B18-Core EXAFS
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Diamond Proposal Number(s):
[39179]
Open Access
Abstract: Developing photocatalysts that can efficiently utilize the full solar spectrum is a crucial step toward transforming sustainable energy solutions. Due to their light absorption limitations, most photo-responsive metal−organic frameworks (MOFs) are constrained to the ultraviolet (UV) and blue light regions. Expanding their absorp-tion to encompass the entire solar spectrum would unlock their full potential, greatly enhancing efficiency and applicability. Here, we report the design and synthesis of a series of highly stable boron-dipyrromethene (bodipy) based MOFs (BMOFs) by reacting dicar-boxyl-functionalized bodipy ligands with Zr-oxo clusters. Leveraging the acidity of the methyl groups on the bodipy backbone, we ex-panded the conjugation system through a solid-state condensation reaction with various aldehydes, achieving full-color absorption, thereby extending the band edge into the near-infrared (NIR) and infrared (IR) regions. These BMOFs demonstrated exceptional reac-tivity and recyclability in heterogeneous photocatalytic activities, including C−H bond activation of saturated aza-heterocycles and C−N bond cleavage of N,N-dimethylanilines to produce amides under visible light. Our findings highlight the transformative potential of BMOFs in photocatalysis, marking a significant leap forward in the design of advanced photocatalytic materials with tunable properties.
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Apr 2025
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B18-Core EXAFS
I11-High Resolution Powder Diffraction
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Xu
Chen
,
Dhruv
Menon
,
Xiaoliang
Wang
,
Meng
He
,
Mohammad Reza
Alizadeh Kiapi
,
Mehrdad
Asgari
,
Yuexi
Lyu
,
Xianhui
Tang
,
Luke L.
Keenan
,
William
Shepard
,
Lik H.
Wee
,
Sihai
Yang
,
Omar K.
Farha
,
David
Fairen-Jimenez
Diamond Proposal Number(s):
[32566, 34552]
Open Access
Abstract: Selective CO2 capture from industry is crucial for reducing emissions from fossil fuel combustion. Flexible metal-organic frameworks (MOFs) have shown promise for CO2 adsorption via differential binding and size-exclusion mechanisms. However, achieving precise pore-size control to selectively capture CO2, particularly in the presence of N2 and water, remains a challenge. Here, we demonstrate a strategy for frustrating framework flexibility in a MOF to create an optimal, confined pore environment that enhances selective CO2 recognition while maintaining high working capacity. We designed a flexible MOF, Cambridge University (CU)-4, by using a bulky cubane-derived ligand and In3+ ions that undergo dynamic breathing with a 2 Å contraction upon solvent exchange and removal. In situ synchrotron X-ray diffraction and molecular simulations reveal that the stable narrow-pore configuration creates a hydrogen-rich cavity that selectively binds CO2 via multiple hydrogen bonds. This physisorption-based CO2 recognition remains effective even at 80% humidity, making CU-4 promising for post-combustion carbon capture.
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Jan 2025
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
E01-JEM ARM 200CF
E02-JEM ARM 300CF
I20-EDE-Energy Dispersive EXAFS (EDE)
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Lu
Chen
,
Xuze
Guan
,
Zhaofu
Fei
,
Hiroyuki
Asakura
,
Lun
Zhang
,
Zhipeng
Wang
,
Xinlian
Su
,
Zhangyi
Yao
,
Luke L.
Keenan
,
Shusaku
Hayama
,
Matthijs A.
Van Spronsen
,
Burcu
Karagoz
,
Georg
Held
,
Christopher S.
Allen
,
David G.
Hopkinson
,
Donato
Decarolis
,
June
Callison
,
Paul J.
Dyson
,
Feng Ryan
Wang
Diamond Proposal Number(s):
[30622, 33257, 31922]
Open Access
Abstract: Selective catalytic oxidation (SCO) of NH3 to N2 is one of the most effective methods used to eliminate NH3 emissions. However, achieving high conversion over a wide operating temperature range while avoiding over-oxidation to NOx remains a significant challenge. Here, we report a bi-metallic surficial catalyst (PtSCuO/Al2O3) with improved Pt atom efficiency that overcomes the limitations of current catalysts. It achieves full NH3 conversion at 250 °C with a weight hourly space velocity of 600 ml NH3·h−1·g−1, which is 50 °C lower than commercial Pt/Al2O3, and maintains high N2 selectivity through a wide temperature window. Operando XAFS studies reveal that the surface Pt atoms in PtSCuO/Al2O3 enhance the redox properties of the Cu species, thus accelerating the Cu2+ reduction rate and improving the rate of the NH3-SCO reaction. Moreover, a synergistic effect between Pt and Cu sites in PtSCuO/Al2O3 contributes to the high selectivity by facilitating internal selective catalytic reduction.
