Browsing by Author "Chevreau, H"

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    Adsorption of CO2 and CD4 in UiO-66: a combination of neutron diffraction and modelling
    (Australian Institute of Physics, 2015-02-06) Chevreau, H; Laing, W; Kearley, GJ; Duyker, SG; D’Alessandro, DM; Peterson, VK
    Over the last twenty years, tremendous progress has been achieved in the field of Metal Organic Frameworks. Among these materials, the zirconium terephthalate UiO-66(Zr) [1] has attracted a growing attention because of its interesting thermal, chemical and water stability and has shown to be a promising material for the separation of CO2/CH4 gas mixtures. In order to get a better understanding of its sorption behavior towards CO2 and CH4, a Neutron Powder Diffraction (NPD) investigation of UiO-66 loaded with sequential doses of CO2 and CD4 has been carried out on the High Resolution Powder Diffractometer instrument “Echidna” at the OPAL reactor (ANSTO, Sydney). In total, three adsorption sites for CO2 and three adsorption sites for CD4 within the UiO- 66(Zr) have been located by neutron powder-diffraction then characterised by a combination of first-principles Density Functional Theory (DFT) calculations and Quantum Atoms In Molecules (QTAIM) theory. An example of the first CO2 adsorption site is given in figure 1.
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    Concentration-dependent binding of CO2 and CD4 in UiO-66 (Zr)
    (American Chemical Society, 2015-04-02) Chevreau, H; Liang, WB; Kearley, GJ; Duyker, SG; D'Alessandro, DM; Peterson, VK
    Porous metal–organic frameworks (MOFs) have emerged as promising materials for the capture of carbon dioxide (CO2) and its separation from methane (CH4) during the industrially important “sweetening” of sour natural-gas. The excellent thermal and chemical stability of the highly porous UiO-66(Zr) material, combined with good selectivity for CO2 over CH4, makes this material a prime candidate for such applications. Using a combination of neutron powder-diffraction and density-functional theory, we examine the details of the binding of CO2 and CH4 in UiO-66(Zr) over the industrially relevant 3.6–9.0 mmol/g concentration range, corresponding to the material that is half to fully saturated with CO2. This work builds on the previously reported preferred site for CO2 and CH4 in UiO-66(Zr), establishing further sites and determining the strength and nature of the guest–host interaction at these. We find the UiO-66(Zr)···CO2 interactions are significantly affected by the concentration of CO2 as the binding of CO2 is enhanced by interguest interactions. © 2015 American Chemical Society
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    Continuous negative-to-positive tuning of thermal expansion achieved by controlled gas sorption in porous coordination frameworks
    (Springer Nature, 2018-11-19) Auckett, JE; Barkhordarian, AA; Ogilvie, SH; Duyker, SG; Chevreau, H; Peterson, VK; Kepert, CJ
    Control of the thermomechanical properties of functional materials is of great fundamental and technological significance, with the achievement of zero or negative thermal expansion behavior being a key goal for various applications. A dynamic, reversible mode of control is demonstrated for the first time in two Prussian blue derivative frameworks whose coefficients of thermal expansion are tuned continuously from negative to positive values by varying the concentration of adsorbed CO2. A simple empirical model that captures site-specific guest contributions to the framework expansion is derived, and displays excellent agreement with the observed lattice behaviour. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License.
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    Guest–host complexes of TCNQ and TCNE with Cu3(1,3,5-benzenetricarboxylate)2
    (American Chemical Society, 2017-11-02) Usov, PM; Jiang, H; Chevreau, H; Peterson, VK; Leong, CF; D'Alessandro, DM
    A combined spectroscopic and structural study was undertaken to investigate the nature of the incorporation of the electron acceptor guest 7,7,8,8-tetracyanoquinodimethane (TCNQ) and the closely related guest tetracyanoethylene (TCNE) into the host porous framework [Cu3(BTC)2] (BTC = 1,3,5-benzenetricarboxylate)—a guest–host system recently shown to be highly conductive. We find that the guest concentration in the system can be modulated via the synthesis reaction time and temperature. A suite of spectroscopic, X-ray and neutron powder diffraction, and density functional theory techniques revealed the mechanism of guest binding within the framework host, including the guest redox states. This work provides insights into the way that electrical conductivity arises in porous framework host–guest systems and contributes to understanding how fine-tuning framework properties influences conductivity. © 2017 American Chemical Society
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    Metal organic frameworks for CO2 capture
    (Australian Institute of Nuclear Science and Engineering (AINSE), 2013-12-03) Chevreau, H; Duyker, SG; Peterson, VK
    Since 1970, the global emission of carbon dioxide (CO2) has increased by approximately 80%, largely due to our use of fossil fuels for energy generation leading to drastic environmental change. The 'Science and Industry Endowment Fund' (SIEF)-Energy Waste Research Project aims to solve this issue, namely the development of new materials and processes for the capture and utilization of CO2. One of the most promising classes of materials of the recent years are the Metal Organic Frameworks (MOFs), also named Porous Coordination Polymers (PCPs), which are built up from inorganic moieties and organic molecules to give rise to a 3D porous network. They have attracted attention owing to their properties such as gas storage, separation, energy storage, catalysis and biomedicine. Our work has thus been focused on the understanding of the CO2 uptake within these materials by using Neutron Powder Diffraction (NPD) combined with first principle Density Functional Theory (DFT) calculations. Our recent study have been carried out on the famous Zr (IV)-based UiO-66 2.
