Complex of carbon structure and covalent organic framework, preparation method therefor, and use thereof

Abstract

The present invention relates to a complex comprising a covalent organic framework (COF) synthesized on the surface of a carbon structure, a preparation method therefor, and use thereof, and specifically to a complex of a carbon structure and a covalent organic framework, wherein the specific surface area or pore volume of the covalent organic framework synthesized on the surface of the carbon surface is larger than the specific surface area or the pore volume of the covalent organic framework prepared without the carbon structure; a preparation method therefor; and use thereof.

Claims

1. A complex comprising a covalent organic framework (COF) synthesized on the surface of a carbon structure, wherein the carbon structure is a carbon nanotube.

2. The complex of claim 1, wherein the covalent organic framework is synthesized on the surface of the carbon structure by a sonochemical reaction.

3. The complex of claim 1, wherein the specific surface area or pore volume of the covalent organic framework synthesized on the surface of the carbon structure is larger than the specific surface area or pore volume of the covalent organic framework prepared without the carbon structure in the same synthesis conditions.

4. The complex of claim 1, wherein reactants used for synthesizing the covalent organic framework are aromatic compounds capable of - stacking.

5. The complex of claim 1, wherein the covalent organic framework is COF-1, COF-102, COF-103, PPy-COF, COF-102-C.sub.12, COF-102-allyl, COF-5, COF-105, COF-108, COF-6, COF-8, COF-10, COF-11 , COF-14 , COF-16 , COF-18 , TP-COF, Pc-PBBA COF, NiPc-PBBA COF, 2D-NiPc-BTDA COF, NiPc COF, BTP-COF, HHTP-DPB COF, x % N.sub.3-COF-5(x=5, 25, 50, 75, or 100), 100% N.sub.3-NiPc-COF, COF-66, ZnPc-Py COF, ZnPc-DPB COF, ZnPc-NDI COF, ZnPc-PPE COF, CTC-COF, H.sub.2P-COF, ZnP-COF, CuP-COF, COF-202, CTF-1, CTF-2, COF-300, COF-LZU1, COF-366, COF-42, COF-43, COF-320, COF-102-Li, COF-103-Li, COF-102-Na, COF-103-Na, COF-301-PdCl.sub.2, COF-103-Eth-trans, COF-102-Ant, or a combination thereof.

6. A method for preparing the complex of claim 1, comprising adding the carbon structure and reactants used for synthesizing covalent organic framework to a solvent, followed by ultrasonic treatment (Step 1).

7. The method of claim 6, wherein the reactants used for synthesizing the covalent organic framework form the covalent organic framework on the surface of the carbon structure through a sonochemical reaction by the ultrasonic treatment in Step 1.

8. The method of claim 6, wherein the carbon structure has a concentration in the range of 0.2 mg/mL to 2 mg/mL in the solvent.

9. The method of claim 6, wherein the reactants used for synthesizing the covalent organic framework are aromatic compounds capable of - stacking.

10. The method of claim 9, wherein the reactants used for synthesizing the covalent organic framework are benzene-1,4-diboronic acid (BDBA), 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP), or a combination thereof.

11. The method of claim 6, wherein the reactants used for synthesizing the covalent organic framework have a concentration in the range of 10 mg/mL to 60 mg/mL in the solvent.

12. The method of claim 6, wherein the solvent is mesitylene, 1,4-dioxane, or a mixture thereof.

13. The method of claim 6, wherein ultrasonic wave of the ultrasonic treatment is in the range of 20 kHz to 1,000 kHz.

14. The method of claim 6, wherein the ultrasonic treatment is conducted at an output power of 50 W to 500 W for 30 minutes to 6 hours.

15. A composition of adsorbing, storing, separating, or concentrating gases comprising the complex of claim 1.

16. The composition of claim 15, wherein the complex is used as a catalyst.

17. A gas sensor comprising the complex of claim 1.

18. The gas sensor of claim 17, wherein the gas sensor detects a gas selected from the group consisting of CO.sub.2, Ar, Ne, He, CF.sub.4, H.sub.2, N.sub.2, O.sub.2, and C.sub.nH.sub.2n+2 (wherein n is an integer of 1 to 4).

19. The complex of claim 1, wherein the carbon nanotube comprises multi-walled carbon nanotubes.

20. A method for preparing a complex comprising a covalent organic framework (COF) synthesized on the surface of a carbon structure, the method comprising: adding the carbon structure and reactants used for synthesizing the covalent organic framework to a solvent to form a mixture, wherein: the carbon structure has a concentration in the range of 0.2 mg/mL to 2 mg/mL in the solvent; and the reactants used for synthesizing the covalent organic framework have a concentration in the range of 10 mg/mL to 60 mg/mL in the solvent; and ultrasonically treating the mixture.

