CN111057246B

CN111057246B - COF-5 two-dimensional flaky crystal material and preparation method thereof

Info

Publication number: CN111057246B
Application number: CN201911273886.6A
Authority: CN
Inventors: 刘曰利; 王子威; 陈文�
Original assignee: Wuhan University of Technology WUT
Current assignee: Wuhan University of Technology WUT
Priority date: 2019-12-12
Filing date: 2019-12-12
Publication date: 2021-04-02
Anticipated expiration: 2039-12-12
Also published as: CN111057246A

Abstract

The invention provides a COF-5 two-dimensional flaky crystal material and a preparation method thereof, wherein the preparation method comprises the following steps: step 1, mixing 2,3,6,7,10, 11-hexahydroxy triphenyl, 1, 4-phenyl diboronic acid, 1,3, 5-trimethylbenzene and 1, 4-dioxane according to the addition ratio of 0.4-0.8 mmol: 0.6-1.4 mmol: 10-15 mL to form a mixture in an anhydrous and oxygen-free environment; step 2, sealing the mixture, ultrasonically dispersing and oscillating to obtain uniform dispersion liquid; step 3, heating the dispersion liquid to a certain temperature, and reacting for a period of time; and 4, washing the reaction product, then carrying out vacuum drying, finally introducing protective gas, and carrying out heat treatment at a set temperature for a period of time to obtain the COF-5 two-dimensional flaky crystal material. The method has simple preparation process, and the prepared product has regular shape and uniform size.

Description

COF-5 two-dimensional flaky crystal material and preparation method thereof

Technical Field

The invention belongs to the technical field of porous materials, and particularly relates to a COF-5 two-dimensional flaky crystal material and a preparation method thereof.

Background

The covalent organic framework material is formed by combining the problems of Omar Yaghi in the earliest 2005, is a novel organic porous polymer with periodicity and crystallinity, is formed by connecting light elements such as C, H, O, N, B and the like through strong covalent bonds, and has the characteristics of low density, higher thermal stability, high chemical stability, high specific surface area and the like. COF materials, which have high gas adsorption capacity, have been used for storing gases such as hydrogen, carbon dioxide, and sulfur dioxide, and are widely used and industrialized in fuel cells, new energy vehicles, and industrial waste gas treatment. With the research of researchers on COF materials, the researchers find that the COF materials have great application potential in the fields of gas catalysis, energy storage, photoelectricity, sensing and the like, and further arouse strong research interest of people on the COF materials.

Efficient synthesis of COF materials is a major challenge that currently exists. It has been shown that since atoms in COF materials are all connected by strong covalent bonds, higher activation energy is required for the formation and extension of material constituent units, and in addition, control of reaction conditions is required for good growth of COF crystals. Therefore, in order to satisfy thermodynamic and kinetic conditions of COF synthesis, organic monomers participating in the reaction should be in a mild reaction environment with low temperature and pressure, and undergo a reversible reaction at a low reaction rate for a long time.

COF-5 is a typical two-dimensional borate COF material, and the earliest researchers carried out related researches on the material as a hydrogen storage material. In addition, borate functional groups are uniformly distributed on a COF-5 molecular layer and can possibly become active sites for gas chemical adsorption, so that the COF-5 molecular layer has certain application potential in the fields of catalysis, gas sensitivity and the like. However, the research on COF-5 is relatively less, and the specific synthetic process and mechanism are not clear. In published scientific papers relating to COF-5, the problems of irregular crystal morphology, small size and non-uniformity of the obtained COF-5 are common. If the problem can be solved, the COF-5 material with good crystal growth and relatively regular appearance can be obtained, which is possibly helpful for deeply researching the growth process and mechanism of the COF-5, provides reference for the preparation of similar COF materials, improves the working performance of the COF-5 in various applications, and expands the application field of the COF material. Particularly, compared with COF-5 materials with other morphologies, the two-dimensional sheet COF-5 material has better heat conduction and electric conduction performance, and the exposed number of active sites on the surface of the sheet molecules is more, so that the sheet molecules are suitable to be used as host materials, are more beneficial to chemical combination of guest molecules, and can have higher sensitivity and shorter response time when being used in the fields of sensing detection and the like. Therefore, it is important to study a method for producing COF-5 in order to obtain a COF-5 two-dimensional sheet crystal having a good crystal growth.

