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15 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2 [Next/Last]

Instruments / Technical Area	Publication Details	Published
	Energy dispersive-EXAFS of Pd nucleation at a liquid/liquid interface S.-Y. Chang , S. G.l Booth , A. Uehara-Kasuno , J. F. W. Mosselmans , G. Cibin , V.-T. Pham , L. Nataf , R. A. W. Dryfe , S. L. M. Schroeder Journal Of Physics: Conference Series 712 XAFS 16 DOI: 10.1088/1742-6596/712/1/012058 Open Access Show Abstract ▼ Abstract: Energy dispersive extended X-ray absorption fine structure (EDE) has been applied to Pd nanoparticle nucleation at a liquid/liquid interface under control over the interfacial potential and thereby the driving force for nucleation. Preliminary analysis focusing on Pd K edge-step height determination shows that under supersaturated conditions the concentration of Pd near the interface fluctuate over a period of several hours, likely due to the continuous formation and dissolution of sub-critical nuclei. Open circuit potential measurements conducted ex-situ in a liquid/liquid electrochemical cell support this view, showing that the fluctuations in Pd concentration are also visible as variations in potential across the liquid/liquid interface. By decreasing the interfacial potential through inclusion of a common ion (tetraethylammonium, TEA+) the Pd nanoparticle growth rate could be slowed down, resulting in a smooth nucleation process. Eventually, when the TEA+ ions reached an equilibrium potential, Pd nucleation and particle growth were inhibited.	May 2016
	The significance of bromide in the Brust–Schiffrin synthesis of thiol protected gold nanoparticles S. G. Booth , A. Uehara , Sin-Yuen Chang , C. La Fontaine , T. Fujii , Y. Okamoto , T. Imai , S. L. M. Schroeder , R. A. W. Dryfe Chemical Science 8, 7954 - 7962 DOI: 10.1039/C7SC03266H Open Access Show Abstract ▼ Abstract: The mechanism of the two-phase Brust–Schiffrin synthesis of alkane thiol protected metal nanoparticles is known to be highly sensitive to the precursor species and reactant conditions. In this work X-ray absorption spectroscopy is used in conjunction with liquid/liquid electrochemistry to highlight the significance of Br− in the reaction mechanism. The species [AuBr4]− is shown to be a preferable precursor in the Brust–Schiffrin method as it is more resistant to the formation of Au(I) thiolate species than [AuCl4]−. Previous literature has demonstrated that avoidance of the Au(I) thiolate is critical to achieving a good yield of nanoparticles, as [Au(I)X2]− species are more readily reduced by NaBH4. We propose that the observed behavior of [AuBr4]− species described herein explains the discrepancies in reported behavior present in the literature to date. This new mechanistic understanding should enable nanoparticle synthesis with a higher yield and reduce particle size polydispersity.	Sep 2017
B18-Core EXAFS	Detection and characterisation of sub-critical nuclei during reactive Pd metal nucleation by X-ray absorption spectroscopy S.-Y. Chang , Y. Grunder , S. G. Booth , L. B. Molleta , A. Uehara , J. F. W. Mosselmans , G. Cibin , V.-T. Pham , L. Nataf , R. A. Dryfe , S. L. M Schroeder Crystengcomm DOI: 10.1039/C5CE01883H Diamond Proposal Number(s): [8405] Open Access Show Abstract ▼ Abstract: The interfacial reduction of aqueous [PdCl4]2− at the interface with an organic solution of ferrocene has been characterised by X-ray absorption fine structure (XAFS) spectroscopy. Use of a liquid–liquid interface as a model for homogeneous nucleation permits control of the thermodynamic driving force for nucleation, through variation of the [PdCl4]2− and ferrocene concentrations in the bulk of the adjacent phases. We demonstrate that this approach permits characterisation of the system under conditions of (i) no particle nucleation, (ii) fast spontaneous nucleation of stable nanoparticles and (iii) an intermediate state, in which formation of metastable Pd sub-critical nuclei takes place. Analysis of the XAFS spectra in the metastable state revealed a stochastically fluctuating equilibrium in which Pd nuclei are constantly formed and re-dissolved, as evident from oxidation state fluctuations detected by the Pd XAFS. Supersaturation was evidently sufficient to induce nanoparticle formation but insufficient for nuclei to grow beyond the critical cluster size. We were able to maintain a system in this metastable state for several hours. Such sub-critical clusters are predicted by classical nucleation theory, but have not been detected except in liquid-cell TEM imaging and scanning electrochemical microscopy studies.	Dec 2015
