B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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Diamond Proposal Number(s):
[40403]
Open Access
Abstract: γ-Valerolactone (GVL) is a valuable bio-based chemical, solvent and fuel additive derived from levulinic acid, a key platform chemical from lignocellulosic biomass. Catalytic transfer hydrogenation (CTH) of levulinic acid using secondary alcohols as hydrogen donors presents a sustainable alternative to conventional hydrogenation with molecular hydrogen and can be efficiently carried out with inexpensive oxides. Here, we demonstrate how controlled silica incorporation onto zirconia provides a route to tailor acidity and thus direct reactivity in the CTH of levulinic acid and its esters to GVL. Silica-doped zirconia catalysts with varying Si loadings were synthesised via colloidal deposition and comprehensively characterised using ICP-OES, TEM/EDX, XRD, BET, NH3-TPD, pyridine-adsorbed DRIFTS, XPS and NEXAFS. Moderate silica incorporation enhanced surface area, stabilised the tetragonal ZrO2 phase, and increased total acidity, and most importantly, altered the Brønsted-to-Lewis acid balance that dictated the reactivity. Ethyl levulinate conversion was favoured over Lewis acid-rich catalysts, whereas LA conversion required higher Brønsted acidity. The optimal catalyst (6 wt% Si) delivered 80% GVL yield from levulinic acid at 190 °C in 4 hours. Isopropyl levulinate was identified as a side-product that can also convert to GVL via CTH, though less efficiently. The 6 wt% Si/ZrO2 catalyst exhibited excellent stability across three consecutive cycles without calcination, demonstrating resistance to leaching, a major drawback of heterogeneous catalysts in liquid-phase reactions, as well as to carbon deposition. This study demonstrates that silica doping provides an effective means of tuning zirconia acidity, resulting in catalysts that combine good stability with practical applicability in sustainable chemistry.
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Jan 2026
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Open Access
Abstract: Biofuels are critical drop-in replacement energy sources to support the decarbonisation of hard-to-abate sectors such as aviation and marine shipping. Transesterification of non-edible oils is a well-established route to biodiesel as a versatile liquid transport fuel, but is challenging to scale using existing homogeneous liquid base catalysts. In this work, we report the synthesis, characterisation, and application of silica-supported MgO solid base catalysts for triglyceride transesterification with methanol and highlight the impact of silica pore structure on performance. True liquid crystal templating enables the one-pot synthesis of mesoporous MgO/SBA-15 catalysts with variable Mg content, or hierarchical macroporous–mesoporous MgO/SBA-15 analogues through the addition of polystyrene nanospheres. Both MgO/SBA-15 families exhibit highly ordered pore networks; however, ~280 nm macropores stabilise Mg-O-Si interfacial species even at high Mg loading, in contrast to the mesoporous support that permits sintering of ~14 nm MgO nanocrystals. Hierarchical porous MgO/SBA-15 catalysts exhibit higher specific activity and conversion of tributyrin to methyl butyrate than their mesoporous analogues (3 mmol⋅h−1⋅g−1 versus 2 mmol⋅h−1⋅g−1 at 60 °C and 11 wt% Mg). The magnitude of this rate enhancement increases with triglyceride chain length, being approximately three-fold for trilaurin (C12) transesterification at 90 °C, attributed to superior in-pore mass transport of bulky reactants through the hierarchical porous catalyst.
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Nov 2025
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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Mark A.
Isaacs
,
Charalampos
Drivas
,
Arthur
Graf
,
Sasha
Kroon
,
Santosh
Kumar
,
Junxi
Liu
,
Antonio
Torres‐lopez
,
Cameron
Price
,
Edward
Garland
,
Ines
Lezcano-Gonzalez
,
Christopher M. A.
Parlett
,
Vannia C.
Dos Santos-Durndell
,
Lee J.
