Effect of metal atom in zeolitic imidazolate frameworks (ZIF-8 & 67) for removal of Pb2+ & Hg2+ from water

The zeolitic imidazolate frameworks ZIF-8 and ZIF-67 harbour a series of fascinating stimuli responsive properties. Looking at their responsitivity to hydrostatic pressure as stimulus, open questions exist regarding the isotropic compression with non-penetrating pressure transmitting media. By applying a state-of-the-art high-pressure powder X-ray diffraction setup, we revisit the high-pressure behaviour of ZIF-8 and ZIF-67 up to p = 0.4 GPa in small pressure increments. We observe a drastic, reversible change of high-pressure powder X-ray diffraction data at p = 0.3 GPa, discovering large volume structural flexibility in ZIF-8 and ZIF-67. Our results imply a shallow underlying energy landscape in ZIF-8 and ZIF-67, an observation that might point at rich polymorphism of ZIF-8 and ZIF-67, similar to ZIF-4(Zn).

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Revisiting the High-Pressure Properties of the Metal-Organic Frameworks ZIF-8 and ZIF-67

10.26434/chemrxiv.13146278 ◽

2020 ◽

Author(s):

Pia Vervoorts ◽

Stefan Burger ◽

Karina Hemmer ◽

Gregor Kieslich

Keyword(s):

High Pressure ◽

State Of The Art ◽

Energy Landscape ◽

Structural Flexibility ◽

Zeolitic Imidazolate Frameworks ◽

Stimuli Responsive ◽

X Ray Diffraction ◽

X Ray ◽

Open Questions ◽

Metal Organic

The zeolitic imidazolate frameworks ZIF-8 and ZIF-67 harbour a series of fascinating stimuli responsive properties. Looking at their responsitivity to hydrostatic pressure as stimulus, open questions exist regarding the isotropic compression with non-penetrating pressure transmitting media. By applying a state-of-the-art high-pressure powder X-ray diffraction setup, we revisit the high-pressure behaviour of ZIF-8 and ZIF-67 up to p = 0.4 GPa in small pressure increments. We observe a drastic, reversible change of high-pressure powder X-ray diffraction data at p = 0.3 GPa, discovering large volume structural flexibility in ZIF-8 and ZIF-67. Our results imply a shallow underlying energy landscape in ZIF-8 and ZIF-67, an observation that might point at rich polymorphism of ZIF-8 and ZIF-67, similar to ZIF-4(Zn).

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Influence of Metal Substitution on the Pressure-Induced Phase Change in Flexible Zeolitic Imidazolate Frameworks

10.26434/chemrxiv.7108706.v1 ◽

2018 ◽

Author(s):

C. Michael McGuirk ◽

Tomče Runčevski ◽

Julia Oktawiec ◽

Ari Turkiewicz ◽

mercedes K. taylor ◽

...

Keyword(s):

Phase Change ◽

Single Crystal ◽

Gas Adsorption ◽

High Capacity ◽

Phase Changes ◽

Zeolitic Imidazolate Frameworks ◽

Metal Substitution ◽

Heat Management ◽

Metal Organic ◽

First Time

Metal–organic frameworks that display step-shaped adsorption profiles arising from discrete pressure-induced phase changes are promising materials for applications in both high-capacity gas storage and energy-efficient gas separations. The thorough investigation of such materials through chemical diversification, gas adsorption measurements, and in situ structural characterization is therefore crucial for broadening their utility. We examine a series of isoreticular, flexible zeolitic imidazolate frameworks (ZIFs) of the type M(bim)2 (SOD; M = Zn (ZIF-7), Co (ZIF-9), Cd (CdIF-13); bim– = benzimidazolate), and elucidate the effects of metal substitution on the pressure-responsive phase changes and the resulting CO2 and CH4 step positions, pre-step uptakes, and step capacities. Using ZIF-7 as a benchmark, we reexamine the poorly understood structural transition responsible for its adsorption steps and, through high-pressure adsorption measurements, verify that it displays a step in its CH4 adsorption isotherms. The ZIF-9 material is shown to undergo an analogous phase change, yielding adsorption steps for CO2 and CH4 with similar profiles and capacities to ZIF-7, but with shifted threshold pressures. Further, the Cd2+ analogue CdIF-13 is reported here for the first time, and shown to display adsorption behavior distinct from both ZIF-7 and ZIF-9, with negligible pre-step adsorption, a ~50% increase in CO2 and CH4 capacity, and dramatically higher threshold adsorption pressures. Remarkably, a single-crystal-to-single-crystal phase change to a pore-gated phase is also achieved with CdIF-13, providing insight into the phase change that yields step-shaped adsorption in these flexible ZIFs. Finally, we show that the endothermic phase change of these frameworks provides intrinsic heat management during gas adsorption.

