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14 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2 [Next/Last]

Instruments / Technical Area	Publication Details	Published
E02-JEM ARM 300CF I15-1-X-ray Pair Distribution Function (XPDF) I22-Small angle scattering & Diffraction	Mixed hierarchical local structure in a disordered metal–organic framework Adam F. Sapnik , Irene Bechis , Sean M. Collins , Duncan N. Johnstone , Giorgio Divitini , Andrew J. Smith , Philip A. Chater , Matthew A. Addicoat , Timothy Johnson , David A. Keen , Kim E. Jelfs , Thomas D. Bennett Nature Communications 12 DOI: 10.1038/s41467-021-22218-9 Diamond Proposal Number(s): [20038, 24563] Open Access Show Abstract ▼ Abstract: Amorphous metal–organic frameworks (MOFs) are an emerging class of materials. However, their structural characterisation represents a significant challenge. Fe-BTC, and the commercial equivalent Basolite® F300, are MOFs with incredibly diverse catalytic ability, yet their disordered structures remain poorly understood. Here, we use advanced electron microscopy to identify a nanocomposite structure of Fe-BTC where nanocrystalline domains are embedded within an amorphous matrix, whilst synchrotron total scattering measurements reveal the extent of local atomic order within Fe-BTC. We use a polymerisation-based algorithm to generate an atomistic structure for Fe-BTC, the first example of this methodology applied to the amorphous MOF field outside the well-studied zeolitic imidazolate framework family. This demonstrates the applicability of this computational approach towards the modelling of other amorphous MOF systems with potential generality towards all MOF chemistries and connectivities. We find that the structures of Fe-BTC and Basolite® F300 can be represented by models containing a mixture of short- and medium-range order with a greater proportion of medium-range order in Basolite® F300 than in Fe-BTC. We conclude by discussing how our approach may allow for high-throughput computational discovery of functional, amorphous MOFs.	Apr 2021
E02-JEM ARM 300CF I15-1-X-ray Pair Distribution Function (XPDF)	Stepwise collapse of a giant pore metal–organic framework Adam F. Sapnik , Duncan N. Johnstone , Sean M. Collins , Giorgio Divitini , Alice M. Bumstead , Christopher W. Ashling , Philip A. Chater , Dean S. Keeble , Timothy Johnson , David A. Keen , Thomas D. Bennett Dalton Transactions 38 DOI: 10.1039/D1DT00881A Diamond Proposal Number(s): [20038, 20198] Open Access Show Abstract ▼ Abstract: Defect engineering is a powerful tool that can be used to tailor the properties of metal–organic frameworks (MOFs). Here, we incorporate defects through ball milling to systematically vary the porosity of the giant pore MOF, MIL-100 (Fe). We show that milling leads to the breaking of metal–linker bonds, generating additional coordinatively unsaturated metal sites, and ultimately causes amorphisation. Pair distribution function analysis shows the hierarchical local structure is partially retained, even in the amorphised material. We find that solvents can be used to stabilise the MIL-100 (Fe) framework against collapse, which leads to a substantial retention of porosity over the non-stabilised material.	Mar 2021
I11-High Resolution Powder Diffraction I12-JEEP: Joint Engineering, Environmental and Processing	Single-step synthesis and interface tuning of core–shell metal–organic framework nanoparticles Kieran W. P. Orr , Sean M. Collins , Emily M. Reynolds , Frank Nightingale , Hanna L. B. Bostroem , Simon J. Cassidy , Daniel M. Dawson , Sharon E. Ashbrook , Oxana Magdysyuk , Paul A. Midgley , Andrew L. Goodwin , Hamish H.-M. Yeung Chemical Science 13 DOI: 10.1039/D0SC03940C Diamond Proposal Number(s): [20946, 18786] Open Access Show Abstract ▼ Abstract: Control over the spatial distribution of components in metal–organic frameworks has potential to unlock improved performance and new behaviour in separations, sensing and catalysis. We report an unprecedented single-step synthesis of multi-component metal–organic framework (MOF) nanoparticles based on the canonical ZIF-8 (Zn) system and its Cd analogue, which form with a core–shell structure whose internal interface can be systematically tuned. We use scanning transmission electron microscopy, X-ray energy dispersive spectroscopy and a new composition gradient model to fit high-resolution X-ray diffraction data to show how core–shell composition and interface characteristics are intricately controlled by synthesis temperature and reaction composition. Particle formation is investigated by in situ X-ray diffraction, which reveals that the spatial distribution of components evolves with time and is determined by the interplay of phase stability, crystallisation kinetics and diffusion. This work opens up new possibilities for the control and characterisation of functionality, component distribution and interfaces in MOF-based materials.	Feb 2021
