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Studying the materials chemistry in solution utilizing X-ray spectroscopic and scattering studies

The newest generation X-ray synchrotron sources and FELs provide opportunity to study chemistry of materials with an ultra high temporal-, energy- and spatial-resolution, thereby enabling the scientific investigation not covered by textbooks. The aim of this symposium is to overarch the cutting edge research in this vigorously emerging field of X-rays scattering and spectroscopy.


The two days symposium will focus on research making use of modern large-scale research facilities like synchrotrons, X-ray free electron lasers for studying chemistry of organic, inorganic and bio-inorganic materials. It would be an excellent opportunity to bring together scientists from different communities employing novel X-rays spectroscopic and scattering techniques to study wide range of chemical transformations in solution.

The ultimate goal of the symposium is to highlight how the modern methods can be utilized in identifying and resolving the central questions related to colloidal nano-materials, photo-, electro- and biological catalysis and to the lesser extends on the methods themselves.

In this context, the symposium will allow to establish the fundamental knowledge, which in the future will leverage the discovery of the new chemical reactions, efficient catalytic processes and nano-materials with unique novel properties.

Moreover, symposium will particularly showcase the chemical processes at different time scales ranging from ultrafast molecular movies, which are visualizing the bond formation during catalytic or biological processes to the relatively “slow” kinetics of nanoparticles growth.

Hot topics to be covered by the symposium:

The proposed symposium will cover the X-ray  synchrotron and FEL scattering and spectroscopic studies related to the research areas related to Bio- & Nano Inorganic Materials, particularly:

  • Bio-inorganic molecules, clusters and complexes
  • Inorganic clusters, colloidal synthesis of nanoparticle and complex nano-structures, 
  • Synthesis and properties of colloidal 2D materials
  • Hydrothermal, solvothermal and supercritical reactions and synthesis of nanoparticles and metal-organic-frameworks
  • Nucleation, growth and phase transition of nanoparticles in solution
  • Assembly inorganic building blocks into complex structures & bio-mineralization
  • Ferrofluids and their theranostic application
  • Light-driven chemical reactions in solution
  • Photo-catalytic materials and reactions
  • Photo-electrochemical reactions incl. flow batteries, electrolytes for Li-ion batteries  
  • Reactors and micro-reactors for time resolved studies in solution

List of invited speakers (confirmed):

  • Majed Chergui, EPFL, Switzerland
  • Mari-Ann Einarsrud, NTNU, Ålesund, Norway
  • Yoshihisa Harada, The University of Tokyo, Japan
  • Bo Iversen, Aarhus University, Denmark
  • A. Platero-Prats, Universidad Autónoma de Madrid, Spain
  • David M. Tieder, Argonne National Laboratory, USA
  • Moniek Tromp, University of Groningen, The Netherlands
  • Junko Yano, Lawrence Berkley National Laboratory, Physical Biosciences Division, USA
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Session 1 : Dorota Koziej
Authors : Bo Brummerstedt Iversen
Affiliations : Department of Chemistry & iNANO, Aarhus University, DK-8000 Aarhus C, Denmark

Resume : X-ray and neutron investigations of the atomic structure of crystalline matter represent a shining cornerstone in science, but so far crystallography has essentially concerned “static”, “average” structures of materials at idealized conditions. Tremendous progress can be achieved if we can study real structures of real materials under real conditions in real time. The rapid development of X-ray total scattering facilitated by immense progress in radiation sources and analysis software has given the possibility to study non-crystalline samples. Using special in situ reactors we have followed nanocrystal nucleation and growth [1, 2] and shown that classical nucleation theories are far from the truth [3]. In this talk recent examples on MOFs [4] and core-shell nanocatalysts [5] will be discussed. References 1. In Situ Studies of Solvothermal Synthesis of Energy Materials, Jensen, K. M. Ø.; Tyrsted, C.; Bremholm, M.; Iversen, B. B. ChemSusChem 2014, 7, 1594-1611 2. Pitfalls and reproducibility of in situ synchrotron powder X-ray diffraction studies of solvothermal nanoparticle formation, Andersen, H. L.; Bøjesen, E. D.; Birgisson, S.; Christensen, M.; Iversen, B. B. J. Appl. Crystallogr. 2018, 51, 526-540 3. The chemistry of nucleation, Bøjesen, E. D.; Iversen, B. B. CrystEngComm 2016, 18, 8332 – 8353 4. The Chemistry of Nucleation: In situ Pair Distribution Function analysis of secondary building units during UiO-66 MOF formation, Xu, H.; Sommer, S.; Broge, N. L. N.; Gao, J.; Iversen, B. B. Chem. Eur. J. 2019, in press 5. Formation mechanism of epitaxial palladium-platinum core-shell nanocatalysts during versatile and scalable supercritical synthesis, Broge, N. L. N.; Søndergaard-Pedersen, F. M.; Sommer, S.; Iversen, B. B., in review

Authors : Jonathan De Roo,1,4 Soham Banerjee,5 Hannes Rijckaert,1 Katrien De Keukeleere,1 Fabien Delpech,2 Yannick Coppel,3 Zeger Hens,1 Isabel Van Driessche,1 Jonathan Owen,4 Simon Billinge5
Affiliations : 1. Department of Chemistry, Ghent University, Gent B-9000, Belgium 2. INSA, UPS, CNRS, Laboratoire de Physique et Chimie des Nano-Objets (LPCNO), Universitéde Toulouse, 31077 Toulouse cedex 9, France 3. Laboratoire de Chimie de Coordination, CNRS, UPR 8241, Université de Toulouse, 31077 Toulouse cedex 9, France 4. Department of Chemistry, Columbia University, New York 10027, United States 5. Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA

Resume : Colloidal inorganic nanocrystals (NCs) are complex structures for a which a single technique is insufficient to completely elucidate the total structure. Here,[1,2] we analyze zirconia NCs that are synthesized in tri-n-octylphosphine oxide (TOPO). Through a combination of transmission electron microcopy, x-ray pair distribution function analysis, dynamic light scattering and nuclear magnetic resonances (both liquid and solid state) we interrogate the NC structure at different length and time scales. First, we establish that the NCs have a distorted tetragonal crystal structure. Disregarding a small structural misfit in the low-r region of the PDF (from ligand-NC correlations that are not included in the refinement), the agreement factor Rw is exceptionally low, approaching the value for the Ni calibrant, thus indicating a very high phase purity of the nanocrystal. Second we show that the NC surface is capped by di-n-octylphosphinate and P,P′-(di-n-octyl) pyrophosphonate. In addition, hydrogen chloride associates with the metal oxide NC surface and protonates TOPO. The resulting hydroxyl-tri-noctylphosphonium is tightly associated with the NC surface due to electrostatic interactions and hydrogen bonding. As such, we have elucidated both the core and the surface structure of these ZrO2 NCs, arriving at a complete structural model. [1] Rijckaert, H. et al, Materials, 2018, 11, 1066 [2] De Roo, J. et a. Chemistry of Materials 2017, 29, 10233

Authors : Gilles Philippot (1), Aimery Auxemery (1), Denis Testemale(2), Jean-Louis Hazemann(2), Bo Iversen(3) & Cyril Aymonier (1)
Affiliations : (1) CNRS, Univ. Bordeaux, Bordeaux INP, ICMCB, UMR 5026, F-33600 Pessac, France, (2) CNRS, Université Grenoble Alpes, Institut NEEL, F-38000 Grenoble, France (3) Center for Materials Crystallography, Department of Chemistry and iNANO, Aarhus University, Aarhus, Denmark

Resume : For more than 20 years, the development of nanomaterials has been at the heart of many technological innovations, ranging from catalysis to optics and electronics. In any case, it is always necessary to use materials whose characteristics of size, crystallinity, purity, composition, etc. are perfectly controlled. It is in this context that the technology implementing supercritical fluids is an interesting alternative. Indeed, where the so-called conventional methods can reach their limits for the production of particles of a few nanometers, this technology enables the continuous synthesis of high-quality nanocrystals in a single step. Nevertheless, the synthesis being fast (a few seconds), it is necessary to develop in situ tools in order to track in real time the formation of these nanocrystals from the molecular organization in solution to the nanocrystals growth. This allows us to better understand the reaction mechanisms and therefore improve our control over the nanocrystals produced in terms of size, size distribution, crystallinity, etc. To do this, the use of large instruments is essential because it allows to perform absorption or X-ray diffraction analysis in situ with a good compromise between acquisition time and signal resolution. In this paper, we first propose to introduce this innovative synthesis process using fluids under supercritical conditions. Then, we will present the reactors developed to meet the specificities of large instruments in order to perform in situ measurements. Finally, we will illustrate our presentation by presenting the study of ZrO2 nanocrystals the formation, notably by the total X-ray scattering method and in particular the analysis of the pair distribution function (PDF).