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Electronic properties of quasi two-dimensional transition metals chalcogenides with low-dimensional magnetism

Doklady BGUIR ◽

10.35596/1729-7648-2020-18-7-87-95 ◽

2020 ◽

Vol 18 (7) ◽

pp. 87-95

Author(s):

M. S. Baranava ◽

P. A. Praskurava

Keyword(s):

Transition Metal ◽

Transition Metals ◽

Exchange Interaction ◽

Electronic Properties ◽

Metal Atom ◽

Transition Metal Atom ◽

Two Dimensional ◽

Transition Metal Atoms ◽

Ground Magnetic ◽

Low Dimensional

The search for fundamental physical laws which lead to stable high-temperature ferromagnetism is an urgent task. In addition to the already synthesized two-dimensional materials, there remains a wide list of possible structures, the stability of which is predicted theoretically. The article suggests the results of studying the electronic properties of MAX3 (M = Cr, Fe, A = Ge, Si, X = S, Se, Te) transition metals based compounds with nanostructured magnetism. The research was carried out using quantum mechanical simulation in specialized VASP software and calculations within the Heisenberg model. The ground magnetic states of twodimensional MAX3 and the corresponding energy band structures are determined. We found that among the systems under study, CrGeTe3 is a semiconductor nanosized ferromagnet. In addition, one is a semiconductor with a bandgap of 0.35 eV. Other materials are antiferromagnetic. The magnetic moment in MAX3 is localized on the transition metal atoms: in particular, the main one on the d-orbital of the transition metal atom (and only a small part on the p-orbital of the chalcogen). For CrGeTe3, the exchange interaction integral is calculated. The mechanisms of the formation of magnetic order was established. According to the obtained exchange interaction integrals, a strong ferromagnetic order is formed in the semiconductor plane. The distribution of the projection density of electronic states indicates hybridization between the d-orbital of the transition metal atom and the p-orbital of the chalcogen. The study revealed that the exchange interaction by the mechanism of superexchange is more probabilistic.

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Electrochemical actuators based on nitrogen-doped carbons derived from zeolitic imidazolate frameworks

Materials & Design ◽

10.1016/j.matdes.2019.108405 ◽

2020 ◽

Vol 187 ◽

pp. 108405

Author(s):

Fangzhou Lu ◽

Kai Xiang ◽

Yanni Wang ◽

Tian Chen

Keyword(s):

Zeolitic Imidazolate Frameworks ◽

Nitrogen Doped

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Zeolitic Imidazolate Frameworks (ZIF-8)-Induced Porous α-Fe2O3/SnO2/ZnO Heterostructures as Remarkable Gas-Sensing Materials for Acetone Detection

Journal of Electronic Materials ◽

10.1007/s11664-021-08886-9 ◽

2021 ◽

Author(s):

Qian Ma ◽

Jia Guo ◽

Ying Chen ◽

Hui Li

Keyword(s):

Gas Sensing ◽

Zeolitic Imidazolate Frameworks ◽

Acetone Detection

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Activating Metal Oxides Nanocatalysts for Electrocatalytic Water Oxidation by Quenching-Induced Near-Surface Metal Atom Functionality

Journal of the American Chemical Society ◽

10.1021/jacs.1c04737 ◽

2021 ◽

Vol 143 (35) ◽

pp. 14169-14177

Author(s):

Changchun Ye ◽

Juzhe Liu ◽

Qinghua Zhang ◽

Xiaojing Jin ◽

Yun Zhao ◽

...

Keyword(s):

Metal Oxides ◽

Metal Atom ◽

Water Oxidation ◽

Near Surface ◽

Surface Metal ◽

Surface Metal Atom

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Self-templated formation of hierarchically yolk-shell-structured ZnS/NC dodecahedra with superior lithium storage properties

Nanoscale ◽

10.1039/d0nr07450k ◽

2021 ◽

Author(s):

Ping Wang ◽

Aihua Yuan ◽

Zhitao Wang ◽

Xiao Ping Shen ◽

Hantao Chen ◽

...

Keyword(s):

Synthetic Method ◽

Zeolitic Imidazolate Frameworks ◽

Lithium Storage ◽

Storage Properties

The hierarchical ZnS/NC dodecahedra are successfully constructed via a two-step synthetic method combining a sulfidation process and subsequent carbonization treatment, benefiting from the inherit merits of zeolitic imidazolate frameworks as...

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