Poly-metallic-mof-derived composite nitrogen-doped carbon material thin film, preparation method and application thereof

Abstract

The application discloses a kind of multi-metal MOF derived composite nitrogen-doped carbon material film, preparation method and application thereof.The method first Co (NO3) 2·6H2O, Ni (NO3) 2·6H2O, FeCl2·4H2O and H4DOT are dissolved in the mixed solution of DMF, H2O and ethanol, and pyrolysis is obtained FeCoNi@C;Zn (NO3) 2 methanol solution is added dropwise to 2-methylimidazole methanol solution to prepare ZIF-8 nano cube, then Co (NO3) 2·6H2O, 2-methylimidazole methanol solution is added to the methanol solution of ZIF-8 nano cube to prepare ZIF-8@ZIF-67, and pyrolysis is obtained NC@Co / NC;Finally, FeCoNi@C and NC@Co / NC are mixed in proportion to prepare composite film.The synthesis method is simple, and the preparation process is controllable, and the prepared composite film has excellent electromagnetic wave absorption performance, and has wide application prospect as microwave absorbing material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of wave-absorbing materials, and relates to a multi-metal MOF-derived composite nitrogen-doped carbon material film, a preparation method and application thereof. BACKGROUND

[0002] With the rapid development and use of various electronic devices and wireless communication devices, the application of electromagnetic waves has involved various fields, especially in the fields of industrial production and medical diagnosis. However, although these applications have brought convenience, they have also posed a huge threat to the living environment of human beings, and the reason is that the large-scale application of electromagnetic waves can cause the generation of electromagnetic pollution, which seriously threatens biological systems and information security. Specifically, electromagnetic radiation can interfere with the normal operation of digital devices, and can also heat human cells or interfere with the inherent electromagnetic field of the human body, thereby adversely affecting human health. Therefore, it is necessary to develop various advanced electromagnetic wave absorbing materials. The main indicators of an excellent electromagnetic wave absorber are high reflection loss (RL), thin thickness, wide bandwidth and low density.

[0003] In the past few decades, several traditional materials such as ferrite, carbon, carbon nanotubes and reduced graphene oxide have been well studied in the application of microwave absorption. However, the effective absorption width of these materials at high frequencies is not sufficient to meet the needs of high-tech applications. Currently, some new synthesis methods and multifunctional composite materials have been used to prepare microwave absorbing materials with excellent practical application performance, such as metal-organic framework (MOF) materials, which have recently been proven to be a very good candidate for high-performance microwave absorbing materials. The most attractive feature of MOF materials is their designable composition, which can be converted into carbon-coated metals or metal oxides through controlled thermal cracking reactions. However, most researchers have focused on single-metal MOF microwave absorbing materials, or MOF microwave absorbing materials doped with elements such as nitrogen and boron, but there are few reports on multi-metal MOF materials, especially tri-metal MOF materials. In addition, in terms of metal centers and ligand structures, the tunability of multi-metal MOF absorbers is significantly better than that of single MOF absorbers. Therefore, constructing multi-metal MOFs is a reliable method to obtain metal-carbon-based absorbing materials. SUMMARY

[0004] The application aims to provide a multi-metal MOF-derived composite nitrogen-doped carbon material film, a preparation method and application thereof.

[0005] The technical scheme for achieving the application is as follows:

[0006] The preparation method of the multi-metal MOF-derived composite nitrogen-doped carbon material film includes the following specific steps:

[0007] Step 1, Co(NO3)2·6H2O, Ni(NO3)2·6H2O, FeCl2·4H2O and 2,5-dihydroxyterephthalic acid (H4DOT) are ultrasonically dissolved in a mixed solution of N,N-dimethylformamide (DMF), H2O and ethanol, stirred until mixed uniformly, hydrothermally reacted at 120±5℃ for 24 hours or more, after the reaction is completed, cooled, centrifuged, washed, vacuum dried, then pyrolyzed at 700±100℃ for 2-4h under a nitrogen atmosphere to obtain FeCoNi@C hollow spheres;