10:00 Coffee Break    
Authors : Mari-Ann Einarsrud
Affiliations : Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, Trondheim, Norway

Resume : We are developing an aqueous synthesis platform for thin films and nanostructured piezoelectric oxide materials based on an in situ characterization toolbox to gain knowledge about the nucleation and growth mechanisms. This knowledge gives us valuable information to design materials with desired properties. Aqueous chemical synthesis is environmental friendly and highly flexible route to tailored thin films and nanostructured piezoelectric materials. For studies of hydrothermal synthesis an in situ cell using synchrotron X-ray radiation has been developed. We have investigated the formation mechanisms of lead-free MNbO3 (M = K, Na), BaTiO3 and SrxBa1-xNb2O6 piezoelectrics from salt and oxide precursors. Fast detectors and high brilliance synchrotron X-ray source facilitates the investigation of the nucleation and formation on a sub-second scale even for dilute chemical reactions that is required to obtain a high control and reproducibility. Chemical solution deposition of piezoelectric thin films demands a strong control of processing parameters to obtain phase pure oriented films and we have developed an in situ cell with atmospheric control for synchrotron X-ray studies of the pyrolysis step during aqueous chemical solution deposition processing. Understanding the evolution of the nucleation and crystallization of K0.5Na0.5NbO3, BaTiO3 and SrxBa1-xNb2O6 thin films guide designing the optimal procedure for fabrication and tuning the desired piezoelectric properties.

Authors : Juliusz Kuciakowski 1 2, Angelika Kmita 1, Dorota Lachowicz 1, Krzysztof Pitala 1 2, Magdalena Wytrwał 1, Sara Lafuerza 3, James Ablett 4, Amélie Juhin 5, Dorota Koziej 6, Marcin Sikora 1
Affiliations : 1. ACMiN, AGH University of Science and Technology, Kraków, Poland; 2. PACS, AGH University of Science and Technology, Kraków, Poland; 3. European Synchrotron Radiation Facility, Grenoble, France; 4. Synchrotron SOLEIL, Gif-sur-Yvette, France; 5. IMPMC, Sorbonne Universités, UMR CNRS 7590, Paris, France; 6, CHyN, Hamburg University, Hamburg, Germany

Resume : Magnetic properties of superparamagnetic iron oxide nanoparticles (SPION) in solution are routinely determined using volume magnetometry probes, namely VSM or SQUID. However, quantitative analysis of these results is often challenged by uncertainty in concentration, size distribution and chemical composition of particles, especially when probed directly after synthesis and/or separation. In this talk we will assess the application of hard X-ray photon-in photon-out magnetic spectroscopy, namely 1s2p RIXS-MCD, for in-situ quantitative probing of SPION magnetic properties. Details of the experimental procedure and results of preliminary measurements performed on dispersions of maghemite, zinc doped iron oxide and cobalt ferrite nanoparticles will be discussed. We will present the feasibility of probing site selectively magnetic properties of iron ions simultaneously with their site distribution in spinel ferrite lattice. Moreover, we will demonstrate that carrier-free magnetization profiles of SPION can be directly derived from the field dependence of RIXS-MCD intensity. Thus, the distribution of magnetic diameters of SPION in solution can be derived without the uncertainty related to diamagnetic contribution of carrier fluid.

Authors : Dr. Susan R Cooper, Asst. Prof. Kirsten Jensen, Prof. James Hutchison
Affiliations : University of Copenhagen, University of Oregon

Resume : The main goal of synthetic chemistry is to achieve the rational design of materials to be used in applications. However, for inorganic metal oxide nanoparticles there is a lack in mechanistic understanding of formation, making it difficult to synthesize the exact particle of interest. In fact, in the case of nanoparticles, only broad mechanistic models, like classical nucleation and growth theory, are used to describe their formation and therefore, the specific chemistry of the material being formed is overlooked. By studying the properties of spinel iron oxide nanoparticles we have shown that the specific chemistry of the system makes an impact because different synthetic techniques produce particles with different magnetic properties though they have the same core diameter. A new synthetic technique, a continuous growth method, allows for sub nanometer control of particle diameter. Particles made by continuous growth were analyzed by Total X-Ray Scattering with Pair Distribution Function analysis in order to obtain structural information on particles from 3-8 nm in diameter. With an increased understanding of how structure evolves over size, we are able to explain observed growth behavior in the continuous growth method. From this we gain mechanistic insight on how particles form and how the changing size of the nanoparticle core impacts growth. This work is an example of how Total X-ray Scattering studies can be used to enable rational design of metal oxide nanoparticles.

Authors : Alexandra CANTARANO, Denis TESTEMALE, Alain IBANEZ, Géraldine DANTELLE
Affiliations : Institut Néel, CNRS UPR 2940, 25 avenue des Martyrs, 38042 GRENOBLE Cedex 09, FRANCE

Resume : Ce3+-doped Y3Al5O12 nanocrystals (YAG:Ce NCs) are under development for light converters based on their potential high photoluminescence efficiency, with foreseen applications in nanostructured white LED devices. Two parameters are key to produce highly efficient YAG:Ce Ncs: the control of the NC crystal quality and the minimization of the quantity of Ce4+ ions, which are detrimental for photoluminescence properties. In this context, size-controlled highly crystalline NCs were synthesized by a modified solvothermal route, which offers fine control over nucleation and growth steps during YAG:Ce formation. Cerium oxidation state was determined during the NC synthesis by in situ XANES. Using high energy resolution fluorescence-detected X-ray absorption spectroscopy, Ce3+ and Ce4+ XANES signals could be distinguished, allowing the quantification of each ion within the nanocrystals. Thus, we showed that partial oxidation of luminescent Ce3+ into optically-silent Ce4+ was favoured at high synthesis temperatures (≥ 400°C). The Ce3+/Ce4+ ratio was also determined for other types of garnet-type NCs, showing that the host nature influences significantly the oxidation rate of cerium dopant. These results underpin a better understanding of the origin of cerium partial oxidation, thus opening the route to YAG:Ce NCs syntheses with reduced Ce4+ ions presence.

Authors : Coline Bretz, Andrea Vaccaro, Andreas C. Völker
Affiliations : LS Instruments, Fribourg, Switzerland,

Resume : Self-assembly occurring in colloidal suspensions generates a broad range of structures with fascinating properties. The formation and utilization of such colloidal assemblies has been an extensive subject of research and a promising route for the fabrication of advanced materials. Among the various techniques employed to characterize the properties of colloidal suspensions, Static (SLS) and Dynamic (DLS) Light Scattering stand out as extremely versatile and powerful tools. Accurate characterization using SLS and DLS methods mandates the measurement and analysis of singly scattered light. Structures however typically only appear in concentrated samples. The suppression of multiple scattering is therefore required to obtain meaningful results. To achieve this, the so-called Modulated 3D cross-correlation technique [1,2] uses two temporally separated light scattering experiments performed at the same scattering vector on the same sample volume in order to extract only the single scattering information common to both. In this presentation, we will give an overview of the Modulated 3D technology and its performances in Static Light Scattering studies. Using a charge-stabilized suspension of Poly-n-Butylacrylamide-Polystyrene copolymer, we demonstrate the measurement of a structure factor. We will show how the Modulated 3D cross-correlation technology enables us to fully characterize the sample properties by detecting features not accessible by traditional light scattering techniques. [1] Patent EP2365313 A1 [2] Ian D. Block and Frank Scheffold, “Modulated 3D cross-correlation light scattering: Improving turbid sample characterization”, Rev. Sci. Instrum. 81, 123107 (2010).

