I15-1-X-ray Pair Distribution Function (XPDF)
|
Laura G.
Graversen
,
Nicolas
Schlegel
,
Freja B.
Holde
,
Adrian
Sanz Arjona
,
Stefanie
Punke
,
Tobias M.
Nielsen
,
Andy S.
Anker
,
Jonas
Forner
,
Gustav K. H.
Wiberg
,
Matthias
Arenz
,
Rebecca K.
Pittkowski
,
Kirsten M. Ø.
Jensen
Diamond Proposal Number(s):
[30653]
Open Access
Abstract: Iridium oxide nanoparticles are efficient catalysts for the acidic oxygen evolution reaction (OER). We present a straightforward one-pot hydrothermal synthesis method to produce sub-1 nm Ir oxide nanoparticles in a single step, with size control achieved through post-synthesis annealing. By combining X-ray total scattering and pair distribution function (PDF) analysis with small-angle X-ray scattering (SAXS), we find that the sub-nanometer-sized oxide has an increased number of edge-sharing [IrO6]-octahedra compared to the thermodynamically favorable rutile structure. PDF modelling using various cluster motifs reveals that a sheet-like cluster, derived from rutile and comprising seven [IrO6]-octahedra with a (110)-exposed surface, can describe the increased Ir–Ir edge-sharing connectivity. We further find that cluster growth leads to a decrease in the number of edge-sharing motifs, going towards the bulk rutile structure upon annealing. Operando X-ray total scattering and PDF analysis during OER reveal high structural stability of the ultra-small (<3 nm) Ir oxides.
|
Jun 2026
|
|
B18-Core EXAFS
|
Diamond Proposal Number(s):
[42455]
Open Access
Abstract: The direct synthesis of amorphous metal–organic frameworks (aMOFs) is an appealing yet often avoided approach due to the perceived unpredictability of amorphous network formation. Here, we develop a strategy for aMOF synthesis using pre-formed nanoclusters and rigid organic linkers, providing enhanced control over disorder and defect chemistry while bypassing the traditional crystallise–amorphise approach. By systematically comparing this approach to other direct synthesis routes and using X-ray pair distribution function, thermogravimetric, and statistical analyses, we establish key design principles governing aMOF formation. We demonstrate that kinetic control—fast reactions under basic conditions at room temperature—suppresses crystallisation and drives amorphous network formation. The nanocluster approach consistently yields highly disordered frameworks with the shortest coherence lengths among direct synthesis methods. Additionally, we show that tuning metal composition through doping with kinetically inert cations restricts coordination reversibility, significantly increasing defect density and structural disorder. Structural analysis reveals that while aMOFs share motifs with crystalline polymorphs, they cannot be directly mapped onto known structures, highlighting the importance of more nuanced characterisation approaches. By developing a systematic approach to aMOF design, this work provides a foundation for tailoring structural disorder, expanding their potential for catalysis, adsorption, and transport applications.
|
Apr 2026
|
|
I15-1-X-ray Pair Distribution Function (XPDF)
|
Adam F.
Sapnik
,
Philip A.
Chater
,
Dean S.
Keeble
,
John S. O.
Evans
,
Federica
Bertolotti
,
Antonietta
Guagliardi
,
Lise J.
Støckler
,
Elodie A.
Harbourne
,
Anders B.
Borup
,
Rebecca S.
Silberg
,
Adrien
Descamps
,
Clemens
Prescher
,
Benjamin D.
Klee
,
Axel
Phelipeau
,
Imran
Ullah
,
Kárel G.
Medina
,
Tobias A.
Bird
,
Viktoria
Kaznelson
,
William
Lynn
,
Andrew L.
Goodwin
,
Bo B.
Iversen
,
Celine
Crepisson
,
Emil S.
Bozin
,
Kirsten M. Ø.
Jensen
,
Emma E.
Mcbride
,
Reinhard B.
Neder
,
Ian
Robinson
,
Justin S.