E02-JEM ARM 300CF I15-1-X-ray Pair Distribution Function (XPDF)	A new route to porous metal–organic framework crystal–glass composites Shichun Li , Shuwen Yu , Sean M. Collins , Duncan N. Johnstone , Christopher W. Ashling , Adam F. Sapnik , Philip A. Chater , Dean S. Keeble , Lauren N. Mchugh , Paul A. Midgley , David A. Keen , Thomas D. Bennett Chemical Science 11, 9910 - 9918 DOI: 10.1039/D0SC04008H Diamond Proposal Number(s): [20038, 22632, 21979] Open Access Show Abstract ▼ Abstract: Metal–organic framework crystal–glass composite (MOF CGC) materials consist of a crystalline MOF embedded within a MOF–glass matrix. In this work, a new synthetic route to these materials is demonstrated through the preparation of two ZIF-62 glass-based CGCs, one with crystalline ZIF-67 and the other with crystalline UiO-66. Previous attempts to form these CGCs failed due to the high processing temperatures involved in heating above the melting point of ZIF-62. Annealing of the ZIF-62 glass above the glass transition with each MOF however leads to stable CGC formation at lower temperatures. The reduction in processing temperatures will enable the formation of a greatly expanded range of MOF CGCs.	Sep 2020
E02-JEM ARM 300CF	Direct imaging of correlated defect nanodomains in a metal-organic framework Duncan N. Johnstone , Francesca C. N. Firth , Clare P. Grey , Paul A. Midgley , Matthew J. Cliffe , Sean M. Collins Journal Of The American Chemical Society DOI: 10.1021/jacs.0c04468 Diamond Proposal Number(s): [20195, 21979, 20198] Show Abstract ▼ Abstract: Defect engineering can enhance key properties of metal-organic frameworks (MOFs). Tailoring the distribution of de-fects, for example in correlated nanodomains, requires characterization across length scales. However, a critical na-noscale characterization gap has emerged between the bulk diffraction techniques used to detect defect nanodomains and the sub-nanometer imaging used to observe individual defects. Here, we demonstrate that the emerging technique of scanning electron diffraction (SED) can bridge this gap uniquely enabling both nanoscale crystallographic analysis and the low-dose formation of multiple diffraction contrast images for defect analysis in MOFs. We directly image defect nanodomains in the MOF UiO-66(Hf) over an area of ca. 1 000 nm and with a spatial resolution ca. 5 nm to reveal domain morphology and distribution. Based on these observations, we suggest possible crystal growth processes underpinning synthetic control of defect nanodomains. We also identify likely dislocations and small angle grain boundaries, illustrating that SED could be a key technique in developing the potential for engineering the distribution of defects, or “microstruc-ture”, in functional MOF design.	Jul 2020
E02-JEM ARM 300CF	Factors governing the chemical stability of shear-exfoliated ZnSe(alkylamine) II–VI layered hybrids Mengwen Yan , Sean Collins , Paul A. Midgley , Jeremy I. Feldblyum Chemistry Of Materials DOI: 10.1021/acs.chemmater.9b04800 Diamond Proposal Number(s): [21980] Show Abstract ▼ Abstract: Advances in the production of two-dimensional (2D) materials such as graphene and MoS2 during the past two decades have spurred the search for other van der Waals materials with distinct functional properties. However, reducing the dimensionality of bulk van der Waals materials can lead to structural rearrangement and chemical degradation, especially in the presence of air. These challenges have slowed the progress of the discovery and analysis of chemically diverse 2D materials. Here, we provide a case study on the shear exfoliation of a class of wide band gap van der Waals materials termed II–VI layered hybrids (II–VI LHs) and show how reducing their dimension influences their structural and chemical stabilities. ZnSe(butylamine) and ZnSe(octylamine) are exfoliated, yielding shear-thinned material whose resistance toward degradation via oxidation is studied in depth by a variety of macro- and microscopic characterization techniques. Mechanical energy input, solvent–ligand interaction, and exposure to ambient conditions all play important roles in the stability of these materials. Our findings suggest that moderately coordinating alkylamine layers stabilize 2D materials that would otherwise degrade during exfoliation and exposure to air.	Mar 2020
