B18-Core EXAFS
E01-JEM ARM 200CF
E02-JEM ARM 300CF
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Runjia
Lin
,
Liqun
Kang
,
Tianqi
Zhao
,
Jianrui
Feng
,
Veronica
Celorrio
,
Guohui
Zhang
,
Giannantonio
Cibin
,
Anthony
Kucernak
,
Dan
Brett
,
Furio
Cora
,
Ivan P.
Parkin
,
Guanjie
He
Diamond Proposal Number(s):
[25410, 29207]
Open Access
Abstract: Electrocatalytic organic compound oxidation reactions (OCORs) have been intensively studied for energy and environmentally benign applications. However, relatively little effort has been devoted to developing a fundamental understanding of OCOR, including the detailed competition with side reactions and activity limitations, thus inhibiting the rational design of high-performance electrocatalysts. Herein, by taking NiWO4-catalysed urea oxidation reaction (UOR) in aqueous media as an example, the competition between the OCOR and the oxygen evolution reaction (OER) within a wide potential range is examined. It is shown that the root of the competition can be ascribed to insufficient surface concentration of dynamic Ni3+, an active site shared by both UOR and OER. Similar phenomenon are observed in other OCOR electrocatalysts and systems. To address the issue, a “controllable reconstruction of pseudo-crystalline bimetal oxides” design strategy is proposed to maximise the dynamic Ni3+ population and manipulate the competition between UOR and OER. The optimised electrocatalyst delivers best-in-class performance and a ~10-fold increase in current density at 1.6 V versus the reversible hydrogen electrode for alkaline urea electrolysis compared to that of the pristine materials.
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Mar 2022
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I21-Resonant Inelastic X-ray Scattering (RIXS)
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Diamond Proposal Number(s):
[25589]
Open Access
Abstract: Oxidation and reduction of the oxide ions in the bulk of cathode materials is a potential route towards increasing the energy density of Li-ion batteries. Here, we present neutron PDF data which demonstrates the presence of short 1.2 Å O–O distances in a charged O-redox cathode material, corresponding to the bond length of molecular O2. This was achieved by collecting our data close to absolute zero (2 K), suppressing thermal motion which may have obscured detection by PDF previously. This direct detection of molecular O2 trapped in the material by diffraction complements the X-ray spectroscopy studies by e.g. RIXS while avoiding issues of possible beam damage as well as being a bulk average technique.
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Dec 2021
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I14-Hard X-ray Nanoprobe
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Sofiia
Kosar
,
Andrew J.
Winchester
,
Tiarnan A. S.
Doherty
,
Stuart
Macpherson
,
Christopher E.
Petoukhoff
,
Kyle
Frohna
,
Miguel
Anaya
,
Nicholas S.
Chan
,
Julien
Madéo
,
Michael K. L.
Man
,
Samuel D.
Stranks
,
Keshav M.
Dani
Diamond Proposal Number(s):
[19023]
Open Access
Abstract: With rapidly growing photoconversion efficiencies, hybrid perovskite solar cells have emerged as promising contenders for next generation, low-cost photovoltaic technologies. Yet, the presence of nanoscale defect clusters, that form during the fabrication process, remains critical to overall device operation, including efficiency and long-term stability. To successfully deploy hybrid perovskites, we must understand the nature of the different types of defects, assess their potentially varied roles in device performance, and understand how they respond to passivation strategies. Here, by correlating photoemission and synchrotron-based scanning probe X-ray microscopies, we unveil three different types of defect clusters in state-of-the-art triple cation mixed halide perovskite thin films. Incorporating ultrafast time-resolution into our photoemission measurements, we show that defect clusters originating at grain boundaries are the most detrimental for photocarrier trapping, while lead iodide defect clusters are relatively benign. Hexagonal polytype defect clusters are only mildly detrimental individually, but can have a significant impact overall if abundant in occurrence. We also show that passivating defects with oxygen in the presence of light, a previously used approach to improve efficiency, has a varied impact on the different types of defects. Even with just mild oxygen treatment, the grain boundary defects are completely healed, while the lead iodide defects begin to show signs of chemical alteration. Our findings highlight the need for multi-pronged strategies tailored to selectively address the detrimental impact of the different defect types in hybrid perovskite solar cells.