[0008] Step 2, a methanol solution of Zn(NO3)2 is added dropwise to a methanol solution of 2-methylimidazole (MeIM), stirred to react, after the reaction is completed, ZIF-8 nanocubes are precipitated by centrifugation, ultrasonically dispersed in methanol;

[0009] Step 3, Co(NO3)2·6H2O is ultrasonically dispersed in a methanol solution of 2-methylimidazole, then added to a methanol solution of ZIF-8 nanocubes, stirred to react for 24 hours or more, after the reaction is completed, ZIF-8@ZIF-67 polyhedrons are precipitated by centrifugation, pyrolyzed at 800±100℃ for 2-4h under a nitrogen atmosphere to obtain NC@Co / NC carbon nanocages;

[0010] Step 4, the FeCoNi@C hollow spheres and the NC@Co / NC carbon nanocages are mixed in a mass ratio of 1:1-3:1, PVDF is added, ground uniformly, then N-methylpyrrolidone is added dropwise, coated into a uniform film to prepare a multi-metal MOF-derived composite nitrogen-doped carbon material film.

[0011] Preferably, in step 1, the molar ratio of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, FeCl2·4H2O and H4DOT is 2:1:1:1.25.

[0012] Preferably, in step 1, the volume ratio of DMF, H2O and ethanol is 1:0.06:0.06.

[0013] Preferably, in step 1, the washing method is to wash with ethanol and water for 4 times; the centrifugation condition is 11000r / min for 2min; the vacuum drying temperature is 50-60℃, and the drying time is 6-10h.

[0014] Preferably, in step 2, the molar ratio of Zn(NO3)2 and 2-methylimidazole is 1:6-8.

[0015] Preferably, in step 3, the molar ratio of Co(NO3)2·6H2O and 2-methylimidazole is 1:8.

[0016] Preferably, in step 4, PVDF is used as a binder, and the amount added is 10% to 30% of the total mass of FeCoNi@C hollow spheres and NC@Co / NC carbon nanocages.

[0017] Preferably, in step 4, the mass ratio of FeCoNi@C hollow spheres to NC@Co / NC carbon nanocages is 1:1 to 2:1.

[0018] The present invention provides a composite nitrogen-doped carbon material thin film derived from a multi-metal MOF prepared by the above method.

[0019] Furthermore, the present invention provides the application of the above-mentioned multi-metal MOF-derived composite nitrogen-doped carbon material thin film as a microwave absorbing material in microwave absorption.

[0020] Compared with existing technologies, the advantages of this invention are as follows:

[0021] (1) The method of the present invention is simple and the preparation process is controllable. It only requires stirring reaction at room temperature.

[0022] (2) The multi-metal MOF-derived composite nitrogen-doped carbon material thin film of the present invention has excellent electromagnetic wave absorption performance and minimum reflection loss (RL). min The microwave absorption layer can reach -7.12dB. A special coating process can be used to prepare a microwave absorption layer, which can be extended to other MOF diffraction absorbing materials and other absorbing materials, and has a wide range of application prospects. Attached Figure Description

[0023] Figure 1 This is a physical image of the composite film when the FeCoNi@C and NC@Co / NC mixing ratio is 1:1 in Example 1.

[0024] Figure 2 This is a graph showing the microwave absorption performance of the composite film when the FeCoNi@C and NC@Co / NC mixing ratio is 1:1 in Example 1.

[0025] Figure 3 This is a graph showing the microwave absorption performance of the composite film when the mixing ratio of FeCoNi@C and NC@Co / NC is 2:1 in Example 2.

[0026] Figure 4 This is a graph showing the microwave absorption performance of the composite film when the mixing ratio of FeCoNi@C and NC@Co / NC is 3:1 in Example 3.

[0027] Figure 5 This is a graph showing the microwave absorption performance of the composite film in Comparative Example 1 when the mixing ratio of FeCoNi@C and NC@Co / NC is 1:2.