Description

BRIEF DESCRIPTION OF DRAWING

(1) FIG. 1 schematically illustrates synthesis of CNT@COF-5, which is a complex of the present invention.

(2) FIG. 2 is SEM (scanning electron microscope) images of (A) CNT, (B) CNT@COF-5, (C) graphene, and (D) graphene@COF-5, wherein the scale bar is 500 nm.

(3) FIG. 3 is a 3D AFM image of graphene@COF-5, and a height profile extracted therefrom.

(4) FIG. 4 is an SEM image of COF-5 synthesized without a supporting material, wherein the scale bar is 500 nm.

(5) FIG. 5 is Fourier transform infrared (FT-IR) spectra of (A) BDBA, (B) HHTP, (C) COF-5, (D) CNT@COF-5, and (E) graphene @COF-5.

(6) FIG. 6 is X-ray diffraction (XRD) patterns of (A) COF-5, (B) CNT, (C) CNT@COF-5, (D) graphene, and (E) graphene@COF-5.

(7) FIG. 7 is thermogravimetric analysis (TGA) graphs showing the change of mass caused by CO.sub.2 adsorption of (A and B) BDBA, (A and B) HHTP, (A and B) COF-5, (A) CNT@COF-5, and (B) graphene@COF-5.

(8) FIG. 8 is TGA graphs of (A) CNT, (A) CNT@COF-5, (B) graphene, and (B) graphene@COF-5, along with those of COF-5, HHTP, and BDBA for comparison.

PREFERRED EMBODIMENT OF THE INVENTION

(9) Hereinafter, the present invention will be described in more detail with reference to Examples. However, these Examples are for illustrative purposes only, and the invention is not intended to be limited by these Examples.

Example 1: Preparation of a Complex Through COF-5 Synthesis on the Surface of CNT or Graphene

(10) Materials

(11) Multi-walled nanotubes (MWNT) (C.sub.tube 120, metal oxides<3 wt %, average diameter: at most 20 nm, length: 1 m to 25 m, CNT Co., Ltd) and graphene (3 nm graphene nanopowder, grade AO-1, Graphene Supermarket) were used as provided. Benzene-1,4-diboronic acid (95%), acetone (99.9%), and 1,4-dioxane (99.8%) were purchased from the Sigma-Aldrich Corporation, and 2,3,6,7,10,11-hexahydroxytriphenylene (95%) (Tokyo Chemical Industry Co., Ltd.) and mesitylene (98%) (Kanto Chemical Co., Inc.) were used as provided.

(12) Measurement Method

(13) A measurement method using a field emission scanning electron microscope (FE-SEM) was performed using SU-8020 (Hitachi, Tokyo, Japan) at 1 kV, and Fourier transform infrared (FT-IR) spectrum was measured with Varian 660-IR (Varian Medical Systems, Inc., California, USA). The X-ray diffraction (XRD) measurements in the range of 2.5<2 <20 were performed on a SmartLab (Rigaku, Tokyo, Japan) at 40 kV and 30 mA (CuK radiation, =0.154 nm) and the morphology of the composite was analyzed with atomic-force microscopy (AFM) (NX10, Park Systems Corp., Suwon, Korea) equipped with a noncontact cantilever at a scanning speed of 0.5 Hz. The TGA was performed by heating up to 900 C. at 5 C./min in the atmosphere of N.sub.2. Specific surface area was measured according to the Brunauer, Emmett and Teller (BET) method based on nitrogen adsorption at 77 K by using BELSORP-minill (BEL, Osaka, Japan).

Preparation of a Complex Through COF-5 Synthesis on the Surface of CNT or Graphene

(14) A complex of carbon material with the COF-5 core-shell structure was prepared by in situ synthesis of COF-5 set forth below.

(15) Above all, CNT (15 mg) was added into a solvent mixture of mesitylene (10 mL) and 1,4-dioxane (10 mL), added with benzene-1,4-diboronic acid (BDBA) (185 mg, 1.116 mmol) and 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) (241.5 mg, 0.745 mmol). Then, the mixture was treated with ultrasonic wave of 20 kHz at 160 W for 2 hours using the chip-type sonicator (Digital Sonifier Branson). A thus-produced precipitate was repeatedly centrifuged (20,000 g, 0.5 h), was collected to wash with acetone (500 mL or more), and was then dried in a vacuum oven at 40 C.

(16) A complex of graphene and COF-5 were prepared in the same process.

(17) Both complexes of graphene and CNT exhibited 55% to 65% yields on the basis of the starting materials.

