B18-Core EXAFS
|
Yu
Zhu
,
Fei
Guo
,
Qiliang
Wei
,
Feiyan
Lai
,
Runzhe
Chen
,
Jianing
Guo
,
Manxi
Gong
,
Shunqiang
Zhang
,
Zichen
Wang
,
Jun
Zhong
,
Guanjie
He
,
Niancai
Cheng
Diamond Proposal Number(s):
[34632]
Open Access
Abstract: The oxygen spillover on the metal/oxide electrocatalysts interface acts as an essential role in promoting the oxygen evolution reaction (OER) for proton exchange membrane water electrolyzers (PEMWEs). However, oxygen spillover mechanisms and corresponding regulatory strategies are still unclear for addressing slow OH-migration kinetics. Herein, an interface is constructed between Iridium (Ir) and Niobium (Nb)-doped Titanium oxide (TiO2) with abundant oxygen vacancies area by plasma processing, enabling oxygen spillover from the metal Ir to supports. The optimized Ir/Nb-doped TiO2 with a significant OER activity (η = 253 mV) and durability in acids compared to commercial IrO2. In situ experiments combined with theoretical computations reveal the presence of interfacial oxygen vacancies not only regulates the Ir structure toward boosted activity but also constructs a directional spillover pathway from Ir to interfacial oxygen vacancies area and then TiO2 via the OH*-filling route, which strikingly mitigates the OH* migration barriers. In addition, the optimized Ir/Nb-doped TiO2 exhibits excellent performance (1.69 V/1.0 A cm−2@80 °C) and long-term stability (≈500 h@1.0 A cm−2) with practical potential in PEMWEs. This work provides a unique insight into the role of oxygen spillover, paving the way for designing Ir-based catalysts for PEMWEs.
|
Jan 2025
|
|
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
|
|
Aquilos-CryoFIB at Diamond
Krios II-Titan Krios II at Diamond
|
Diamond Proposal Number(s):
[33808]
Open Access
Abstract: Inorganic minerals that form via regulated biological processes exhibit remarkable properties. This is due to the involvement of macromolecules that control biomineralization. Even though the interactions of these biopolymers with solid mineral phases are intensely studied, not much is known about their involvement in the preceding steps of intracellular transport of the mineral building blocks. In this work, the model system of coccolith calcite crystallization is utilized to address the role of mineral-associated polysaccharides in the transport of calcium ions. State-of-the-art cryo-electron tomography is used to image in situ ion-rich dense phases in the wild-type and in two mutant strains, defected in coccolith production. The results show that the abundance and solubility of the calcium-rich condensates need to be finely tuned for proper crystallization. When the native macromolecular assemblage is compromised, calcium is still present in the calcifying fluid as a solute, but this is not sufficient for coccolith development. These results suggest that biomineralizing systems achieve superior regulation of crystallization due to the use of dense macromolecule-rich phases.
|
Nov 2024
|
|
I15-1-X-ray Pair Distribution Function (XPDF)
|
Diamond Proposal Number(s):
[34409]
Open Access
Abstract: Per- and polyfluoroalkyl substances (PFAS) are emerging as bioaccumulative and toxic water pollutants, posing a large threat to human and aquatic organisms. This threat is aggravated by their extreme persistence to common degradation methods. Adsorption is regarded as the most conventional method to treat these contaminants, however, existing sorbents present considerable limitations on performance. The development of more efficient PFAS adsorbents is therefore of urgent need. The class of metal-organic frameworks (MOFs) can hold great promise for these purposes, featuring porous materials with high tailoring potential. Herein, a series of functionalized Zr-MOFs have been designed with boosted capacities for the adsorption of short- and long-chain perfluorinated carboxylic acids of environmental interest. The approach relies on chemistry-based concepts to introduce targeted post-synthetic modifications that promote PFAS···MOF interactions, specifically through coordinative bonding and hydrophobic effects. In particular, the framework TFA-MOF-808 (TFA = trifluoroacetic acid) displays the highest capture capacities reported for MOF materials in this pollutant class. Mechanistic studies, assisted by advanced synchrotron characterization techniques and theoretical calculations, support a ligand exchange process occurring during the adsorption phenomena. The results demonstrate the potential of this design approach in developing advanced PFAS sorbents with optimal performance.
|
Aug 2024
|
|
I06-Nanoscience (XPEEM)
|
Ryuji
Fujita
,
Gautam
Gurung
,
Mohamad‐assaad
Mawass
,
Alevtina
Smekhova
,
Florian
Kronast
,
Alexander Kang-Jun
Toh
,
Anjan
Soumyanarayanan
,
Pin
Ho
,
Angadjit
Singh
,
Emily
Heppell
,
Dirk
Backes
,
Francesco
Maccherozzi
,
Kenji
Watanabe
,
Takashi
Taniguchi
,
Daniel A.