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Jan 2025
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Fangfang
Peng
,
Bin
Zhang
,
Runyao
Zhao
,
Shiqiang
Liu
,
Yuxuan
Wu
,
Shaojun
Xu
,
Luke L.
Keenan
,
Huizhen
Liu
,
Qingli
Qian
,
Tianbin
Wu
,
Haijun
Yang
,
Zhimin
Liu
,
Jikun
Li
,
Bingfeng
Chen
,
Xinchen
Kang
,
Buxing
Han
Open Access
Abstract: Selective hydrogenolysis of biomass-derived furanic compounds is a promising approach for synthesizing aliphatic polyols by opening the furan ring. However, there remains a significant need for highly efficient catalysts that selectively target the Csp2–O bond in the furan ring, as well as for a deeper understanding of the fundamental atomistic mechanisms behind these reactions. In this study, we present the use of Pt–Fe bimetallic catalysts supported on layered double hydroxides [PtFex/LDH] for the hydrogenolysis of furanic compounds into aliphatic alcohols, achieving over 90% selectivity toward diols and triols. Our findings reveal that the synergy between Pt nanoparticles, atomically dispersed Pt sites and the support facilitates the formation of hydride-proton pair at the Ptδ+⋯O2− Lewis acid–base unit of PtFex/LDH through hydrogen spillover. The hydride specifically targets the Csp2–O bond in the furan ring, initiating an SN2 reaction and ring cleavage. Moreover, the presence of Fe improves the yield of desired alcohols by inhibiting the adsorption of vinyl groups, thereby suppressing the hydrogenation of the furan ring.
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Nov 2024
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I20-EDE-Energy Dispersive EXAFS (EDE)
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Diamond Proposal Number(s):
[28203]
Abstract: Understanding nature of intermediates/active species in reactions is a major challenge in chemistry. This is because spectator species typically dominate the experimentally derived data and consequently active phase contributions are masked. Transient methods offer a means to bypass this difficulty. In particular, modulation excitation with phase-sensitive detection (ME-PSD) provides a mechanism to distinguish between spectator and reacting species. Herein, modulation excitation (ME) time-resolved (energy dispersive) X-ray absorption spectroscopy, assisted by phase sensitive detection (PSD) analysis, has been applied to the study of a liquid phase process; in this case the classic ferrocyanide/ferricyanide redox couple. Periodic switches of the electrical potential (anodic/cathodic) enabled the use of the ME approach. Structural changes at fractions as low as 2% of the total number of electroactive species were detected within the X-ray beam probe volume containing ~30 pmol of Fe(II)/Fe(III).
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Aug 2024
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Open Access
Abstract: Storing and utilising electricity from renewable sources is of growing importance as we move away from our reliance on fossil fuels. Batteries and supercapacitors are becoming ever more present in our day to day lives; in order to improve the next generation of batteries and supercapacitors, we must understand on an atomic scale what happens to electrode materials upon charge and discharge. In order to do this, we must combine structural and electrochemical studies, using techniques which use both different length scales and different timescales. These experiments are known as operando experiments and are a valuable tool in analysing new materials for energy storage.
Transition metal niobates of the columbite structure (MNb2O6, M = transition or alkali earth metal) have previously been studied for their photocatalytic and magnetic properties but recently have garnered interest as negative electrode materials for batteries and supercapacitors.1 In this study, a series of columbite materials have been studied using a range of operando and ex-situ techniques. Samples were prepared using both solid-state synthesis2 and solution methods. Ex-situ X-ray diffraction and scanning electron microscopy were used to characterise the columbites prior to electrochemical testing. Operando X-ray absorption spectroscopy and operando Raman studies have been used to probe the changes in oxidation state of the transition metals and local structure upon charge/discharge.
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Aug 2024
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
E01-JEM ARM 200CF
I09-Surface and Interface Structural Analysis
I20-EDE-Energy Dispersive EXAFS (EDE)
I20-Scanning-X-ray spectroscopy (XAS/XES)
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Xuze
Guan
,
Rong
Han
,
Hiroyuki
Asakura
,
Bolun
Wang
,
Lu
Chen
,
Jay Hon Cheung
Yan
,
Shaoliang
Guan
,
Luke
Keenan
,
Shusaku
Hayama
,
Matthijs A.
