I06-Nanoscience (XPEEM)
|
Yang
Li
,
Yan
Wang
,
Andrew F.
May
,
Mauro
Fianchini
,
Chiara
Biz
,
Saeyoung
Oh
,
Yiru
Zhu
,
Hu Young
Jeong
,
Jieun
Yang
,
Jose
Gracia
,
Manish
Chhowalla
Diamond Proposal Number(s):
[33245]
Open Access
Abstract: Spin selective catalysis is an emerging approach for improving the thermodynamics and kinetics of reactions. The role of electron spins has been scarcely studied in catalytic reactions. One exception is the oxygen evolution reaction (OER) where strongly correlated metals and oxides are used as catalysts. In OER, spin alignment facilitates the transition of singlet state of the reactant to the triplet state of O2. However, the influence of strong correlations on spin exchange mechanism and spin selective thermodynamics of most catalytic reactions remain unclear. Here we decouple the strongly correlated catalyst from the electrolyte to study spin exchange in two-dimensional (2D) magnetic iron germanium telluride (FGT) heterostructure. We demonstrate that transmission of spin and electrochemical information between the catalyst and the reactant can occur through quantum exchange interaction despite the catalyst of FGT being completely encapsulated by graphene or hexagonal boron nitride (hBN). The strong correlations in FGT that lead to enhanced spin exchange in OER are observed in graphene or hBN layers with thicknesses of up to 6 nm. We demonstrate that spin alignment in FGT leads to a lowering of thermodynamic barrier for adsorption of hydroxide ion and electron transfer to the catalyst. This results in up to fivefold enhancement in OER performance and improved kinetics. Our results provide clear evidence that transmission of both quantum mechanical and electrochemical information through quantum spin exchange interaction in FGT leads to an enhancement in catalytic performance.
|
Dec 2024
|
|
B18-Core EXAFS
|
Nivetha
Jeyachandran
,
Wangchao
Yuan
,
Xiang
Li
,
Akshayini
Muthuperiyanayagam
,
Stefania
Gardoni
,
Jiye
Feng
,
Qingsheng
Gao
,
Martin
Wilding
,
Peter
Wells
,
Devis
Di Tommaso
,
Cristina
Giordano
Diamond Proposal Number(s):
[29721]
Open Access
Abstract: The rising levels of CO2 have spurred growing concerns for our environment, and curbing CO2 emissions may not be practically viable with the expanding human population. One attractive strategy is the electrochemical CO2 reduction (CO2RR) into value added chemicals but because of the chemical inertness of the CO2 molecule, the electrochemical reduction requires a suitable catalyst. Cu-based catalysts have been largely investigated for CO2RR, however, the difficulty achieving a high selectivity and faradaic efficiency towards specific products, especially hydrocarbons, is still a challenge, alongside the concern over cost, stability and scarcity of the metal catalyst. The present research focuses on tuning the crystallinity of Cu nanoparticles via a green, cost-friendly, and facile method, called the urea glass route. Remarkably, the incorporation of a selected nitrogen-carbon rich source (namely, 4,5 dicyanoimidazole) at low temperatures allow the formation of an oxidized derived amorphous Cu system, whilst a second thermal treatment enables the transformation to crystalline Cu0. We found that the combination of surface Cu0 and Cu1+ (observed via XPS studies) present in our amorphous and crystalline Cu nanoparticles leads to interesting differences in the final catalytic activity when tested under CO2 reaction conditions. The combination of extended X-ray absorption fine structure (EXAFS) experiments and molecular dynamics simulations provides compelling evidence for the amorphous and metallic nature of Cu nanoparticles.
|
Dec 2024
|
|
I22-Small angle scattering & Diffraction
|
Diamond Proposal Number(s):
[29651]
Open Access
Abstract: Degradation tests are a key step in the development of a bioresorbable stent. The present study focused on the degradation of bioresorbable stents made from PLLA filaments, and examined the variation of the physical, thermal, and mechanical properties of the material and the devices under both real-time and accelerated degradation conditions. Results showed that the undegraded filaments were highly crystalline and composed by both
and
crystalline phases, induced by both the melt spinning and heat treatment processes. The latter was shown to have an important influence on the further formation of
crystalline phase and therefore crystalline structure perfectioning. Real-time degradation tests showed that the devices maintained structural stability for up to a year, meeting the required 6-month degradation period for vascular stents. Degradation was shown to primarily affect the crystalline regions, and to cause a gradual loss of material ductility before any mass loss or decrease in crystallinity. In turn, a constant decrease of molecular weight was observed, with stent failure occurring around day 389 due to a drop in molecular weight below 10,000 g/mol. Accelerated degradation tests mirrored real-time results until mass loss began. Subsequently a slower molecular weight decrease was observed, with an increase and subsequent decrease of material crystallinity. The consistency of the data obtained between real-time and accelerated degradation before mass loss confirmed the possibility to gain insights into real-time degradation through an accelerated protocol. However, attention must be paid to the initial molecular weight of the material, which has been shown to highly influence the acceleration rate. This study provides a wide range of experimental data both on the real-time and thermally accelerated degradation behaviour of PLLA braided stents that can be used as benchmark for further studies in the field.
