A5079144541- Electrocatalysts for Energy Conversion
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- CO2 Reduction Techniques and Catalysts
- Metal-Catalyzed Oxygenation Mechanisms
- Photosynthetic Processes and Mechanisms
- Enzyme Structure and Function
- X-ray Spectroscopy and Fluorescence Analysis
- Porphyrin and Phthalocyanine Chemistry
- Ionic liquids properties and applications
- Magnetism in coordination complexes
- Advanced battery technologies research
- Electrochemical Analysis and Applications
- Catalytic Processes in Materials Science
- Metal complexes synthesis and properties
- Advanced X-ray Imaging Techniques
- Advanced Electron Microscopy Techniques and Applications
- Spectroscopy and Quantum Chemical Studies
- Advanced Photocatalysis Techniques
- Carbon dioxide utilization in catalysis
- Electron and X-Ray Spectroscopy Techniques
- Astronomy and Astrophysical Research
- Copper-based nanomaterials and applications
- Semiconductor materials and devices
- Atomic and Molecular Physics
Synchrotron soleil
2014-2024
Lawrence Berkeley National Laboratory
2012-2015
Berkeley College
2014-2015
Institut de Biologie et Technologies
2009-2014
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2009-2014
Université Paris-Sud
2006-2013
Institut de Chimie Moléculaire et des Matériaux d'Orsay
2006-2013
Centre National de la Recherche Scientifique
2007-2013
Energy Biosciences Institute
2011
Université Paris Cité
2007-2009
An oxygen evolution catalyst that forms as a thin film from Ni(aq)(2+) solutions containing borate electrolyte (Ni-B(i)) has been studied by in situ X-ray absorption spectroscopy. A dramatic increase catalytic rate, induced anodic activation of the electrodeposited films, is accompanied structure and oxidation state changes. Coulometric measurements correlated with near-edge spectra active show nickel centers activated films possess an average +3.6, indicating substantial proportion exist...
In situ X-ray absorption spectroscopy (XAS) is a powerful technique that can be applied to electrochemical systems, with the ability elucidate chemical nature of electrocatalysts under reaction conditions. this study, we perform in XAS measurements on bifunctional manganese oxide (MnOx) catalyst high activity for oxygen reduction (ORR) and evolution (OER). Using near edge structure (XANES) extended fine (EXAFS), find exposure an ORR-relevant potential 0.7 V vs RHE produces disordered...
Abstract Molecular catalysts that combine high product selectivity and current density for CO 2 electrochemical reduction to or other chemical feedstocks are urgently needed. While earth-abundant metal-based molecular electrocatalysts with conversion known, they characterized by densities significantly lower than those obtained solid-state metal materials. Here, we report a cobalt phthalocyanine bearing trimethyl ammonium group appended the macrocycle is capable of reducing in water activity...
Intense femtosecond x-ray pulses produced at the Linac Coherent Light Source (LCLS) were used for simultaneous diffraction (XRD) and emission spectroscopy (XES) of microcrystals photosystem II (PS II) room temperature. This method probes overall protein structure electronic Mn4CaO5 cluster in oxygen-evolving complex PS II. XRD data are presented from both dark state (S1) first illuminated (S2) Our XRD-XES study shows that crystals intact during our measurements LCLS, not only with respect to...
The oxygen evolution reaction (OER) is a key process that enables the storage of renewable energies in form chemical fuels. Here, we describe catalyst exhibits turnover frequencies higher than state-of-the-art catalysts operate alkaline solutions, including benchmark nickel iron oxide. This new easily prepared from readily available and industrially relevant foam, it stable for many hours. Operando X-ray absorption spectroscopic data reveal made nanoclusters γ-FeOOH covalently linked to...
The sandwich-type polyoxometalate (POM) [(PW9O34)2Co4(H2O)2]10– was immobilized in the hexagonal channels of Zr(IV) porphyrinic MOF-545 hybrid framework. resulting composite fully characterized by a panel physicochemical techniques. Calculations allowed identifying localization POM vicinity Zr6 clusters and porphyrin linkers constituting MOF. material exhibits high photocatalytic activity good stability for visible-light-driven water oxidation. It thus represents rare example an all-in-one...
The reduction of protons into dihydrogen is important because its potential use in a wide range energy applications. preparation efficient and cheap catalysts for this reaction one the issues that need to be tackled allow widespread hydrogen as an carrier. In paper, we report study amorphous molybdenum sulfide (MoSx) proton reducing electrocatalyst under functional conditions, using situ X-ray absorption spectroscopy. We probed local electronic structures both sulfur elements prepared...
Abstract Conversion of CO 2 into valuable molecules is a field intensive investigation with the aim developing scalable technologies for making fuels using renewable energy sources. While electrochemical reduction and formate are approaching industrial maturity, current challenge obtaining more reduced products like methanol. However, literature on matter scarce, even use molecular catalysts. Here, we demonstrate that cobalt phthalocyanine, well‐known catalyst conversion to CO, can also...
