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Design of efficient Pt-based electrocatalysts through characterization by x-ray absorption spectroscopy

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Frontiers in Energy 2017年第3期11卷 236-244页

作者： Nebojsa S. MARINKOVIC Kotaro SASAKI Radoslav R. ADZIC Synchrotron Catalysis Consortium and Columbia University NY 10027 USA Brookhaven National Laboratory Upton NY 11973 USA

A method is described to determine the internal structure of electrocatalyst nanoparticles by in situ x-ray absorption spectroscopy （xAS）. The nondestructive spec- troscopic technique typically utilizing synchrotron radiation as the source measures changes in the x-ray absorption coefficient as a function of energy. The bulk technique has found its use for materials characterization in all scientific areas, including nanomaterials. The analysis of the internal structure of nanoparticles reveals intera- tomic distances and coordination numbers for each element, and their values and mutual relations indicate whether the elements form a homogeneous or hetero- geneous mixture. The core-shell heterogeneous structure in which certain elements are predominantly located in the core, and others form the encapsulating shell is of particular importance in catalysis and electrocatalysis because it may reduce the amount of precious metals in nanoparticles by replacing the atoms in the core of nanoparticles with more abundant and cheaper alternatives. The examples of nanoparticle structures designed in the laboratory and the approach to model efficient catalysts through systematic analysis of xAS data in electrochemical systems consisting of two and three metals are also demonstrated.

关键词： x-ray absorption spectroscopy ExAFS xANES nanocatalysts core shell

Investigation of the sodium storage mechanism of iron fluoride hydrate cathodes using x-ray absorption spectroscopy and mossbauer spectroscopy

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Journal of Energy Chemistry 2023年第2期77卷 535-542,I0014页

作者： Ghulam Ali Muhammad Akbar Faiza Jan Iftikhar Qamar Wali Beata Kalska Szostko Dariusz Satuła Kyung Yoon Chung Energy Storage Research Center Korea Institute of Science and TechnologyHwarang-ro 14 gil 5Seongbuk-guSeoul 02792South Korea USPCAS-E National University of Sciences and Technology(NUST)H-12Islamabad 44000Pakistan Division of Energy&Environment Technology KIST SchoolKorea University of Science and Technology(UST)Hwarang-ro 14-gil-5Seongbuk-guSeoul 02792South Korea NUTECH School of Applied Sciences and Humanities National University of TechnologyIslamabad 44000Pakistan University of Białystok Faculty of ChemistryCiołkowskiego 1K15-424 BiałystokPoland University of Białystok Faculty of PhysicsCiołkowskiego 1L15-424 BiałystokPoland

Elucidation of a reaction mechanism is the most critical aspect for designing electrodes for highperformance secondary ***,we investigate the sodium insertion/extraction into an iron fluoride hydrate(FeF_(3)·0.5H_(2)O)electrode for sodium-ion batteries(SIBs).The electrode material is prepared by employing an ionic liquid 1-butyl-3-methylimidazolium-tetrafluoroborate,which serves as a reaction medium and precursor for F^(-)*** crystal structure of FeF_(3)·0.5H_(2)O is observed as pyrochlore type with large open 3-D tunnels and a unit cell volume of 1129A^(3).The morphology of FeF_(3)·0.5H_(2)O is spherical shape with a mesoporous *** microstructure analysis reveals primary particle size of around 10 *** FeF_(3)·0.5H_(2)O cathode exhibits stable discharge capacities of 158,210,and 284 mA h g^(-1) in three different potential ranges of 1.5-4.5,1.2-4.5,and 1.0-4.5 V,respectively at 0.05 C *** specific capacities remained stable in over 50 cycles in all three potential ranges,while the rate capability was best in the potential range of 1.5-4.5 *** electrochemical sodium storage mechanism is studied using x-ray absorption spectroscopy,indicating higher conversion at a more discharged ***-situ M?ssbauer spectroscopy strengthens the results for reversible reduction/oxidation of *** results will be favorable to establish high-performance cathode materials with selective voltage window for SIBs.