Wark
,
Michał
Andrzejewski
,
Ulrike
Boesenberg
,
Erik
Brambrink
,
Carolina
Camarda
,
Valerio
Cerantola
,
Sebastian
Goede
,
Hauke
Höppner
,
Oliver S.
Humphries
,
Zuzana
Konopkova
,
Naresh
Kujala
,
Thomas
Michelat
,
Motoaki
Nakatsutsumi
,
Alexander
Pelka
,
Thomas R.
Preston
,
Lisa
Randolph
,
Michael
Roeper
,
Andreas
Schmidt
,
Cornelius
Strohm
,
Minxue
Tang
,
Peter
Talkovski
,
Ulf
Zastrau
,
Karen
Appel
,
David A.
Keen
Diamond Proposal Number(s):
[39017]
Open Access
Abstract: High-quality total scattering data, a key tool for understanding atomic-scale structure in disordered materials, require stable instrumentation and access to high momentum transfers. This is now routine at dedicated synchrotron instrumentation using high-energy X-ray beams, but it is very challenging to measure a total scattering dataset in less than a few microseconds. This limits their effectiveness for capturing structural changes that occur at the much faster timescales of atomic motion. Current X-ray free-electron lasers (XFELs) provide femtosecond-pulsed X-ray beams with maximum energies of ∼24 keV, giving the potential to measure total scattering and the attendant pair distribution functions (PDFs) on femtosecond timescales. We demonstrate that this potential has been realized using the HED scientific instrument at the European XFEL and present normalized total scattering data for 0.35 Å−1 < Q < 16.6 Å−1 and their PDFs from a broad spectrum of materials, including crystalline, nanocrystalline and amorphous solids, liquids and clusters in solution. We analyzed the data using a variety of methods, including Rietveld refinement, small-box PDF refinement, joint reciprocal–real-space refinement, cluster refinement and Debye scattering analysis. The resolution function of the setup is also characterized. We conclusively show that high-quality data can be obtained from a single ∼30 fs XFEL pulse for multiple different sample types. Our efforts not only significantly increase the existing maximum reported Q range for an S(Q) measured at an XFEL but also mean that XFELs are now a viable X-ray source for the broad community of people using reciprocal-space total scattering and PDF methods in their research.
|
Sep 2025
|
|
I15-1-X-ray Pair Distribution Function (XPDF)
|
Diamond Proposal Number(s):
[21791]
Open Access
Abstract: We investigate how synthesis method affect the crystallite size and atomic structure of cobalt iron oxide nanoparticles. By using a simple solvothermal method, we first synthesize cobalt ferrite nanoparticles of ca. 2 and 7 nm, characterized by Transmission Electron Microscopy (TEM), Small Angle X-ray scattering (SAXS), X-ray and neutron total scattering. The smallest particle size corresponds to only a few spinel unit cells, nevertheless, Pair Distribution Function (PDF) analysis of X-ray and neutron total scattering data show that the atomic structure in even the smallest nanoparticles is well described by the spinel structure, however with significant disorder and a contraction of the unit cell parameter. These effects can be explained by surface oxidation of the small nanoparticles, which is confirmed by X-ray near edge absorption spectroscopy (XANES). Neutron total scattering data and PDF analysis reveal a larger degree of inversion of the spinel of the smallest nanoparticles. Neutron total scattering data furthermore allows magnetic PDF (mPDF) analysis, which show that the ferrimagnetic domains correspond to ca. 80% of the crystallite size in the larger particles. A similar but less well-defined magnetic ordering was observed for the smallest nanoparticles. Finally, we use a co-precipitation synthesis method at room temperature to synthesize ferrite nanoparticles of similar size as the smallest crystallites synthesized by the solvothermal method. Structural analysis with PDF demonstrates that the ferrite nanoparticles synthesized via this method exhibit a significantly more defective structure compared to those synthesized via a solvothermal method.
