B18-Core EXAFS
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Panpan
Zhang
,
Mingchao
Wang
,
Yannan
Liu
,
Yubin
Fu
,
Mingming
Gao
,
Gang
Wang
,
Faxing
Wang
,
Zhiyong
Wang
,
Guangbo
Chen
,
Sheng
Yang
,
Youwen
Liu
,
Renhao
Dong
,
Minghao
Yu
,
Xing
Lu
,
Xinliang
Feng
Abstract: Although two-dimensional conjugated metal–organic frameworks (2D c-MOFs) provide an ideal platform for precise tailoring of capacitive electrode materials, high-capacitance 2D c-MOFs for non-aqueous supercapacitors remain to be further explored. Herein, we report a novel phthalocyanine-based nickel-bis(dithiolene) (NiS4)-linked 2D c-MOF (denoted as Ni2[CuPcS8]) with outstanding pseudocapacitive properties in 1 M TEABF4/acetonitrile. Each NiS4 linkage is disclosed to reversibly accommodate two electrons, conferring the Ni2[CuPcS8] electrode a two-step Faradic reaction with a record-high specific capacitance among the reported 2D c-MOFs in non-aqueous electrolytes (312 F g–1) and remarkable cycling stability (93.5% after 10,000 cycles). Multiple analyses unveil that the unique electron-storage capability of Ni2[CuPcS8] originates from its localized lowest unoccupied molecular orbital (LUMO) over the nickel-bis(dithiolene) linkage, which allows the efficient delocalization of the injected electrons throughout the conjugated linkage units without inducing apparent bonding stress. The Ni2[CuPcS8] anode is used to demonstrate an asymmetric supercapacitor device that delivers a high operating voltage of 2.3 V, a maximum energy density of 57.4 Wh kg–1, and ultralong stability over 5000 cycles.
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Mar 2023
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I19-Small Molecule Single Crystal Diffraction
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Diamond Proposal Number(s):
[29217]
Open Access
Abstract: Metal-organic frameworks (MOFs) are well known for their ability to adsorb various gases. The use of MOFs for the storage and release of biologically active gases, particularly nitric oxide (NO) and carbon monoxide (CO), has been a subject of interest. To elucidate the binding mechanisms and geometry of these gases, an in situ single crystal X-ray diffraction (scXRD) study using synchrotron radiation at Diamond Light Source has been performed on a set of MOFs that display promising gas adsorption properties. NO and CO, were introduced into activated Ni-CPO-27 and the related Co-4,6-dihydroxyisophthalate (Co-4,6-dhip). Both MOFs show strong binding affinity towards CO and NO, however CO suffers more from competitive co-adsorption of water. Additionally, we show that morphology can play an important role in the ease of dehydration for these two systems.
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Mar 2023
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B22-Multimode InfraRed imaging And Microspectroscopy
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Lixia
Guo
,
Joseph
Hurd
,
Meng
He
,
Wanpeng
Lu
,
Jiangnan
Li
,
Danielle
Crawshaw
,
Mengtian
Fan
,
Sergey A.
Sapchenko
,
Yinlin
Chen
,
Xiangdi
Zeng
,
Meredydd
Kippax-Jones
,
Wenyuan
Huang
,
Zhaodong
Zhu
,
Pascal
Manuel
,
Mark D.
Frogley
,
Daniel
Lee
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[30398]
Open Access
Abstract: The development of stable sorbent materials to deliver reversible adsorption of ammonia (NH3) is a challenging task. Here, we report the efficient capture and storage of NH3 in a series of robust microporous aluminium-based metal-organic framework materials, namely MIL-160, CAU-10-H, Al-fum, and MIL-53(Al). In particular, MIL-160 shows high uptakes of NH3 of 4.8 and 12.8 mmol g−1 at both low and high pressure (0.001 and 1.0 bar, respectively) at 298 K. The combination of in situ neutron powder diffraction, synchrotron infrared micro-spectroscopy and solid-state nuclear magnetic resonance spectroscopy reveals the preferred adsorption domains of NH3 molecules in MIL-160, with H/D site-exchange between the host and guest and an unusual distortion of the local structure of [AlO6] moieties being observed. Dynamic breakthrough experiments confirm the excellent ability of MIL-160 to capture of NH3 with a dynamic uptake of 4.2 mmol g−1 at 1000 ppm. The combination of high porosity, pore aperture size and multiple binding sites promotes the significant binding affinity and capacity for NH3, which makes it a promising candidate for practical applications.