B18-Core EXAFS	In situ XAFS study of palladium electrodeposition at the liquid/liquid interface Samuel G. Booth , Sin-Yuen Chang , Akihiro Uehara , Camille La Fontaine , Giannantonio Cibin , Sven Schroeder , Robert A. W. Dryfe Electrochimica Acta DOI: 10.1016/j.electacta.2017.03.059 Diamond Proposal Number(s): [13953] Show Abstract ▼ Abstract: We report the use of XAFS (X-ray absorption fine structure) as an in situ method to follow the electrochemically driven deposition of palladium nanoparticles at a liquid/liquid interface. A novel glass/plastic hybrid electrochemical cell was used to enable control of the potential applied to the liquid/liquid interface. In situ measurements indicate that the nucleation of metallic nanoparticles can be triggered through chronoamperometry or cyclic voltammetry. In contrast to spontaneous nucleation at the liquid/liquid interface, whereby fluctuations in Pd oxidation state and concentration are observed, under a fixed interfacial potential the growth process occurs at a steady rate leading to a build-up of palladium at the interface. Raman spectroscopy of the deposit suggests that the organic electrolyte binds directly to the surface of the deposited nanoparticles. It was found that the introduction of citric acid results in the formation of spherical nanoparticles at the interface.	Mar 2017
B18-Core EXAFS	The role of the reducible dopant in solid electrolyte–lithium metal interfaces Innes Mcclelland , Hany El-Shinawi , Samuel G. Booth , Anna Regoutz , Jasmin Clough , Sebastian Altus , Edmund J. Cussen , Peter J. Baker , Serena A. Cussen Chemistry Of Materials 21 DOI: 10.1021/acs.chemmater.2c00379 Diamond Proposal Number(s): [14239] Open Access Show Abstract ▼ Abstract: Garnet solid electrolytes, of the form Li7La3Zr2O12 (LLZO), remain an enticing prospect for solid-state batteries owing to their chemical and electrochemical stability in contact with metallic lithium. Dopants, often employed to stabilize the fast ion conducting cubic garnet phase, typically have no effect on the chemical stability of LLZO in contact with Li metal but have been found recently to impact the properties of the Li/garnet interface. For dopants more “reducible” than Zr (e.g., Nb and Ti), contradictory reports of either raised or reduced Li/garnet interfacial resistances have been attributed to the dopant. Here, we investigate the Li/LLZO interface in W-doped Li7La3Zr2O12 (LLZWO) to determine the influence of a “reducible” dopant on the electrochemical properties of the Li/garnet interface. Single-phase LLZWO is synthesized by a new sol–gel approach and densified by spark plasma sintering. Interrogating the resulting Li/LLZWO interface/interphase by impedance, muon spin relaxation and X-ray absorption spectroscopies uncover the significant impact of surface lithiation on electrochemical performance. Upon initial contact, an interfacial reaction occurs between LLZWO and Li metal, leading to the reduction of surface W6+ centers and an initial reduction of the Li/garnet interfacial resistance. Propagation of this surface reaction, driven by the high mobility of Li+ ions through the grain surfaces, thickens the resistive interphases throughout the material and impedes Li+ ion transport between the grains. The resulting high resistance accumulating in the system impedes cycling at high current densities. These insights shed light on the nature of lithiated interfaces in garnet solid electrolytes containing a reducible dopant where high Li+ ion mobility and the reducible nature of the dopant can significantly affect electrochemical performance.	May 2022