E02-JEM ARM 300CF	Structure sensitivity and evolution of nickel-bearing nitrogen-doped carbons in the electrochemical reduction of CO2 Simon Büchele , Antonio J. Martin , Sharon Mitchell , Frank Krumeich , Sean M. Collins , Shibo Xi , Armando Borgna , Javier Pérez-ramírez Acs Catalysis DOI: 10.1021/acscatal.9b05333 Diamond Proposal Number(s): [23504] Show Abstract ▼ Abstract: The emergence of nickel single-atoms on nitrogen-doped carbons as high-performance catalysts amenable to rationalization due to their well-defined structure could lead to applicable technologies for the electrocatalytic CO2 reduction reaction (eCO2RR). However, real materials are unlikely to display a uniform site structure, which limits the scope of current efforts focused on idealized models for future implementation. Here, we prepare distinct nickel entities (single atoms or nanoparticles) on nitrogen-doped carbons and evaluate them in eCO2RR. Single atoms demonstrate a characteristic high selectivity to CO. However, this is not altered by the presence of metal nanoparticles formed upon reducing the nitrogen content of the carrier. In contrast, nanoparticles incorporated via a colloidal route promote the parasitic hydrogen evolution reaction. In these systems, the CO selectivity evolves upon repeated exposure to potential, reaching values comparable to single atoms. By introducing CO stripping voltammetry as a characterization tool for this class of materials, we identify a decreased metallic surface, suggesting that the nanoparticle surface is altered by CO. The findings highlight the critical role of dynamic effects in catalyst design for eCO2RR.	Feb 2020
E02-JEM ARM 300CF	Decoration of plasmonic Mg nanoparticles by partial galvanic replacement Jérémie Asselin , Christina Boukouvala , Yuchen Wu , Elizabeth R. Hopper , Sean M. Collins , John S. Biggins , Emilie Ringe The Journal Of Chemical Physics 151 DOI: 10.1063/1.5131703 Diamond Proposal Number(s): [21980] Show Abstract ▼ Abstract: Plasmonic structures have attracted much interest in science and engineering disciplines, exploring a myriad of potential applications owing to their strong light-matter interactions. Recently, the plasmonic concentration of energy in subwavelength volumes has been used to initiate chemical reactions, for instance by combining plasmonic materials with catalytic metals. In this work, we demonstrate that plasmonic nanoparticles of earth-abundant Mg can undergo galvanic replacement in a nonaqueous solvent to produce decorated structures. This method yields bimetallic architectures where partially oxidized 200–300 nm Mg nanoplates and nanorods support many smaller Au, Ag, Pd, or Fe nanoparticles, with potential for a stepwise process introducing multiple decoration compositions on a single Mg particle. We investigated this mechanism by electron-beam imaging and local composition mapping with energy-dispersive X-ray spectroscopy as well as, at the ensemble level, by inductively coupled plasma mass spectrometry. High-resolution scanning transmission electron microscopy further supported the bimetallic nature of the particles and provided details of the interface geometry, which includes a Mg oxide separation layer between Mg and the other metal. Depending on the composition of the metallic decorations, strong plasmonic optical signals characteristic of plasmon resonances were observed in the bulk with ultraviolet-visible spectrometry and at the single particle level with darkfield scattering. These novel bimetallic and multimetallic designs open up an exciting array of applications where one or multiple plasmonic structures could interact in the near-field of earth-abundant Mg and couple with catalytic nanoparticles for applications in sensing and plasmon-assisted catalysis.	Dec 2019
E02-JEM ARM 300CF I15-1-X-ray Pair Distribution Function (XPDF)	Synthesis and properties of a compositional series of MIL-53(Al) metal-organic framework crystal-glass composites Christopher W. Ashling , Duncan N. Johnstone , Remo N. Widmer , Jingwei Hou , Sean M. Collins , Adam F. Sapnik , Alice M. Bumstead , Philip A. Chater , David A. Keen , Thomas Bennett Journal Of The American Chemical Society DOI: 10.1021/jacs.9b07557 Diamond Proposal Number(s): [20038, 20195] Show Abstract ▼ Abstract: Metal-organic framework crystal-glass composites (MOF-CGCs) are materials in which a crystalline MOF is dispersed within a MOF glass. In this work, we explore the room temperature stabilization of the open-pore form of MIL-53(Al), usually observed at high-temperature, which occurs upon encapsulation within a ZIF-62(Zn) MOF glass matrix. A series of MOF-CGCs containing different loadings of MIL-53(Al) were synthesized and characterized using X-ray diffraction and nuclear magnetic resonance spectroscopy. An upper limit of MIL-53(Al) that can be stabilized in the composite was determined for the first time. The nanostructure of the composites was probed using pair distribution function analysis and scanning transmission electron microscopy. Notably, the distribution and integrity of the crystalline compo-nent in a sample series was determined, and these findings related to the MOF-CGC gas adsorption capacity in order to identify the optimal loading necessary for maximum CO2 sorption capacity.	Sep 2019
E02-JEM ARM 300CF	Mapping non-crystalline nanostructure in beam sensitive systems with low-dose scanning electron pair distribution function analysis Joonatan E. M. Laulainen , Duncan N. Johnstone , Ivan Bogachev , Sean M. Collins , Louis Longley , Thomas Bennett , Paul A. Midgley Microscopy And Microanalysis 25, 1636 - 1637 DOI: 10.1017/S1431927619008912 Diamond Proposal Number(s): [16983, 19130, 20195, 21979]	Aug 2019

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