Experimental Example 1: Morphology of a Complex Prepared by COF-5 Synthesis on the Surface of CNT or Graphene

(18) Aromatic molecules, such as benzene, pyrene, anthracene, triphenylene, and porphyrin derivatives, have been used as building blocks for the COFs. Such molecules have been used as superior CNT- and graphene-dispersants due to their strong - interactions. The CNT adsorbing the aromatic molecules is solvated according to the ultrasonic treatment process, and a well-dispersed CNT solution can be obtained.

(19) As shown in FIG. 2, the composite of CNT and COF-5 (CNT@COF-5) showed thicker diameter than those of the pristine CNTs while maintaining its shapes, suggesting the well-controlled decoration of COF-5 on CNT surfaces. As shown in FIG. 3, the graphene flakes decorated by the COF-5 (graphene@COF-5) also exhibited shapes with thicker 2D plates of 10 nm or thicker.

(20) The decorated COF-5 materials were found to exhibit morphologies similar to the COF-5 material synthesized without supporting materials (FIG. 4). Fourier transform infrared (FT-IR) spectra also indicated the formation of COF-5 as shown in FIG. 5; the newly appeared peaks at 1325 and 1236 cm.sup.1 are attributed to the B-O and C-O vibrations, respectively, produced by covalent bonds between boronic acids of benzene-1,4-diboronic acid (BDBA) and hydroxy groups of 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP). Furthermore, the X-ray diffraction (XRD) patterns of the complexes showed patterns similar to the corresponding COF-5 (FIG. 6) and all the obtained results strongly suggested the formation of the COF-5 nanocomposites.

Experimental Example 2: CO2 Adsorption Capacity

(21) The CO.sub.2 adsorption experiment was conducted with TGA Q500 (TA Instruments, New Castle, USA) according to previously reported methods (E. P. Dillon et al., ACS Nano, 2008, 2, 156-164; E. A. Roth et al., Energy Fuels, 2013, 27, 4129-4136; W. Wang et al., Appl. Energy, 2014, 113, 334-341). N.sub.2 and CO.sub.2 were used as gases for purge and furnace at the flow rates of 40 mL/min and 60 mL/min, respectively. The experiments were conducted after confirming no change in the weight of N.sub.2 followed by purging the sample of moisture and gas with N.sub.2 for 4 hours. The temperature of the furnace was raised to 70 C. at 20 C./min, and the furnace was changed to CO.sub.2. After an isothermal process at each temperature (70, 55, 40, and 25 C.) for 3 hours, the furnace gas was changed from CO.sub.2 to N.sub.2 during heating from 25 C. to 70 C.

(22) As shown in FIG. 7, the pristine COF-5 showed higher CO.sub.2 adsorption capacity (1.25 wt %) than that of the CNTs (0.24 wt %) and graphene (0.48 wt %) as well as COF-5 reactants such as BDBA (0.04 wt %) and HHTP (0.58 wt %), under the same conditions, which indicates the formation of porous nanostructures within COF-5. Interestingly, it has been found that CNT@COF-5 (1.42 wt %) exhibits improved CO.sub.2 adsorption capacity than COF-5 (1.25 wt %). Since the weight ratio of CNT in the CNT@COF-5 is negligible (FIG. 8), this improvement in CO.sub.2 adsorption capacity was thought to occur in COF-5, which gives rise to changes in the nanostructure and surface behavior of the composite.

(23) The zeolitic imidazolate framework-8 (ZIF-8), one of the metal organic structures (MOFs), using graphene quantum dots (GQDs) as the core material reportedly showed improved water vapor adsorption capacity compared to the pristine ZIF-8, which was explained by the change in hydrophilicity of the ZIF-8 surface (B. P. Biswal et al., Nanoscale, 2013, 5, 10556-10561). However, covalently-bonded boronate esters in the COF-5 are sufficiently rigid than the flexible coordinate bond of 2-methylimidazole in the ZIF-8, therefore, it is hard to obtain such the effect even with the CNT core.

(24) The improved CO.sub.2 adsorption capacity of CNT@COF-5 may be demonstrated by the specific surface areas in Table 2 below.

(25) TABLE-US-00002 TABLE 2 COF-5 CNT@COF-5 Graphene@COF-5 Surface area (m.sup.2g.sup.1) 8.17 57.6 9.83 Pore volume (cm.sup.2g.sup.1) 0.0223 0.220 0.0773 Pore size (nm) 10.9 14.8 31.5 CO.sub.2 uptakes (wt %) 1.25 1.42 0.92

(26) Table 2 above demonstrates that the highest specific surface area and total pore volume, which are 7 and 10 times higher than those of the pristine COF-5, respectively, are observed with CNT@COF-5 This effect appears to be due to the fact that COF-5 of 2D crystal structure on a high-curvature CNT surface is difficult to form large microcrystalline, resulting in a small microcrystalline aggregate.