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379 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2, 3, 4, 5, 6, 7, 8 [Next/Last]

Instruments / Technical Area	Publication Details	Published
B18-Core EXAFS	Unravelling synergistic effects in bi-metallic catalysts: deceleration of palladium-gold nanoparticles coursing in the hydrogenation of cinnamaldehyde Jose Pinto , Andreas Weilhard , Luke T. Norman , Rhys W. Lodge , David M. Rogers , Aitor Gual , Israel Cano , Andrei N. Khlobystov , Peter Licence , Jesum Alves Fernandes Catalysis Science & Technology DOI: 10.1039/D3CY00289F Diamond Proposal Number(s): [19850, 17198] Open Access Show Abstract ▼ Abstract: In this work, we demonstrate that the synergistic effect of PdAu nanoparticles (NPs) in hydrogenation reactions is not only related to high activity but also to their stability when compared to Pd mono-metallic NPs. To demonstrate this, a series of mono- and bi-metallic NPs; Pd, Pd0.75Au0.25, Pd0.5Au0.5, Pd0.25Au0.75 and Au in ionic liquid [C4C1Im][NTf2] have been fabricated via magnetron sputtering process. Bi-metallic NPs possess external shells enriched with Pd atoms that interact with [NTf2]- of the ionic liquid resulting in enhanced catalytic performance in hydrogenation of cinnamanaldehyde compared to their mono-metallic counterparts. This is ascribed to their higher stability over 24 h reaction, whilst the catalytic activity and selectivity are comparable for both catalysts. Using a bespoke kinetic model for in situ catalyst deactivation investigations and electron microscopy imaging at nanoscale, we have shown that PdAu has a deactivation rate constant of 0.13 h-1, compared to 0.33 h-1 for Pd NPs, leaving 60 % and 40 % of available sites after the reaction, respectively. Beyond that, the kinetic model demonstrates that the reaction product has a strong stabilizing factor for bimetallic NPs against coarsening and deactivation, which is not the case for Pd NPs. In summary, our kinetic model enables the evaluation of the catalyst performance over the entire chemical reaction space, probing the contribution of each individual components of the reaction mixture and allowing the design of high-performance catalysts.	Jun 2023
I14-Hard X-ray Nanoprobe	An in situ liquid environment for synchrotron hard X-ray nanoprobe microscopy Gea T. Van De Kerkhof , Jessica M. Walker , Surabhi Agrawal , Stuart M. Clarke , Mobbassar H. Sk , Dominic J. Craske , Robert Lindsay , Michael Dowhyj , Ayomide Osundare , Manfred E. Schuster , Julia E. Parker Materials At High Temperatures DOI: 10.1080/09603409.2023.2213579 Diamond Proposal Number(s): [28835] Open Access Show Abstract ▼ Abstract: Studying chemical reactions in an environment that closely mimics the system’s natural operating conditions can offer crucial insights into dynamic oxidation processes. Transmission Electron Microscopes (TEMs) and X-ray Nanoprobes allow the use of imaging and spectroscopy to access nanoscale chemical and structural information about these processes. However, the controlled operating conditions and constraints make the design and implementation of in situ sample environments challenging. Here, we outline the setup of an in situ liquid sample environment for the Hard X-ray Nanoprobe beamline (I14) at Diamond Light Source. The liquid environment allows for the imaging and spectroscopic analysis of samples exposed to liquid flow, with heating up to 80℃. The capability is demonstrated with an example experiment studying iron corrosion. The design of the sample cell offers the prospect of combining X-ray and electron microscopy for the in situ multi-length scale imaging and spectroscopy of samples in liquid.	May 2023
