B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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Lewis G.
Parker
,
Frances K.
Towers Tompkins
,
Jake M.
Seymour
,
Ekaterina
Gousseva
,
Christopher D.
Smith
,
Roger A.
Bennett
,
Pilar
Ferrer
,
David C.
Grinter
,
Claudia
Kolbeck
,
Dennis
Hein
,
Garlef
Wartner
,
Robert
Seidel
,
Denis
Céolin
,
Robert
Temperton
,
Robert G.
Palgrave
,
Richard P.
Matthews
,
Kevin R. J.
Lovelock
Diamond Proposal Number(s):
[33378, 35207, 36765, 36196]
Open Access
Abstract: Anion interactions with cations/molecules are crucial across chemistry and biology: in battery electrolytes, synthesis, atmospheric processes, and protein denaturation. Selecting the optimum anion represents an immense challenge, as anion interactions are diverse and complex. Descriptors are needed that quantitatively capture the ability of anions to interact with cations and molecules. However, only a small number of experimental anion interaction descriptors exist, all with similar limitations. Here we show that core-level anion electron binding energies, EB(core,anion), can be used to produce a new atomic-level descriptor for each of the key donor elements for anion interactions (O, N, F, Cl, Br, I, S), the element-specific donor number (DNE-XPS). DNE-XPS descriptors are intrinsic, capturing the anion interaction abilities independent of any probe, countercation, or solvent. DNE-XPS descriptors are also interpretable, as EB(core,anion) and therefore DNE-XPS are proportional to the electrostatic potential at the specific donor atom nucleus. Experimental core-level X-ray photoelectron spectroscopy (XPS) is used to measure EB(core,anion) and therefore DNE-XPS. Furthermore, DNE-XPS descriptors are produced easily and at low cost using lone-anion-SMD (solvation model density) calculations, a significant advance on the current anion descriptors, greatly reducing and potentially removing the need for experimental anion characterization. This work will greatly facilitate anion selection, especially for complex anions capable of forming interactions through multiple different atoms. We envisage our calculation method enabling the production of a very large database of DNE-XPS for each key element, ideal for use as machine learning training data sets.
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Aug 2026
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I09-Surface and Interface Structural Analysis
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Galo J.
Paez Fajardo
,
Daniela E.
Dogaru
,
Hrishit
Banerjee
,
Muhammad
Ans
,
Matthew J. W.
Ogley
,
Veronika
Majherova
,
Gerard
Bree
,
Innes
Mcclelland
,
Shohei
Hayashida
,
Pascal
Puphal
,
Masahiko
Isobe
,
Bernhard
Keimer
,
Pardeep K.
Thakur
,
Tien-Lin
Lee
,
Dave C.
Grinter
,
Pilar
Ferrer
,
Serena A.
Cussen
,
Matthias
Hepting
,
Louis F. J.
Piper
Diamond Proposal Number(s):
[33459, 35075, 36917, 30201]
Open Access
Abstract: Describing lithium-based battery positive electrodes based on different transition metal or oxygen-redox regimes can cause confusion in understanding metal–ligand hybridization, oxygen dimerization and degradation processes. Therefore, it is urgent to investigate the electronic structure of these materials and identify the role each cation and anion has in charge compensation at the subnanoscale. Here, using X-ray resonance photoemission spectroscopy, single-impurity Anderson models, spectral simulations and theoretical calculations, we examine redox mechanisms in positive electrodes during lithium-based battery operation. This approach reconciles the redox description of two positive electrode active materials—LiMn0.6Fe0.4PO4 and LiNiO2—in terms of varying degrees of charge transfer using the Zaanen–Sawatzky–Allen framework. In LiMn0.6Fe0.4PO4, the lack of strong hybridization indicates that the capacity results from the depopulation of metal 3d states, that is, conventional metal redox. However, in cells with LiNiO2-based positive electrodes, negative charge transfer dominates, and redox occurs through the formation and elimination of ligand-hole states. These results clarify the role of oxygen in Ni-rich systems and provide a framework to explain how the charge/discharge capacities are linked to oxygen-dominated states in highly covalent systems, without the need to consider oxygen dimerization.