12:00 Lunch    
Session 2 : Karena Chapman
Authors : M. Chergui
Affiliations : Lab. of Ultrafast Spectroscopy (LSU) Lausanne Centre for Ultrafast Science (LACUS) Ecole Polytechnique Fédérale de Lausanne ISIC, FSB, Station 6 CH-1015 Lausanne, Switzerland

Resume : Using a combination of steady-state and ultrafast X-ray and deep-ultraviolet (UV) spectroscopies, we have investigated: a) the electron dynamics and charge trapping in anatase TiO2 nanoparticles (NPs) in solution.(1) While free carriers relax at extremely fast time scales (<50 fs) to the bottom of the conduction band,(2) charge trapping also takes place immediately after their creation.(3,4) The electron traps are due to pentacoordinated defects in the defect rich shell region of the NPs.(3) b) we also report on electron cooling in ZnO, which turns out to be much slower than in TiO2. Furthermore, time-resolved X-ray absorption and emission spectroscopy reveals signatures of hole trapping in ZnO NPs,(5) which is found to proceed slowly (>1 ps). These results are discussed from a fundamental point of view, but also in relation to applications in photovoltaics and photocatalysis. References: 1. Strongly bound excitons in anatase TiO2 single crystals and nanoparticles E. Baldini, L. Chiodo, S. Moser, J. Levallois, E. Pomarico, G. Auböck, A. Magrez, L. Forro, M. Grioni, A. Rubio and M. Chergui. Nature Communications 8 (2017) 13 2. Clocking the Ultrafast Electron Cooling in Anatase Titanium Dioxide Edoardo Baldini, Tania Palmieri, Enrico Pomarico, Gerald Auböck, and Majed Chergui ACS Photonics 5 (2018) 1241−1249 3. Mapping the trapping of electrons in photoexcited TiO2 by picosecond X-ray absorption spectroscopy M. Hannelore Rittmann-Frank, C.J. Milne, J. Rittmann, M. Reinhard, T. J. Penfold and M. Chergui Angewandte Chemie International Edition 53 (2014) 5858 –5862 4. Femtosecond X-ray absorption study of electron localization in photoexcited anatase TiO2 F. G. Santomauro, A. Lübcke, J. Rittmann, E. Baldini, A. Ferrer, M. Silatani, P. Zimmermann, S. Grübel, J. A. Johnson, S. O. Mariager, P. Beaud, D. Grolimund, C. Borca, G. Ingold, S.L. Johnson, M. Chergui Scientific Reports 5 (2015) 14834-1-6 5. Revealing hole trapping in ZnO nanoparticles by time-resolved X-ray spectroscopy Thomas J. Penfold, Jakub Szlachetko, Fabio G. Santomauro, Alexander Britz, Wojciech Gawelda, Gilles Doumy, Anne Marie March, Stephen H. Southworth, Jochen Rittmann, Rafael Abela, Majed Chergui and Christopher J. Milne. Nature Communications 9 (2018) 478

Authors : Y. Harada (1,2,3), K. Yamazoe (2), J. Miyawaki (1,2,3), Y.-T. Cui (2,3), Y. Higaki (4,5), Y. Inutsuka (4), D. Murakami (4,5), M. Tanaka (4,5) and A. Takahara (4,5)
Affiliations : 1: Department of Advanced Materials Science, The University of Tokyo, Japan; 2: Institute for Solid State Physics, The University of Tokyo, Japan. 3: Synchrotron Radiation Research Organization, The University of Tokyo, Japan. 4: Graduate School of Engineering, Kyushu University, Japan. 5: Institute for Materials Chemistry and Engineering, Kyushu University, Japan

Resume : X-ray absorption (XAS) and emission (XES) spectroscopy of liquid water are one of the cutting-edge techniques to determine the local hydrogen bond structure of liquid water through observation of the valence electronic structure.[1-3] An XES study of liquid water at an interface gives us a good opportunity to explore isolated or highly ordered water molecules unexpected in bulk liquid water. In this paper, XES studies on such “unique” water molecules are presented. Water encapsulated in an electrolyte polymer brush, Poly(2-(methacryloyloxy)ethyl trimethylammonium chloride), is well suited for the investigation of interaction between water and polymers as well as confinement of water by these polymer brushes.[4,5] The apparent relationship between each XAS/XES spectral profile and a specific hydrogen bond configuration characterized by its strength and local symmetry is demonstrated. The results indicated that the confined water has tetrahedrally coordinated hydrogen bonds with a uniform distortion like high pressure ice, which should be naturally connected to control the antifouling and lubricating functions of polyelectrolyte brushes. [1] T. Fransson, Y. Harada, N. Kosugi et al., Chem. Rev. 116, 7551 (2016). [2] S. Myneni, Y. Luo, L.-Å. Näslund et al. J. Phys.: Condens. Matter 14, L213 (2002). [3] T. Tokushima, Y. Harada, O. Takahashi et al., Chem. Phys. Lett. 460, 387 (2008). [4] K. Yamazoe, Y. Higaki, Y. Inutsuka et al., Langmuir 33, 3954 (2017). [5] M. Kobayashi, Y. Terayama, H. Yamaguchi et al., Langmuir 28, 7212 (2012).

Authors : Jonathan Quinson |1], Sarah Neumann [2], Laura Kacenauskaite [1], Alessandro Zana [3], Jacob J. K. Kirkensgaard [4], Søren B. Simonsen [5], Luise Theil Kuhn [5], Mehtap. Oezaslan [6], Sebastian Kunz [2], Matthias Arenz [3]
Affiliations : [1] University of Copenhagen, Chemistry Department, Universitetsparken 5, 2100 Copenhagen Ø, Denmark [2] University of Bremen, Institute for Applied and Physical Chemistry, Leobenerstraße, 28359 Bremen, Germany [3] Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark [4] Technical University of Denmark, Imaging and Structural Analysis, Department of Energy Conversion and Storage, Freriksborgvej 399, 4000 Roskilde, Denmark [5] Carl von Ossietzky Universität Oldenburg, School of Mathematics and Science Department of Chemistry, 26111 Oldenburg, Germany [6] University of Bern, Department of Chemistry and Biochemistry, Freiestrasse 3 CH-3012 Bern, Switzerland

Resume : The Co4Cat (colloids for catalysts) synthesis is a recently reported method to produce colloidal dispersions of surfactant-free precious metal nanoparticles (NPs) in alkaline mono-alcohols [1]. The Co4Cat technology leads to NPs with superior catalytic performances versus industrial benchmarks. To optimise the synthesis and the catalytic properties, a detailed understanding of the NP growth mechanism is gained using X-ray absorption spectroscopy but also in-situ small angle X-ray scattering and transmission electron microscopy. The growth mechanism strongly differs in the two simplest mono-alcohols suitable for the synthesis: in methanol a fast nucleation and moderate growth is achieved whereas in ethanol nucleation is followed by a continuous growth [2]. Together with infra-red spectroscopy studies these results are explained by the in-situ formation of CO adsorbed on the NP surface by oxidation of the solvent (or absence of these species due to poor oxidation properties) while the original Pt(IV) precursor is reduced to Pt(II) and Pt(0) during the synthesis. This knowledge leads to optimised syntheses, e.g. to achieve a fast nucleation at room temperature [3] and propose different strategies to achieve NP size control. Pair distribution function analyses are currently performed to gain further knowledge and control on the formation of the surfactant-free NPs. [1] Quinson et al. Angew. Chem. 2018, 57, 12338. [2] Quinson et al. In preparation. [3] Quinson et al. In preparation.

Authors : Dr. Huayna Terraschke
Affiliations : Institute of Inorganic Chemistry, University of Kiel

Resume : The future of materials research depends on understanding their crystallization process for precisely optimizing their structure-related properties and designing rational synthesis protocols. On the one hand, in-situ X-ray diffraction (XRD) analysis is a powerful tool for monitoring phenomena like nucleation, crystal growth and phase transitions. On the other hand, it is not able to characterize amorphous (intermediate) phases, ions in solutions or very small nanoparticles and depends on synchrotron radiation for penetrating the reactor walls, limiting the availability of this method. In order to overcome these limitations, in-situ XRD can be combined with the so-called in-situ luminescence analysis of coordination sensors (ILACS) approach. This technique introduces emissive ions like the lanthanides or transition metals to the structure of the studied compound as local sensors. The spectroscopic properties of these ions are influenced by changes in the coordination environment, allowing to track structural transformations under real reaction conditions using fast charge-coupled device (CCD)-based detectors, in combination with in-situ XRD in the synchrotron facilities and also in common university laboratories. This work shows the remarkable symbiosis of these techniques for monitoring the events happening not only inside the solid materials but also in the liquid media surrounding elucidating the wet chemical synthesis of emissive complexes, bioceramics and quantum dots.

Authors : Troels Lindahl Christiansen, Mikkel Juelsholt, Kirsten M. Ø. Jensen
Affiliations : Department of Chemistry, University of Copenhagen

Resume : Nano-sized particles of MoO2 are studied for applications both as anode material for Li/Na batteries and in catalysis. The structure of pristine MoO2 is a distorted rutile, however upon nanosizing, the structure is changed due to defects in the connectivity of the [MoO6]-octahedra that make up the structure. This change in structure has a profound influence on the properties of MoO2, and thus control of the defect formation during synthesis must be achieved, in order to obtain the desired properties in any application. With this goal in mind, we have studied the hydrothermal synthesis of MoO2 using in-situ total scattering and pair distribution function (PDF) analysis. In solution, molybdenum ions form a range of polyoxometalate ions, POMs, where [MoO6] units are arranged in large, closed-shell clusters. Upon synthesis, these break down to form the MoO2 structures, and the POM may be considered pre-nucleation clusters. The nature of the POM present in solution is highly dependent on solvent properties, temperature and pH. By utilizing this, we alter the prenucleation cluster structure, and in this way control the synthesis product to obtain both the pristine and highly defected MoO2 structure. Similarities are evident in the local structure of the prenucleation clusters and the local structure of the obtained products. The differences in the structure of the products are explained by the distinct reaction pathways from the clusters to the final product.