[0028] Figure 6This is a graph showing the microwave absorption performance of the composite film in Comparative Example 2 when the mixing ratio of FeCoNi@C and NC@Co / NC is 1:3. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0030] Example 1

[0031] (1) 419.1 mg Co(NO3)2·6H2O, 209.4 mg Ni(NO3)2·6H2O, 143.1 mg FeCl2·4H2O and 180 mg H4DOT were ultrasonically dissolved in a mixed solution containing 60 ml DMF, 3.6 ml H2O and 3.6 ml ethanol, and magnetically stirred for 25 minutes. The resulting solution was then transferred to a 100 ml stainless steel autoclave and kept at 120 °C for 24 h. After cooling, the solution was centrifuged, washed four times with ethanol and water, and vacuum dried at 60 °C for 12 h. The dried sample was then transferred to a corundum crucible, placed in a tube furnace, and heated at 700 °C for 2 h under a nitrogen atmosphere at a heating rate of 5 °C / min to obtain FeCoNi@C hollow spheres.

[0032] (2) Dissolve 7.12g Zn(NO3)2·6H2O in 240ml methanol and 7.84g 2-methylimidazole in 120ml methanol to obtain two solutions; quickly pour the 2-MeIm solution into the Zn(NO3)2·6H2O solution, stir at room temperature for 6h, collect the white precipitate by centrifugation with ethanol multiple times, and dry at 60℃ to obtain ZIF-8 nanocubes.

[0033] (3) 0.2 g ZIF-8 nanocubes were dispersed in 60 ml of methanol and sonicated until completely dissolved. Then, 0.3 g Co(NO3)2·6H2O and 20 ml of methanol solution containing 0.65 g 2-MeIm were added to the ZIF-8 nanocube dispersion solution, stirred for 24 h, centrifuged multiple times with ethanol, and dried at 60 °C to obtain core-shell structured ZIF-8@ZIF-67 polyhedra. The dried sample was transferred to a corundum crucible, placed in a tube furnace, and heated at 800 °C for 2 h under a nitrogen atmosphere at a heating rate of 2 °C / min to obtain NC@Co / NC carbon nanocages.

[0034] (4) FeCoNi@C hollow spheres and NC@Co / NC carbon nanocages were mixed in a mass ratio of 1:1, doped with 20% PVDF, ground evenly, and then an appropriate amount of N-methylpyrrolidone was added. The sample was coated into a uniform film of 18cm×18cm to obtain a composite nitrogen-doped carbon material film derived from multi-metal MOF. After drying at 60℃, the microwave absorption performance was tested.

[0035] Example 2

[0036] (1) 419.1 mg Co(NO3)2·6H2O, 209.4 mg Ni(NO3)2·6H2O, 143.1 mg FeCl2·4H2O and 180 mg H4DOT were ultrasonically dissolved in a mixed solution containing 60 ml DMF, 3.6 ml H2O and 3.6 ml ethanol, and magnetically stirred for 25 minutes. The resulting solution was then transferred to a 100 ml stainless steel autoclave and kept at 120 °C for 24 h. After cooling, the solution was centrifuged, washed four times with ethanol and water, and vacuum dried at 60 °C for 12 h. The dried sample was then transferred to a corundum crucible, placed in a tube furnace, and heated at 700 °C for 2 h under a nitrogen atmosphere at a heating rate of 5 °C / min to obtain FeCoNi@C hollow spheres.

[0037] (2) Dissolve 7.12g Zn(NO3)2·6H2O in 240ml methanol and 7.84g 2-methylimidazole in 120ml methanol to obtain two solutions; quickly pour the 2-MeIm solution into the Zn(NO3)2·6H2O solution, stir at room temperature for 6h, collect the white precipitate by centrifugation with ethanol multiple times, and dry at 60℃ to obtain ZIF-8 nanocubes.

[0038] (3) 0.2 g ZIF-8 nanocubes were dispersed in 60 ml of methanol and sonicated until completely dissolved. Then, 0.3 g Co(NO3)2·6H2O and 20 ml of methanol solution containing 0.65 g 2-MeIm were added to the ZIF-8 nanocube dispersion solution, stirred for 24 h, centrifuged multiple times with ethanol, and dried at 60 °C to obtain core-shell structured ZIF-8@ZIF-67 polyhedra. The dried sample was transferred to a corundum crucible, placed in a tube furnace, and heated at 800 °C for 2 h under a nitrogen atmosphere at a heating rate of 2 °C / min to obtain NC@Co / NC carbon nanocages.