B18-Core EXAFS I11-High Resolution Powder Diffraction	Anion redox as a means to derive layered manganese oxychalcogenides with exotic intergrowth structures Shunsuke Sasaki , Souvik Giri , Simon J. Cassidy , Sunita Dey , Maria Batuk , Daphne Vandemeulebroucke , Giannantonio Cibin , Ronald I. Smith , Philip Holdship , Clare P. Grey , Joke Hadermann , Simon J. Clarke Nature Communications 14 DOI: 10.1038/s41467-023-38489-3 Diamond Proposal Number(s): [25166, 14239] Open Access Show Abstract ▼ Abstract: Topochemistry enables step-by-step conversions of solid-state materials often leading to metastable structures that retain initial structural motifs. Recent advances in this field revealed many examples where relatively bulky anionic constituents were actively involved in redox reactions during (de)intercalation processes. Such reactions are often accompanied by anion-anion bond formation, which heralds possibilities to design novel structure types disparate from known precursors, in a controlled manner. Here we present the multistep conversion of layered oxychalcogenides Sr2MnO2Cu1.5Ch2 (Ch = S, Se) into Cu-deintercalated phases where antifluorite type [Cu1.5Ch2]2.5- slabs collapsed into two-dimensional arrays of chalcogen dimers. The collapse of the chalcogenide layers on deintercalation led to various stacking types of Sr2MnO2Ch2 slabs, which formed polychalcogenide structures unattainable by conventional high-temperature syntheses. Anion-redox topochemistry is demonstrated to be of interest not only for electrochemical applications but also as a means to design complex layered architectures.	May 2023
B16-Test Beamline DIAD-Dual Imaging and Diffraction Beamline E01-JEM ARM 200CF E02-JEM ARM 300CF I08-Scanning X-ray Microscopy beamline (SXM) I12-JEEP: Joint Engineering, Environmental and Processing I13-1-Coherence I13-2-Diamond Manchester Imaging I14-Hard X-ray Nanoprobe	Synchrotron X-ray studies of the structural and functional hierarchies in mineralised human dental enamel: a state-of-the-art review Cyril Besnard , Ali Marie , Sisini Sasidharan , Robert A. Harper , Richard M. Shelton , Gabriel Landini , Alexander M. Korsunsky Dentistry Journal 11 DOI: 10.3390/dj11040098 Open Access Show Abstract ▼ Abstract: Hard dental tissues possess a complex hierarchical structure that is particularly evident in enamel, the most mineralised substance in the human body. Its complex and interlinked organisation at the Ångstrom (crystal lattice), nano-, micro-, and macro-scales is the result of evolutionary optimisation for mechanical and functional performance: hardness and stiffness, fracture toughness, thermal, and chemical resistance. Understanding the physical–chemical–structural relationships at each scale requires the application of appropriately sensitive and resolving probes. Synchrotron X-ray techniques offer the possibility to progress significantly beyond the capabilities of conventional laboratory instruments, i.e., X-ray diffractometers, and electron and atomic force microscopes. The last few decades have witnessed the accumulation of results obtained from X-ray scattering (diffraction), spectroscopy (including polarisation analysis), and imaging (including ptychography and tomography). The current article presents a multi-disciplinary review of nearly 40 years of discoveries and advancements, primarily pertaining to the study of enamel and its demineralisation (caries), but also linked to the investigations of other mineralised tissues such as dentine, bone, etc. The modelling approaches informed by these observations are also overviewed. The strategic aim of the present review was to identify and evaluate prospective avenues for analysing dental tissues and developing treatments and prophylaxis for improved dental health.	Apr 2023
I18-Microfocus Spectroscopy	Deep anoxic aquifers could act as sinks for uranium through microbial-assisted mineral trapping Ivan N. Pidchenko , John N. Christensen , Martin Kutzschbach , Konstantin Ignatyev , Ignasi Puigdomenech , Eva-Lena Tullborg , Nick M. W. Roberts , E. Troy Rasbury , Paul Northrup , Ryan Tappero , Kristina O. Kvashnina , Thorsten Schäfer , Yohey Suzuki , Henrik Drake Communications Earth & Environment 4 DOI: 10.1038/s43247-023-00767-9 Diamond Proposal Number(s): [28254] Open Access Show Abstract ▼ Abstract: Uptake of uranium (U) by secondary minerals, such as carbonates and iron (Fe)-sulfides, that occur ubiquitously on Earth, may be substantial in deep anoxic environments compared to surficial settings due to different environment-specific conditions. Yet, knowledge of U reductive removal pathways and related fractionation between 238U and 235U isotopes in deep anoxic groundwater systems remain elusive. Here we show bacteria-driven degradation of organic constituents that influences formation of sulfidic species facilitating reduction of geochemically mobile U(VI) with subsequent trapping of U(IV) by calcite and Fe-sulfides. The isotopic signatures recorded for U and Ca in fracture water and calcite samples provide additional insights on U(VI) reduction behaviour and calcite growth rate. The removal efficiency of U from groundwater reaching 75% in borehole sections in fractured granite, and selective U accumulation in secondary minerals in exceedingly U-deficient groundwater shows the potential of these widespread mineralogical sinks for U in deep anoxic environments.	Apr 2023