B18-Core EXAFS I11-High Resolution Powder Diffraction	Suppression of Fe-cation migration by indium substitution in LiFe2–xInxSbO6 cathode materials Xabier Martinez De Irujo-Labalde , Heather Grievson , Josie-May Mortimer , Samuel G. Booth , Alex Scrimshire , Paul A. Bingham , Emmanuelle Suard , Serena A. Cussen , Michael A. Hayward Chemistry Of Materials DOI: 10.1021/acs.chemmater.2c03418 Diamond Proposal Number(s): [25166] Open Access Show Abstract ▼ Abstract: Cation migration on electrochemical cycling can significantly influence the performance of li-ion cathode materials. Phases of composition LiFe2–xInxSbO6 (0 < x <1) adopt crystal structures described in space group Pnnm, consisting of a hexagonally close-packed array of oxide ions, with Fe/In and Sb cations ordered on octahedral sites, and lithium cations located within partially occupied tetrahedral sites. NPD, SXRD, and 57Fe Mössbauer data indicate that on reductive lithium insertion (either chemically or electrochemically), LiFe2SbO6 is converted to Li2Fe2SbO6 accompanied by large-scale cation migration, to form a partially Fe/Li cation-ordered and Fe2+/Fe3+ charge-ordered phase from which lithium cations cannot be easily removed, either chemically or electrochemically. Partial substitution of Fe with In suppresses the degree of cation migration that occurs on lithium insertion such that no structural change is observed when LiFeInSbO6 is converted into Li1.5FeInSbO6, allowing the system to be repeatedly electrochemically cycled between these two compositions. Phases with intermediate levels of In substitution exhibit low levels of Fe migration on Li insertion and electrochemical capacities which evolve on cycling. The mechanism by which the In3+ cations suppress the migration of Fe cations is discussed along with the cycling behavior of the LiFe1.5In0.5SbO6–Li1.75Fe1.5In0.5SbO6.	Dec 2022
B18-Core EXAFS I18-Microfocus Spectroscopy	Electrochemical insight into the brust–schiffrin synthesis of Au nanoparticles Akihiro Uehara , Samuel Booth , Sin-Yuen Chang , Sven L. M. Schroeder , Takahito Imai , Teruo Hashimoto , J. Frederick W. Mosselmans , Robert A. W. Dryfe Journal Of The American Chemical Society 137 (48), 15135–15144 DOI: 10.1021/jacs.5b07825 PMID: 26559785 Diamond Proposal Number(s): [11293, 8861] Open Access Show Abstract ▼ Abstract: The mechanism of the Brust-Schiffrin gold nanoparticle synthesis has been investigated through the use of ion transfer voltammetry at the water\|1,2-dichloroethane (DCE) solution interface, combined with X-ray absorption fine structure (XAFS) of the reaction between [AuCl4]- and thiol (RSH) in homogeneous toluene (TL) solution. Ion transfer calculations indi- cate the formation of [AuCl2]- at RSH:Au ratios from 0.2 – 2 with a time-dependent variation observed over several days. At RSH:Au ratios above 2 and after time periods greater than 24 hours, the formation of Au(I)SR is also observed. The relative concentrations of reaction products observed at the liquid/liquid interface are in excellent agreement with those observed by XAFS for the corresponding reaction in a single homogeneous phase. BH4- ion transfer reactions between water and DCE indicate that the reduction of [AuCl4]- and/or [AuCl2]- to Au nanoparticles by BH4- proceeds in the bulk organic phase. On the other hand, BH4- was unable to reduce the insoluble [Au(I)SR]n species to Au nanoparticles. The number and size of the nanoparticles formed was dependent on the concentration ratio of RSH:Au, as well as the experimental duration because of the competing formation of the [Au(I)SR]n precipitate. Higher concentrations of nanoparticles, with diameters of 1.0 – 1.5 nm, were formed at RSH:Au ratios from 1 to 2.	Nov 2015
I09-Surface and Interface Structural Analysis I21-Resonant Inelastic X-ray Scattering (RIXS)	Oxygen-redox activity in non-lithium-excess tungsten-doped LiNiO2 cathode A. S. Menon , B. J. Johnston , S. G. Booth , L. Zhang , K. Kress , B. E. Murdock , G. Paez Fajardo , N. N. Anthonisamy , N. Tapia-Ruiz , S. Agrestini , M. Garcia-Fernandez , K. Zhou , P. K. Thakur , T. L. Lee , A. J. Nedoma , S. A. Cussen , L. F. J. Piper Prx Energy 2 DOI: 10.1103/PRXEnergy.2.013005 Diamond Proposal Number(s): [29104, 29113] Open Access Show Abstract ▼ Abstract: The desire to increase the energy density of stoichiometric layered Li TM O 2 (TM = 3d transition metal) cathode materials has promoted investigation into their properties at high states of charge. Although there is increasing evidence for pronounced oxygen participation in the charge compensation mechanism, questions remain whether this is true O -redox, as observed in Li -excess cathodes. Through a high-resolution O K-edge resonant inelastic x-ray spectroscopy (RIXS) study of the Mn -free Ni -rich layered oxide Li Ni 0.98 W 0.02 O 2 , we demonstrate that the same oxidized oxygen environment exists in both Li -excess and non- Li -excess systems. The observation of identical RIXS loss features in both classes of compounds is remarkable given the differences in their crystallographic structure and delithiation pathways. This lack of a specific structural motif reveals the importance of electron correlation in the charge compensation mechanism for these systems and indicates how a better description of charge compensation in layered oxides is required to understand anionic redox for energy storage.	Mar 2023