关键词： Iron fluoride Sodium-ion batteries Pyrochlore x-ray absorption spectroscopy Mössbauer spectroscopy

Dynamical investigation of tunable magnetism in Au@Ni-carbide nanocrystals by a combined soft and hard x-ray absorption spectroscopy

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Nano Research 2022年第5期15卷 4320-4326页

作者： Weifeng Huang Jianxin Kang Tingwen Chen Dawei Pang Lihua Wang Hang Wei Changchun Yang Dongfeng Zhang Lin Guo College of Chemistry and Chemical Engineering Inner Mongolia UniversityHohhot 010021China School of Electronic Engineering Jiujiang UniversityJiujiang 332005China School of Chemistry Beihang UniversityBeijing 100191China Institute of Microstructure and Property of Advanced Materials Beijing University of TechnologyBeijing 100124China

Nickel based magnetic nanocrystals have been widely applied in magnetic and catalytic *** magnetic properties of nickel can be easily obtained via non-magnetic doping or phase ***,phase transformation from face centered cubic(fcc)to hexagonal close packed(hcp)induced magnetism adjustment of Ni are always confused with nickel carbide(Ni_(3)C),due to the similar atomic structures of hcp-Ni and ***,we present series of Au@Ni-carbide magnetic materials achieved from the controlled carbonation of Au@Ni core-shell structures,whose magnetism is tunable by adjusting the amount of carbon in the Ni ***-situ hard x-ray absorption spectroscopy(xAS)at the metal K edge and soft xAS at both metal L edge and carbon K edge provide solid evidence for the carbonation process from fcc-Ni to Ni_(x)C,rather than phase transformation to *** investigation reveals that the magnetism of the hybrids is mainly contributed from the residual *** result represents an accurate and effective way to distinguish hexagonal Ni_(3)C from hcp-Ni,and provides the pathway to control magnetism of Ni-based materials for applications.

关键词： x-ray absorption spectroscopy soft x-ray absorption spectroscopy carbide nickel carbonation process magnetism

Multiple scattering approach to x-ray absorption spectroscopy

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Nuclear Science and Techniques 2003年第1期14卷 9-19页

作者： M.BENFATTO INFN Laboratori Nazionali di Frascati 00044 Frascati Italy

In this paper we present the state of the art of the theoretical background needed for analyzing x-ray absorption spectra in the whole energy range. The multiple-scattering (MS) theory is presented in detail with some applications on real systems. We also describe recent progress in performing geometrical fitting of the xANES (x-ray absorption near-edge structure) energy region and beyond using a full multiple-scattering approach.

关键词： x-ray absorption spectroscopy x-ray absorption near-edge structure. Multiple-scattering theory

The state of gold in phases of the Cu-Fe-S system:In situ x-ray absorption spectroscopy study

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Geoscience Frontiers 2023年第3期14卷 103-116页

作者： Boris R.Tagirov Olga N.Filimonova Alexander L.Trigub Ilya V.Vikentyev Elena V.Kovalchuk Maximilian S.Nickolsky Andrey A.Shiryaev Vladimir L.Reukov Dmitry A.Chareev Institute of Geology of Ore Deposits(IGEM RAS) 35Staromonetnyi per119017 MoscowRussia National Research Centre‘Kurchatov Institute’ 1Akademika Kurchatova pl123182 MoscowRussia Institute of Physical Chemistry and Electrochemistry(IPCE RAS) 31Leninsky Prospect119071 MoscowRussia Institute of Experimental Mineralogy(IEM RAS) 142432 ChernogolovkaMoscow RegionRussia