I18-Microfocus Spectroscopy	Degradation of fourteenth-century mordant gilding layers: synchrotron-based microfocus XRF, XRD, and XANES analyses of two paintings by Pietro Lorenzetti Helen Howard , Jens Najorka , Paul F. Schofield , Kalotina Geraki Studies In Conservation 89, 1 - 16 DOI: 10.1080/00393630.2023.2201094 Diamond Proposal Number(s): [17644] Show Abstract ▼ Abstract: Analyses of the degraded mordant gilding on two early fourteenth-century paintings by Pietro Lorenzetti were undertaken at the UK synchrotron facility Diamond Light Source. Previous studies revealed a complex orpiment-tinted mordant and its application for adhering two separate layers of silver and gold leaf and demonstrated degradation of the original materials. A new study involving synchrotron radiation (SR) microfocus X-ray fluorescence (µ-XRF) maps on cross-sections of the discolored mordant allowed imaging of the extent of migration of mobile As-Ag-S bearing species and provided ideal positions from which to collect microfocus X-ray absorption near edge structure (µ-XANES) maps of As, Ag, and S for oxidation state analysis. SR µ-XANES indicates that arsenolite (As2O3) is present throughout the mordant suggesting light-induced photooxidation of orpiment. Both As3+ (as oxide) and As5+ have been detected and these are known signs for orpiment degradation. SR microfocus X-ray diffraction (µ-XRD) was used to reveal the nature of altered phases in the mordant layer and identified the presence of acanthite Ag2S, xanthoconite Ag3AsS3, and arsenolite As2O3. The analysis confirmed that the darkening of the mordant is most probably caused by finely dispersed grey-colored Ag + -bearing acanthite particles (Ag2S). The results are discussed in the context of analysis of contemporary paintings and recent studies on the alteration of orpiment.	Apr 2023
B18-Core EXAFS	Electrodeposition of manganese dioxide coatings onto graphene foam substrates for electrochemical capacitors Filipe Braga , Gabriel Casano , Luke M. Daniels , Marco Caffio , Laurence J. Hardwick Electrochimica Acta 7 DOI: 10.1016/j.electacta.2023.142433 Diamond Proposal Number(s): [14239] Open Access Show Abstract ▼ Abstract: Optimisation of electrodeposition routes of birnessite manganese dioxide (MnO2) coatings onto 3D graphene foam substrates enabled greater attainable capacitances. Current pulse deposition method resulted in highest achievable areal capacitance of 530 mF/cm2 under a 10 mA/cm2 current rate, cycling performance with 91% retention after 9000 cycles, as well as improved rate capability when compared to the cyclic voltammetry or galvanostatic deposition. Introduction of oxygen functional groups to the graphene foam added initial pseudocapacitance and accelerated the rate for nucleation and growth of the MnO2 crystal grains, resulting in an areal capacitance of 410 mF/cm2 under a 10 mA/cm2 current rate. However, in this case the increase in specific capacitance was accompanied by sluggish kinetic for charge storage seen via impedance spectroscopy. The charge storage mechanism of the deposited MnO2 films was investigated using in situ Raman microscopy and analysis of peak shifts revealed expansion and contraction of birnessite MnO2, relating to exchange of Na+ and H2O at the MnO2 interface.	Apr 2023