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Jun 2026
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
B18-Core EXAFS
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Ainara
Aguadero
,
Federico
Baiutti
,
Monica
Burriel
,
Markus
Kubicek
,
Alexander Karl
Opitz
,
Juergen
Fleig
,
David
Munoz-Rojas
,
Christophe
Vallée
,
Marceline
Bonvalot
,
Alexia
Popescu
,
Nicola H
Perry
,
Francesco M.
Chiabrera
,
Álex
Morata
,
Juan Carlos
Gonzalez-Rosillo
,
Alexander
Stangl
,
Ramon
Escobar-Galindo
,
Mattias
Krause
,
Sivakkumaran
Sukumaran
,
Sarah
Fearn
,
Richard J.
Chater
,
Stephen J.
Skinner
,
John
Kilner
,
Sören
Möller
,
Martin
Finsterbusch
,
Manoj Kumar
Ghosalya
,
Samuli
Urpelainen
,
Christoph
Baeumer
,
Santosh
Kumar
,
Veronica
Celorrio
,
Diego
Gianolio
,
David C.
Grinter
,
Pilar
Ferrer-Escorihuela
,
Georg
Held
,
Jordi
Cabana
,
Sandrine
Lyonnard
,
Dorthe
Bomholdt Ravnsbaek
,
M. Rosa
Palacin
,
Montserrat
Casas-Cabanas
,
Julie
Villanova
,
Aline
Léon
,
Qiucheng
Xu
,
Jakub
Drnec
,
Brian
Seger
,
David R
Diercks
,
Nejc
Hodnik
,
Lluís
Yedra
,
Sonia
Estrade
,
Francesca
Peiró
,
Neus
Domingo
,
Maciej O
Liedke
,
Enric
Menéndez
,
David J.
Keeble
,
Jakub
Čížek
,
Ralf F.
Ziesche
,
Oriol
Sans Planell
,
Nikolay
Kardjilov
,
Ingo
Manke
,
Daniele
Pergolesi
,
Jochen
Stahn
Open Access
Abstract: A strong societal and political drive is motivating the development and optimization of novel
energy
conversion and storage systems for decarbonization. The successful implementation of solid
state devices such as fuel cells and secondary batteries depends, however, on achieving
ambitious targets in terms of performance, reliability and cost competitiveness. Research and
technology are addressing these needs through a holistic approach including exploration of new
materials and nanoarchitectures, as well as system engineering. These significant efforts require
the support of appropriate characterization tools capable of assessing nanometer-scale
phenomena such as concentration profiles of ionic and electronic charges, local chemical
compositions and their evolution over time across interfaces.
This roadmap provides an overview of selected advanced characterization techniques for
energy materials and devices. Specific focus is put on in situ/operando methods for probing
electrochemical phenomena in real-time under realistic working conditions. Experts in the field
provide an extensive review of the current state of the art in 2025 and the current and future
challenges for the characterization of local chemistry and kinetics in the bulk of the material, in
nanoarchitectures (e.g. thin films) and at the interfaces (e.g. grain boundaries, phase contacts,
solid/liquid and solid/gas interfaces) . The aim is to provide a detailed guide to the techniques,
describing opportunities and bottlenecks for their practical deployment and examples of
successful
applications.
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May 2026
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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Guangmeimei
Yang
,
Wei
Huang
,
Yifeng
Wang
,
Caiwu
Liang
,
Yuxiang
Zhou
,
Santosh
Kumar
,
Pilar
Ferrer Escorihuela
,
Parnia
Navabpour
,
Giuseppe
Sanzone
,
Trevor
Ferris
,
Georg
Held
,
Mark
Turner
,
Sarah J.