Authors : Ola G. Grendal, Anders B. Blichfeld, Dong Hou, Satoshi Tominaka, Sverre M. Selbach, Tor Grande, Mari-Ann Einarsrud
Affiliations : Department of Material Science and Engineering, NTNU Norwegian University of Science and Technology, 7034 Trondheim, Norway; Department of Material Science and Engineering, NTNU Norwegian University of Science and Technology, 7034 Trondheim, Norway; Department of Material Science and Engineering, NTNU Norwegian University of Science and Technology, 7034 Trondheim, Norway; International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan; Department of Material Science and Engineering, NTNU Norwegian University of Science and Technology, 7034 Trondheim, Norway; Department of Material Science and Engineering, NTNU Norwegian University of Science and Technology, 7034 Trondheim, Norway; Department of Material Science and Engineering, NTNU Norwegian University of Science and Technology, 7034 Trondheim, Norway

Resume : Nanosized one dimensional (1D) ferroelectrics are investigated for applications in sensors, actuators and energy harvesting devices. Hydrothermal synthesis, being a cheap, clean and low temperature synthesis route, with a large parameter space for optimization, stands out as one of the best routes for controlled synthesis of 1D nanostructured ferroelectrics. Today, optimization relies mainly on trial-and-error processes, which is time consuming and costly, and there is a general agreement in the field that a better understanding of the nucleation and growth mechanisms are needed for better control, further development and to improve reproducibility. Here we present in situ synchrotron diffraction studies for hydrothermal synthesis of SrxBa1-xNb2O6 (SBN), giving insight into the nucleation and growth. SBN is a tetragonal tungsten bronze with interesting ferroelectric and optical properties. A combination of conventional powder X-ray diffraction with Rietveld refinement and X-ray total scattering with PDF analysis is used to follow the reactions from the non-crystalline precursors, all the way to final crystalline product. Batch reciprocal and real space Rietveld refinement was used to extract time dependent development of relative amount, size, strain, lattice parameters and thermal parameters of the crystalline and amorphous phases. X-ray total scattering and PDF analysis allowed studies of the systems before crystallization, aiding in understanding the early formation stages.

16:00 Coffee Break    
Poster session : Kirsten Jensen
Authors : Cecilia Zito12, Lukas Grote23, Krzysztof Pitala4, Ann-Christin Dippel3, Kristina Kvashnina5, Stephen Bauters5, Dorota Koziej2
Affiliations : 1 São Paulo State University UNESP, Rua Cristóvão Colombo 2265, 15054000 São José do Rio Preto, Brazil; 2 University of Hamburg, Center for Hybrid Nanostructures, Luruper Chaussee 149, 22761 Hamburg, Germany; 3 Deutsches Elektronensynchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany; 4 Academic Center for Materials and Nanotechnology, AGH University of Science and Technology, Kawiory, 30-001 Krakow, Poland; 5 European Synchrotron Radiation Facility ESRF, 71 Avenue des Martyrs, 38000 Grenoble, France

Resume : Nanomaterials made from earth-abundant elements are of particular interest in current energy-related research. Specially, cobalt oxides have shown high catalytic efficiency for example in artificial photosynthetic systems. Size, shape and crystal structure of nanoparticles are decisive for their performance. Knowledge on the formation mechanism, ligand interaction and surface intermediates is essential for a well-controllable synthesis of cobalt-based nanomaterials from solution. Here, we investigated the formation mechanism of cobalt oxide nanoparticles from cobalt(III) acetylacetonate in benzyl alcohol. Multicomponent curve resolution−alternating least squares (MCR-ALS) analysis of in situ high energy resolution fluorescence-detected (HERFD) XANES data measured at the 1s2p transition (Kα1) revealed the reduction of the Co3 precursor to cobalt(II) acetylacetonate, followed by the formation of a CoO phase. Pair distribution functions (PDF) obtained from total X-ray scattering measurements indicate the presence of more than one crystalline phases throughout the reaction, where the final product matches with CoO. Finally, HERFD-XANES spectra measured at multiple energies around the 1s3p (Kβ1,3) emission line provide intrinsic species-selectivity due to a shift of the emission energy depending on the chemical environment of cobalt, thus complementing the MCR-ALS analysis of HERFD-XANES data measured at Kα1.

Authors : Jette K. Mathiesen and Kirsten M. Ø. Jensen
Affiliations : Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen Ø

Resume : Platinum has been widely studied for catalysis due to e.g. its high activity for the oxygen reduction reaction, ORR, in fuel cells [1]. However, large-scale implementation is challenged by high Pt cost and low stability towards reaction intermediates [2]. Instead, intermetallic nanoparticles composed of noble metals (i.e. palladium, Pd) and inexpensive metals (i.e. copper, Cu) have attracted significant interest by demonstrating excellent catalytic activity [3]. The ordering transformation of the intermetallic structure (Pm-3m) from a disordered face-centered cubic (fcc) alloy (Fm-3m) is known to be crucial for the catalytic properties and is dependent on the size of the particles [4,5]. However, synthesizing small intermetallic nanoparticles in a controllable manner remains a challenge due to highly varying redox properties of the metals involved, and often, intermetallics are therefore prepared at rather high temperatures hindering structural engineering on the nanoscale. Recent work has led to the development of new synthesis pathways applying organic solvents for controlled reactions, but the reaction mechanisms are still unknown [6]. In order to tailormake designed intermetallic catalysts, we must obtain insight into their formation, as well as their metal order/disorder and dealloying. Through in situ total scattering and pair distribution function analysis (PDF), the disorder-order transformation was revealed to involve an intermediate stage characterized as an ordered fcc structure followed by further ordering into the intermetallic bcc structure. References [1] Zhang, J. (Ed.), Springer Science & Business Media, 2008. [2] Wu, G., More, K. L., Johnston, C. M., & Zelenay, P., Science, 2011, 332, 443-447. [3] Jiang, K., Wang, P., Guo, S., Zhang, X., Shen, X., Lu, G., ... and Huang, X., Angewandte Chemie International Edition, 2016, 55, 9030-9035. [4] Wang, C., Chen, D. P., Sang, X., Unocic, R. R., and Skrabalak, S. E., ACS nano, 2016, 10, 6345-6353. [5] Luo, M., Sun, Y., Wang, L., & Guo, S., Advanced Energy Materials, 2017, 7, 1602073. [6] Bai, S., Shao, Q., Wang, P., Dai, Q., Wang, X., & Huang, X, 2017, Journal of the American Chemical Society, 139, 6827-6830.

Authors : D.V.Novikov, R.Grifone, J.Raabe, A.Khadiev
Affiliations : DESY Photon Science, Notkestrasse 85, 22607 Hamburg, Germany

Resume : In-situ and nano X-ray diffraction beamline at the PETRA III storage ring at DESY went into user operation in September 2018. The scientific case of the beamline concentrates on physics and chemistry of systems dominated by low dimensional and confinement effects, with an emphasis on in situ and operando techniques. The beamline offers a variety of diffraction methods, ranging from conventional single crystal, powder and surface diffraction to nano-scale, coherent beam and time-resolved techniques. The currently available absorption and secondary emission methods include anomalous scattering, x-ray fluorescence analysis, XANES and conventional and X-ray excited optical luminescence. The beamline undulator source and optics are optimized to provide up to 10^13 photons/sec in the energy range 5-35 keV into variable spot sizes from 1 mm and down to sub-micrometer values. The beamline currently operates one experimental hutch equipped with a custom designed HUBER diffractometer, which can carry user sample cells with up to 150 kg in the 4 circle mode and up to 15 kg on an Eulerian cradle in the 5+2 circle mode. The beamline instrumentation pool is aimed for multiscale analysis of nanostructured materials and devices. In the presentation, we shall show the possibilities provided by the new beamline, present the results of some experimental applications, including in situ electrochemistry, chemical gas and liquid reactors, and discuss the plans for future developments.