Durndell
Diamond Proposal Number(s):
[40403]
Open Access
Abstract: 2.5% of global carbon emissions result from air travel, underscoring the need for sustainable aviation fuels (SAF) derived from second-generation lignocellulosic biomass to enhance the green credentials of the aviation sector. This study demonstrates the first solvent-free photocatalytic conversion of furfural (FAL) and cyclopentanone (CPO) to produce 2,5-bis(2-furylmethylidene)cyclopentanone (F2Cp), a jet fuel precursor, using Ti-SBA-15 catalysts, synthesized via alkoxide grafting and controlled titanium surface coverage. Sub-monolayer titania films on SBA-15 supports are achieved with tuneable Ti content, confirmed by XPS (X-ray photoelectron spectroscopy), UPS (ultraviolet photoelectron spectroscopy), REELS (reflectance electron energy loss spectroscopy), ISS (ion scattering spectroscopy), and Raman analysis. XPS analyses reveal coverage-dependent Ti speciation, transitioning from isolated Ti atoms to interconnected Ti-O-Ti networks, with corresponding shifts in Auger parameters, indicating increased surface polarizability and Lewis acidity. Optimized Ti-SBA-15 catalysts exhibit a fourfold activity enhancement in photocatalytic activity over bulk TiO₂, attributed to improved mass transport, active site accessibility, and surface stability. This work highlights the potential of rationally designed hierarchical catalysts for scalable, energy-efficient biomass valorization into SAF precursors, offering a scalable, energy-efficient pathway for sustainable jet fuel production. By elucidating the structure-function relationships in sub-monolayer Ti-SBA-15 materials, this study provides critical insights for advancing photocatalytic technologies in renewable energy applications.
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Jul 2025
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B22-Multimode InfraRed imaging And Microspectroscopy
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Leila
Abylgazina
,
Irena
Senkovska
,
Mariia
Maliuta
,
Christopher
Bachetzky
,
Marcus
Rauche
,
Kathrin
Pöschel
,
Johannes
Schmidt
,
Mark
Isaacs
,
David
Morgan
,
Michal
Otyepka
,
Eva
Otyepkova
,
Matthias
Mendt
,
Yogeshwar D.
More
,
Robin
Buschbeck
,
Andreas
Schneemann
,
Alla
Synytska
,
Andreas
Pöppl
,
Lukas M.
Eng
,
Jin-Chong
Tan
,
Eike
Brunner
,
Stefan
Kaskel
Diamond Proposal Number(s):
[30369]
Open Access
Abstract: A unique feature of flexible metal–organic frameworks (MOFs) is their ability to respond dynamically towards molecular stimuli by structural transitions, resulting in pore-opening and closing processes. One of the most intriguing modes is the “gating”, where the material transforms from the dense to the porous state. The conditions required for the solid phase structural transition are controlled by the kinetic barriers, including nucleation of the new phase commencing on the crystallite's outer surface. Thus, surface deformation may influence the nucleation, enabling deliberate tailoring of the responsivity. In the present contribution, we investigate how chemical surface treatments (surface deformation) affect the gate opening characteristics of a typical representative of gate pressure MOFs, DUT-8(Ni) ([Ni2(ndc)2(dabco)]n, ndc = 2,6-naphthalenedicarboxylate, dabco = 1,4-diazabicyclo[2.2.2]octane). A combination of various complementary advanced characterization techniques, such as NMR, nanoFTIR, terahertz, in situ XPS, in situ EPR spectroscopies, and inverse gas chromatography, are applied to unravel the changes in surface energy and mechanism of surface deformation.
