E01-JEM ARM 200CF
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Naomi
Lawes
,
Igor
Kowalec
,
Sofia
Mediavilla-Madrigal
,
Kieran J.
Aggett
,
Louise R.
Smith
,
Malcolm
Dearg
,
Thomas J. A.
Slater
,
Eimear
Mccarthy
,
Herzain I.
Rivera-Arrieta
,
Matthias
Scheffler
,
David J.
Morgan
,
David J.
Willock
,
Andrew M.
Beale
,
Andrew J.
Logsdail
,
Nicholas F.
Dummer
,
Michael
Bowker
,
C. Richard A.
Catlow
,
Stuart H.
Taylor
,
Graham J.
Hutchings
Diamond Proposal Number(s):
[3104]
Open Access
Abstract: A series of PdZn/TiO2 catalysts prepared by chemical vapor impregnation (CVI) were tested for CO2 hydrogenation at 20 bar pressure and at temperatures of 230–270 °C. Changing the Pd and Zn molar ratio (Zn:Pd = 0–20) in a PdZn/TiO2 catalyst has a dramatic effect on selectivity for the CO2 hydrogenation reaction. Pd alone shows three main products: methanol, CO, and methane. Addition of small quantities of Zn results in the formation of a PdZn alloy, preventing methanation. At equimolar ratios of Pd and Zn, a 1:1 β-PdZn alloy is formed and a reverse water gas shift catalyst is produced. Adding Zn in excess relative to the Pd loading results in the formation of ZnO on the TiO2 surface in addition to the PdZn alloy, dramatically increasing methanol selectivity from 5% at Zn:Pd = 1 to 55% for Zn:Pd = 2. Through a combination of theory and experiment, the active site for methanol synthesis is concluded to be the interface between PdZn nanoparticles and the ZnO overlayer on the TiO2, where interfacial formate can react with hydrogen dissociated by the metal nanoparticle.
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Jan 2026
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B18-Core EXAFS
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Run
Ran
,
Haoliang
Huang
,
Qingqing
Chen
,
Fei
Lin
,
Zhipeng
Yu
,
Weifeng
Su
,
Chenyue
Zhang
,
Qingsen
Jia
,
Jingwei
Wang
,
Yang
Zhao
,
Kaiyang
Xu
,
Binwen
Zeng
,
Yaowen
Xu
,
Weimian
Zhang
,
Zhijian
Peng
,
Lifeng
Liu
Diamond Proposal Number(s):
[36104]
Abstract: Sulfur quantum dots (SQDs) represent an emerging class of metal-free, biocompatible luminescent nanomaterials, yet their synthesis remains challenged by harsh conditions, high energy consumption, and limited scalability. Herein, we report a highly value-added strategy coupling SQD synthesis with hydrogen production through sulfion (S2−) oxidation reaction (SOR) assisted alkaline-modified seawater electrolysis (SWE). Such coupling substantially lowers the energy demand for electrolysis and effectively circumvents the interfering chlorine evolution at the anode. An efficient and stable cobalt single-atom catalyst (Co-SAs-PNC) is developed to boost SOR, achieving a large current density of 500 mA cm−2 at 0.536 V vs. reversible hydrogen electrode in alkaline-modified natural seawater and operating stably for 116 h. A flow cell comprising Co-SAs-PNC as the anode catalyst and commercial Pt/C as the cathode catalyst requires only 1.01 V to reach 500 mA cm−2 and shows outstanding durability of >450 h. Besides valuable hydrogen generated at the cathode, the polysulfides electrochemically derived at the anode can be readily converted to multicolor photoluminescent SQDs. Comprehensive in situ/operando experiments and theoretical calculations elucidate the SOR mechanism at isolated Co sites. This work not only opens a new avenue for sustainable SQD production but also remarkably enhances the economic viability of the SWE technology.
