A method for preparing metal-organic framework nanosheets by liquid phase exfoliation

A metal-organic framework and liquid phase stripping technology, which is applied in the production of bulk chemicals, can solve the problems of unstable dispersion, low yield, and collapse of the skeleton structure, and achieve shortened ultrasonic time, high stripping efficiency, and large lateral area. Effect

Active Publication Date: 2020-08-04
JIANGNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Most of the 2D MOF nanosheets reported so far are prepared by the exfoliation method, such as Top-down fabrication of crystalline metal–organic framework nanosheets. (Chemical Communications, 47(29), 8436-8438) and Metal-organic framework nanosheets as building blocks formolecular sieving membranes. (Science, 346(6215), 1356-1359), but the above methods generally have irregular structure of 2D MOF nanosheets, collapse of skeleton structure, destruction of crystal structure, low yield (usually yield<15%), Dispersion instability and other issues

Method used

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  • A method for preparing metal-organic framework nanosheets by liquid phase exfoliation
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  • A method for preparing metal-organic framework nanosheets by liquid phase exfoliation

Examples

Experimental program
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Effect test

Embodiment 1

[0024] 0.01mol Zn(NO 3 ) 2 ·6H 2 O and 0.1 mol of benzimidazole were dissolved in 1000 mL of DMF, and after magnetic stirring for 1 h, the solution was allowed to stand at room temperature for 24 h, centrifuged, washed with methanol and deionized water three times, and then dried in a vacuum oven at 80 °C for 24 h. Get ZIF-7. The obtained ZIF-7 solid was dispersed into 500ml of deionized water, refluxed at 80°C for 48h, centrifuged, washed with deionized water and methanol three times, and dried overnight at 50°C to obtain the layered MOF precursor Zn 2 (bim) 4 , and its scanning electron micrograph is shown in figure 1 shown; the precursor Zn 2 (bim) 4 (mass m 0 ) is dispersed in the solution that the ionic liquid 1-octyl-3-methylimidazolium chloride salt and the mass ratio of deionized water are 1:1, and the precursor Zn in the dispersion liquid 2 (bim) 4 The concentration is 1mg / mL, ultrasonic treatment is carried out with an ultrasonic cell pulverizer, the ultraso...

Embodiment 2

[0027] 0.01mol Zn(NO 3 ) 2 ·6H 2O and 0.15 mol of benzimidazole were dissolved in 1000 mL of DMF, and after magnetic stirring for 1 h, the solution was allowed to stand at room temperature for 48 h, followed by washing and drying as in Example 1 to obtain ZIF-7. The obtained ZIF-7 solid was dispersed into 500ml deionized water, refluxed at 100°C for 24h, centrifuged, washed and dried to obtain the layered MOF precursor Zn 2 (bim) 4 ; the layered precursor Zn 2 (bim) 4 Disperse into a solution of ionic liquid 1-octyl-3-methylimidazolium chloride salt and deionized water with a mass ratio of 3:2, the concentration of layered MOF in the dispersion is 2mg / mL, the ultrasonic time of 400w is 60min, and the rest The experiment process was the same as that in Example 1, and the MOF nanosheets were obtained with a peeling efficiency of 55%.

Embodiment 3

[0029] 0.01mol Zn(NO 3 ) 2 ·6H 2 O and 0.2 mol of benzimidazole were dissolved in 1000 mL of DMF, and after magnetic stirring for 1 h, the solution was allowed to stand at room temperature for 72 h, followed by washing and drying as in Example 1 to obtain ZIF-7. The obtained ZIF-7 solid was dispersed into 500ml deionized water, refluxed at 100°C for 48h, centrifuged, washed and dried to obtain the layered MOF precursor Zn 2 (bim) 4 ; the layered precursor Zn 2 (bim) 4 Dispersed into a solution of ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt and deionized water with a mass ratio of 7:3, the concentration of layered MOF in the dispersion was 3mg / mL, ultrasonic treatment was performed with an ultrasonic cell pulverizer, the ultrasonic power was 300W, and the ultrasonic time was 180min. The rest of the experimental process was the same as in Example 1 to obtain MOF nanosheets with a peeling efficiency of 70%.

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Abstract

The invention discloses a method for preparing a metal-organic framework (MOF) nanosheet by adopting a liquid-phase stripping method. The preparation method comprises the following steps that (1) a known zeolite imidazate framework ZIF-7 is converted to synthesize a lamellar MOF precursor Zn2(bim)4 through hydrothermal conversion; (2) the lamellar precursor is dispersed into a mixed solvent of ionic liquid and deionized water, ultrasonic treatment is carried out for a period of time, and obtained dispersion liquid is centrifuged at a low speed after the ultrasonic treatment is finished so as to remove non-stripped Zn2(bim)4, and the upper-layer solution is MOF nanosheet dispersion liquid; and (3) the obtained nanosheet dispersion liquid is centrifuged at a high speed, then is washed with ethanol several times and finally is subjected to vacuum drying so as to obtain the MOF nanosheet. The preparation method has the advantages of being simple, short in consumed time and high in stripping efficiency, and the prepared MOF nanosheet has the advantages of being large in transverse area, high in degree of crystallinity and relatively complete in structure.

Description

technical field [0001] The invention relates to a liquid phase exfoliation method for preparing metal organic framework Zn 2 (bim) 4 The nanosheet method belongs to the technical field of two-dimensional metal-organic framework (MOF) nanosheet preparation. Background technique [0002] Metal-organic framework (MOF) materials are crystalline porous coordination polymers formed by the ordered assembly of metal ion or ion cluster nodes and organic ligands. Two-dimensional (2D) nanomaterials with atomic or molecular thickness have attracted much attention due to their unique dimension-dependent properties. 2D MOF nanomaterials not only maintain the crystalline porous framework structure of MOF materials, but also keep the thickness of MOF materials at the atomic level, which is a new type of graphene-like material. Compared with traditional layered MOF crystals, 2D MOF nanosheets have the advantages of larger specific surface area, more active sites, smaller mass transfer res...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G83/00
CPCC08G83/008Y02P20/54
Inventor 桑欣欣倪才华刘冬寅石刚王大伟
Owner JIANGNAN UNIV
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