Vacuum-arc synthesis of metal-organic framework structures based on ZrO2

2021 ◽  
pp. 30-35
Author(s):  
Igor Karpov ◽  
◽  
Anatoly Ushakov ◽  
Leonid Fedorov ◽  
Elena Goncharova ◽  
...  

The vacuum-arc synthesis of nanopowders based on zirconium oxide and metal-organic framework structures was carried out using a low-pressure arc discharge plasma. The obtained material was studied by several methods (XRF, IR, TEM, DTA). The TEM method showed that Zr-MOK is a highly agglomerated particle of an almost spherical shape. The image clearly shows the crystalline ordering of nanoparticles with a large (about 2 nm) lattice parameter. Particle sizes range from 5 to 30 nm. Average particle size 9.4 nm. XRD showed that the proportion of ZrO relative to Zr-MOK, calculated from the most intense lines of the diffractogram, is 65%. XRF results are in good agreement with IR studies. The DTA curve demonstrates a continuous exothermic process associated with a number of features of the plasma-chemical synthesis and morphology of the resulting nanoparticles, which is in full agreement with studies using transmission microscopy.

2020 ◽  
Vol 19 (05) ◽  
pp. 2050003
Author(s):  
I.V. Karpov ◽  
A.V. Ushakov

Plasma-chemical synthesis of nanopowders based on copper oxide and metal-organic framework structures was carried out using low-pressure arc discharge plasma. The study of the obtained material was carried out by several methods (XRD, FTIR, TEM, TGA and EIS). TEM showed that the obtained powder is highly agglomerated particles with an average particle size of 13 nm, and the crystalline ordering of nanoparticles with a large (about 2 nm) lattice parameter is clearly visible. XRD showed the presence of four crystalline phases corresponding to [Cu3 (BTC)2], Cu, Cu2O and CuO. XRD results are in good agreement with FTIR studies. The DTA curve demonstrates a continuous exothermic process associated with a number of features of plasma-chemical synthesis and the morphology of the obtained nanoparticles. The study of the electrochemical properties of the materials obtained by the method of impedance spectroscopy revealed an anomalous accumulation of electrical charges around the electrodes due to electrochemical reactions for [Cu3 (BTC)2], which are associated with various reactions involving copper species in the organic framework.


2021 ◽  
Author(s):  
Jintong Liu ◽  
Jing Huang ◽  
Lei Zhang ◽  
Jianping Lei

We review the general principle of the design and functional modulation of nanoscaled MOF heterostructures, and biomedical applications in enhanced therapy.


2020 ◽  
Author(s):  
Jesse Park ◽  
Brianna Collins ◽  
Lucy Darago ◽  
Tomce Runcevski ◽  
Michael Aubrey ◽  
...  

<b>Materials that combine magnetic order with other desirable physical attributes offer to revolutionize our energy landscape. Indeed, such materials could find transformative applications in spintronics, quantum sensing, low-density magnets, and gas separations. As a result, efforts to design multifunctional magnetic materials have recently moved beyond traditional solid-state materials to metal–organic solids. Among these, metal–organic frameworks in particular bear structures that offer intrinsic porosity, vast chemical and structural programmability, and tunability of electronic properties. Nevertheless, magnetic order within metal–organic frameworks has generally been limited to low temperatures, owing largely to challenges in creating strong magnetic exchange in extended metal–organic solids. Here, we employ the phenomenon of itinerant ferromagnetism to realize magnetic ordering at <i>T</i><sub>C</sub> = 225 K in a mixed-valence chromium(II/III) triazolate compound, representing the highest ferromagnetic ordering temperature yet observed in a metal–organic framework. The itinerant ferromagnetism is shown to proceed via a double-exchange mechanism, the first such observation in any metal–organic material. Critically, this mechanism results in variable-temperature conductivity with barrierless charge transport below <i>T</i><sub>C</sub> and a large negative magnetoresistance of 23% at 5 K. These observations suggest applications for double-exchange-based coordination solids in the emergent fields of magnetoelectrics and spintronics. Taken together, the insights gleaned from these results are expected to provide a blueprint for the design and synthesis of porous materials with synergistic high-temperature magnetic and charge transport properties. </b>


2019 ◽  
Author(s):  
Timothée Stassin ◽  
Ivo Stassen ◽  
Joao Marreiros ◽  
Alexander John Cruz ◽  
Rhea Verbeke ◽  
...  