Authors : S. Dridi1,2*, N. Bitri1, S. Mahjoubi 1, F. Chaabouni1
Affiliations : 1:Université de Tunis El Manar, Ecole Nationale d’Ingénieurs de Tunis, Laboratoire de Photovoltaïque et matériaux semi-conducteurs, 1002, Tunis, Tunisie. 2:Université de Tunis, Ecole Nationale Supérieure d’Ingénieurs de Tunis.

Resume : The single step of « Spray Pyrolysis » technique was developed for preparing Cu2NiSnS4 (CNTS) thin films followed by an annealing treatment process. Originally, the spray technique was successfully used to deposit the samples onto glass substrates at 250 °C for 60 min spray duration. Again, the prepared samples were annealed in sulfur atmosphere at a temperature of 500 °C during 30 min. Herein, The annealed sample exhibits (111), (220) and (311) orientations corresponds well to cubic CNTS structure. The SEM data exhibit a uniform, rough and compact topography. The absorption coefficient is found to be higher than 104 cm-1 in the visible region while the direct band energy of 1.3 eV, which is eminently suitable for use in solar cell. The complex impedance diagrams indicate the decrease of resistance by increasing temperature, which attribute to a semiconductor behavior. The close values of activation energies 1.22 and 1.09 eV determined from both angular frequency and DC conductivity indicate that the carrier transport mechanism is thermally activated.

Authors : Maria Storm Thomsen; Thomas Just Sørensen
Affiliations : Thomas Just Sørensen

Resume : The correlation between structure and properties in molecular chemistry is indisputable.1 While the solid state structure can be easily obtained with single-crystal X-ray diffraction2, determining the dynamic solution structure is—particularly for f-elements–less straight forward.3 Advances in solution phase total scattering are being made constantly.4 There is, however, a pressing need for a way of directly connecting solution structure and observed solution properties. Our approach incorporates a study of molecular structures from single-crystal X-ray diffraction, as well as doped structures with isolated distinctive properties, to individual molecules in solution. Extensive research has been done on the kinetically inert Ln[DOTA]- complexes, primarily as a direct consequence of the use of Gd(III) complexes in magnetic resonance imaging.5 Despite the rigid nature, Ln[DOTA]- complexes in solution exists as four structural ligand conformers6, which gives rise to different physicochemical properties.7 By employing solid state structures to map dis-tinct structure-property relations, we aim to understand dynamic structures and averaged properties in solution. Solid state and solution state are bridged by dilute solid state structures of Ln[DOTA]- complexes. This makes it possible to isolate physicochemical properties coming from a specific form in the solid state and relate that to what is observed in solution. 1. L. G. Nielsen, A. K. R. Junker and T. J. Sørensen, Dalton transactions, 2018, 47, 10360-10376. 2. M. E. Boulon, G. Cucinotta, J. Luzon, C. Degl'Innocenti, M. Perfetti, K. Bernot, G. Calvez, A. Caneschi and R. Sessoli, Angewandte Chemie, 2013, 52, 350-354. 3. a) P. Caravan, J. J. Ellison, T. J. McMurry and R. B. Lauffer, Chemical Reviews, 1999, 99, 2293-2352. b) T. J. Sørensen and S. Faulkner, Acc Chem Res, 2018, 51, 2493-2501. 4. Kirsten M. Ø. Jensen, Mogens Christensen, Pavol Juhas, Christoffer Tyrsted, Espen D. Bøjesen, Nina Lock, Simon J. L. Billinge, and Bo B. Iversen, Journal of the American Chemical Society, 2012, 134 (15), 6785-6792 5. a) E. M. Gale, P. Caravan, A. G. Rao, R. J. McDonald, M. Winfeld, R. J. Fleck and M. S. Gee, Pediatric Radiology, 2017, 47, 507-521. b) P. Caravan, J. J. Ellison, T. J. McMurry and R. B. Lauffer, Chemical Reviews, 1999, 99, 2293-2352. 6. a) L. G. Nielsen, A. K. R. Junker, T. J. Sørensen, Dalton Trans., 2018,47, 10360-10376. b) P. Caravan, J. J. Ellison, T. J. McMurry and R. B. Lauffer, Chemical Reviews, 1999, 99, 2293-2352. 7. a) Silvio Aime, Mauro Botta, and Giuseppe Ermondi, Inorganic Chemistry, 1992, 31 (21), 4291-4299. b) D. Parker, R. S. Dickins, H. Puschmann, C. Crossland and J. A. K. Howard, Chemical Reviews, 2002, 102, 1977-2010.

Authors : Andy S. Anker, Troels Lindahl Christiansen, Marcus Weber, Martin Schmiele, Erik Brok, Emil T. S. Kjaer, Pavol Juhás, Rico Thomas, Michael Mehring and Kirsten M. Ø. Jensen
Affiliations : Nanoscience Center and Department of Chemistry, University of Copenhagen; Nanoscience Center and Department of Chemistry, University of Copenhagen; Institute of Chemistry, Chemnitz; Niels Bohr Institute, University of Copenhagen, Nanoscience Center and Department of Chemistry, University of Copenhagen; Niels Bohr Institute, University of Copenhagen, Nanoscience Center and Department of Chemistry, University of Copenhagen; Nanoscience Center and Department of Chemistry, University of Copenhagen; Computational Science Initiative, Brookhaven National Laboratory; Chemistry, University of Copenhagen; Chemistry, University of Copenhagen; Nanoscience Center and Department of Chemistry, University of Copenhagen

Resume : Metal oxides of bismuth and its oxido clusters in solution have attracted much attention with potential applications ranging from antibacterial agents to photocatalysis. In order to improve the photocatalytic activity of β-Bi2O3, it has been shown that easily accessible {Bi38O45}-based clusters represent well suited molecular precursors [1]. However, the chemical processes involved in the cluster formation are not well understood: While the molecular structures of various clusters have been solved by single crystal diffraction, it is much more challenging to study structures of such clusters directly in solution. Bismuth oxido clusters exist in a range of sizes, most of them built up by simple or edge-sharing octahedral {Bi6OX} units, but studies on their conversion processes are restricted to electrospray mass spectrometry. Here, we use in situ X-ray total scattering with PDF analysis to study the formation of a {Bi38O45} cluster starting from [Bi6O5(OH)3(NO3)5]·(H2O)3 crystals dissolved in DMSO. The PDF analysis gives unique insight into the structural rearrangements on the atomic scale. By combining with Small Angle X-ray Scattering, SAXS, we furthermore investigate the size, morphology and size dispersion of the clusters taking place in the process. These two techniques complement each other, allowing us to follow the cluster chemistry as it takes place. [1] M. Schlesinger, et. al, Dalton T 42 (2013), 1047-1056 [2] M. Mehring in Metal Oxido Clusters of Group 13–15 Elements, in Clusters – Contemporary Insight in Structure and Bonding, Editor S. Dehnen, Springer International Publishing: Cham. (2017), p. 201-268. [3] C. Falaise et. Al, J Am Chem Soc, 135(42): (2013) ,15678-81. [4] K. J. Mitchell, K.A. Abboud, and G. Christou, Nat Commun., 8(1) (2017), 1445. [5] L. Söderholm et. al., Angew. Chem. Int. Ed. Engl., 47(2) (2008), 298-302.

Authors : Jae Yeon Park, Jitendra Pal Singh, Jun Lim, Sangsul Lee
Affiliations : Pohang Accelerator Laboratory

Resume : X-ray absorption near edge structure (XANES) imaging technique has been developed to visualize the oxidation state of elements. One of the most issued materials in XANES imaging is the lithium-ion battery such as LFP or NMC, which has delithiation process that switches the oxidation state depending on charging level. The oxidation state of an interesting sample in a partially charged state is measured with reference samples in the pristine state and the fully charged. The samples are prepared with micro-sized pieces or practical cell-types. Synchrotron based X-ray absorption images are acquired in a range of K-edge energies at 7C X-ray nano imaging beamline at Pohang Light Source II. X-ray absorption coefficients are obtained by the imaging process; reference correction, objective alignment and spectral normalization. The final process maps the linear-combination (LC) fitting result. The sample is also captured by the tomographic technique. We confirms the charging distribution using the 2D LC mapping data as well as the 3D tomogram. This method has the potential as a tool to analyze the charging distribution of Li-ion batteries.