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Sep 2021
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I12-JEEP: Joint Engineering, Environmental and Processing
I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[13824, 9866, 17606]
Open Access
Abstract: Injection of CO2 into shale reservoirs to enhance gas recovery and simultaneously sequester greenhouse gases is a potential contributor towards the carbon-neutral target. It offers a low-carbon, low-cost, low-waste and large-scale solution during the energy transition period. A precondition to efficient gas storage and flow is a sound understanding of how the shale's micro-scale impacts on these phenomena. However, the heterogeneous and complex nature of shales limits the understanding of microstructure and pore systems, making feasibility analysis challenging. This study qualitatively and quantitatively investigates the Bowland shale microstructure in 3D at five length scales: artificial fractures at 10–100 μm scale, matrix fabric at 1–10 μm-scale, individual mineral grains and organic matter particles at 100 nm–1 μm scale, macropores and micro-cracks at 10–100 nm scale and organic matter and mineral pores at 1–10 nm-scale. For each feature, the volume fraction variations along the bedding normal orientation, the fractal dimensions and the degrees of anisotropy were analysed at all corresponding scales for a multi-scale heterogeneity analysis. The results are combined with other bulk laboratory measurements, including supercritical CO2 and CH4 adsorption at reservoir conditions, pressure-dependent permeability and nitrogen adsorption pore size distribution, to perform a comprehensive analysis on the storage space and flow pathways. A cross-scale pore size distribution, ranging from 2 nm to 3 μm, was calculated with quantified microstructure. The cumulative porosity is calculated to be 8%. The cumulative surface area is 17.6 m2 g−1. A model of CH4 and CO2 flow pathways and storage with quantified microstructure is presented and discussed. The feasibility of simultaneously enhanced gas recovery and subsurface CO2 storage in Bowland shale, the largest shale gas potential formation in the UK, was assessed based using multi-scale microstructure analysis. The potential is estimated to store 19.0–21.2 Gt CO2 as free molecules, together with 18.3–28.5 Gt CO2 adsorbed onto pore surfaces, implying a theoretical maximum of 47.5–49.5 Gt carbon storage in the current estimate of 38 trillion cubic metres (∼1300 trillion cubic feet) of Bowland shale. Simple estimates suggest 6.0–15.8 Gt CO2 may be stored in practice.
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Jun 2021
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B16-Test Beamline
I13-1-Coherence
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Diamond Proposal Number(s):
[22503, 22217]
Open Access
Abstract: The performance and durability of Ni-rich cathode materials are controlled in no small part by their mechanical durability, as chemomechanical breakdown at the nano-scale leads to increased internal resistance and decreased storage capacity. The mechanical degradation is caused by the transient lithium diffusion processes during charge and discharge of layered oxide spherical cathode micro-particles, leading to highly anisotropic incompatible strain fields. Experimental characterisation of the transient mechanisms underlying crack and void formation requires the combination of very high resolution in space (sub-micron) and time (sub-second) domains without charge interruption. The present study is focused on sub-micron focused operando synchrotron X-ray diffraction and in situ Ptycho-Tomographic nano-scale imaging of a single nano-structured LiNi0.8Co0.1Mn0.1O2 core-shell particle during charge to obtain a thorough understanding of the anisotropic deformation and damage phenomena at a particle level. Preferential grain orientation within the shell of a spherical secondary cathode particle provides improved lithium transport but is also associated with spatially varying anisotropic expansion of the hexagonal unit cell in the c-axis and contraction in the a-axis. These effects were resolved in relation to the grain orientation, and the link established with the nucleation and growth of intergranular cracks and voids that causes electrical isolation of active cathode material. Coupled multi-physics Finite Element Modelling of diffusion and deformation inside a single cathode particle during charge and discharge was validated by comparison with experimental evidence and allowed unequivocal identification of key mechanical drivers underlying Li-ion battery degradation.
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Aug 2020
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I04-1-Macromolecular Crystallography (fixed wavelength)
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Open Access
Abstract: Genetically engineering a cysteine (thiolate) close to the distal [4Fe–4S] cluster of a [NiFe]-hydrogenase creates a highly specific target for attachment of Ag nanoclusters templated in polymethyl acrylate, the resulting ‘hard-wired’ enzyme catalysing rapid hydrogen evolution by visible light. The rate is further enhanced by binding to metal oxide nanoparticles – results of investigations focusing on P-25 TiO2 and including anatase TiO2, rutile TiO2, ZnO, SrTiO3 and ZrO2 leading to the proposal that these act as active or structural scaffolds to promote intra-assembly electron transfer.