|
Sep 2024
|
|
I15-1-X-ray Pair Distribution Function (XPDF)
|
Diamond Proposal Number(s):
[21791]
Open Access
Abstract: Manganese dioxide compounds are widely used in electrochemical applications e.g. as electrode materials or photocatalysts. One of the most used polymorphs is γ-MnO2 which is a disordered intergrowth of pyrolusite β-MnO2 and ramsdellite R-MnO2. The presence of intergrowth defects alters the material properties, however, they are difficult to characterise using standard X-ray diffraction due to anisotropic broadening of Bragg reflections. We here propose a characterisation method for intergrown structures by modelling of X-ray diffraction patterns and pair distribution functions (PDF) using γ-MnO2 as an example. Firstly, we present a fast peak-fitting analysis approach, where features in experimental diffraction patterns and PDFs are matched to simulated patterns from intergrowth structures, allowing quick characterisation of defect densities. Secondly, we present a structure-mining-based analysis using simulated γ-MnO2 superstructures which are compared to our experimental data to extract trends on defect densities with synthesis conditions. We applied the methodology to a series of γ-MnO2 samples synthesised by a hydrothermal route. Our results show that with synthesis time, the intergrowth structure reorders from a R-like to a β-like structure, with the β-MnO2 fraction ranging from ca. 27 to 82% in the samples investigated here. Further analysis of the structure-mining results using machine learning can enable extraction of more nanostructural information such as the distribution and size of intergrown domains in the structure. Using this analysis, we observe segregation of R- and β-MnO2 domains in the manganese oxide nanoparticles. While R-MnO2 domains keep a constant size of ca. 1–2 nm, the β-MnO2 domains grow with synthesis time.
|
Sep 2022
|
|
I15-1-X-ray Pair Distribution Function (XPDF)
|
Jette K.
Mathiesen
,
Espen D.
Bøjesen
,
Jack K.
Pedersen
,
Emil T. S.
Kjær
,
Mikkel
Juelsholt
,
Susan
Cooper
,
Jonathan
Quinson
,
Andy S.
Anker
,
Geoff
Cutts
,
Dean S.
Keeble
,
Maria S.
Thomsen
,
Jan
Rossmeisl
,
Kirsten M. Ø.
Jensen
Diamond Proposal Number(s):
[20187]
Open Access
Abstract: Intermetallic nanoparticles (NPs) have shown enhanced catalytic properties as compared to their disordered alloy counterparts. To advance their use in green energy, it is crucial to understand what controls the formation of intermetallic NPs over alloy structures. By carefully selecting the additives used in NP synthesis, it is here shown that monodisperse, intermetallic PdCu NPs can be synthesized in a controllable manner. Introducing the additives iron(III) chloride and ascorbic acid, both morphological and structural control can be achieved. Combined, these additives provide a synergetic effect resulting in precursor reduction and defect-free growth; ultimately leading to monodisperse, single-crystalline, intermetallic PdCu NPs. Using in situ X-ray total scattering, a hitherto unknown transformation pathway is reported that diverges from the commonly reported coreduction disorder–order transformation. A Cu-rich structure initially forms, which upon the incorporation of Pd(0) and atomic ordering forms intermetallic PdCu NPs. These findings underpin that formation of stoichiometric intermetallic NPs is not limited by standard reduction potential matching and coreduction mechanisms, but is instead driven by changes in the local chemistry. Ultimately, using the local chemistry as a handle to tune the NP structure might open new opportunities to expand the library of intermetallic NPs by exploiting synthesis by design.
|
Apr 2022
|
|
B18-Core EXAFS
|
Gustav W.
Sievers
,
Anders W.
Jensen
,
Jonathan
Quinson
,
Alessandro
Zana
,
Francesco
Bizzotto
,
Mehtap
Oezaslan
,
Alexandra
Dworzak
,
Jacob J. K.
Kirkensgaard
,
Thomas E. L.
Smitshuysen
,
Shima
Kadkhodazadeh
,
Mikkel
Juelsholt
,
Kirsten M. Ø.