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Jan 2026
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B18-Core EXAFS
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Diamond Proposal Number(s):
[34446]
Open Access
Abstract: Understanding the redox behavior and structural stability of aliovalent substituents in ionic conductors is critical, as their variable oxidation states can inadvertently introduce electronic conductivity and alter transport mechanisms under different atmospheric conditions. Here, we report the atmosphere-dependent redox behavior and local coordination of Mo in LaNb0.9Mo0.1O4.05, focusing on its influence on phase transition and transport properties, where the as-sintered LaNb0.9Mo0.1O4.05 was systematically annealed under pure O2, pure N2, vacuum (∼1.6 × 10–8 mbar), and 5% H2/N2 at 800 °C for different dwell times. Electron paramagnetic resonance (EPR) spectroscopy results demonstrate the emergence of Mo5+ under 5% H2/N2. In situ X-ray absorption near edge structure (XANES) measurements reveal the reversible redox behavior of Mo, where Mo5+ formed under 5% H2/N2 reoxidizes to Mo6+ upon exposure to static air, while complementary in situ extended X-ray absorption fine structure (EXAFS) analysis shows that the Nb coordination environment also transitions from prototypical LaNbO4 structure under reducing conditions back to the Mo-substituted LaNbO4 structure upon reoxidation. This change of the oxidation states of Mo could correspondingly alter the band structure of the sample, which further enhances charge transport: the sample annealed in 5% H2/N2 for 24 h exhibits a reduced activation energy and increased electronic conductivity. These results highlight a strong coupling among substituent redox flexibility, local structure, and transport properties, providing an understanding of tailoring the properties of ionic conductors through controlled redox environments.
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Dec 2025
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B18-Core EXAFS
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Diamond Proposal Number(s):
[34632]
Abstract: Electrocatalytic CO2 reduction (ECO2R) to high-value chemicals is a promising method to upcycle emitted CO2, but it is also a fascinating scientific challenge. Catalyst materials, as well as cell configurations, play a pivotal role in the efficacy and efficiency of the ECO2R reaction, which also dictates reaction pathways and product selectivity. In this work, we employ the isotopological Zr- and Ce-based UiO-67 metal–organic frameworks (MOFs) that contain Pd species in a zero-gap gas diffusion cathode electrode configuration, where the water content, i.e., relative humidity (RH) level, in the CO2 gas stream can be varied. We show that only UiO-67-based MOFs containing Pd embedded in their pores can produce syngas, while the product selectivity can be controlled by varying the RH levels in the gas stream. The pristine MOFs (precatalysts) undergo chemical and structural transformation during the ECO2R reaction, forming the active catalysts toward CO2 electroreduction to syngas. Our work highlights the effect of water content on the selectivity during ECO2R, but also the need for predictive catalyst design for effective electroreduction of CO2 to high-value chemicals.
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Dec 2025
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B18-Core EXAFS
E01-JEM ARM 200CF
I09-Surface and Interface Structural Analysis
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Thomas J.
Liddy
,
Benjamin J.
Young
,
Emerson C.
Kohlrausch
,
Andreas
Weilhard
,
Gazi N.
Aliev
,
Yifan
Chen
,
Manfred E.
Schuster
,
Mohsen
Danaie
,
Luke L.
Keenan
,
Donato
Decarolis
,
Diego
Gianolio
,
Siqi
Wang
,
Mingming
Zhu
,
Graham J.
Hutchings
,
David M.
Grant
,
Wolfgang
Theis
,
Tien-Lin
Lee
,
David A.
Duncan
,
Alberto
Roldan
,
Andrei N.
Khlobystov
,
Jesum
Alves Fernandes
Diamond Proposal Number(s):
[38764]
Open Access
Abstract: Ammonia is an attractive hydrogen carrier, yet its practical use is limited by the need for efficient catalytic decomposition. We demonstrate that in-situ N-doping of Ru nanoparticles and graphitized carbon nanofiber supports during reaction produces a sharp increase in hydrogen production during the first 40 h, followed by stable activity. Spectroscopic and microscopic analyses, together with density functional theory simulations, reveal that Ru nitridation is rapid and support-independent, resulting in a mechanistic shift from the traditional Langmuir–Hinshelwood to a Mars–van Krevelen pathway, further confirmed by isotopic labelling experiments. In contrast, the progressive nitridation of the carbon support, observed via X-ray photoelectron spectroscopy, modulates the electronic environment of Ru and functions as a dynamic nitrogen reservoir that enables reversible N atoms exchange with the Ru particles, facilitating N desorption from the Ru surface and thereby governing the catalytic activity enhancement. These new findings provide new mechanistic insight into ammonia decomposition and establish progressive nitrogen doping of carbon supports as a strategy for designing efficient metal-based catalysts for hydrogen production.