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Oct 2018
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B18-Core EXAFS
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Abstract: We have presented a detailed investigation of the effects of Mg substitution on the structure, electrochemical performance and Na-ion diffusion in high voltage P2-type Na2/3Ni1/3-xMgxMn2/3O2 (0
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Mar 2018
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[12336, 17193]
Abstract: Phonon-glass electron-crystal (PGEC) behaviour is realised in La0.5Na0.5Ti1–xNbxO3 thermoelectric oxides. The vibrational disorder imposed by the presence of both La3+ and Na+ cations on the A site of the ABO3 perovskite oxide La0.5Na0.5TiO3 produces a phonon-glass with a thermal conductivity, κ, 80% lower than that of SrTiO3 at room temperature. Unlike other state-of-the-art thermoelectric oxides, where there is strong coupling of κ to the electronic power factor, the electronic transport of these materials can be optimised independently of the thermal transport through cation substitution at the octahedral B site. The low κ of the phonon-glass parent is retained across the La0.5Na0.5Ti1–xNbxO3 series without disrupting the electronic conductivity, affording PGEC behaviour in oxides.
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Aug 2017
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I12-JEEP: Joint Engineering, Environmental and Processing
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Donal P.
Finegan
,
Eric
Darcy
,
Matthew
Keyser
,
Bernhard
Tjaden
,
Thomas M. M.
Heenan
,
Rhodri
Jervis
,
Josh J.
Bailey
,
Romeo
Malik
,
Nghia T.
Vo
,
Oxana V.
Magdysyuk
,
Robert
Atwood
,
Michael
Drakopoulos
,
Marco
Dimichiel
,
Alexander
Rack
,
Gareth
Hinds
,
Dan J. L.
Brett
,
Paul R.
Shearing
Diamond Proposal Number(s):
[13884]
Open Access
Abstract: Lithium-ion batteries are being used in increasingly demanding applications where safety and reliability are of utmost importance. Thermal runaway presents the greatest safety hazard, and needs to be fully understood in order to progress towards safer cell and battery designs. Here, we demonstrate the application of an internal short circuiting device for controlled, on-demand, initiation of thermal runaway. Through its use, the location and timing of thermal runaway initiation is pre-determined, allowing analysis of the nucleation and propagation of failure within 18[thin space (1/6-em)]650 cells through the use of high-speed X-ray imaging at 2000 frames per second. The cause of unfavourable occurrences such as sidewall rupture, cell bursting, and cell-to-cell propagation within modules is elucidated, and steps towards improved safety of 18[thin space (1/6-em)]650 cells and batteries are discussed.
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Mar 2017
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I11-High Resolution Powder Diffraction
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Open Access
Abstract: Sodium-ion batteries are a more sustainable alternative to the existing lithium-ion technology and could alleviate some of the stress on the global lithium market as a result of the growing electric car and portable electronics industries. Fundamental research focused on understanding the structural and electronic processes occurring on electrochemical cycling is key to devising rechargeable batteries with improved performance. We present an in-depth investigation of the effect of Mg doping on the electrochemical performance and structural stability of Na2/3MnO2 with a P2 layer stacking by comparing three compositions: Na2/3Mn1−yMgyO2 (y = 0.0, 0.05, 0.1). We show that Mg substitution leads to smoother electrochemistry, with fewer distinct electrochemical processes, improved rate performance and better capacity retention. These observations are attributed to the more gradual structural changes upon charge and discharge, as observed with synchrotron, powder X-ray, and neutron diffraction. Mg doping reduces the number of Mn3+ Jahn–Teller centers and delays the high voltage phase transition occurring in P2-Na2/3MnO2. The local structure is investigated using 23Na solid-state nuclear magnetic resonance (ssNMR) spectroscopy. The ssNMR data provide direct evidence for fewer oxygen layer shearing events, leading to a stabilized P2 phase, and an enhanced Na-ion mobility up to 3.8 V vs. Na+/Na upon Mg doping. The 5% Mg-doped phase exhibits one of the best rate performances reported to date for sodium-ion cathodes with a P2 structure, with a reversible capacity of 106 mA h g−1 at the very high discharge rate of 5000 mA g−1. In addition, its structure is highly reversible and stable cycling is obtained between 1.5 and 4.0 V vs. Na+/Na, with a capacity of approximately 140 mA h g−1 retained after 50 cycles at a rate of 1000 mA g−1.
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Aug 2016
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