Authors : Atefeh Jafari1, Desiree Della Monica Ferreira1, Lan Mai Vu1, Sara Svendsen1, Sonny Massahi1, Shima Kadkhodazadeh3, Takeshi Kasama3, Brian Shortt2, Finn Erland Christensen1
Affiliations : 1-DTU Space, Technical University of Denmark, 2800, Kongens Lyngby, Denmark; 2. European Space Agency (ESTEC), Keplerlaan 1, PO Box 299, 2200 AG, Noordwijk, Netherlands, 3. Center for Electron Nanoscopy, Technical University of Denmark, Fysikvej, 2800, Kongens Lyngby, Denmark

Resume : A deep understanding of the X-ray mirror coating materials is a key point to produce optimized and durable mirrors, which are the main parts of the optical elements in any astronomical instrumentation. Therefore, it is necessary to evaluate the true composition of coating materials and contaminants to reveal the cause and their effects on the mirror performance. We analyzed the fine-scale structures of the multilayer mirrors using transmission electron microscopy (TEM), electron energy loss spectroscopy (EELS) and X-ray photoelectron spectroscopy (XPS). The X-ray reflectivity performance of iridium-based X-ray mirrors is investigated at desired grazing angle and energy range. This research helps to gain insights into the mirror coatings from the surface to the depth and at interfaces. In addition, the optimized methodology research is applicable to future studies on a wide range of X-ray mirrors.

Authors : V.K. Egorov, E.V. Egorov
Affiliations : IMT RAS, Chernogolovka, Moscow district, Russia 142432; IMT RAS, Chernogolovka, Moscow district, Russia, 142432 and RUDN, Moscow Russia

Resume : The phenomenon of radiation fluxes waveguide-resonance propagation is featured by the uniform interference field of X-ray standing wave appearing and device worked in frame of the phenomenon is called the planar X-ray waveguide-resonator (PXWR) [1]. In works devoted to decreasing of angular divergence at integral intensity retention of PXWR emergent beam we revealed that the effect is achieved at use the composite planar X-ray waveguide-resonator (CPXWR) consisted of two simplest PXWR deposited one after another on some distance with mutual aligning. The observed effect was the result of mutual influence of X-ray standing waves interference fields excited inn both PXWRs [2]. Inasmuch as the interference picture appearing is a feature of any radiation fluxes reflection one can expect that the waveguide-resonance propagation mechanism will be characteristic of its. By virtue of the wave-corpuscle dualism the flux particles propagation mechanism possessing by non zero rest mass will be characterized by the radiation standing wave interference field appearing. So, we can expected that interference field interaction will be able to prepare new materials by its the mutual influence use. These radiation standing waves interference fields must be excited by atomic fluxes of initial substances, portraying the low energy nuclear synthesis cold fusion of materials. [1] V. Egorov, E. Egorov. X-ray Spectrometry. v33 (2004) 360. [2] V. Egorov, E. Egorov. Optics and Spectroscopy. v124 (2018) 838.

Authors : Noopur Jain, Ahin Roy. N Ravishnakar
Affiliations : Materials Research Centre, Indian Institute of Science

Resume : An understanding of the surface reducibility of a catalytically active oxide support is a pre-requisite to understanding its catalytic behaviour. In this work, we report that through a stringent control over the phase and morphology of catalytically active MnO2 supports, a control over the surface reducibility can be achieved. Through temperature-programmed reduction (TPR), we prove a higher availability of lattice oxygen for the α-MnO2 phase, compared to that of β-MnO2. X-ray photoelectron spectroscopy is used to comment of the surface reducibility in both the materials. Furthermore, by modifying the synthesis method, we could engineer the morphology of the α-phase into nanoflowers which in turn leads to a higher surface area, further enhancing the activity. On the engineered support, decoration of Pt nanoparticles can lower the full conversion temperature for CO oxidation as low as ~90 oC.

Authors : Yan Duan
Affiliations : Shengnan Sun, Yuanmiao Sun, Shibo Xi, Xiao Chi, Qinghua Zhang, Xiao Ren, Jingxian Wang, Samuel Jun Hoong Ong, Yonghua Du, Lin Gu, Alexis Grimaud, Zhichuan J. Xu

Resume : Developing highly active electrocatalysts for oxygen evolution reaction (OER) is critical for the commercial effectiveness of water splitting to produce hydrogen fuels. Low-cost spinel oxides have attracted increasing interest as alternatives to noble-metal-based OER catalysts. A rational design of spinel catalysts can be guided by studying the structural/elemental properties which determine the reaction mechanism and activity. The exploring on these properties relies on characterization methods. Here, from density functional theory (DFT) calculations, we find that the relative position of O p-band and MOh (Co and Ni in octahedron) d-band centre in ZnCo2-xNixO4 (x=0-2) correlates with its stability as well as the possibility for lattice oxygen to participate in OER. We therefore testified it by synthesizing ZnCo2-xNixO4 spinel oxides, investigating on their OER performance and surface evolution by X-ray absorption spectroscopy (XAS) and Transmission electron microscope (TEM). Stable ZnCo2-xNixO4 (x=0-0.4) follows adsorbates evolving mechanism (AEM) under OER conditions. Lattice oxygen participate in the OER of metastable ZnCo2-xNixO4 (x=0.6, 0.8) which gives rise to continuously formed oxyhydroxide as surface-active species and consequently enhanced OER activity. This surface change has been evidenced by XAS. ZnCo1.2Ni0.8O4 exhibits performance superior to the benchmarked IrO2. X-ray spectroscopies works as a crucial tool for our understanding of the surface reconstruction of highly active metastable spinel electrocatalysts. Our work illuminates the design of electrocatalysts through the prediction of the reaction mechanism and OER activity by determining the relative positions of the O p-band and MOh d-band centre.

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Session 3 : Kirsten Jensen
Authors : David M. Tiede, Gihan Kwon, Karen Mulfort, and Alex B. F. Martinson
Affiliations : David M. Tiede, Chemical Sciences Division Argonne National Laboratory; Gihan Kwon, National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York, USA; Karen Mulfort, Chemical Sciences Division Argonne National Laboratory; Alex B. F. Martinson, Material Science Division, Argonne National Laboratory, Argonne, Illinois, USA;

Resume : A key challenge for designing and gaining control of catalysis and energy-converting chemistry at electro- and photo-active surfaces, lies in resolving functional interfacial atomic structures and dynamics. In our on-going work, we show how high energy (>50 keV) X-ray scattering and pair distribution function (PDF) analysis with sub-angstrom spatial resolution usefully complements atomic structure and electronic characterization using a combination of soft X-ray absorption (XAS), resonant X-ray emission (RXES), resonant inelastic X-ray scattering (RIXS). However, the small scattering cross-section and high penetration depth for high energy X-rays typically limits PDF analyses for interfacial structures. Accordingly, we have developed high-surface area porous electrode architectures that allow structural characterization of interfacial thin-film and molecular catalysts with high spatial resolution under device-relevant electrochemical conditions. We demonstrate PDF measurements with 0.2 Å spatial resolution for amorphous cobalt oxide water-splitting catalyst films with thickness down to 50 nm using porous electrode architectures with 40 ?m diameter pores. Further, we extended this approach by the development of 100 nm porous electrode architectures which enable the use of PDF to resolve outer-sphere ligand structure for molecular dyes and catalysts bound to oxide surfaces. These measurements distinguish between coordination structures for solution and surface-bound molecular states, and provide an approach to investigate interfacial catalyst structure and function.

Authors : Nicholas M. Bedford
Affiliations : School of Chemical Engineering, University of New South Wales

Resume : The need to undercover atomic-scale structural motifs that occur during electrocatalytic reactions is key to understanding the fundamental science driving chemical transformations for eventual use in establishing rational design rules for emergent catalytic materials. Synchrotron radiation characterization methods provide a route forward for obtaining this information under conditions more resemblant of those in working electrochemical devices. This presentation will summarize recent efforts understanding changes in atomic structure during electrocatalysts using both X-ray absorption spectroscopy (XAS) and atomic pair distribution function (PDF) analysis. In-situ electrochemical XAS has been utilized to examine a number of metal oxide, carbide and nitride catalyst and showcase structural changes that appear to be a function of electrochemical reaction conditions and initial synthetic pathways. To obtain longer range structural information, in-situ electrochemical PDF measurements were also performed using a custom-made capillary cell. By using both techniques, access to a wealth of structural information is available to aid in the design on new catalytic materials.

