B18-Core EXAFS
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Open Access
Abstract: Metal nanoparticles are widely considered for heterogeneous catalysis due to their high atomic efficiency and tunable active microenvironment, but their specific functional tendencies are still unclear. Here, we report that a Rh@ZrO2/NC catalyst with only 0.1 wt% Rh exhibits exceptional catalytic performance and high selectivity (p-nitroacetophenone conversion-98.6 %, p-aminoacetophenone selectivity-100 %, r-56.4 molp-nitroacetophenone/(molRh·min)) towards the hydrogenation of the -NO2 group in nitroarene to -NH2. This is because the interaction between Rh species and “ZrO2-N” results in significant hydrogen spillover in the catalyst, as supported by DFT calculations. Extensive characterizations from TG, DTG, NAP-XPS, in-situ Raman spectroscopy, in-situ DRIFT spectroscopy and DFT calculations further confirm the adsorption, activation and dissociation of hydrogen on Rh nanoparticles. The H* species migrate readily over ZrO2-NC, to facilitate the catalytic activity and selectivity for the hydrogenation of nitroarene. This study presents a new approach to develop highly efficient and selective metal nanoparticle-catalysts for cost-effective hydrogenation reactions.
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Dec 2025
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B18-Core EXAFS
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Diamond Proposal Number(s):
[36598]
Open Access
Abstract: O3 phase NiFeMn- based layered transition metal oxides have attracted interest for positive electrode materials for Na-ion batteries. However, they generally suffer from challenges like phase transitions and Fe migration. Recently, the substitution of Ca into the Na layer, serving as a ‘pillar’, has proven to be an effective approach to overcome these challenges. Here, we systematically studied the composition-dependent Ca pillaring effect on the electrochemical performance and structure evolution of two O3 phase NiFeMn-based layered transition metal oxides. It is found that, although moderate Ca doping in high-Ni system - Na1-2xCaxNi0.25Mn0.25Fe0.5O2 (x = 0.00, 0.03) enhances cycling stability and reduces polarization, excessive doping compromises rate capability and does not effectively prevent Fe migration. Conversely, high-Mn system - Na1-2xCaxNi0.17Mn0.33Fe0.5O2 (x = 0.00, 0.04) exhibits a more robust and beneficial response to Ca incorporation, showing enhanced structural integrity, improved redox reversibility, and effective suppression of Fe migration. This study provides insights into the tunable chemical environments of transition metal oxides, thereby advancing the design of high-performance positive electrode materials and contributing to the development of next-generation sodium-ion batteries.
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Dec 2025
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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Diamond Proposal Number(s):
[34919, 37955]
Open Access
Abstract: A combination of experimental methods and computational techniques have been used to investigate the composition of the zinc ferrite (ZnFe2O4) (1 1 1) single crystal surface under different preparation methods. Surface-sensitive XPS and NEXAFS measurements show that upon annealing in ultra-high vacuum (UHV), Zn depletion occurs, leading to the formation of an iron-rich (1 1 1) surface, whereas annealing in the presence of O2 gas maintains a more bulk-like ZnFe2O4 surface composition. Analysis of the Fe 2p photoemission (XPS) and Fe L edge X-ray absorption signals shows a clear difference in iron oxidation state and distribution between the two different preparation conditions. After annealing in UHV, a mixed Fe2+/Fe3+ oxidation state and a cation distribution like that of a magnetite (Fe3O4) structure is observed, whereas after annealing in oxygen gas only Fe3+, mostly in octahedral coordination, is observed, as expected for a ZnFe2O4 structure. Temperature-dependent XPS confirms significant Zn depletion in the near-surface region above 500 °C under UHV, with almost no Zn remaining at 600 °C; under an O2 atmosphere no zinc depletion is observed up to 600 °C. A theoretical model based on DFT simulations illustrates how reduction from ZnFe2O4 to Fe3O4 with formation of O2 and Zn gas is thermodynamically feasible under UHV conditions, whereas the same reaction is not favourable at higher oxygen partial pressures. Our findings demonstrate the strong impact that UHV treatment has on zinc ferrite surfaces, and cautions that UHV environments, routinely employed for surface analysis, can themselves induce substantial modifications to the surface, thereby complicating the interpretation of measurements in the context of catalytically relevant conditions.
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Dec 2025
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B18-Core EXAFS
I18-Microfocus Spectroscopy
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Diamond Proposal Number(s):
[33674, 35117, 35776, 40942]
Open Access
Abstract: Metal–organic frameworks (MOFs) are entering water technologies on the premise that abiotic stability predicts ecological safety. We overturn this assumption by showing that UiO-66 – often regarded as chemically and structurally robust – remains intact after 7-day aging in natural borehole water yet undergoes rapid in vivo transformation in Daphnia magna. Synchrotron Microfocus X-ray absorption spectroscopy (XAS) revealed collapse of the ordered Zr–carboxylate coordination into disordered Zr–O environments within the gut; Extended X-ray Absorption Fine Structure (EXAFS) showed loss of second-shell features, and Transmission Electron Microscopy (TEM) confirmed loss of crystallinity with nanoscale aggregates appearing within 24 h of ingestion. Although acute immobilization was limited (48 h EC50 ≈ 26.5 μg mL–1), a sublethal, environmentally relevant exposure (10 μg mL–1) caused pronounced chronic effects: brood initiation was delayed by 3–5 days and cumulative reproduction decreased by ∼74% without mortality. We attribute these outcomes to gut-level transformation and associated energetic/physiological burdens, not captured by standard acute tests. These results show that abiotic stability does not necessarily imply biological inertness and highlight the need to integrate in vivo transformation pathways with chronic end points in environmental risk assessment for water-sector materials. This perspective provides a mechanistic basis to inform Safe-and-Sustainable-by-Design (SSbD) MOFs before widespread deployment in water treatment.