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    One-step approach for synthesis of nanosized Cu-doped zeolite A crystals using the Cu–EDTA-complex
    (Elsevier, 2014-11-14) Yordanov, I; Karatchevtseva, I; Chevreau, H; Avdeev, M; Holmes, R; Thorogood, GJ; Hanley, TL
    Copper-doped nanosized zeolite A crystals were synthesized by an in situ templating approach using [Cu(EDTA)]2−-complex. The structural properties of the copper containing zeolite crystals were characterized by a suite of different techniques including SEM–EDX, ESR, mid-IR and Far-IR, Raman, in situ XRD and non-ambient neutron powder diffraction. The SEM investigations on the morphology show spheroidal zeolite A crystals with average size ∼200 nm. The asymmetric ESR spectrum shows that the Cu2+ ion is in a tetragonal-distorted octahedral crystal field. FT-IR and Raman spectroscopies provide information on coordination environment of the copper ion. The band due to stretching vibration of C–N bond, where N is coordinated to the copper ion (C–N–Cu), was observed at 1109 cm−1 in the mid-infrared region. The Raman band due to the Cu–O bond is present at 630 cm−1 indicating the coordination of the Cu2+-cation to COO−-group of the EDTA-ion. The XRD data shows an enlarged d-spacing between the adjacent zeolite lattice planes due to the presence of the [Cu(EDTA)]2−-complex in comparison to template-free LTA zeolite structure. LeBail fitting approach on temperature-dependent in situ X-ray and neutron diffraction profiles have demonstrated the expansion of the zeolite cell during the thermal treatment followed by subsequent contraction with the decomposition of the organic template. © 2014, Elsevier
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    Square grid metal–chloranilate networks as robust host systems for guest sorption
    (John Wiley & Sons, Inc, 2019-02-02) Kingsbury, CJ; Abrahams, BF; Auckett, JE; Chevreau, H; Dharma, AD; Duyker, SG; He, QL; Hua, C; Hudson, TA; Murray, KS; Phonsri, W; Peterson, VK; Robson, R; White, KF
    Reaction of the chloranilate dianion with Y(NO3)3 in the presence of Et4N+ in the appropriate proportions results in the formation of (Et4N)[Y(can)2], which consists of anionic square-grid coordination polymer sheets with interleaved layers of counter-cations. These counter-cations, which serve as squat pillars between [Y(can)2] sheets, lead to alignment of the square grid sheets and the subsequent generation of square channels running perpendicular to the sheets. The crystals are found to be porous and retain crystallinity following cycles of adsorption and desorption. This compound exhibits a high affinity for volatile guest molecules, which could be identified within the framework by crystallographic methods. In situ neutron powder diffraction indicates a size-shape complementarity leading to a strong interaction between host and guest for CO2 and CH4. Single-crystal X-ray diffraction experiments indicate significant interactions between the host framework and discrete I2 or Br2 molecules. A series of isostructural compounds (cat)[MIII(X-an)2] with M=Sc, Gd, Tb, Dy, Ho, Er, Yb, Lu, Bi or In, cat=Et4N, Me4N and X-an=chloranilate, bromanilate or cyanochloranilate bridging ligands have been generated. The magnetic properties of representative examples (Et4N)[Gd(can)2] and (Et4N)[Dy(can)2] are reported with normal DC susceptibility but unusual AC susceptibility data noted for (Et4N)[Gd(can)2]. © 2019 Wiley-VCH Verlag GmbH & Co
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    Tuning pore size in a zirconium–tricarboxylate metal–organic framework
    (Royal Society of Chemistry, 2014-06-04) Liang, WB; Chevreau, H; Ragon, F; Southon, PD; Peterson, VK; D'Alessandro, DM
    The water-stable zirconium–tricarboxylate series of frameworks, [Zr6O4(OH)4(X)6(btc)2]·nH2O, where X = formate (F), acetate (A), or propionate (P), exhibit tunable porosity by virtue of systematic modulation of the chain length of the monocarboxylate ligand X. This modification not only impacts the pore size of the framework, but provides an important avenue for the construction of mixed-linker MOFs. © 2014, The Royal Society of Chemistry.
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    Using neutron powder diffraction and first-principles calculations to understand the working mechanisms of porous coordination polymer sorbents
    (International Union of Crystallography, 2015-01-01) Chevreau, H; Duyker, SG; Peterson, VK
    Metal-organic frameworks (MOFs) are promising solid sorbents, showing gas selectivity and uptake capacities relevant to many important applications, notably in the energy sector. To improve and tailor the sorption properties of these materials for such applications, it is necessary to gain an understanding of their working mechanisms at the atomic and molecular scale. Specifically, it is important to understand how features such as framework porosity, topology, chemical functionality and flexibility underpin sorbent behaviour and performance. Such information is obtained through interrogation of structure-function relationships, with neutron powder diffraction (NPD) being a particularly powerful characterization tool. The combination of NPD with first-principles density functional theory (DFT) calculations enables a deep understanding of the sorption mechanisms, and the resulting insights can direct the future development of MOF sorbents. In this paper, experimental approaches and investigations of two example MOFs are summarized, which demonstrate the type of information and the understanding into their functional mechanisms that can be gained. Such information is critical to the strategic design of new materials with targeted gas-sorption properties. Copyright © International Union of Crystallography