed Fe(II) by goethite is kinetically inhibited on structurally perfect surfaces. We used a combination 57Fe Mössbauer spectroscopy, synchrotron X-ray absorption and magnetic circular dichroism (XAS/XMCD) spectroscopies to investigate whether Fe(II)–goethite transfer influenced defects. Specifically, Fe L-edge O K-edge XAS indicates the...
We investigate the growth of a two-dimensional polymer obtained by dehydration 1,4-benzenediboronic acid (BDBA). The molecules are vapor deposited under ultrahigh vacuum conditions on well-oriented noble metal---Ag(111), Ag(100), Au(111), and Cu(111)---surfaces. Molecular flux substrate temperature varied to obtain optimum quality, whose structure best approaches that an ideal honeycomb network. find high molecular (\ensuremath{\sim}0.1 monolayer/minute) is necessary initiate BDBA...
Insights at the microscopic level of process radiocesium adsorption and interaction with clay mineral particles have improved substantially over past several years, triggered by pressing social issues such as management huge amounts waste soil accumulated after Fukushima Dai–ichi nuclear power plant accident. In particular, computer–based molecular modeling supported advanced hardware algorithms has proven to be a powerful approach. Its application can now generally encompass full complexity...
Iron-based redox-active minerals are ubiquitous in soils, sediments, and aquatic systems. Their dissolution is of great importance for microbial impacts on carbon cycling the biogeochemistry lithosphere hydrosphere. Despite its widespread significance extensive prior study, atomic-to-nanoscale mechanisms remain poorly understood, particularly interplay between acidic reductive processes. Here, we use situ liquid-phase-transmission electron microscopy (LP-TEM) simulations radiolysis to probe...
Abstract Magnetic spinel oxides have attracted extensive research interest due to their rich physics and wide range of applications. However, these materials invariably suffer suppressed magnetization, structural imperfections (e.g., disorder, anti‐site defects, etc.). Herein, a dramatic enhanced magnetization is obtained with an increasement 5 µ B /u.c in CoFe 2 O 4 (CFO) through ionic liquid gating induced hydrogen doping. The intercalated ions lead both distinct lattice expansion ≈0.7%...
We used density functional theory simulations in combination with ab initio thermodynamics to determine the H2 partial pressure (p_("H" _"2" )) dependent energetics associated activation and recovery at various defect sites hexagonal boron nitride (h-BN). found that some defects are very reactive hydrogen thereby definitely trapping defective h-BN. However, depending on pressure, less can be populated. Because of lower binding capability these sites, they would allow for recycled recovered....
A detailed analysis of the N(1s) and C(1s) X-Ray Photoelectron Spectroscopy (XPS) is made, where measured XPS compared with theoretical Sudden Approximation (SA) intensities Binding Energies (BEs). There remarkably good agreement between predictions XPS; in particular, different full width at half maximum values for BEs are explained terms unresolved C atoms pyridine. This work demonstrates that combination theory measurements can extract relevant to molecular electronic structure. The used...
The self-assembly of benzene diboronic acid molecules on KCl(001) is investigated at room temperature by means noncontact atomic force microscopy. When depositing the freshly cleaved surface, self-assemble into an extended two-dimensional supramolecular phase driven H-bonds. Theoretical calculations based density functional theory show that cohesion energy structure yields almost 1 eV per molecule. In combination with high-resolution structural analysis molecular layer and theoretical...
X-ray absorption near-edge structure (XANES) and magnetic circular dichroism (XMCD) spectroscopies are tools in widespread use for providing detailed local atomic structure, oxidation state, information materials organometallic complexes. The analysis of these spectra transition-metal L-edges is routinely performed on the basis ligand-field multiplet theory because one- two-particle mean-field ab initio methods typically cannot describe structure. Here we show that multireference...
The discontinuation of the bulk structure at interface between metal oxide particles and water leads to altered bonding characteristics unique facet-dependent molecular environments. Surface hydration hydroxylation add further complexity interface, details that for (oxy)hydroxides are especially difficult isolate from background signal structural hydroxyls. Here, we probe first time surface hydroxyl structures effect on basal surfaces gibbsite (α-Al(OH)3) boehmite (γ-AlOOH) nanoplates under...
Ferrihydrite is a poorly crystalline iron oxyhydroxide nanomineral that serves critical role as the most bioavailable form of ferric for living systems. However, its atomic structure and composition remain unclear due in part to ambiguities interpretation X-ray scattering results. Prevailing models so far have not considered prospect at level individual nanoparticles multiple indistinguishable phases could coexist. Using ab initio thermodynamics we show ferrihydrite likely nanocomposite...
Abstract Perovskite structured transition metal oxides are important technological materials for catalysis and solid oxide fuel cell applications. Their functionality often depends on oxygen diffusivity mobility through complex heterostructures, which can be significantly impacted by structural chemical modifications, such as doping. Further, when utilized within electrochemical cells, interfacial reactions with other components (e.g., Ni‐ Cr‐based alloy electrodes interconnects) influence...
Understanding the electrochemical properties of mineral–water interfaces tends to rely upon electrical double layer (EDL) models, but these models are based on assumption that electrostatic equilibrium is constantly maintained. In reality, interfacial reactions, ion diffusion, and their signatures in nonequilibrium conditions locally or globally imbalanced fields where current EDL have limited purview. Here, we performed molecular dynamics (MD) simulations orthoclase (001) surface contact...
Developing a better understanding of water ordering and hydroxylation at oxide mineral surfaces is important across breath application spaces. Recent vibrational sum frequency generation (vSFG) measurements on MgO(100) ambient conditions showed that dissociates hydroxylates the surface yielding non-hydrogen bonded hydroxyl species. Starting from previously determined patterns MgO(100), we performed
We report density functional theory calculations aimed at predicting thermodynamically stable structures for ferrihydrite across a range of possible compositions determined by the amount structural water. Based on an assumed formula unit Fe5O8H + nH2O, we performed ab initio with evolutionary searching to find lowest enthalpy as function water content up n = 2. This is most exhaustive search structure conducted so far; more than 5000 unique configurations were generated and evaluated over...
Epitaxial LaFeO 3 exhibits thickness dependent OER electrocatalysis which balances catalysis at surface defect states with charge transport through the film.
Crystal dissolution, which is a fundamental process in both natural and technological settings, has been predominately viewed as of ion-by-ion detachment into surrounding solvent. Here we report mechanism dissolution by particle (DPD) that dominates mesocrystals formed via crystallization attachment (CPA). Using liquid phase electron microscopy to directly observe hematite crystals - compact rhombohedra coaligned nanoparticles find the evolve branched structures, disintegrate individual...
Our understanding of how Fe(II) reacts with Fe(III) oxides has evolved based on evidence for electron transfer at the oxide–water interface and Fe(II)-catalyzed recrystallization. There is, however, some that these, other processes, such as microbial reduction, cease after continued contact Fe oxide becomes "passivated". Here, we explore mechanism passivation by measuring whether exposure to inhibits Fe(II)–goethite transfer, this inhibition is reversible. To quantify extent used selective...
Storage conditions affect the initial tetrahedral iron and hydroxyl populations of ferrihydrite, both are correlated decrease over time as function ageing.