B18-Core EXAFS	Closing the knowledge gap on the composition of the asbestos bodies F Bardelli , C. Giacobbe , P. Ballirano , V. Borelli , F. Di Benedetto , G. Montegrossi , D. Bellis , A. Pacella Environmental Geochemistry And Health 11 DOI: 10.1007/s10653-023-01557-0 Diamond Proposal Number(s): [30124] Open Access Show Abstract ▼ Abstract: Asbestos bodies (AB) form in the lungs as a result of a biomineralization process initiated by the alveolar macrophages in the attempt to remove asbestos. During this process, organic and inorganic material deposit on the foreign fibers forming a Fe-rich coating. The AB start to form in months, thus quickly becoming the actual interface between asbestos and the lung tissue. Therefore, revealing their composition, and, in particular, the chemical form of Fe, which is the major component of the AB, is essential to assess their possible role in the pathogenesis of asbestos-related diseases. In this work we report the result of the first x-ray diffraction measurements performed on single AB embedded in the lung tissue samples of former asbestos plant workers. The combination with x-ray absorption spectroscopy data allowed to unambiguously reveal that Fe is present in the AB in the form of two Fe-oxy(hydroxides): ferrihydrite and goethite. The presence of goethite, which can be explained in terms of the transformation of ferrihydrite (a metastable phase) due to the acidic conditions induced by the alveolar macrophages in their attempt to phagocytose the fibers, has toxicological implications that are discussed in the paper.	Apr 2023
B18-Core EXAFS	Interfacial chemistry in the electrocatalytic hydrogenation of CO2 over C-supported Cu-based systems Diego Gianolio , Michael D. Higham , Matthew G. Quesne , Matteo Aramini , Ruoyu Xu , Alex I. Large , Georg Held , Juan-Jesús Velasco-Vélez , Michael Haevecker , Axel Knop-Gericke , Chiara Genovese , Claudio Ampelli , Manfred Erwin Schuster , Siglinda Perathoner , Gabriele Centi , C. Richard A. Catlow , Rosa Arrigo Acs Catalysis DOI: 10.1021/acscatal.3c01288 Diamond Proposal Number(s): [24919] Open Access Show Abstract ▼ Abstract: Operando soft and hard X-ray spectroscopic techniques were used in combination with plane-wave density functional theory (DFT) simulations to rationalize the enhanced activities of Zn-containing Cu nanostructured electrocatalysts in the electrocatalytic CO2 hydrogenation reaction. We show that at a potential for CO2 hydrogenation, Zn is alloyed with Cu in the bulk of the nanoparticles with no metallic Zn segregated; at the interface, low reducible Cu(I)–O species are consumed. Additional spectroscopic features are observed, which are identified as various surface Cu(I) ligated species; these respond to the potential, revealing characteristic interfacial dynamics. Similar behavior was observed for the Fe–Cu system in its active state, confirming the general validity of this mechanism; however, the performance of this system deteriorates after successive applied cathodic potentials, as the hydrogen evolution reaction then becomes the main reaction pathway. In contrast to an active system, Cu(I)–O is now consumed at cathodic potentials and not reversibly reformed when the voltage is allowed to equilibrate at the open-circuit voltage; rather, only the oxidation to Cu(II) is observed. We show that the Cu–Zn system represents the optimal active ensembles with stabilized Cu(I)–O; DFT simulations rationalize this observation by indicating that Cu–Zn–O neighboring atoms are able to activate CO2, whereas Cu–Cu sites provide the supply of H atoms for the hydrogenation reaction. Our results demonstrate an electronic effect exerted by the heterometal, which depends on its intimate distribution within the Cu phase and confirms the general validity of these mechanistic insights for future electrocatalyst design strategies.	Apr 2023
B18-Core EXAFS	Mo and W carbide catalysts - An approach towards sustainable conversions Marlene Führer Show Abstract ▼ Abstract: Catalysts play an important role in the shift from fossil-based chemical industry to a more sustainable, bio-based industry. Current used catalysts are noble metals like platinum or gold. However, noble metals are scarce, hence expensive, which makes it desirable to find more abundant alternatives. In this thesis, we focused on the production of new catalysts based on abundant materials for the conversion of bio-based feedstocks. (Mixed) molybdenum and tungsten carbide catalysts were used as alternatives for noble-based catalysts.	Apr 2023

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