Jensen
,
Kirsten
Anklam
,
Hao
Wan
,
Jan
Schäfer
,
Klára
Čépe
,
María
Escudero-Escribano
,
Jan
Rossmeisl
,
Antje
Quade
,
Volker
Brüser
,
Matthias
Arenz
Diamond Proposal Number(s):
[12746]
Abstract: Several concepts for platinum-based catalysts for the oxygen reduction reaction (ORR) are presented that exceed the US Department of Energy targets for Pt-related ORR mass activity. Most concepts achieve their high ORR activity by increasing the Pt specific activity at the expense of a lower electrochemically active surface area (ECSA). In the potential region controlled by kinetics, such a lower ECSA is counterbalanced by the high specific activity. At higher overpotentials, however, which are often applied in real systems, a low ECSA leads to limitations in the reaction rate not by kinetics, but by mass transport. Here we report on self-supported platinum–cobalt oxide networks that combine a high specific activity with a high ECSA. The high ECSA is achieved by a platinum–cobalt oxide bone nanostructure that exhibits unprecedentedly high mass activity for self-supported ORR catalysts. This concept promises a stable fuel-cell operation at high temperature, high current density and low humidification.
|
Aug 2020
|
|
B18-Core EXAFS
|
Jonathan
Quinson
,
Masanori
Inaba
,
Sarah
Neumann
,
Andreas Abildgaard
Swane
,
Jan
Bucher
,
Søren Bredmose
Simonsen
,
Luise
Theil Kuhn
,
Jacob Judas Kain
Kirkensgaard
,
Kirsten M. O.
Jensen
,
Mehtap
Oezaslan
,
Sebastian
Kunz
,
Matthias
Arenz
Diamond Proposal Number(s):
[12746]
Abstract: Colloidal platinum nanoparticles are obtained via a surfactant-free polyol process in alkaline ethylene glycol. In this popular synthesis, ethylene glycol functions as solvent and reducing agent. The preparation procedure is known for its reproducibility to obtain 1-2 nm nanoparticles, but at the same time the controlled preparation of larger nanoparticles is challenging. A reliable size control without the use of surfactants is a fundamental yet missing achievement for systematic investigations. In this work it is demonstrated how the molar ratio between NaOH and the platinum precursor determines the final particle size and how this knowledge can be used to prepare and study in a systematic way supported catalysts with defined size and metal loading. Using small-angle X-ray scattering, transmission electron microscopy, infra-red spectroscopy, X-ray absorption spectroscopy, pair distribution function and electrochemical analysis it is shown that changing the NaOH/Pt molar ratio from 25 to 3, the Pt nanoparticle size is tuned from 1 to 5 nm. This size range is of interest for various catalytic applications, such as the oxygen reduction reaction (ORR). Supporting the nanoparticles onto a high surface area carbon, we demonstrate how the particle size effect can be studied keeping the catalyst loading constant, an important aspect that in previous studies could not be accomplished.
|
Jun 2018
|
|
I12-JEEP: Joint Engineering, Environmental and Processing
|
Abstract: Solvothermal and hydrothermal synthesis, that is, synthesis taking place in a solvent at elevated temperature and pressure, is a powerful technique for the production of advanced energy materials as it is versatile, cheap, and environmentally friendly. However, the fundamental reaction mechanisms dictating particle formation and growth under solvothermal conditions are not well understood. In order to produce tailor-made materials with specific properties for advanced energy technologies, it is essential to obtain an improved understanding of these processes and, in this context, in situ studies are an important tool as they provide real time information on the reactions taking place. Here, we present a review of the use of powder diffraction and total scattering methods for in situ studies of synthesis taking place under solvothermal and hydrothermal conditions. The experimental setups used for in situ X-ray and neutron studies are presented, and methods of data analysis are described. Special attention is given to the methods used to extract structural information from the data, for example, Rietveld refinement, whole powder pattern modelling and pair distribution function analysis. Examples of in situ studies are presented to illustrate the types of chemical insight that can be obtained.
|
Jun 2014
|
|