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Mar 2025
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[19354]
Open Access
Abstract: Laser powder bed fusion (LPBF) of Polyamide 12 (PA12) using a near-infra-red (NIR) beam is largely unexplored; therefore, the beam-matter interaction, evolution mechanisms of the melt pool and defects remain unclear. Here, we employed a combination of in situ synchrotron X-ray imaging, ex situ materials characterisation techniques, and high-fidelity process simulations to study these behaviours during LPBF of PA12. Our results demonstrate that the NIR absorption of PA12 can be improved by 600 times through powder surface modification with C, P and Al species. In situ X-ray images reveal that the PA12 powders undergo melting, viscous merging, volume expansion, warping, solidification, and shrinkage before forming a solid track. Our results uncover the bubble evolution mechanisms during LPBF of PA12. During laser scanning, the high-energy laser beam produces organic substances/vapours which are trapped inside bubbles during viscous merging. These bubbles continue to shrink due to vapour condensation as the polymer cools under a cooling rate range of 200 - 600 K s−1. Using the collected data, we have developed a data-driven bubble shrinkage criterion to predict the bubble shrinkage coefficient using the bubble half-life, improving the build quality of LPBF polymeric parts.
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Feb 2025
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B18-Core EXAFS
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Santhosh K.
Matam
,
Preetam K.
Sharma
,
Eileen H.
Yu
,
Charalampos
Drivas
,
Mohammad D.
Khan
,
Martin
Wilding
,
Nitya
Ramanan
,
Diego
Gianolio
,
Mark A.
Isaacs
,
Shaoliang
Guan
,
Philip R.
Davies
,
C. Richard A.
Catlow
Diamond Proposal Number(s):
[29271]
Open Access
Abstract: We present a novel operando X-ray absorption spectroscopic (XAS) flow cell, consisting of a gas chamber for CO2 and a liquid chamber for the electrolyte, to monitor electrochemical CO2 reduction (eCO2R) over a gas diffusion electrode (GDE). The feasibility of the flow cell is demonstrated by collecting XAS data (during eCO2R over Cu-GDE) in a transmission mode at the Cu K-edge. The dynamic behaviour of copper during eCO2R is captured by XAS which is complemented by quasi in situ Raman and X-ray photoelectron spectroscopy (XPS). The linear combination analyses (LCA) of X-ray absorption near edge structure (XANES) indicate that copper oxides are the only species present during the first 20 min of eCO2R, corroborated by complementary Raman and XPS. Significantly, the complementary spectroscopic data suggests that the copper composition in the bulk and on the surface Cu-GDE evolve differently at and above 30 min of eCO2R. LCA indicates that at 60 min, 77% of copper occurs as metallic Cu and the remainder 23% in Cu (II) oxidation state, which is not evident from XPS that shows 100% of copper in < 2+ oxidation state. Thus, the Cu (II) is probably in the bulk of Cu-GDE, as also evident from Raman. The ethylene formation correlates very well with the occurrence of copper oxides and hydroxide species in Cu-GDE. The results not only demonstrate the applicability and versatility of the operando XAS GDE flow cell, but also illustrate the unique advantages of combining XAS with complementary Raman and XPS that enables the monitoring of the catalyst structural evolution from the bulk to surface and surface adsorbed species.
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Dec 2024
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B18-Core EXAFS
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Diamond Proposal Number(s):
[34446]
Open Access
Abstract: LaNb0.84W0.16O4+δ and LaNb0.84Mo0.16O4+δ produced via a solid-state reaction route exhibited excellent phase stability after annealing under 5%-H2/N2 atmosphere at 800 °C, confirming their potential for application in reducing environments, such as fuel electrodes in electrochemical devices. The crystal structures, compositions, and oxidation states were studied before and after treatment showing excellent structural, compositional and redox stability of LaNb0.84W0.16O4+δ, while LaNb0.84Mo0.16O4+δ was reduced forming an oxygen stoichiometric phase. The electrochemical performance of the more promising LaNb0.84W0.16O4+δ composition measured under reducing atmospheres was further investigated. Higher conductivity was observed for the samples measured under reducing atmospheres. However, the larger conductivity enhancement in the low temperature range (400°C to 600°C) compared with the high temperature range (600°C to 800°C) deviated from the conventional electronic conductivity emerging from reduction. DC polarization measurements confirmed the predominant protonic conductivity in LaNb0.84W0.16O4+δ under reducing atmospheres.