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Mar 2023
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I07-Surface & interface diffraction
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Diamond Proposal Number(s):
[24284]
Open Access
Abstract: A previous investigation of the structure of TCNQ adsorbed on Ag(111) using normal-incidence X-ray standing waves (NIXSW) and density functional theory (DFT) provided indirect evidence that Ag adatoms must be incorporated into the molecular overlayer. New surface X-ray diffraction (SXRD) results, presented here, provide direct evidence for the presence and location of these Ag adatoms and clearly distinguishes between two alternative models of the adatom registry favored by two different DFT studies.
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Feb 2023
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I15-1-X-ray Pair Distribution Function (XPDF)
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Mohamed. A.
Ali
,
Wessel M. W.
Winters
,
Moushira A.
Mohamed
,
Dezhi
Tan
,
Guojun
Zheng
,
Rasmus S. K.
Madsen
,
Oxana V.
Magdysyuk
,
Maria
Diaz-Lopez
,
Biao
Cai
,
Nan
Gong
,
Yijue
Xu
,
Ivan
Hung
,
Zhehong
Gan
,
Sabyasachi
Sen
,
Hong-Tao
Sun
,
Thomas D.
Bennett
,
Xiaofeng
Liu
,
Yuanzheng
Yue
,
Jianrong
Qiu
Diamond Proposal Number(s):
[30401]
Abstract: Glassy metal coordination compounds (MCC) [e.g., metal-organic framework (MOF), coordination polymer, and metal inorganic-organic complex (MIOC)] are emerging members of the hybrid glass family. So far, a limited number of crystalline MCCs can be converted into glasses by the melt-quenching. Here, we report a universal wet-chemistry method, by which the super-sized supramolecular MIOC glasses can be synthesized from non-meltable MOFs. Alcohol and acid were used as agents to inhibit crystallization. The MIOC glasses demonstrate unique features including high transparency, shaping capability, and anisotropic network. Directional photoluminescence with a large polarization ratio (~47%) was observed from samples doped with organic dyes. This crystallization-suppressing approach enables fabrication of MCC glasses, which cannot be achieved by conventional vitrification methods, and thus allows for exploring new MCC glasses possessing photonic functionalities.
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Feb 2023
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B22-Multimode InfraRed imaging And Microspectroscopy
I11-High Resolution Powder Diffraction
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Yu
Han
,
Yinlin
Chen
,
Yujie
Ma
,
Jamie
Bailey
,
Zi
Wang
,
Daniel
Lee
,
Alena M.
Sheveleva
,
Floriana
Tuna
,
Eric J. L.
Mcinnes
,
Mark D.
Frogley
,
Sarah J.
Day
,
Stephen P.
Thompson
,
Ben F.
Spencer
,
Marek
Nikiel
,
Pascal
Manuel
,
Danielle
Crawshaw
,
Martin
Schroeder
,
Sihai
Yang
Diamond Proposal Number(s):
[30398]
Open Access
Abstract: Benzene is an important air pollutant and a key chemical feedstock for the synthesis of cyclohexane. Because of the small difference of 0.6°C in their boiling points, the separation of benzene and cyclohexane is extremely challenging. Here, we report the high adsorption of benzene at low pressure and efficient separation of benzene/cyclohexane, achieved by the control of pore chemistry of two families of robust metal-organic frameworks, UiO-66 and MFM-300. At 298 K, UiO-66-CuII shows an exceptional adsorption of benzene of 3.92 mmol g−1 at 1.2 mbar and MFM-300(Sc) exhibits a high selectivity of 166 for the separation of benzene/cyclohexane (v/v = 1/1) mixture. In situ synchrotron X-ray diffraction and neutron powder diffraction, and multiple spectroscopic techniques reveal the binding mechanisms of benzene and cyclohexane in these materials. We also report the first example of direct visualization of reversible binding of benzene at an open Cu(II) site within metal-organic frameworks.