Mayoh
,
Geetha
Balakrishnan
,
Gerrit
Van Der Laan
,
Thorsten
Hesjedal
Diamond Proposal Number(s):
[31730]
Open Access
Abstract: The van der Waals interaction enables atomically thin layers of exfoliated 2D materials to be interfaced in heterostructures with relaxed epitaxy conditions, however, the ability to exfoliate and freely stack layers without any strain or structural modification is by no means ubiquitous. In this work, the piezoelectricity of the exfoliated van der Waals piezoelectric α-In2Se3 is utilized to modify the magnetic properties of exfoliated Fe3GeTe2, a van der Waals ferromagnet, resulting in increased domain wall density, reductions in the transition temperature ranging from 5 to 20 K, and an increase in the magnetic coercivity. Structural modifications at the atomic level are corroborated by a comparison to a graphite/α-In2Se3 heterostructure, for which a decrease in the Tuinstra-Koenig ratio is found. Magnetostrictive ferromagnetic domains are also observed, which may contribute to the enhanced magnetic coercivity. Density functional theory calculations and atomistic spin dynamic simulations show that the Fe3GeTe2 layer is compressively strained by 0.4%, reducing the exchange stiffness and magnetic anisotropy. The incorporation of α-In2Se3 may be a general strategy to electrostatically strain interfaces within the paradigm of hexagonal boron nitride-encapsulated heterostructures, for which the atomic flatness is both an intrinsic property and paramount requirement for 2D van der Waals heterojunctions.
|
Mar 2024
|
|
I06-Nanoscience (XPEEM)
|
Xinqi
Liu
,
Puyang
Huang
,
Yunyouyou
Xia
,
Lei
Gao
,
Liyang
Liao
,
Baoshan
Cui
,
Dirk
Backes
,
Gerrit
Van Der Laan
,
Thorsten
Hesjedal
,
Yuchen
Ji
,
Peng
Chen
,
Yifan
Zhang
,
Fan
Wu
,
Meixiao
Wang
,
Junwei
Zhang
,
Guoqiang
Yu
,
Cheng
Song
,
Yulin
Chen
,
Zhongkai
Liu
,
Yumeng
Yang
,
Yong
Peng
,
Gang
Li
,
Qi
Yao
,
Xufeng
Kou
Abstract: To harness the intriguing properties of 2D van der Waals (vdW) ferromagnets (FMs) for versatile applications, the key challenge lies in the reliable material synthesis for scalable device production. Here, the epitaxial growth of single-crystalline 1T-CrTe2 thin films on 2-inch sapphire substrates are demonstrated. Benefiting from the uniform surface energy of the dangling bond-free Al2O3(0001) surface, the layer-by-layer vdW growth mode is observed right from the initial growth stage, which warrants precise control of the sample thickness beyond three monolayer and homogeneous surface morphology across the entire wafer. Moreover, the presence of the Coulomb interaction at the CrTe2/Al2O3 interface plays an important role in tailoring the anomalous Hall response, and the structural optimization of the CrTe2-based spin-orbit torque device leads to a substantial switching power reduction by 54%. The results may lay out a general framework for the design of energy-efficient spintronics based on configurable vdW FMs.
|
Sep 2023
|
|
B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
B18-Core EXAFS
|
Diamond Proposal Number(s):
[29781, 29392]
Open Access
Abstract: Fe-based potassium Prussian blue analogs (K-PBAs) are commonly used as K-ion battery (KIB) cathodes. Interestingly, K-PBAs are appealing cathodes for Na-ion batteries (NIBs). In a hybrid NIB cell, where Na-ion is in the electrolyte and K-ion is in the PBA cathode, cation intercalation and electrochemical performance of the cathode can be significantly affected by [Fe(CN)6]4− anion vacancy. This work studies the effect of anion vacancy in K-PBAs on regulating K-ion/Na-ion intercalation mechanism in hybrid NIB cells, by comparing two K-PBA cathodes with different vacancy contents. The results demonstrate that introducing a level of anion vacancy can maximize the number of K-ion intercalation sites and enhance K-ion diffusion in the PBA framework. This facilitates K-ion intercalation and suppresses Na-ion intercalation, resulting in a K-ion-dominated and high-discharge-voltage ion storage process in the hybrid NIB cell. The K-PBA cathode with 20% anion vacancy delivers 128 mAh g−1 at 25 mA g−1 and 67 mAh g−1 at 1000 mA g−1, as well as retains 89% and 81% capacity after 100 and 300 cycles, respectively. It completely outperforms the counterpart with 7% anion vacancy, which exhibits increased Na-ion intercalation but overall deteriorated ion storage.