Unveiling the mechanism of electrocatalytic processes is fundamental for search more efficient and stable electrode materials clean energy conversion devices. Although several in situ techniques are now available to track structural changes during electrocatalysis, especially water oxidation, a direct observation, real space, morphological nanostructured electrocatalysts missing. Herein, we implement an electrochemical Transmission Electron Microscopy (in EC-TEM) methodology studying oxygen...
An electrospun liquid microjet has been developed that delivers protein microcrystal suspensions at flow rates of 0.14–3.1 µl min −1 to perform serial femtosecond crystallography (SFX) studies with X-ray lasers. Thermolysin microcrystals flowed 0.17 and diffracted beyond 4 Å resolution, producing 14 000 indexable diffraction patterns, or four per second, from 140 µg protein. Nanoflow electrospinning extends SFX biological samples necessitate minimal sample consumption.
Light–water reactor: An amorphous molybdenum sulfide species structurally similar to reduced MoS3 is shown be photocatalytically active for hydrogen generation from H2O with visible light (see picture; TEOA=triethanolamine). Thermally deposited in one step, photosensitized by quantum-controlled semiconductor nanocrystals that serve as model systems the photophysics of solar fuel generation.
Most of the dioxygen on earth is generated by oxidation water photosystem II (PS II) using light from sun. This light-driven, four-photon reaction catalyzed Mn 4 CaO 5 cluster located at lumenal side PS II. Various X-ray studies have been carried out cryogenic temperatures to understand intermediate steps involved in mechanism. However, necessity for collecting data room temperature, especially studying transient during O–O bond formation, requires development new methodologies. In this...
We report the generation and characterization of a new high-spin iron(IV)–oxo complex supported by trigonal nonheme pyrrolide platform. Oxygen-atom transfer to [(tpaMes)FeII]− (tpaAr = tris(5-arylpyrrol-2-ylmethyl)amine) in acetonitrile solution affords Fe(III)–alkoxide product [(tpaMes2MesO)FeIII]− resulting from intramolecular C–H oxidation with no observable ferryl intermediates. In contrast, treatment phenyl derivative [(tpaPh)FeII]− trimethylamine N-oxide produces [(tpaPh)FeIV(O)]− that...
The GALAXIES beamline at the SOLEIL synchrotron is dedicated to inelastic X-ray scattering (IXS) and photoelectron spectroscopy (HAXPES) in 2.3-12 keV hard range. These two techniques offer powerful complementary methods of characterization materials with bulk sensitivity, chemical orbital selectivity, resonant enhancement high resolving power. After a description components endstations, capabilities are demonstrated through selection recent works both solid gas phases using either IXS or...
The structural and electronic properties of a series manganese complexes with terminal oxido ligands are described. span three different oxidation states at the center (III-V), have similar molecular structures, contain intramolecular hydrogen-bonding networks surrounding Mn-oxo unit. Structural studies using X-ray absorption methods indicated that each complex is mononuclear occurs centers, which also supported by electron paramagnetic resonance (EPR) studies. This gives high-spin Mn(V)-oxo...
The ultrabright femtosecond X-ray pulses provided by free-electron lasers open capabilities for studying the structure and dynamics of a wide variety systems beyond what is possible with synchrotron sources. Recently, this “probe-before-destroy” approach has been demonstrated atomic determination serial diffraction microcrystals. There question whether similar can be extended to probe local electronic spectroscopy. To address this, we have carried out emission spectroscopy (XES) at Linac...
Oxomanganese(V) species have been implicated in a variety of biological and synthetic processes, including their role as key reactive center within the oxygen-evolving complex photosynthesis. Nearly all mononuclear Mn(V)-oxo complexes tetragonal symmetry, producing low-spin species. A new high-spin that was prepared from well-characterized oxomanganese(III) having trigonal symmetry is now reported. Oxidation experiments with [FeCp(2)](+) were monitored optical electron paramagnetic resonance...
Abstract Combining high activity and stability, iridium oxide remains the gold standard material for oxygen evolution reaction in acidic medium green hydrogen production. The reasons higher electroactivity of amorphous oxides compared to their crystalline counterpart is still matter an intense debate literature and, a comprehensive understanding needed optimize its use allow development water electrolysis. By producing iridium-based mixed using aerosol, we are able decouple electronic...
Carbon dioxide reduction reaction (CO2RR) is a promising method for converting CO2 into value-added products. CO2RR over single-atom catalysts (SACs) widely known to result in chemical compounds such as carbon monoxide and formic acid that contain only one atom (C1). Indeed, at least two active sites are commonly believed be required C–C coupling synthesize compounds, ethanol propylene (C2+), from CO2. However, experimental evidence suggests iron phthalocyanine (PcFe), which possesses single...
L-edge spectroscopy of 3d transition metals provides important electronic structure information and has been used in many fields. However, the use this method for studying dilute aqueous systems, such as metalloenzymes, not prevalent because severe radiation damage lack suitable detection systems. Here we present spectra from a Mn solution using high-transmission zone-plate spectrometer at Linac Coherent Light Source (LCLS). The optimized discriminating signal overwhelming O K-edge...