[0039] (4) FeCoNi@C hollow spheres and NC@Co / NC carbon nanocages were mixed in a mass ratio of 2:1, doped with 20% PVDF, ground evenly, and then an appropriate amount of N-methylpyrrolidone was added. The sample was coated into a uniform film of 18cm×18cm to obtain a composite nitrogen-doped carbon material film derived from multi-metal MOF. After drying at 60℃, the microwave absorption performance was tested.

[0040] Example 3

[0041] (1) 419.1 mg Co(NO3)2·6H2O, 209.4 mg Ni(NO3)2·6H2O, 143.1 mg FeCl2·4H2O and 180 mg H4DOT were ultrasonically dissolved in a mixed solution containing 60 ml DMF, 3.6 ml H2O and 3.6 ml ethanol, and magnetically stirred for 25 minutes; then the resulting solution was transferred to a 100 ml stainless steel autoclave and kept at 120 °C for 24 h. After cooling, the solution was centrifuged, washed 4 times with ethanol and water, and vacuum dried at 60 °C for 12 h. The dried sample was transferred to a corundum crucible, placed in a tube furnace, and heated at 700 °C for 2 h under a nitrogen atmosphere at a heating rate of 5 °C / min to obtain FeCoNi@C hollow spheres.

[0042] (2) Dissolve 7.12g Zn(NO3)2·6H2O in 240ml methanol and 7.84g 2-methylimidazole in 120ml methanol to obtain two solutions; quickly pour the 2-MeIm solution into the Zn(NO3)2·6H2O solution, stir at room temperature for 6h, collect the white precipitate by centrifugation with ethanol multiple times, and dry at 60℃ to obtain ZIF-8 nanocubes.

[0043] (3) 0.2 g ZIF-8 nanocubes were dispersed in 60 ml of methanol and sonicated until completely dissolved. Then, 0.3 g Co(NO3)2·6H2O and 20 ml of methanol solution containing 0.65 g 2-MeIm were added to the ZIF-8 nanocube dispersion solution, stirred for 24 h, centrifuged multiple times with ethanol, and dried at 60 °C to obtain core-shell structured ZIF-8@ZIF-67 polyhedra. The dried sample was transferred to a corundum crucible, placed in a tube furnace, and heated at 800 °C for 2 h under a nitrogen atmosphere at a heating rate of 2 °C / min to obtain NC@Co / NC carbon nanocages.

[0044] (4) FeCoNi@C hollow spheres and NC@Co / NC carbon nanocages were mixed at a mass ratio of 3:, doped with 20% PVDF, ground evenly, and then an appropriate amount of N-methylpyrrolidone was added. The sample was coated into a uniform film of 18cm×18cm to obtain a composite nitrogen-doped carbon material film derived from multi-metal MOF. After drying at 60℃, the microwave absorption performance was tested.

[0045] Comparative Example 1

[0046] (1) 419.1 mg Co(NO3)2·6H2O, 209.4 mg Ni(NO3)2·6H2O, 143.1 mg FeCl2·4H2O and 180 mg H4DOT were ultrasonically dissolved in a mixed solution containing 60 ml DMF, 3.6 ml H2O and 3.6 ml ethanol, and magnetically stirred for 25 minutes. The resulting solution was then transferred to a 100 ml stainless steel autoclave and kept at 120 °C for 24 h. After cooling, the solution was centrifuged, washed 4 times with ethanol and water, and vacuum dried at 60 °C for 12 h. The dried sample was then transferred to a corundum crucible, placed in a tube furnace, and heated at 700 °C for 2 h under a nitrogen atmosphere at a heating rate of 5 °C / min to obtain FeCoNi@C hollow spheres.

[0047] (2) Dissolve 7.12g Zn(NO3)2·6H2O in 240ml methanol and 7.84g 2-methylimidazole in 120ml methanol to obtain two solutions; quickly pour the 2-MeIm solution into the Zn(NO3)2·6H2O solution, stir at room temperature for 6h, collect the white precipitate by centrifugation with ethanol multiple times, and dry at 60℃ to obtain ZIF-8 nanocubes.