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Dec 2024
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I20-EDE-Energy Dispersive EXAFS (EDE)
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Donato
Decarolis
,
Monik
Panchal
,
Matthew
Quesne
,
Khaled
Mohammed
,
Shaojun
Xu
,
Mark
Isaacs
,
Adam H.
Clark
,
Luke L.
Keenan
,
Takuo
Wakisaka
,
Kohei
Kusada
,
Hiroshi
Kitagawa
,
C. Richard A.
Catlow
,
Emma K.
Gibson
,
Alexandre
Goguet
,
Peter
Wells
Diamond Proposal Number(s):
[21593]
Open Access
Abstract: Unravelling kinetic oscillations, which arise spontaneously during catalysis, has been a challenge for decades but is important not only to understand these complex phenomena but also to achieve increased activity. Here we show, through temporally and spatially resolved operando analysis, that CO oxidation over Rh/Al2O3 involves a series of thermal levering events—CO oxidation, Boudouard reaction and carbon combustion—that drive oscillatory CO2 formation. This catalytic sequence relies on harnessing localized temperature episodes at the nanoparticle level as an efficient means to drive reactions in situations in which the macroscopic conditions are unfavourable for catalysis. This insight provides a new basis for coupling thermal events at the nanoscale for efficient harvesting of energy and enhanced catalyst technologies.
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Jul 2024
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
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Elizabeth
Jones
,
Charalampos
Drivas
,
Joshua
Gibson
,
Jack
Swallow
,
Leanne
Jones
,
Thomas
Bricknell
,
Matthijs
Van Spronsen
,
Georg
Held
,
Mark
Isaacs
,
Christopher
Parlett
,
Robert S.
Weatherup
Diamond Proposal Number(s):
[30358]
Open Access
Abstract: Environmental cells sealed with photoelectron-transparent graphene windows are promising for extending X-ray photoelectron spectroscopy (XPS) to liquid and high-pressure gas environments for in situ and operando studies. However, the reliable production of graphene windows that are sufficiently leak-tight for extended measurements remains a challenge. Here we demonstrate a PDMS/Au(100 nm)-supported transfer method that reliably produces suspended graphene on perforated silicon nitride membranes without significant contamination. A yield of ~95% is achieved based on single-layer graphene covering >98% of the holes in the silicon nitride membrane. Even higher coverages are achieved for stacked bilayer graphene, allowing wet etching (aqueous KI/I2) of the Au support to be observed in a conventional lab-based XPS system, thereby demonstrating the in situ formation of leak-tight, suspended graphene windows. Furthermore, these windows allow gas-phase measurements at close to atmospheric pressure, showing future promise for XPS under higher-pressure gas environments in conventional lab-based systems.
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Apr 2024
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B18-Core EXAFS
E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[19850]
Open Access
Abstract: Alcohol oxidations are a key industrial chemical transformation, with aldehydes and ketones finding use in an array of applications. Nobel metals are known for their activity towards this chemoselective transformation, however, sustainable catalyst synthesis requires optimal utilisation of these scarce elements. Here, we report Au catalytic systems based on the deposition of isolated Au sites on different morphologies of ceria in which different surface facets of the support are exposed. Through tailoring the support morphology and from extensive catalyst characterisation, it is shown that the exposed facet is critical for controlling the formation (or not) of isolated Au sites. Both the 110 and 111 facets are capable of this feat, yielding single-atom sites for rod, octahedron, and polyhedron morphologies. In contrast, the 100 facet is not, resulting in Au nanoparticles on cubic ceria. This dictation over Au species is critical to benzyl alcohol oxidation capacity at mild conditions and in the absence of a soluble base, with only single-atom catalyst (SAC) systems demonstrating activity. Furthermore, the exposed surface facet also governs the degree of surface oxygen vacancies, which is critical to catalyst activity and arises from its control over substrate adsorption strength, as revealed through T1/T2 NMR relaxation measurements.
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Apr 2024
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