Haigh
,
Caterina
Ducati
,
Andreas
Kafizas
,
Reshma
Rao
Diamond Proposal Number(s):
[37550]
Open Access
Abstract: The scarcity of Ir presents a major challenge for scaling up its use as a water oxidation electrocatalyst in proton exchange membrane (PEM) water electrolysers. Developing conductive and stable supports is an effective way to reduce iridium loading while maintaining performance. However, the influence of support conductivity and stability on Ir-based catalytic activity remains poorly understood. The behaviour of the support is often obscured in conventional membrane electrode assembly (MEA) systems because IrOx itself is both highly conductive and exceptionally stable. To decouple support conductivity and passivation effects from the intrinsic conductivity of IrOx, we demonstrate a screening platform by studying a series of Ti-Nb alloy thin films produced by sputter deposition and investigate their performance as supports for IrOx water oxidation electrocatalysts. A range of electrochemical tests including accelerated stress tests (AST) were carried out on these samples, where characterisation techniques, including X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM), demonstrated the in situ formation of passivation layers on these supports during water oxidation. Our results suggest that a ~10 nm oxide passivation layer forms on metallic Ti-based supports. On alloying Nb with Ti metal, a more insulating rutile TiO2 phase forms during water oxidation whereas an anatase TiO2, with higher conductivity, is observed on the pure Ti support. Consequently, although alloying Ti with Nb improves the bulk conductivity, the structure of the oxide passivation layer results in a drastic decrease of conductivity and water oxidation activity. Our results demonstrate the importance of the structure and composition of surface oxide phases formed during water oxidation in controlling the overall stability and conductivity of support materials.
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Apr 2026
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
E01-JEM ARM 200CF
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Alexander I.
Large
,
Henry
Hoddinott
,
Haamidah
Sana
,
Elizabeth
Jones
,
James J. C.
Counter
,
Matthijs
Van Spronsen
,
Santosh
Kumar
,
David C.
Grinter
,
Pilar
Ferrer
,
Bernd
Von Issendorff
,
Richard Edward
Palmer
,
Georg
Held
Diamond Proposal Number(s):
[29320, 29935, 33291]
Open Access
Abstract: The importance of cluster-size eects in heterogeneous catalysis is now well recognized. X-ray photoelectron spectroscopy (XPS) is an obvious technique to study size-dependent changes in the chemical composition and electronic structure of catalyst nanoparticles. However, as XPS is an averaging technique based on the detection of electrons, experiments require a narrow distribution of cluster size and a conducting homogeneous support in order to avoid sample charging, which would prevent accurate measurements of chemical shifts. Traditional methods of catalyst synthesis by impregnation/calcination of support powders lead to very large particle size distributions (typically ± 50 %) and insulating samples. They therefore fail both of the above criteria and make it extremely dicult to extract precise sample characterisation. Here we present an alternative approach designed to enable XPS analysis in vacuum and under reaction conditions, whereby: (i) nanoparticles are synthesized by gas condensation and passed through a mass filter, which allows size selection in the range of 1 to 10000 atoms with typically ±4% accuracy; (ii) these particles are deposited onto a thin Al2O3 film grown on Al foil, which mimics the properties of conventional alumina supports while being conductive enough to avoid any charging-related artefacts in the XPS spectra. In vacuum, size-dependent Pd 3d binding-energy shifts up to 1.65 eV were recorded for supported Pd nanoparticles. Changes in the chemical composition of Pd nanoparticles were studied by near-ambient pressure (NAP)-XPS under dry and wet reaction conditions for methane oxidation (CH4 + O2 [+ H2O]) in the temperature range between 150 ◦C and 450 ◦C. Under dry reaction conditions large Pd particles appeared to oxidise almost fully to Pd(II), whereas smaller clusters showed a mix of Pd(0) and Pd(II) oxidation states. Under wet conditions, oxidation starts at lower temperatures and particles of all sizes were fully oxidised when the highest temperature was reached. Sintering during the temperature ramp cannot be excluded, especially for the smaller particles, and may be part of the reason for the dierent behaviour under wet conditions. This study clearly shows composition changes which are particle-size dependent and demonstrate.
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Mar 2026
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
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James J. C.
Counter
,
Santosh
Kumar
,
Christopher M.
Zalitis
,
Mark
Clapp
,
Alexander I.
Large
,
David C.
Grinter
,
Matthijs A.
Van Spronsen
,
Pilar
Ferrer
,
Burcu
Karagoz
,
Tugce
Eralp Erden
,
Roger A.