[0048] (3) 0.2 g ZIF-8 nanocubes were dispersed in 60 ml of methanol and sonicated until completely dissolved. Then, 0.3 g Co(NO3)2·6H2O and 20 ml of methanol solution containing 0.65 g 2-MeIm were added to the dispersion solution, stirred for 24 h, centrifuged multiple times with ethanol, and dried at 60 °C to obtain core-shell structured ZIF-8@ZIF-67 polyhedra. The dried sample was transferred to a corundum crucible, placed in a tube furnace, and heated at 800 °C for 2 h under a nitrogen atmosphere at a heating rate of 2 °C / min to obtain NC@Co / NC carbon nanocages.

[0049] (4) FeCoNi@C hollow spheres and NC@Co / NC carbon nanocages were mixed at a mass ratio of 1:2, doped with 20% PVDF, ground evenly, and then an appropriate amount of N-methylpyrrolidone was added. The sample was coated into a uniform film of 18cm×18cm to obtain a composite nitrogen-doped carbon material film derived from multi-metal MOF. After drying at 60℃, the microwave absorption performance was tested.

[0050] Comparative Example 2

[0051] (1) 419.1 mg Co(NO3)2·6H2O, 209.4 mg Ni(NO3)2·6H2O, 143.1 mg FeCl2·4H2O and 180 mg H4DOT were ultrasonically dissolved in a mixed solution containing 60 ml DMF, 3.6 ml H2O and 3.6 ml ethanol, and magnetically stirred for 25 minutes. The resulting solution was then transferred to a 100 ml stainless steel autoclave and kept at 120 °C for 24 h. After cooling, the solution was centrifuged, washed 4 times with ethanol and water, and vacuum dried at 60 °C for 12 h. The dried sample was then transferred to a corundum crucible, placed in a tube furnace, and heated at 700 °C for 2 h under a nitrogen atmosphere at a heating rate of 5 °C / min to obtain FeCoNi@C hollow spheres.

[0052] (2) Dissolve 7.12g Zn(NO3)2·6H2O in 240ml methanol and 7.84g 2-methylimidazole in 120ml methanol to obtain two solutions; quickly pour the 2-MeIm solution into the Zn(NO3)2·6H2O solution, stir at room temperature for 6h, collect the white precipitate by centrifugation with ethanol multiple times, and dry at 60℃ to obtain ZIF-8 nanocubes.

[0053] (3) 0.2g ZIF-8 nanocubes were dispersed in 60ml methanol and sonicated until completely dissolved. Then, 0.3g Co(NO3)2·6H2O and 20ml methanol solution containing 0.65g 2-MeIm were added to the dispersion solution and stirred for 24h. After centrifugation with ethanol several times, the sample was dried at 60℃ to obtain a core-shell structured ZIF-8@ZIF-67 polyhedron. The dried sample was transferred to a corundum crucible and placed in a tube furnace. Under a nitrogen atmosphere, the temperature was increased at a rate of 2℃ / min and held at 800℃ for 2h to obtain NC@Co / NC carbon nanocages.

[0054] (4) FeCoNi@C hollow spheres and NC@Co / NC carbon nanocages were mixed at a mass ratio of 1:3, doped with 20% PVDF, ground evenly, and then an appropriate amount of N-methylpyrrolidone was added. The sample was coated into a uniform film of 18cm×18cm to obtain a composite nitrogen-doped carbon material film derived from multi-metal MOF. After drying at 60℃, the microwave absorption performance was tested.

[0055] Figure 1 This is a physical image of the composite film in Example 1 when the mixing ratio of FeCoNi@C and NC@Co / NC is 1:1, with a coating area greater than 18cm*18cm.

[0056] Figure 2 This is a graph showing the microwave absorption performance of the composite film in Example 1 when the mixing ratio of FeCoNi@C and NC@Co / NC is 1:1. The graph shows that the minimum reflection loss (RL) is... minIt reached -5.75dB.

[0057] Figure 3 This is a graph showing the microwave absorption performance of the composite film when the FeCoNi@C and NC@Co / NC mixing ratio is 2:1 in Example 2. The graph shows that the film exhibits excellent microwave absorption performance at this ratio, with minimal reflection loss (RL). min It reached -7.12dB.