|
Dec 2024
|
|
|
|
Abstract: Through a combination of magnetic susceptibility, specific heat, and neutron powder diffraction measurements we have revealed a sequence of four magnetic phase transitions in the columnar quadruple perovskite Er2CuMnMn4O12. A key feature of the quadruple perovskite structural framework is the complex interplay of multiple magnetic sublattices via frustrated exchange topologies and competing magnetic anisotropies. It is shown that in Er2CuMnMn4O12, this phenomenology gives rise to multiple spin-reorientation transitions driven by the competition of easy-axis single ion anisotropy and the Dzyaloshinskii–Moriya interaction; both within the manganese B-site sublattice. At low temperature, one Er sublattice orders due to a finite f-d exchange field aligned parallel to its Ising axis, while the other Er sublattice remains non-magnetic until a final, symmetry-breaking phase transition into the ground state. This non-trivial low-temperature interplay of transition metal and rare-earth sublattices, as well as an observed k = (0, 0, ½) periodicity in both manganese spin canting and Er ordering, raises future challenges to develop a complete understanding of the R2CuMnMn4O12 family.
|
Dec 2024
|
|
I19-Small Molecule Single Crystal Diffraction
|
Mariya
Aleksich
,
Yeongsu
Cho
,
Daniel W.
Paley
,
Maggie C.
Willson
,
Hawi N.
Nyiera
,
Patience A.
Kotei
,
Vanessa
Oklejas
,
David W.
Mittan-Moreau
,
Elyse A.
Schriber
,
Kara
Christensen
,
Ichiro
Inoue
,
Shigeki
Owada
,
Kensuke
Tono
,
Michihiro
Sugahara
,
Satomi
Inaba-Inoue
,
Mohammad
Vakili
,
Christopher J.
Milne
,
Fabio
Dallantonia
,
Dmitry
Khakhulin
,
Fernando
Ardana-Lamas
,
Frederico
Lima
,
Joana
Valerio
,
Huijong
Han
,
Tamires
Gallo
,
Hazem
Yousef
,
Oleksii
Turkot
,
Ivette J. Bermudez
Macias
,
Thomas
Kluyver
,
Philipp
Schmidt
,
Luca
Gelisio
,
Adam R.
Round
,
Yifeng
Jiang
,
Doriana
Vinci
,
Yohei
Uemura
,
Marco
Kloos
,
Adrian P.
Mancuso
,
Mark
Warren
,
Nicholas K.
Sauter
,
Jing
Zhao
,
Tess
Smidt
,
Heather J.
Kulik
,
Sahar
Sharifzadeh
,
Aaron S.
Brewster
,
J. Nathan
Hohman
Diamond Proposal Number(s):
[35300]
Abstract: X-ray free electron laser (XFEL) microcrystallography and synchrotron single-crystal crystallography are used to evaluate the role of organic substituent position on the optoelectronic properties of metal–organic chalcogenolates (MOChas). MOChas are crystalline 1D and 2D semiconducting hybrid materials that have varying optoelectronic properties depending on composition, topology, and structure. While MOChas have attracted much interest, small crystal sizes impede routine crystal structure determination. A series of constitutional isomers where the aryl thiol is functionalized by either methoxy or methyl ester are solved by small molecule serial femtosecond X-ray crystallography (smSFX) and single crystal rotational crystallography. While all the methoxy examples have a low quantum yield (0-1%), the methyl ester in the ortho position yields a high quantum yield of 22%. The proximity of the oxygen atoms to the silver inorganic core correlates to a considerable enhancement of quantum yield. Four crystal structures are solved at a resolution range of 0.8–1.0 Å revealing a collapse of the 2D topology for functional groups in the 2- and 3- positions, resulting in needle-like crystals. Further analysis using density functional theory (DFT) and many-body perturbation theory (MBPT) enables the exploration of complex excitonic phenomena within easily prepared material systems.