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Dec 2025
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B18-Core EXAFS
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Diamond Proposal Number(s):
[38116]
Open Access
Abstract: Increasing use of lithium-ion batteries (LIBs) urges for efficient recycling strategies for their components. Direct recycling methods for cathode materials, based on repairing the structure of the degraded cathode particles without destroying the bulk phase, are promising energy-saving alternatives to traditional metallurgy processes that involve several steps and use large volumes of chemicals causing secondary pollution. Herein, we report a novel and scalable method for the direct electrochemical recycling of spent lithium iron phosphate (LFP) powder in a flow cell via redox mediation. In this method, pellets of spent LFP powder (S-LFP) placed in a tank are directly reduced and relithiated by a redox mediator dissolved in a Li-containing aqueous electrolyte, pumped from an electrochemical cell stack to the relithiation tank. Redox mediators transport charge to the S-LFP pellets from the electrochemical cell, where Li4Fe(CN)6 is oxidized and Li ions are supplied from a Li4Fe(CN)6-containing counter compartment through an ion-selective membrane. The consumption of the regenerating redox mediator solution is minimal via a closed-loop electrochemical regeneration reaction. Successful S-LFP regeneration using two redox mediators, with different energy demand processes, is confirmed by structural and electrochemical characterization.
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Dec 2025
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B18-Core EXAFS
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Diamond Proposal Number(s):
[29950]
Open Access
Abstract: Aims: To investigate the phase changes of bismuth oxide in contact with sodium hypochlorite responsible for tooth discolouration. Methodology: Bismuth oxide (monoclinic α−phase; C) was mixed with sodium hypochlorite at 20°C, 37°C, and 60°C (B20, B37, B60) for a period of 24 weeks with weekly refreshing of solutions. The products were imaged by scanning electron and optical microscopy and characterized by thermographic analysis (TGA), phase analysis by X-ray diffraction (XRD) using Bragg Brentano geometry and Pilatus detector, infrared spectroscopy (FT-IR), and X-ray absorption fine structure (XAFS). Results: The interaction of bismuth oxide with sodium hypochlorite resulted in a change in microstructure and colour. The thermographic assessment showed a change in mass (5%–10% weight change) and colour reversal to the yellow bismuth oxide at ~450°C. Phase changes dependent on temperature were demonstrated with δ-bismuth oxide, sodium bismuthate and bismuth oxychloride formed as by-products at the different temperatures. Conclusions: The δ-phase bismuth oxide formation led to the material darkening which will cause tooth discolouration in a clinical setting. Due to the phase changes, the material chemistry after the interaction is different from that of the material placed in the tooth. The by-products of the reaction have not been tested for use in patients. It is recommended to ban the use of bismuth oxide from dental materials and other clinical use due to its instability. The clinical guidance for endodontic treatment needs to be changed to reflect this.
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Dec 2025
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B18-Core EXAFS
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Diamond Proposal Number(s):
[36104]
Abstract: Seawater splitting has been considered an environmentally friendly and cost-effective method for hydrogen production. However, developing efficient electrocatalysts capable of enduring the severe corrosive conditions of natural seawaters for extended durations remains a notable technical challenge. Herein, the Ni3S2 supported NiFe oxalate ((NiFe)C2O4/Ni3S2) nanorod arrays were synthesised through hydrothermal and impregnation precipitation methods. Structural and spectroscopic analyses revealed that the (NiFe)C2O4/Ni3S2 catalyst formed an integrated oxide-sulfide interface with coexisting Ni–O/Ni–S coordination. This dual coordination environment, coupled with the presence of Fe in a higher oxidation state, confirmed interfacial electronic reorganization characterized by directional electron transfer from Ni to Fe. The resulting charge transfer pathway enhanced the electron delocalisation between active centers, thereby improving active site utilization. The obtained (NiFe)C2O4/Ni3S2 demonstrated remarkable catalytic activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in a simulated alkaline seawater solution (NaCl + KOH), with overpotentials of 363 mV (HER) and 295 mV (OER) at a current density of 500 mA cm−2 for industrial electrolysis requirements and remarkable stability over 100 h of durability testing. Additionally, the (NiFe)C2O4/Ni3S2 electrode pairs only required a cell voltage of 1.81 V to achieve 100 mA cm−2 with Faradaic efficiency of 98 % in 1.0 M KOH + seawater. This study presents a novel approach for fabricating multifunctional electrocatalysts, providing a promising pathway for advancing seawater electrolysis and supporting the development of cost-effective green hydrogen production technologies.