[0058] Figure 4 This is a graph showing the microwave absorption performance of the composite film in Example 3 when the mixing ratio of FeCoNi@C and NC@Co / NC is 3:1. The graph shows that the minimum reflection loss (RL) is... min The absorption rate reached -5.64dB, which is a decrease in absorption performance compared to the 2:1 mixing ratio.

[0059] Figure 5 This is a graph showing the microwave absorption performance of the composite film in Comparative Example 1 when the mixing ratio of FeCoNi@C and NC@Co / NC is 1:2. The graph shows that the minimum reflection loss (RL) is... min The absorption rate reached -3.92dB, which is not as good as the sample with a mixing ratio of 1:1.

[0060] Figure 6 This is a graph showing the microwave absorption performance of the composite film in Comparative Example 2 when the mixing ratio of FeCoNi@C and NC@Co / NC is 1:3. The graph shows that the minimum reflection loss (RL) is... min The absorption rate reached -3.63dB, indicating poor absorption performance.

Claims

1. A method for preparing composite nitrogen-doped carbon material thin films derived from multimetal MOFs, characterized in that, The specific steps are as follows: Step 1: Co(NO3)2·6H2O, Ni(NO3)2·6H2O, FeCl2·4H2O and H4DOT were ultrasonically dissolved in a mixed solution of DMF, H2O and ethanol. The mixture was stirred until homogeneous and then hydrothermally reacted at 120±5 ℃ for more than 24 hours. After the reaction was completed, the mixture was cooled, centrifuged, washed, and vacuum dried. Then, it was pyrolyzed at 700±100 ℃ for 2~4 h under a nitrogen atmosphere to obtain FeCoNi@C hollow spheres. The molar ratio of Co(NO3)2·6H2O, Ni(NO3)2·6H2O, FeCl2·4H2O and H4DOT was 2:1:1:1.

25. Step 2: Add the methanol solution of Zn(NO3)2 dropwise to the methanol solution of 2-methylimidazole, stir the reaction, and after the reaction is completed, centrifuge to precipitate ZIF-8 nanocubes, which are then ultrasonically dispersed in methanol. Step 3: Co(NO3)2·6H2O was ultrasonically dispersed in a methanol solution of 2-methylimidazole, and then added to a methanol solution of ZIF-8 nanocubes. The mixture was stirred and reacted for more than 24 hours. After the reaction was completed, ZIF-8@ZIF-67 polyhedra were precipitated by centrifugation and then pyrolyzed at 800±100 °C for 2~4 h under a nitrogen atmosphere to obtain NC@Co / NC carbon nanocages. Step 4: FeCoNi@C hollow spheres and NC@Co / NC carbon nanocages are mixed at a mass ratio of 2:1, and PVDF is added. After grinding evenly, N-methylpyrrolidone is added dropwise to coat a uniform film, thus obtaining a multi-metal MOF-derived composite nitrogen-doped carbon material film as a microwave absorbing material.

2. The preparation method according to claim 1, characterized in that, In step 1, the volume ratio of DMF, H2O and ethanol is 1:0.06:0.

06.

3. The preparation method according to claim 1, characterized in that, In step 1, the washing method is to wash with ethanol and water 4 times; the centrifugation conditions are 11000 r / min for 2 min; the vacuum drying temperature is 50 ~ 60 ℃ and the drying time is 6 ~ 10 h.

4. The preparation method according to claim 1, characterized in that, In step 2, the molar ratio of Zn(NO3)2 to 2-methylimidazole is 1:6 ~ 8.

5. The preparation method according to claim 1, characterized in that, In step 3, the molar ratio of Co(NO3)2·6H2O to 2-methylimidazole is 1:

8.

6. The preparation method according to claim 1, characterized in that, In step 4, the amount of PVDF added is 10% to 30% of the total mass of FeCoNi@C hollow spheres and NC@Co / NC carbon nanocages.

7. A multi-metal MOF-derived composite nitrogen-doped carbon material thin film prepared by any one of the preparation methods according to claims 1 to 6.

8. The application of the multi-metal MOF-derived composite nitrogen-doped carbon material thin film as an absorbing material in microwave absorption according to claim 7.

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