Van Spronsen
,
Georg
Held
,
Jie
Zhang
,
Hao
Gu
,
Yifei
Ren
,
Lun
Zhang
,
Zhangyi
Yao
,
Yujiang
Zhu
,
Anna
Regoutz
,
Tsunehiro
Tanaka
,
Yuzheng
Guo
,
Feng Ryan
Wang
Diamond Proposal Number(s):
[23759, 24450, 29092, 31852]
Open Access
Abstract: Single-atom catalysts have garnered significant attention due to their exceptional atom utilization and unique properties. However, the practical application of these catalysts is often impeded by challenges such as sintering-induced instability and poisoning of isolated atoms due to strong gas adsorption. In this study, we employed the mechanochemical method to insert single Cu atoms into the subsurface of Fe2O3 support. By manipulating the location of single atoms at the surface or subsurface, catalysts with distinct adsorption properties and reaction mechanisms can be achieved. It was observed that the subsurface Cu single atoms in Fe2O3 remained isolated under both oxidation and reduction environments, whereas surface Cu single atoms on Fe2O3 experienced sintering under reduction conditions. The unique properties of these subsurface single-atom catalysts call for innovations and new understandings in catalyst design.
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Jul 2024
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I20-EDE-Energy Dispersive EXAFS (EDE)
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Donato
Decarolis
,
Monik
Panchal
,
Matthew
Quesne
,
Khaled
Mohammed
,
Shaojun
Xu
,
Mark
Isaacs
,
Adam H.
Clark
,
Luke L.
Keenan
,
Takuo
Wakisaka
,
Kohei
Kusada
,
Hiroshi
Kitagawa
,
C. Richard A.
Catlow
,
Emma K.
Gibson
,
Alexandre
Goguet
,
Peter
Wells
Diamond Proposal Number(s):
[21593]
Open Access
Abstract: Unravelling kinetic oscillations, which arise spontaneously during catalysis, has been a challenge for decades but is important not only to understand these complex phenomena but also to achieve increased activity. Here we show, through temporally and spatially resolved operando analysis, that CO oxidation over Rh/Al2O3 involves a series of thermal levering events—CO oxidation, Boudouard reaction and carbon combustion—that drive oscillatory CO2 formation. This catalytic sequence relies on harnessing localized temperature episodes at the nanoparticle level as an efficient means to drive reactions in situations in which the macroscopic conditions are unfavourable for catalysis. This insight provides a new basis for coupling thermal events at the nanoscale for efficient harvesting of energy and enhanced catalyst technologies.
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Jul 2024
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B18-Core EXAFS
I20-EDE-Energy Dispersive EXAFS (EDE)
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Khaled
Mohammed
,
Reza
Vakili
,
Donato
Decarolis
,
Shaojun
Xu
,
Luke L.
Keenan
,
Apostolos
Kordatos
,
Nikolay
Zhelev
,
Chris K.
Skylaris
,
Marina
Carravetta
,
Emma K.
Gibson
,
Haresh
Manyar
,
Alexandre
Goguet
,
Peter P.
Wells
Diamond Proposal Number(s):
[28666, 34632]
Open Access
Abstract: The need to achieve net zero requires decarbonisation across all areas of our industrialised society, including the production of chemicals. One example is the production of acetonitrile, which currently relies on fossil carbon. Recently, supported Pd nanoparticles have been shown to promote the selective transformation of bio-derived ethanol to acetonitrile. Elsewhere, current research has demonstrated the importance of interstitial structures of Pd in promoting specific transformations. In this study, we demonstrate through a spatially resolved operando energy-dispersive-EXAFS (EDE) technique that the selectivity to acetonitrile (up to 99%) is concurrent with the formation of a PdNx phase. This was evidenced from the features observed in the X-ray Absorption near edge structure validated against PdNx samples made via known synthesis methods. . Above 240 ℃, the Pd nanoparticles became progressively oxidised which led to the production of unwanted byproducts, primarily CO2. The spatially resolved analysis indicated that the Pd speciation was homogeneous across the catalyst profile throughout the series of studies performed. This work resolved the structural selectivity of Pd nanoparticles that directs ethanol ammoxidation towards acetonitrile, and provides important information on the performance descriptors required to advance this technology.
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Apr 2024
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I20-EDE-Energy Dispersive EXAFS (EDE)
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Diamond Proposal Number(s):
[28536]
Open Access
Abstract: Amorphous metal–organic frameworks are rarely formed via direct synthesis. Our limited understanding of their atomic assembly in solution prevents full exploitation of their unique structural complexity. Here, we use in situ synchrotron X-ray absorption spectroscopy with sub-second time resolution to probe the formation of the amorphous Fe-BTC framework. Using a combination of spectral fingerprinting, linear combination analysis, and principal component analysis coupled with kinetic analyses, we reveal a multi-stage formation mechanism that, crucially, proceeds via the generation of a transient intermediate species.
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Feb 2024
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