|
Dec 2024
|
|
I20-EDE-Energy Dispersive EXAFS (EDE)
|
Abstract: The development and growth of heterogeneous catalysis are directly connected to the knowledge of the structure and associated changes that arise from reactions it has, under specific environmental conditions. In liquid phase catalysed reactions, which was the focus of this thesis, information associated with the reaction, e.g. the active site, is often difficult to obtain due to the solvent being present at higher quantities in comparison to the much smaller quantity of active species. Additionally, difficulties associated with the characterisation of such systems arise from the frequently short lifetime of active species, and the tendency of catalytic events to occur on the surface of the catalyst, with the bulk structure barely participating in any reactions. The purpose of this thesis was to conduct a research study, integrating modulation excitation (ME) approach with total neutron scattering (TNS) and X-ray absorption spectroscopy (XAS) techniques. The combination of periodic modulation excitation with phase-sensitive detection (PSD) analysis, and their integration within TNS and XAS, allowed us to probe surface structural changes. This approach demonstrated an enhanced signal-to-noise ratio of the experimental data and significantly improved the sensitivity of the respective instruments to weak component contributions. Periodic electrical potential switches were employed as external stimulations to perturb the investigated systems reversibly and measure the active species contributions. In contrast to XAS, where ME methodology has been extensively implemented to the study of gas-phase catalytic reactions and most recently to liquid-phase catalytic reactions; combined ME-TNS studies is a novel approach that was successfully developed and demonstrated for the first time in this thesis. Ultimately, the essential instrumentation and innovative analysis procedures to extract useful structural information from the newly acquired ME-TNS data are demonstrated in the results chapters of this thesis. Finally, the ME technique was implemented at the Energy Dispersive EXAFS (EDE) branch of the I20 X-ray absorption spectroscopy beamline at Diamond Light Source, while the NIMROD instrument at ISIS neutron and muon source was developed to enable it to obtain ME-neutron scattering data.
|
Dec 2024
|
|
I13-2-Diamond Manchester Imaging
I14-Hard X-ray Nanoprobe
|
Kamila
Iskhakova
,
Hanna
Cwieka
,
Svenja
Meers
,
Heike
Helmholz
,
Anton
Davydok
,
Malte
Storm
,
Ivo Matteo
Baltruschat
,
Silvia
Galli
,
Daniel
Pröfrock
,
Olga
Will
,
Mirko
Gerle
,
Timo
Damm
,
Sandra
Sefa
,
Weilue
He
,
Keith
Macrenaris
,
Malte
Soujon
,
Felix
Beckmann
,
Julian
Moosmann
,
Thomas
O'Hallaran
,
Roger J.
Guillory
,
D. C. Florian
Wieland
,
Berit
Zeller-Plumhoff
,
Regine
Willumeit-Römer
Diamond Proposal Number(s):
[25078]
Open Access
Abstract: Magnesium (Mg) – based alloys are becoming attractive materials for medical applications as temporary bone implants for support of fracture healing, e.g. as a suture anchor. Due to their mechanical properties and biocompatibility, they may replace titanium or stainless-steel implants, commonly used in orthopedic field. Nevertheless, patient safety has to be assured by finding a long-term balance between metal degradation, osseointegration, bone ultrastructure adaptation and element distribution in organs. In order to determine the implant behavior and its influence on bone and tissues, we investigated two Mg alloys with gadolinium contents of 5 and 10 wt percent in comparison to permanent materials titanium and polyether ether ketone. The implants were present in rat tibia for 10, 20 and 32 weeks before sacrifice of the animal. Synchrotron radiation-based micro computed tomography enables the distinction of features like residual metal, degradation layer and bone structure. Additionally, X-ray diffraction and X-ray fluorescence yield information on parameters describing the bone ultrastructure and elemental composition at the bone-to-implant interface. Finally, with element specific mass spectrometry, the elements and their accumulation in the main organs and tissues are traced. The results show that Mg-xGd implants degrade in vivo under the formation of a stable degradation layer with bone remodeling similar to that of Ti after 10 weeks. No accumulation of Mg and Gd was observed in selected organs, except for the interfacial bone after 8 months of healing. Thus, we confirm that Mg-5Gd and Mg-10Gd are suitable material choices for bone implants.
|
Nov 2024
|
|
|
|
Valerio
Bellucci
,
Sarlota
Birnsteinova
,
Tokushi
Sato
,
Romain
Letrun
,
Jayanath C. P.
Koliyadu
,
Chan
Kim
,
Gabriele
Giovanetti
,
Carsten
Deiter
,
Liubov
Samoylova
,
Ilia
Petrov
,
Luis
Lopez Morillo
,
Rita
Graceffa
,
Luigi
Adriano
,
Helge
Huelsen
,
Heiko
Kollmann
,
Thu Nhi
Tran Calliste
,
Dusan
Korytar
,
Zdenko
Zaprazny
,
Andrea
Mazzolari
,
Marco
Romagnoni
,
Eleni Myrto
Asimakopoulou
,
Zisheng
Yao
,
Yuhe
Zhang
,
Jozef
Ulicny
,
Alke
Meents
,
Henry N.