Chalcopyrite and bornite are the main Au-bearing minerals at Cu porphyry deposits,volcanogenic massive sulfide(VMS)deposits,Cu-Ni deposits of the mafic magmatic complexes,and ores of submarine sulfide *** and intermediate solid solutions with wide compositional variations(bnss and iss–high-temperature chalcopyrite,correspondingly),which can scavenge economic concentrations of Au,appear in the Cu-Fe-S system at ore-forming ***,the state of Au in bnss and iss is yet *** solve this conundrum,we synthesized samples with net chemical composition of bnss and iss,studied them by in situ x–ray absorption spectroscopy(xAS),and used the experimental data to explain the Au distribution among natural ore-forming *** sulfide samples were obtained at 495–700℃ in Au-saturated system by means of salt flux *** bnss contained1.2–1.6 log units more Au than iss:up to 18 wt.%Au in bnss vs 0.4 wt.%Au in iss at 700*** increase of temperature resulted in the sharp increase of Au concentration in both phases,1 log unit per 100℃ at f(S2)close to S_((l)) *** of Au L_(3)-edge spectra recorded at 25–675℃ revealed that at 25℃ Au exists mainly in the metallic *** t>500℃ the spectral features of Audisappear,and “chemically bound”Au *** Au form of occurrence in the iss field is interpreted as Au-bearing clusters with a stromeyerite-like(CuAgS)*** Cu_(2–x)S and bnss contain Au in a mixture of stromeyeritelike and petrovskaite-like(Au_(0.8)Ag_(1.2)S)*** chemical composition of both forms is close to CuAuS,where the nearest Au neighbors are two S atoms at R_(Au-S)=2.34–2.36Å.Results of the present study allow to determine the state of Au and its concentration in the main Cu-bearing minerals of sulfide ores as a function of the T-f(S_(2))-compositional *** to the sharp increase of the CuAuS clusters stability with increasing temperature,in high-temperature ores formed at t>350℃ A

关键词： “Invisible”gold Bornite solid solution Intermediate solid solution Digenite Chalcopyrite x-ray absorption spectroscopy

x-ray absorption spectroscopy Analysis of Lead Species Adsorbed on Various Oxides from High pH Solution

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Journal of Environmental Protection 2020年第10期11卷 807-820页

作者： Takanori Miyake Tetsuo Honma Hiroshi Arimatsu Hiroto Fukunishi Huimin Liu Makoto Sano Yuuki Kakutani Mitsumasa Okada Kaori Shimizu Setsuo Yoshida Kazumasa Suetsugu Faculty of Urban and Environmental Engineering Kansai University Suita Osaka Japan Japan Synchrotron Radiation Institute (JASRI) Sayo-cho Hyogo Japan TOSOH Corporation Shunan Yamaguchi Japan

Lead dissolved in water must be removed in order not to cause diseases, especially from high pH aqueous solution. Various oxides having high specific surface area are often applied to remove lead in water media. To improve removal ability for lead species, it is necessary to understand the adsorbed structure of lead species on oxides. At first, the adsorption behavior of lead from high pH solution in the presence of Ca2+ and Na+ was compared. Lead and calcium species were adsorbed up to the monolayer, and the adsorption isotherm was analyzed as Langmuir-type adsorption. In the presence of Ca2+, the amount of removed lead was reduced. To clarify this influence of Ca2+, x-ray absorption spectroscopy was adopted. It was for the first time revealed that lead species at pH > 12 and pH xides had a similar structure.

关键词： x-ray absorption spectroscopy Water Purification Lead Removal Manganese Oxide Adsorption

Alignment of Vertically Grown Carbon Nanostructures Studied by x-ray absorption spectroscopy

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Materials Sciences and Applications 2014年第13期5卷 966-983页

作者： Jeannot Mane Mane Francois Le Normand Rolant Eba Medjo Costel Sorin Cojocaru Ovidiu Ersen Antoine Senger Carine Laffon Bridinette Thiodjio Sendja César Mbane Biouele Germain Hubert Ben-Bolie Pierre Owono Ateba Philippe Parent IPCMS UMR 7504 CNRSStrasbourgFrance Ecole Nationale Supérieure Polytechnique(National Advanced School of Engineering) Department of Mathematics and Physical SciencesThe University of YaoundéIYaoundeCameroon Physics Department Faculty of ScienceUniversity of YaoundéIYaoundeCameroon Physics Department Faculty of ScienceUniversity of DoualaDoualaCameroon LURE UMR CNRSCentre Universitaire Paris SudOrsayFrance