|
Sep 2023
|
|
I07-Surface & interface diffraction
|
Diamond Proposal Number(s):
[17223]
Open Access
Abstract: Mixed 2D/3D perovskite materials are of particular interest to the photovoltaics and light- emitting diode (LED) communities due to their impressive opto-electronic properties alongside improved moisture stability compared to conventional 3D perovskite absorbers. Here, a mixed lead-tin perovskite containing distinct, self-assembled domains of either 3D structures or highly phase-pure Ruddlesden–Popper 2D structures is studied. The complex energy landscape of the material is revealed with ultrafast optical transient absorption measurements. It is shown that charge transfer between these microscale domains only occurs on nanosecond timescales, consistent with the large size of the domains. Using optical pump-terahertz probe spectroscopy, the effective charge-carrier mobility is shown to be an intermediary between analogous pure 2D and 3D perovskites. Furthermore, detailed analysis of the free carrier recombination dynamics is presented. By combining results from a range of excitation wavelengths within a full dynamic model of the photoexcited carrier population, it is shown that the 2D domains in the film exhibit remarkably similar carrier dynamics to the 3D domains, suggesting that long-range charge-transport should not be impeded by the heterogeneous structure of the material.
|
Aug 2023
|
|
B22-Multimode InfraRed imaging And Microspectroscopy
I11-High Resolution Powder Diffraction
|
Diamond Proposal Number(s):
[27504, 29415]
Open Access
Abstract: Luminescent metal-organic frameworks (LMOFs) are promising materials for nanophotonic applications due to their tuneable structure and programmability. Yet, the 3D nature of LMOFs creates challenges for stability, optical transparency, and device integration. Metal-organic nanosheets (MONs) potentially overcome these limitations by combining the benefits of metal-organic frameworks (MOFs) with an atomically thin morphology of large planar dimensions. Herein, the bottom-up synthesis of few-layer thin ZIF-7-III MONs via facile low-energy salt-templating is reported. Employing guest@MOF design, the fluorophores Rhodamine B and Fluorescein are intercalated into ZIF-7 nanosheets (Z7-NS) to form light emissive systems exhibiting intense and highly photostable fluorescence. Aggregation and Förster resonance energy transfer, enabled by the MON framework, are revealed as the mechanisms behind fluorescence. By varying guest concentration, these mechanisms provide predictable quantified control over emission chromaticity of a dual-guest Z7-NS material and the definition of an “emission chromaticity fingerprint” – a unique subset of the visible spectrum that a material can emit by fluorescence.
|
Jun 2023
|
|
I13-1-Coherence
|
Diamond Proposal Number(s):
[28831]
Open Access
Abstract: Diffractive optical elements such as periodic gratings are fundamental devices in X-ray imaging – a technique that medical, material science, and security scans rely upon. Fabrication of such structures with high aspect ratios at the nanoscale creates opportunities to further advance such applications, especially in terms of relaxing X-ray source coherence requirements. This is because typical grating-based X-ray phase imaging techniques (e.g., Talbot self-imaging) require a coherence length of at least one grating period and ideally longer. In this paper, the fabrication challenges in achieving high-aspect ratio nanogratings filled with gold are addressed by a combination of laser interference and nanoimprint lithography, physical vapor deposition, metal assisted chemical etching (MACE), and electroplating. This relatively simple and cost-efficient approach is unlocked by an innovative post-MACE drying step with hexamethyldisilazane, which effectively minimizes the stiction of the nanostructures. The theoretical limits of the approach are discussed and, experimentally, X-ray nanogratings with aspect ratios >40 are demonstrated. Finally, their excellent diffractive abilities are shown when exposed to a hard (12.2 keV) monochromatic X-ray beam at a synchrotron facility, and thus potential applicability in phase-based X-ray imaging.
|
Jan 2023
|
|