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Nov 2025
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E01-JEM ARM 200CF
E02-JEM ARM 300CF
I18-Microfocus Spectroscopy
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N.
Topping
,
J. C.
Bridges
,
L. J.
Hicks
,
L.
Petera
,
C. S.
Allen
,
J.
Ryu
,
D. G.
Hopkinson
,
M.
Danaie
,
L.
Blase
,
F. M.
Willcocks
,
G.
Douglas
,
H. G.
Changela
,
T.
Noguchi
,
T.
Matsumoto
,
A.
Miyake
Diamond Proposal Number(s):
[30752, 31953, 32874, 35976, 29615, 31641, 35046]
Open Access
Abstract: A correlative multi-technique approach, including electron microscopy and X-ray synchrotron work, has been used to obtain both structural and compositional information of a sulfur-bearing serpentine identified in several carbonaceous chondrites (Winchcombe CM2, Aguas Zarcas CM2, Ivuna CI, and Orgueil CI), and in Ryugu samples returned by the Hayabusa2 mission. S-K edge X-ray absorption spectroscopy was used to determine the oxidation state of sulfur in the serpentine in all samples except Ryugu. The abundance of this phase varies across these samples, with the largest amount in Winchcombe; ~12 vol% of phyllosilicates are identified as sulfur-bearing serpentine characterized by ~10 wt% SO3 equivalent. HRTEM studies reveal a d001-spacing range of 0.64–0.70 nm across all sulfur-bearing serpentine sites, averaging 0.68 nm, characteristic of serpentine. Sulfur-serpentine has variable S6+/ΣStotal values and different sulfur species dependent on specimen type, with CM sulfur-bearing serpentine having values of 0.1–0.2 and S2− as the dominant valency, and CIs having values of 0.9–1.0 with S6+ as the dominant valency. We suggest sulfur is structurally incorporated into serpentine as SH− partially replacing OH−, and trapped as SO42− ions, with an approximate mineral formula of (Mg Fe2+ Fe3+ Al)2-3(Si Al)2O5(OH)5-6(HS−)1-2(SO4)2−0.1-0.7. We conclude that much of the material identified in previous studies of carbonaceous chondrites as TCI-like or PCPs could be sulfur-bearing serpentine. The relatively high abundance of sulfur-bearing serpentine suggests that incorporation of sulfur into this phase was a significant part of the S-cycle in the early Solar System.
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Nov 2025
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B18-Core EXAFS
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Diamond Proposal Number(s):
[32381]
Abstract: This study aimed at determining Ni and Co leaching kinetics from a New Caledonian laterite in an acidic medium (H2SO4 pH 1.5) and in a reductive environment (addition of SO32− or Fe(II)) at 46 °C. The mineralogical study revealed that Co was mainly carried by Mn oxyhydroxides in the limonite sample. Conversely, Ni was hosted by both Fe and Mn oxyhydroxides. In the presence of a reductive reagent, Mn oxyhydroxides dissolved rapidly compared to goethite, the main Fe oxyhydroxide in the sample. Co, Mn and Ni reductive leaching yields reached 79 %, 83 % and 9 % respectively after 2 days. Based on these results, a Mn oxides concentrate was produced in order to efficiently leach Co while limiting Fe oxyhydroxide dissolution. This concentrate resulted from a combination of particle size and gravity separation steps. The volume/mass of sample was drastically decreased since the mass of the final sample was only 3.3 % of the initial one. Co content increased from 0.16 wt% in the limonite to 2.3 wt% in the concentrate, representing an enrichment factor of 13.8 and recovery yield of 60 %. Co, Mn and Ni leaching yields reached 87 %, 95 % and 80 % respectively in the Mn oxides concentrate leaching experiment. The difference in Ni behaviour was consistent with the mineralogical composition: Ni was mainly carried by the goethite in the laterite, while it was hosted mainly by the Mn oxyhydroxides in the Mn oxides concentrate. This study gives a proof of concept for the development a robust pre-concentration process to recover Co.
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Nov 2025
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B18-Core EXAFS
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Open Access
Abstract: The synthesis of VOx/MgO catalysts by solution combustion synthesis was investigated using varying molar ratios of glycine to oxidant. The effect of varying the fuel amount on morphology, phase composition, surface area, crystallite size, elemental distribution, and coordination environment around V was investigated. The results showed that the morphology, surface area, and crystallite size are all dependent on the flame temperature during the combustion process, which is dependent on the amount of fuel added. Results also suggested that adding glycine in excess lowers the combustion temperature. The catalysts were tested for the ODH of n-octane. The catalyst with superior catalytic properties was the stoichiometric sample, in which equal molar ratios of the fuel and oxidizer were added. The better catalytic performance was related to the contribution of the VOx species from the magnesium vanadate phase. This is the only sample in which vanadates were detected. Catalysts synthesized under fuel-lean and fuel-rich conditions were characterized by large crystallites and the absence of detectable magnesium vanadates, using XRD.
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Nov 2025
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