x-ray absorption spectroscopy (xAS) on the carbon K edge of carbon nanostructures (nanotubes, nanofibers, nanowalls) is reported here. They are grown on plain SiO2 (8 nm thick)/Si(100) substrates by a Plasma and Hot Filaments-enhanced Catalytic Chemical Vapor Deposition (PE HF CCVD) process. The morphology and the nature of these carbon nanostructures are characterized by SEM, TEM and Raman spectroscopy. According to conditions of catalyst preparation and DC HF CCVD process, carbon nanotubes (CNTs), carbon nanofibers (CNFs), carbon nanowalls (CNWs), carbon nanoparticles (CNPs) with different orientation of the graphene plans or shells can be prepared. From the angular dependence of the incident light and geometrical morphology of the nanostructures, wide variations of the C K-edge intensity of the transitions to the empty π* and σ* states occur. A full lineshape analysis of the xAS spectra has been carried out using a home-made software, allowing estimating the relative proportion of π* and σ* transitions. A geometrical model of the angular dependence with the incidence angle of the light and the morphology of the carbon nanostructures is derived. With normalization to the HOPG (Highly Oriented Pyrolytic Graphite graphite) reference case, a degree of alignment can be extracted which is representative of the localized orientation of the graphitic carbon π bonds, accounting not only for the overall orientation, but also for local defects like impurities incorporation, structural defects ... This degree of alignment shows good agreement with SEM observations. Thus CNTs films display degrees of alignment around 50%, depending on the occurrence of defects in the course of the growth, whereas no special alignment can be detected with CNFs and CNPs, and a weak one (about 20%) is detected on CNWs.

关键词： x-ray absorption spectroscopy Carbon Nanostructures(CNTs,CNFs,CNWs,CNPs) Plasma-and Hot Filaments-Enhanced Catalytic Chemical Vapor Deposition Geometrical Model Angular Dependence

In situ infrared, Raman and x-ray spectroscopy for the mechanistic understanding of hydrogen evolution reaction

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Journal of Energy Chemistry 2024年第3期90卷 632-651,I0014页

作者： Andi Haryanto Kyounghoon Jung Chan Woo Lee Dong-Wan Kim Department of Chemistry Kookmin UniversitySeoul 02707Republic of Korea School of Civil Environmental and Architectural EngineeringKorea UniversitySeoul 02841Republic of Korea

Hydrogen production by water reduction reactions has received considerable attention because hydrogen is considered a clean-energy carrier,key for a sustainable energy *** methods have been widely used to study the reaction mechanism of the hydrogen evolution reaction(HER),but the calculation results need to be supported by experimental results and direct evidence to confirm the mechanistic *** this review,we discuss the fundamental principles of the in situ spectroscopic strategy and a theoretical model for a mechanistic understanding of the *** addition,we investigate recent studies by in situ Fourier transform infrared(FTIR),Raman spectroscopy,and x-ray absorption spectroscopy(xAS) and cover new findings that occur at the catalyst-electrolyte interface during *** spectroscopic strategies provide practical ways to elucidate catalyst phase,reaction intermediate,catalyst-electrolyte interface,intermediate binding energy,metal valency state,and coordination environment during HER.

关键词： Hydrogen evolution reaction Infrared spectroscopy Raman spectroscopy x-ray absorption spectroscopy Reaction mechanism

Exploring battery material failure mechanisms through synchrotron x-ray characterization techniques

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Journal of Energy Chemistry 2024年第7期94卷 128-135页

作者： Lingzhe Fang xiaozhao Liu Tao Li Department of Chemistry and Biochemistry Northern Illinois UniversityDeKalbIL 60115USA x-ray Science Division and Joint Center forEnergy Storage Research Argonne National LaboratoryLemontIL6439UA

Rechargeable battery cycling performance and related safety have been persistent *** is crucial to decipher the capacity fading induced by electrode material failure via a range of *** these,synchrotron-based x-ray techniques with high flux and brightness play a key role in understanding degradation *** this comprehensive review,we summarize recent advancements in degra-dation modes and mechanisms that were revealed by synchrotron x-ray ***,an overview of x-ray absorption spectroscopy and x-ray scattering techniques is introduced for charac-terizing failure phenomena at local coordination atomic environment and long-range order crystal struc-ture scale,*** last,we envision the future of exploring material failure mechanism.

关键词： Battery failure Synchrotron-based techniques x-ray scattering x-ray absorption spectroscopy