Chapman
,
Richard
Bean
,
Adrian
Mancuso
,
Pablo
Villanueva-Perez
,
Patrik
Vagovic
Open Access
Abstract: X-ray multi-projection imaging (XMPI) is an emerging experimental technique for the acquisition of rotation-free, time-resolved, volumetric information on stochastic processes. The technique is developed for high-brilliance light-source facilities, aiming to address known limitations of state-of-the-art imaging methods in the acquisition of 4D sample information, linked to their need for sample rotation. XMPI relies on a beam-splitting scheme, that illuminates a sample from multiple, angularly spaced viewpoints, and employs fast, indirect, X-ray imaging detectors for the collection of the data. This approach enables studies of previously inaccessible phenomena of industrial and societal relevance such as fractures in solids, propagation of shock waves, laser-based 3D printing, or even fast processes in the biological domain. In this work, we discuss in detail the beam-splitting scheme of XMPI. More specifically, we explore the relevant properties of X-ray splitter optics for their use in XMPI schemes, both at synchrotron insertion devices and XFEL facilities. Furthermore, we describe two distinct XMPI schemes, designed to faciliate large samples and complex sample environments. Finally, we present experimental proof of the feasibility of MHz-rate XMPI at the European XFEL. This detailed overview aims to state the challenges and the potential of XMPI and act as a stepping stone for future development of the technique.
|
Nov 2024
|
|
B22-Multimode InfraRed imaging And Microspectroscopy
|
Dukula
De Alwis Jayasinghe
,
Yinlin
Chen
,
Jiangnan
Li
,
Justyna M.
Rogacka
,
Meredydd
Kippax-Jones
,
Wanpeng
Lu
,
Sergey
Sapchenko
,
Jinyue
Yang
,
Sarayute
Chansai
,
Tianze
Zhou
,
Lixia
Guo
,
Yujie
Ma
,
Longzhang
Dong
,
Daniil
Polyukhov
,
Lutong
Shan
,
Yu
Han
,
Danielle
Crawshaw
,
Xiangdi
Zeng
,
Zhaodong
Zhu
,
Lewis
Hughes
,
Mark D.
Frogley
,
Pascal
Manuel
,
Svemir
Rudic
,
Yongqiang
Chen
,
Christopher
Hardacre
,
Martin
Schroeder
,
Sihai
Yang
Open Access
Abstract: Ammonia (NH3) production in 2023 reached 150 million tons and is associated with potential concomitant production of up to 500 million tons of CO2 each year. Efforts to produce green NH3 are compromised since it is difficult to separate using conventional condensation chillers, but in situ separation with minimal cooling is challenging. While metal–organic framework materials offer some potential, they are often unstable and decompose in the presence of caustic and corrosive NH3. Here, we address these challenges by developing a pore-expansion strategy utilizing the flexible phosphonate framework, STA-12(Ni), which shows exceptional stability and capture of NH3 at ppm levels at elevated temperatures (100–220 °C) even under humid conditions. A remarkable NH3 uptake of 4.76 mmol g–1 at 100 μbar (equivalent to 100 ppm) is observed, and in situ neutron powder diffraction, inelastic neutron scattering, and infrared microspectroscopy, coupled with modeling, reveal a pore expansion from triclinic to a rhombohedral structure on cooperative binding of NH3 to unsaturated Ni(II) sites and phosphonate groups. STA-12(Ni) can be readily engineered into pellets or monoliths without losing adsorption capacity, underscoring its practical potential.
|
Nov 2024
|
|
B18-Core EXAFS
|
Jia-Wei
Wang
,
Fengyi
Zhao
,
Lucia
Velasco
,
Maxime
Sauvan
,
Dooshaye
Moonshiram
,
Martina
Salati
,
Zhi-Mei
Luo
,
Sheng
He
,
Tao
Jin
,
Yan-Fei
Mu
,
Mehmed Z.
Ertem
,
Tianquan
Lian
,
Antoni
Llobet
Diamond Proposal Number(s):
[33134]
Open Access
Abstract: The selective photoreduction of CO2 in aqueous media based on earth-abundant elements only, is today a challenging topic. Here we present the anchoring of discrete molecular catalysts on organic polymeric semiconductors via covalent bonding, generating molecular hybrid materials with well-defined active sites for CO2 photoreduction, exclusively to CO in purely aqueous media. The molecular catalysts are based on aryl substituted Co phthalocyanines that can be coordinated by dangling pyridyl attached to a polymeric covalent triazine framework that acts as a light absorber. This generates a molecular hybrid material that efficiently and selectively achieves the photoreduction of CO2 to CO in KHCO3 aqueous buffer, giving high yields in the range of 22 mmol g−1 (458 μmol g−1 h−1) and turnover numbers above 550 in 48 h, with no deactivation and no detectable H2. The electron transfer mechanism for the activation of the catalyst is proposed based on the combined results from time-resolved fluorescence spectroscopy, in situ spectroscopies and quantum chemical calculations.
|
Nov 2024
|
|