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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):
[40403]
Open Access
Abstract: Metal−organic gels (MOGs) and their derived aerogels (MOAs) offer an alternative to crystalline MOFs, combining the coordination-driven tunability with the flexibility, hierarchical porosity, and easy processability of sol–gel polymers. Their noncrystalline nature enables the integration of functional units without crystallization constraints, facilitating diverse uses, and drawing recent attention for photocatalytic applications. Herein we report the design of a new approach to prepare a titanium-based MOA synthesized via a two-step strategy involving a preformed titanium oxo-cluster ([Ti8O8(benzoato)16]), and a subsequent ligand exchange with benzene-1,3,5-tricarboxylato ligands. A combined chemical, microstructural, and NEXAFS analysis confirms the retention of Ti8 cluster and the presence of uncoordinated −COOH groups after meso-macroporous gel formation. Those enabled a subsequent homogeneous incorporation of single-atom site co-catalysts via coordination with Ru, Co, Ni, and Cu complexes bearing terpyridine, bipyridine, and phenanthroline N-ligands. Photocatalytic hydrogen evolution under 365 nm LED irradiation exhibited significant activity (110 μmol·g–1·h–1), which further increased upon functionalization. The MOAs functionalized with Ru- and Cu-terpyridine complexes showed the highest performance (167 and 164 μmol·g–1·h–1, respectively), surpassing even Pt-loaded analogues and highlighting the role of terpyridine in facilitating multielectron storage. The system also showed stable long-term performance up to 24 h.
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Dec 2025
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Daniel J.
Zheng
,
Kaylee
Mccormack
,
Jiayu
Peng
,
Raul
Garcia-Diez
,
Elmar Yu
Kataev
,
Fabian
Schwarz
,
Susan
Nehzati
,
Jakob
Thyr
,
Wilson
Quevedo-Garzon
,
Benjamin
Howchen
,
Marcus
Bär
,
Yuriy
Román-Leshkov
,
Yang
Shao-Horn
,
Mikaela
Görlin
Abstract: The oxygen evolution reaction (OER) is crucial for electrofuel production. Metal–hydroxide organic frameworks (MHOFs), a subset of metal–organic frameworks with oxyhydroxide-like layers interconnected via organic linkers, have shown great promise as OER electrocatalysts. This study investigates lattice oxygen exchange in four Ni- and Fe-substituted MHOFs with varying linker stabilities using 18O isotope labeling combined with operando Raman spectroscopy. A negative correlation between 18O/16O lattice oxygen exchange and the OER activity is shown, with Fe ions further suppressing exchange. Operando X-ray spectroscopy (XAS) and UV–vis further reveals that lattice oxygen exchange primarily proceeds on reduced Ni2+ sites, with higher linker stability preserving more Ni2+ sites and promoting greater lattice oxygen exchange. Supported by density functional theory, the MHOF surface transforms into an OER-active MOxHy-like phase, explaining the negative correlation of lattice exchange with the OER activity. This work also identifies a noninnocent role of the Raman laser in inducing lattice oxygen exchange and offers critical insights into various lattice oxygen exchange pathways in MHOFs, demonstrating their distinction from the catalytic lattice oxygen evolution reaction mechanism.