Authors : R. Kumar Ramamoorthy, J. A. Vargas, L.-M. Lacroix, P. Roblin, S. Teychené, M. Imperor, V. Petkov, G. Viau
Affiliations : (1) Université de Toulouse, LPCNO, UMR 5215 INSA CNRS UPS, Toulouse, France (2) Department of Physics, Central Michigan University, Mt. Pleasant, Michigan, United States (3) Université de Toulouse, LGC, CNRS, INPT, UPS, Toulouse, France (4) Laboratoire de Physique de Solides, UMR 8502, Université Paris-Sud, Orsay, France

Resume : Ultrathin gold nanowires (Au NWs), exhibiting a diameter below 2 nm and a micrometric length, have attracted expanding interests due to their unique high surface-to-volume ratio, mechanical flexibility and conductivity properties with applications for electrical sensors or transparent electrodes. Ultrathin Au NWs were grown in organic solvents containing oleylamine (OY). Under the electron beam the NWs recrystallize and fracture, leading to the formation of mono-atomic metal chains [1]. The atomic structure of the raw Au NWs was studied by in situ high energy-X-ray diffraction (HE-XRD) showing that they do not crystallize with the expected fcc structure but adopt a tetrahedrally close packed atomic structure [2] resulting from a compromise between a high atomic packing density and a growth confined by the OY supramolecular organization. A bi-layer of OY coating the wires was evidenced by small angle X-ray scattering (SAXS) [3]. The detailed sketch of the wires formation was supplemented by the gold speciation during the growth using X-ray absorption spectroscopy (XAS) showing the molecular precursor self-assembly during the first stage of the reaction. Finally, the interwire distance can be monitored between 2.5-10 nm thanks to ligand exchange at the wire surface [4]. [1] L.-M. Lacroix et al., J. Am. Chem. Soc., 2014, 136, 13075. [2] J. A. Vargas et al., ACS Nano 2018, 12, 9521. [3] A. Loubat et al., Langmuir 2014, 30, 4005. [4] El Said Nouh et al., Langmuir 2017, 33, 5456.

09:30 Coffee Break    
Authors : Moniek Tromp
Affiliations : University of Groningen, Zernike Institute for Advanced Studies, Chair of Materials Chemistry, Groningen, Then Netherlands

Resume : Detailed information on the structural and electronic properties of a catalyst or material and how they change during reaction is required to understand their reaction mechanism and performance. An experimental technique that can provide structural as well as electronic analysis and that can be applied in situ/operando and in a time-resolved mode, is X-ray spectroscopy. A combination of X-ray absorption and emission techniques provide very detailed electronic information. Different approaches have been reported to allow operando time resolved XAS on catalytic systems. Our group has established stopped-flow methodologies allowing simultaneous time-resolved UV–Vis/XAS experimentation on liquid systems down to the millisecond (ms) time resolution. Low X-ray energy systems or for low concentrated systems, longer XAS data acquisition times in fluorescence are required and therefore a stopped-flow freeze-quench procedure has been developed. Pushing the time-resolution has been achieved by fast pump-probe experiments or applying modulation excitation methodologies, which can isolate active from spectator species. This lecture will focus on selective ethene oligomerisation reactions, catalyzed by homogeneous 3d transition metal catalysts, from the industrially applied chromium ones to novel iron and nickel based systems. Solving the complicated puzzles of data from complementary spectroscopic techniques, active and inactive catalyst intermediates as a function of time and process conditions can be proposed and design concepts for novel catalysts derived.

Authors : Ezgi Onur Şahin, Gun-hee Moon, Harun Tüysüz, Candace K. Chan, Wolfgang Schmidt, Claudia Weidenthaler
Affiliations : Ezgi Onur Şahin, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany; Gun-hee Moon, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany; Harun Tüysüz, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany; Candace K. Chan, Arizona State University, Tempe, USA; Wolfgang Schmidt, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany; Claudia Weidenthaler, Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr, Germany

Resume : Amorphous tantalum oxide is a promising photocatalyst for water splitting applications compared to crystalline counterparts [1,2]. The synthesis of this material involves injection of a tantalum(V) ethoxide precursor into a photocatalytic cell filled with a water-methanol solution. The photocatalytic cell is equipped with ultraviolet light and a gas analysis part in order to measure the H2 gas amount obtained during illumination. This study focuses on the structure formation of tantalum oxide in highly dilute solutions. For local structure investigations total scattering methods were used. Scattering data were obtained using synchrotron radiation both for samples in suspension and dried powder samples. Data evaluation was performed by pair distribution function (PDF) analysis. For the samples in dilute suspension, a flow cell was connected to the photocatalytic cell and data were collected while circulating the suspension through the flow cell. After injection of the ethoxide precursor hydrolysis, condensation, and polycondensation reactions of the Ta precursor are proceeding. PDF data reveal that tantalum oxide/ tantalum hydroxide building units smaller than 8 Å have formed. These units are maintained even after drying of the material. The formation of small Ta-O oligomers in solution could be confirmed also for highly diluted solutions with only 0.0347 at.% Ta in the overall suspension. References 1. T. Grewe, H. Tüysüz, ChemSusChem (2015) 8, 3084. 2. H. Tüysüz, C.K. Chan, Nano Energy (2013) 2, 116.

Authors : Khaled Cheaib (1,2), Daniela Mendoza (1,3), Elodie Anxolabéhère-Mallart (3), Marc Robert (3), Zakaria Halime (2), Benedikt Lassalle-Kaiser (1)
Affiliations : 1 Synchrotron SOLEIL, l’Orme des Merisiers, 91192 Gif-sur-Yvette, France. 2 Institut de Chimie Moléculaire et des Matériaux d’Orsay, Université Paris Sud, 91190 Orsay, France. 3 Laboratoire d’Electrochimie Moléculaire, Université Paris Diderot, 15 rue Jean-Antoine de Baïf, 75205 Paris, France.

Resume : A lot of research is currently focused on the utilization of carbon dioxide as a primary feedstock for the chemical and fuel industry. The development of CO2-reducing catalysts with chemical selectivity requires a deep understanding of their structure and functioning mechanism. The high penetration depth and element specificity of X-ray spectroscopy makes it an ideal tool to probe catalysts under functioning conditions, thus providing clues about their local and electronic structures. Such information is crucial in understanding reaction mechanisms and further improve yields and selectivities. In this talk, we will present our latest methodological developments on the use of time-resolved X-ray spectroscopy under cyclic voltametry conditions. In order to observe transient species, we have developed and characterized an X-ray spectroelectrochemical cell that allows recording time-resolved XAS spectra along a cyclic voltamogram. The technique was then applied to CO2-reducing homogeneous molecular catalysts, based on transition metal macrocycles, for which we could observe transient intermediate species as a function of catalytic conditions. Preliminary results seem to corroborate the electronic structure of intermediate species that were postulated on the basis of theoretical calculations. This example highlights the possibilities offered by time-resolved X-ray spectroscopic techniques for the study of electrochemical reactions under in situ conditions.

11:15 Plenary Session    
12:30 Lunch    
Session 4 : Serena De Beer
Authors : Chatterjee, R.(1), Young, I. D.(1), Ibrahim, M.(2), Fuller, F. D.(1,3), Lassalle, L.(1), Gul, S.(1), Fransson, T.(4), Brewster, A. S.(1), Alonso-Mori, R.(3), Hussein, R.(2), Dobbek, H.(2), Bergmann, U.(4), Sauter, N. K.(1), Zouni, A.(2), Messinger, J.(5), Kern, J.(1), Yachandra, V. K.(1), Yano, J.(1)
Affiliations : (1) Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; (2) Institut für Biologie, Humboldt-Universität zu Berlin, D-10099 Berlin, Germany; (3) LCLS, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA; (4) Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA; (5) Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, SE 75237 Uppsala, Sweden.

Resume : The development of XFELs has opened up opportunities for studying the dynamics of catalysis and biological enzymes. Intense XFEL pulses enable us to apply both X-ray diffraction and X-ray spectroscopic techniques to dilute systems or small protein crystals. By taking advantage of ultra-bright femtosecond X-ray pulses, one can also collect the data under functional conditions of temperature and pressure, in a time-resolved manner, after initiating reactions, and follow the chemical dynamics during catalytic reactions and electron transfer. We have developed spectroscopy and diffraction techniques necessary to fully utilize the capability of the XFEL X-rays for a wide variety of metalloenzymes, and to study their chemistry under functional conditions. One of such methods is simultaneous data collection for X-ray crystallography and X-ray spectroscopy, to look at the overall structural changes of proteins and the chemical changes at metal catalytic sites. The sample is photochemically or chemically activated at various time delays to capture reaction intermediates with crystallography and spectroscopy. We have used the above techniques to study photochemical activation of the water oxidation reaction of the Photosystem II (PSII) multi subunit protein complex, in which the Mn4CaO5 cluster catalyzes the reaction. We report the light-induced structure and electronic state changes of the intermediates during the catalysis. The current status of this research and the mechanistic understanding of this metalloenzyme based on the X-ray techniques is presented (Kern et al., Nature, 536, 421).