I15-1-X-ray Pair Distribution Function (XPDF)	Insights into the electrochemical reduction products and processes in silica anodes for next‐generation lithium‐ion batteries Jake E. Entwistle , Samuel G. Booth , Dean S. Keeble , Faisal Ayub , Maximilian Yan , Serena A. Corr , Denis J. Cumming , Siddharth V. Patwardhan Advanced Energy Materials 278 DOI: 10.1002/aenm.202001826 Diamond Proposal Number(s): [2257] Open Access Show Abstract ▼ Abstract: The use of silica as a lithium‐ion battery anode material requires a pretreatment step to induce electrochemical activity. The partially reversible electrochemical reduction reaction between silica and lithium has been postulated to produce silicon, which can subsequently reversibly react with lithium, providing stable capacities higher than graphite materials. Up to now, the electrochemical reduction pathway and the nature of the products were unknown, thereby hampering the design, optimization, and wider uptake of silica‐based anodes. Here, the electrochemical reduction pathway is uncovered and, for the first time, elemental silicon is identified as a reduction product. These insights, gleaned from analysis of the current response and capacity increase during reduction, conclusively demonstrated that silica must be reduced to introduce reversible capacity and the highest capacities of 600 mAh g−1 are achieved by using a constant load discharge at elevated temperature. Characterization via total scattering X‐ray pair distribution function analysis reveal the reduction products are amorphous in nature, highlighting the need for local structural methods to uncover vital information often inaccessible by traditional diffraction. These insights contribute toward understanding the electrochemical reduction of silica and can inform the development of pretreatment processes to enable their incorporation into next‐generation lithium‐ion batteries.	Sep 2020
I15-1-X-ray Pair Distribution Function (XPDF)	Anion-polarisation–directed short-range-order in antiperovskite Li2FeSO Samuel W. Coles , Viktoria Falkowski , Harry S. Geddes , Gabriel E. Pérez , Samuel G. Booth , Alexander G. Squires , Conn O'Rourke , Kit Mccoll , Andrew L. Goodwin , Serena A. Cussen , Simon J. Clarke , Saiful Islam , Benjamin J. Morgan Journal Of Materials Chemistry A DOI: 10.1039/D2TA10037A Diamond Proposal Number(s): [27702] Open Access Show Abstract ▼ Abstract: Short-range ordering in cation-disordered cathodes can have a significant effect on their electrochemical properties. Here, we characterise the cation short-range order in the antiperovskite cathode material Li2FeSO, using density functional theory, Monte Carlo simulations, and synchrotron X-ray pair-distribution-function data. We predict partial short-range cation-ordering, characterised by favourable OLi4Fe2 oxygen coordination with a preference for polar cis-OLi4Fe2 over non-polar trans-OLi4Fe2 configurations. This preference for polar cation configurations produces long-range disorder, in agreement with experimental data. The predicted short-range-order preference contrasts with that for a simple point-charge model, which instead predicts preferential trans-OLi4Fe2 oxygen coordination and corresponding long-range crystallographic order. The absence of long-range order in Li2FeSO can therefore be attributed to the relative stability of cis-OLi4Fe2 and other non-OLi4Fe2 oxygen-coordination motifs. We show that this effect is associated with the polarisation of oxide and sulfide anions in polar coordination environments, which stabilises these polar short-range cation orderings. We propose similar anion-polarisation–directed short-range-ordering may be present in other heterocationic materials that contain cations with different formal charges. Our analysis also illustrates the limitations of using simple point-charge models to predict the structure of cation-disordered materials, where other factors, such as anion polarisation, may play a critical role in directing both short- and long-range structural correlations.	Apr 2023

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