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Feb 2023
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I11-High Resolution Powder Diffraction
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Diamond Proposal Number(s):
[17261, 20785]
Open Access
Abstract: The results are presented of a detailed combined experimental and theoretical investigation of the influence of coadsorbed electron-donating alkali atoms and the prototypical electron acceptor molecule 7,7,8,8-tetracyanoquinodimethane (TCNQ) on the Ag(100) surface. Several coadsorption phases were characterized by scanning tunneling microscopy, low-energy electron diffraction, and soft X-ray photoelectron spectroscopy. Quantitative structural data were obtained using normal-incidence X-ray standing wave (NIXSW) measurements and compared with the results of density functional theory (DFT) calculations using several different methods of dispersion correction. Generally, good agreement between theory and experiment was achieved for the quantitative structures, albeit with the prediction of the alkali atom heights being challenging for some methods. The adsorption structures depend sensitively on the interplay of molecule–metal charge transfer and long-range dispersion forces, which are controlled by the composition ratio between alkali atoms and TCNQ. The large difference in atomic size between K and Cs has negligible effects on stability, whereas increasing the ratio of K/TCNQ from 1:4 to 1:1 leads to a weakening of molecule–metal interaction strength in favor of stronger ionic bonds within the two-dimensional alkali–organic network. A strong dependence of the work function on the alkali donor–TCNQ acceptor coadsorption ratio is predicted.
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Jan 2023
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I15-1-X-ray Pair Distribution Function (XPDF)
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Alice M.
Bumstead
,
Celia
Castillo-Blas
,
Ignas
Pakamore
,
Michael F.
Thorne
,
Adam F.
Sapnik
,
Ashleigh M.
Chester
,
Georgina
Robertson
,
Daniel J. M.
Irving
,
Philip A.
Chater
,
David A.
Keen
,
Ross S.
Forgan
,
Thomas D.
Bennett
Diamond Proposal Number(s):
[20038]
Open Access
Abstract: The chemistries that can be incorporated within melt-quenched zeolitic imidazolate framework (ZIF) glasses are currently limited. Here we describe the preparation of a previously unknown purine-containing ZIF which we name ZIF-UC-7. We find that it melts and forms a glass at one of the lowest temperatures reported for 3D hybrid frameworks.
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Dec 2022
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[21604]
Open Access
Abstract: Metal-organic framework (MOF) glasses are a new class of glass materials with immense potential for applications ranging from gas separation to optics and solid electrolytes. Due to the inherent difficulty to determine the atomistic structure of amorphous glasses, the intrinsic structural porosity of MOF glasses is only poorly understood. Here, we investigate the porosity features (pore size and pore limiting diameter) of a series of prototypical MOF glass formers from the family of zeolitic imidazolate frameworks (ZIFs) and their corresponding glasses. CO2 sorption at 195 K allows quantifying the microporosity of these materials in their crystalline and glassy states, also providing excess to the micropore volume and the apparent density of the ZIF glasses. Additional hydrocarbon sorption data together with X-ray total scattering experiments prove that the porosity features of the ZIF glasses depend on the types of organic linkers. This allows formulating design principles for a targeted tuning of the intrinsic microporosity of MOF glasses. These principles are counterintuitive and contrary to those established for crystalline MOFs but show similarities to strategies previously developed for porous polymers.
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Dec 2022
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B22-Multimode InfraRed imaging And Microspectroscopy
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Diamond Proposal Number(s):
[14902, 25407]
Open Access
Abstract: Owing to their unique functionalities and tailorable properties that are unattainable in conventional materials, metal-organic frameworks (MOFs) have emerged as candidate materials for next-generation chemical sensors and optoelectronics. For instance, the ZnQ@OX-1 composite material, comprising a light-emitting guest encapsulated in the pores of the OX-1 framework, affords excellent sensing performance: a visible color change upon exposure to volatile acetone. In this work, a multimodal study on the exceptional vapochromism of this composite material using high-resolution spectroscopy techniques based on inelastic neutron scattering and synchrotron radiation is presented, supported by density functional theory calculations. While FTIR spectroscopy in the far-IR and mid-IR regions reveals the underlying interactions between ZnQ, OX-1, and acetone, the limit of detection at 50 ppm is determined through in situ gas dosing experiments using fluorescence spectroscopy. In addition, in situ gas dosing on the single crystal level is achieved with near-field infrared nanospectroscopy.
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Dec 2022
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