A simple solvent- and catalyst-free method is presented for the synthesis of the mesoporous metal-organic framework (MOF) MAF-6 (RHO-Zn(eIm)2) based on the reaction of ZnO with 2-ethylimidazole vapor at temperatures ≤ 100 °C. By translating this method to a chemical vapor deposition (CVD) protocol, mesoporous crystalline films could be deposited for the first time entirely from the vapor phase. A combination of PALS and Kr physisorption measurements confirmed the porosity of these MOF-CVD films and the size of the MAF-6 supercages (diam. ~2 nm), in close agreement with powder data and calculations. MAF-6 powders and films were further characterized by XRD, TGA, SEM, FTIR, PDF and EXAFS. The exceptional uptake capacity of the mesoporous MAF-6 in comparison to the microporous ZIF-8 is demonstrated by vapor-phase loading of a molecule larger than the ZIF-8 windows.


2020 ◽  
Vol 24 (16) ◽  
pp. 1876-1891
Author(s):  
Qiuyun Zhang ◽  
Yutao Zhang ◽  
Jingsong Cheng ◽  
Hu Li ◽  
Peihua Ma

Biofuel synthesis is of great significance for producing alternative fuels. Among the developed catalytic materials, the metal-organic framework-based hybrids used as acidic, basic, or supported catalysts play major roles in the biodiesel production. This paper presents a timely and comprehensive review of recent developments on the design and preparation of metal-organic frameworks-based catalysts used for biodiesel synthesis from various oil feedstocks, including MILs-based catalysts, ZIFs-based catalysts, UiO-based catalysts, Cu-BTC-based catalysts, and MOFs-derived porous catalysts. Due to their unique and flexible structures, excellent thermal and hydrothermal stability, and tunable host-guest interactions, as compared with other heterogeneous catalysts, metal-organic framework-based catalysts have good opportunities for application in the production of biodiesel at industrial scale.


2008 ◽  
Vol 73 (1) ◽  
pp. 24-31
Author(s):  
Dayu Wu ◽  
Genhua Wu ◽  
Wei Huang ◽  
Zhuqing Wang

The compound [Cd(4,4'-bpy)2(H2O)2](ClO4)2·(L)2 was obtained by the reaction of Cd(ClO4)2, bis(1-pyrazinylethylidene)hydrazine (L) and 4,4'-bipyridine in aqueous MeOH. Single-crystal X-ray diffraction has revealed its two-dimensional metal-organic framework. The 2-D layers superpose on each other, giving a channel structure. The square planar grids consist of two pairs of shared edges with Cd(II) ion and a 4,4'-bipyridine molecule each vertex and side, respectively. The square cavity has a dimension of 11.817 × 11.781 Å. Two guest molecules of bis(1-pyrazinylethylidene)hydrazine are clathrated in every hydrophobic host cavity, being further stabilized by π-π stacking and hydrogen bonding. The results suggest that the hydrazine molecules present in the network serve as structure-directing templates in the formation of crystal structures.


2020 ◽  
Vol 267 ◽  
pp. 118667 ◽  
Author(s):  
Junxian Qin ◽  
Jun Wang ◽  
Junjie Yang ◽  
Yun Hu ◽  
Mingli Fu ◽  
...  

Polymer ◽  
2020 ◽  
Vol 208 ◽  
pp. 122945
Author(s):  
Konstantin A. Milakin ◽  
Nemanja Gavrilov ◽  
Igor A. Pašti ◽  
Zuzana Morávková ◽  
Udit Acharya ◽  
...  

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