Authors : Ana E. Platero-Prats
Affiliations : Departamento de Química Inorgánica, Universidad Autónoma de Madrid

Resume : Nanoporous crystalline materials are ideal platforms for energy-related applications of molecular nature. Remarkable examples are found in the field of catalysis and separation, where molecules have to interact with the surface, diffuse through the pores, and interact with the active sites. If all these complex steps occur as an orchestrated process, our porous material will catalyze a target chemical reaction or behave as a molecular sieve. Tailored chemical decoration of nanoporous materials, at an atomic level and using well-defined functional groups, offers a new horizon for the next generation energy technologies. As many other materials with fascinating properties, these systems lack of crystallinity at some extent. Defects, disorder, and dynamism within nanoporous crystalline materials, playing a decisive role in properties and ultimate applications, are still difficult to structurally characterize and fundamentally understand. This characterization challenge can be addressed by combining two incisive synchrotron tools such as X-ray Absorption Spectroscopy (XAS) and Pair Distribution Function (PDF) analyses of X-ray total scattering, providing a more realistic structural picture of these materials under conditions relevant for their use.

Authors : Mikkel Juelsholt, Troels Lindahl Christiansen and Kirsten M. Ø. Jensen
Affiliations : Department of Chemistry and Nanoscience Center, University of Copenhagen

Resume : Nanoparticles of tungsten oxides have a range of important applications in e.g. gas-sensing, catalysis and supercapacitors[1]. The properties are highly dependent on the size and structure of the material, and in order to obtain a ‘tailor-made’ material, it is crucial to understand the mechanisms that dictate the formation of the material during synthesis. X-ray total scattering with Pair Distribution Function (PDF) analysis allows following the structural changes that take place all the way from precursor cluster over nucleation clusters to the final crystalline particles[2]. We here present a study of WOx nanostructures formed in a solvothermal synthesis by thermal decomposition of ammonium metatungstate hydrate in water and oleylamine. Using in situ X-ray Total Scattering and Pair Distribution Function analysis, we observe how the solvents induces two distinct pathways of crystallisation. The pathways can be directly linked to the difference between the polyanion formed in each solvent. We show that the pathway heavily influences the defect-chemistry of the formed nanoparticles. 1. Zheng, H., et al., Nanostructured Tungsten Oxide – Properties, Synthesis, and Applications. Advanced Functional Materials, 2011. 21(12): p. 2175-2196. 2. Mikkel Juelsholt, T.L.C., Kirsten M. Ø. Jensen, Mechanisms for Tungsten Oxide Nanoparticle formation in Solvothermal Synthesis: From Polyoxometalates to crystalline materials. Manuscript submitted for Publication, 2018.

Authors : Kristine Bakken, Anders Bank Blichfeld, Dong Hou, Julia Glaum, Tor Grande, Mari-Ann Einarsrud
Affiliations : Department of Materials Science and Engineering, NTNU Norwegian University of Science and Technology, 7034 Trondheim, Norway

Resume : Chemical solution deposition (CSD) is a well-suited, inexpensive and versatile method for fabrication of oxide thin films on an industrial scale. The fabrication process become more environmental friendly by using aqueous precursors. However, to obtain high quality films, it is necessary to understand how the processing parameters influence the nucleation and growth processes, which is detrimental for the properties of the films. For that purpose we have been developing an in situ characterization platform suitable for the investigation of the crystallization of oxide thin films. BaTiO3 based thin films prepared by aqueous CSD served as a model system. In situ synchrotron X-ray diffraction (XRD) was used to study the nucleation and growth mechanisms of the films during thermal processing and annealing. To get detailed insight into the chemistry and early stages of film development, calcined powders made from the precursor solutions were investigated by in situ synchrotron total scattering. The phase development of BaTiO3 prepared by aqueous CSD has distinct features; the precursor develops into the crystalline perovskite phase through the formation of an intermediate metastable oxycarbonate phase. By tuning the process parameters, e.g. atmosphere, heating rate and annealing temperature, control of microstructure and preferred orientation for the thin film is obtained. Polycrystalline and highly textured films was achieved in the same setup with different heating schemes.

Authors : C. Castellano, G. Berti, F. Rubio-Marcos, G. Lamura, S. Sanna, E. Salas-Colera, A. Brambilla, Á. Muñoz-Noval, L. Duò, F. Demartin
Affiliations : Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy; Department of Chemical Physics, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany; Electroceramic Department, Instituto de Cerámica y Vidrio, CSIC, Kelsen 5, 28049 Madrid, Spain; CNR-SPIN, corso Perrone 24, 16146 Genova, Italy; Department of Physics and Astronomy, University of Bologna, 40127 Bologna, Italy; Instituto de Ciencia de Materiales de Madrid, ICMM, CSIC, Sor Juana Inés de la Cruz 3, 28049, Cantoblanc, Madrid, Spain and Spanish CRG BM25 SpLine, ESRF 71 Avenue des Martyrs CS 40220 FR - 38043 Grenoble, France; Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, 20133 Milano, Italy; Laboratory Universidad Complutense de Madrid Facultad de Ciencias Físicas Ciudad Universitaria ES - 28040 Madrid, Spain; Dipartimento di Fisica, Politecnico di Milano, piazza Leonardo da Vinci 32, 20133 Milano, Italy; Dipartimento di Chimica, Università degli Studi di Milano, via Golgi 19, 20133 Milano, Italy

Resume : We present an EXAFS study at the Mo K-edge of novel A2Mo2-yMnyO7 pyrochlores (A = Gd and Ho; y = 0.00, 0.10 and 0.20) performed as a function of temperature and coupled to magnetic susceptibility measurements, to check the relation between local structure parameters and nearest-neighbor magnetic interactions. The A2Mo2O7 undoped compounds display a transition from a spin-glass (SG) to a long-range ferromagnetic (FM) phase on increasing the rare earth average ionic radius on site A and the related Mo-O-Mo bond angle. We found evidence of an anomalous local lattice disorder below 225 K in the first Mo-O shell of the low-temperature FM Gd2Mo2O7 sample related to the location of this peculiar composition on the border between the SG and FM regimes. Otherwise, a local order compatible with a lattice frustration was observed in the SG Ho2Mo2O7 [1]. After Mn-doping we observe a competition between double-exchange (undoped case) and superexchange magnetic couplings. The Ho2Mo2-yMnyO7 samples (y = 0.10 e 0.20) remain SG while the two Gd2Mo2-yMnyO7 compositions show a new SG transition and the disappearance of the huge increase in the local disorder below 225 K. As in the undoped system, we confirm the presence on a local scale of a MoO6 octahedra distortion for all the compounds. Therefore the Mn-doped Gd and Ho samples assume a similar structure and magnetic behaviour, differently from the corresponding undoped compounds. [1] C. Castellano et al., J. All. and Compd. 723, 327 (2017)

Authors : Martin Magnuson
Affiliations : Thin Film Physics Division, Department of Physics, Chemistry and Biology, IFM, Linköping University, SE-58183 Linköping, Sweden.

Resume : The electronic structures and the chemical bonding in 2D ceramic materials (MXenes) are investigated by X-ray photoelectron, X-ray absorption and X-ray emission spectroscopies compared to ab initio electronic structure calculations. By varying the constituting elements and structures in MXenes, a change of the electron population cause a change of covalent bonding between the laminated layers, which enables control of the macroscopic properties of the materials. Synchrotron radiation techniques such as bulk-sensitive soft X-ray absorption and emission spectroscopy are shown to be particularly useful for detecting detailed symmetry in the electronic structure and yield anisotropic information about intercalated termination groups between the interfaces. Angle- and polarization-resolved measurements are shown to reveal differences in orbital occupation across and along the laminate basal plane. Calculated spectra of different compontents using density-functional theory (DFT) including core-to-valence dipole matrix elements are found to yield consistent spectral functions of experimental data. The role of functional –OH, –O and –F temination groups and H2O at the interfaces between nanolaminate layers and their local symmetries at different adsorption sites on MXenes are discussed.


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Symposium organizers
Dorota KOZIEJUniversity of Hamburg, Center for Hybrid Nanostructures

Institute for Nanostructure and Solid-State Physics, Luruper Chaussee 149, 22761 Hamburg, Germany
Karena CHAPMANArgonne National Laboratory

9700 S Cass Avenue, Lemont, Illinois, 60439, USA

+1 6302520127
Kirsten JENSENUniversity of Copenhagen, Department of Chemistry

Universitetsparken 5, 2100 Copenhagen Ø, Denmark

+45 40517636
Serena DE BEERMax Planck Institute for Chemical Energy Conversion

Stiftstr. 34-36, D-45470 Mülheim an der Ruhr, Germany

+49 (208) 306 3605