Bennett
,
Georg
Held
Diamond Proposal Number(s):
[32763, 36143, 34260, 39495]
Open Access
Abstract: In situ soft X-ray spectroscopy provides direct insight into the electronic structure of electrocatalysts under realistic reaction conditions but remains technically challenging due to the need to combine aqueous electrochemistry with ultra-high-vacuum detection. Here, we present a mesoporous carbon–membrane working electrode assembly (WEA) that enables window-free in situ XPS and NEXAFS measurements during electrochemical reactions. The design integrates a Nafion proton-exchange membrane with a mesoporous carbon–ionomer contact layer and a thin IrOx catalyst layer, providing continuous electronic and protonic pathways and stable hydration through the membrane. By tuning the chamber water vapor pressure to 8 mbar, the WEA maintains a nanometer-thin water layer sufficient for the oxygen evolution reaction (OER) while preserving photoelectron detection efficiency. A robust peristaltic pump integrated with an alumina-bed water vapor dosing system maintains steady-state hydration at 6–10 mbar with <±0.1 mbar variation, enabling reproducible in situ spectra over extended periods. In situ Ir 4f and O 1s XPS reveal oxidation of Ir3+/Ir4+ to Ir4+/Ir5+ and dynamic changes in hydroxyl and lattice oxygen species, while O K-edge NEXAFS identify the formation of potential-stabilized μ2–O and μ1–O oxygen ligand species at OER. The WEA thus provides a quantitative, window-free platform for probing electrochemical interfaces under near-ambient conditions and establishes a general methodology for in situ soft X-ray studies of functional electrocatalysts, closely resembling the architecture and operation of industrial membrane-based water electrolyzers. This approach establishes a reliable methodology for coupling electrochemistry with the element specific soft X-ray spectroscopy under realistic reaction conditions.
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Mar 2026
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
B18-Core EXAFS
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Caiwu
Liang
,
Lucas
Garcia Verga
,
Benjamin
Moss
,
Santosh
Kumar
,
Soren B.
Scott
,
Mark A.
Turner
,
Pilar
Ferrer
,
Veronica
Celorrio
,
David C.
Grinter
,
Yemin
Tao
,
Sid
Halder
,
Yifeng
Wang
,
Cindy
Tseng
,
Guangmeimei
Yang
,
Georg
Held
,
Sarah J.
Haigh
,
Aron
Walsh
,
Ifan E. L.
Stephens
,
James R.
Durrant
,
Reshma R.
Rao
Diamond Proposal Number(s):
[34803, 30396, 31886]
Open Access
Abstract: Oxidation states underpin the understanding of active states, reaction mechanisms and catalytic performance of electrocatalysts. However, determining them at complex solid–liquid interfaces is challenging. Here we use multimodal spectroscopy to investigate polarized iridium oxide (IrOx) electrodes, a model water oxidation catalyst, to identify potential-dependent iridium and oxygen oxidation states. By integrating multiple operando spectroscopies (optical (ultraviolet–visible), Ir L-edge and O K-edge X-ray absorption spectroscopy) with electrochemistry mass spectrometry and density functional theory calculations, we identify the sequential depletion of electron densities from the Ir5d band (corresponding to Ir3+→Ir4+→Ir5+), followed by electron removal from the O2p band, forming electrophilic oxygen species (O−1) due to enhanced Ir–O covalency and electronic state overlap. Time-resolved measurements reveal distinct lifetimes for Ir5+ and O−1 states under water oxidation conditions, Ir5+ remains unreactive whereas O−1 is consumed at a time constant commensurate with the reaction rate, indicating that O−1 drives the oxygen evolution reaction. These findings demonstrate the necessity of using multiple operando techniques to gain a unified understanding of the evolution of oxidation states and active sites with potential for water oxidation on oxide catalysts.
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Feb 2026
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
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Diamond Proposal Number(s):
[33956]
Abstract: Multiwavelength light emission was observed in undoped tin oxide thin films deposited by metal-organic chemical vapor deposition at temperatures ranging from 700°C to 800°C. This work presents the relationship between the presence and nature of defects in undoped SnO2 thin films and their emission properties. Blue and orange emissions were observed on SnO2 thin films using a He-Cd laser and an Xe lamp at an excitation wavelength of 325 nm. Systematic characterization and analysis techniques, including low-temperature photoluminescence at temperatures ranging from 77K to 298K and surface-sensitive techniques using brilliant synchrotron radiation facilities, were applied to elucidate the features and origin of emission in undoped SnO2 layers. Based on our results, surface and bulk oxygen and interstitial tin defects play an important role in multi-wavelength emission processes and can be separately activated by controlling the applied light source.
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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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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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