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Dec 2025
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Abstract: The low-temperature performance of mixed-composition perovskite solar cells (PSCs) reflects the complex interplay among thermal effects, bandgap renormalization, and structural phase behavior. Temperature-dependent structural, optical, and electrical measurements reveal a maximum power conversion efficiency at 263 K, which coincides with the onset of the cubic-tetragonal phase coexistence. At this temperature, symmetry lowering is observed, accompanied by a split emission band and increased current–voltage hysteresis, consistent with structural heterogeneity. Device simulations show that any benefit from mixed-phase band alignment is conditional on effective interphase passivation. Consequently, the mixed phase is best described as a loss-minimum condition at well-passivated cubic–tetragonal interphases with stable collection. Our findings identify a narrow mixed-phase window in which phase coexistence couples to the optoelectronic response and enhances the device performance, providing fundamental insight into temperature-dependent structure–property relations in hybrid perovskites.
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Dec 2025
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B18-Core EXAFS
I09-Surface and Interface Structural Analysis
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Abstract: Hydrogen shows promise as the energy vector of the future, but problems with storage and transport are significant. Storage of hydrogen as ammonia has the potential to solve these problems, but current catalysts for its cracking are not efficient enough to enable the large-scale application of ammonia. Carbon materials, such as carbon nanotubes (CNTs), have shown potential as supports for ammonia decomposition catalysts. This thesis investigates the use of graphitised nanofibers (GNFs), which offer high purity and graphitisation, as a support material for Ru catalysts. Ru/GNF was synthesised using magnetron sputtering and tested for catalytic activity in ammonia decomposition and the catalyst exhibited self-improvement over the course of the reaction. The evolution of the Ru nanoclusters on GNF was studied by Identical Location Scanning Transmission Electron Microscopy (IL-STEM). The analysis revealed that the Ru nanoclusters undergo significant morphological changes during the reaction - transforming from flat and amorphous structures to more three-dimensional crystalline nanoclusters. The step-edges on the GNF surface help to stabilise the Ru nanoclusters, preventing excessive growth and maintaining a high density of active sites. Spectroscopic analysis using in-operando EXAFS and ex-situ XPS provide further insights into the mechanism behind the self-improvement. EXAFS data suggest that the Ru nanoparticles undergo bulk nitridation during the reaction. This is supported by XPS analysis, which confirms the formation of a metal nitride species. It is proposed that the formation of bulk nitrided Ru nanoclusters leads to a change in the reaction mechanism, increasing the number of active sites and enhancing the catalyst’s activity. This thesis highlights the importance of studying the dynamic behaviour of catalysts and provides an understanding of the self-improvement mechanism in Ru/GNF. This knowledge can contribute to the design of more efficient and stable catalysts for low-temperature ammonia cracking, advancing sustainable hydrogen production technologies.
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Dec 2025
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B18-Core EXAFS
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Faye
Greaves
,
Vivian
Nassif
,
Maria
Alfredsson
,
Alan V.
Chadwick
,
Ryan
Parmenter
,
Jakub
Čížek
,
Oksana
Melikhova
,
Lei
Lei
,
David M.
Grant
,
Martin
Dornheim
,
Sanliang
Ling
,
Patrick
Cullen
,
Claudia
Zlotea
Open Access
Abstract: Refractory BCC high entropy alloy TiVZrNbHf is a promising material for solid-state hydrogen storage with high hydrogen sorption capacity but unfavourable thermodynamics of hydride phase, i.e. too stable hydride that need high temperature to reversibly recover the absorbed hydrogen. As an attempt to destabilize the hydride phase, this study reports on the effect of Al addition (limited concentrations: 5 and 10 at.%) into this alloy on the physicochemical and hydrogen sorption properties. Despite traces of a V-Al secondary phase, the BCC (TiVZrNbHf)1-xAlx alloys are random solid solutions which form high-capacity FCC hydride phases under hydrogen atmosphere at room temperature, as proven by synchrotron and neutron diffraction. Although Al decreases the hydrogen sorption capacity, the presence of a p element destabilizes the FCC hydride phase. A comparison with previous literature data helps understanding the role of Al which strongly depends on the chemical composition of the initial alloys. XANES studies allowed access to details of the electronic structure of the unoccupied levels complemented by density functional theory calculations. Moreover, the addition of Al favours the formation of larger open volume defects during hydride formation than the initial Al-free alloy which might explain the faster absorption kinetics in Al-containing alloys.
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Dec 2025
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