Disclosure of Invention

The invention aims to solve the problems and provides a COF-5 two-dimensional flaky crystal material and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following scheme:

< preparation method >

The invention provides a preparation method of a COF-5 two-dimensional flaky crystal material, which is characterized by comprising the following steps of:

step 1, adding 2,3,6,7,10, 11-hexahydroxy triphenyl, 1, 4-benzene diboronic acid, 1,3, 5-trimethylbenzene and 1, 4-dioxane into a mixed solution of 1,3, 5-trimethylbenzene and 1, 4-benzene diboronic acid to form a mixture, wherein the adding ratio of the 2,3,6,7,10, 11-hexahydroxy triphenyl to the 1, 4-dioxane is 0.4-0.8 mmol: 0.6-1.4 mmol: 10-15 mL;

step 2, sealing the mixture, ultrasonically dispersing and oscillating to obtain uniform dispersion liquid;

step 3, heating the dispersion liquid to a certain temperature, and reacting for a period of time;

and 4, washing the reaction product, then carrying out vacuum drying, finally introducing protective gas, and carrying out heat treatment on the product at a set temperature for a period of time to obtain the COF-5 two-dimensional flaky crystal material.

Preferably, the preparation method of the COF-5 two-dimensional flaky crystalline material provided by the invention can also have the following characteristics: in the step 3, the heating temperature is 80-100 ℃, and the reaction time is 72-120 h.

Preferably, the preparation method of the COF-5 two-dimensional flaky crystalline material provided by the invention can also have the following characteristics: in step 4, the temperature is set to be 200-300 ℃, and the heat treatment time is 1-3 h.

Preferably, the preparation method of the COF-5 two-dimensional flaky crystalline material provided by the invention can also have the following characteristics: in step 4, the washing reagent is any one of acetone, methanol, benzene, diethyl ether and DMF.

Preferably, the preparation method of the COF-5 two-dimensional flaky crystalline material provided by the invention can also have the following characteristics: in step 4, the protective gas is any one of nitrogen, argon and helium.

< COF-5 two-dimensional plate-like crystalline Material >

The invention also provides a COF-5 two-dimensional flaky crystal material, which is characterized in that: was prepared by the method described in < preparation method > above.

Action and Effect of the invention

According to the method, the COF-5 two-dimensional flaky crystal material is prepared by a solvothermal method by controlling the addition ratio of reactants of 2,3,6,7,10, 11-hexahydroxy triphenyl, 1, 4-phenyl diboronic acid, 1,3, 5-trimethylbenzene and 1, 4-dioxane to be 0.4-0.8 mmol, 0.6-1.4 mmol, 10-15 mL and 10-15 mL; the morphology is further improved and impurities are removed by heat treating the product. The preparation method has simple process, and the prepared COF-5 two-dimensional flaky crystal product has good appearance and uniform size.

Drawings

FIG. 1 is an XRD pattern of a COF-5 two-dimensional plate crystal material prepared in the first example;

FIG. 2 is a FT-IR diagram of the COF-5 two-dimensional plate-like crystalline material prepared in example II;

FIG. 3 is an SEM picture of a COF-5 two-dimensional plate-like crystalline material prepared in example III;

FIG. 4 is an SEM photograph of a COF-5 two-dimensional plate-like crystalline material obtained in example IV;

FIG. 5 is a TEM image of a COF-5 two-dimensional plate-like crystalline material prepared in example V;

FIG. 6 is a gas-sensitive test chart of the COF-5 two-dimensional sheet crystal material prepared in the first example under high-concentration ammonia gas;

FIG. 7 is a gas-sensitive test chart of the COF-5 two-dimensional sheet crystal material prepared in example II under low-concentration ammonia gas.

Detailed Description

Specific embodiments of the COF-5 two-dimensional plate-like crystalline material according to the present invention will be described in detail below with reference to the accompanying drawings.

< example one >

The preparation method of the COF-5 two-dimensional sheet crystal material provided in this embodiment includes the following steps:

(1) mixing 2,3,6,7,10, 11-hexahydroxy triphenyl, 1, 4-phenyl diboronic acid, 1,3, 5-trimethylbenzene and 1, 4-dioxane in a ratio of 0.4mmol to 0.6mmol to 12.5mL in a glove box;

(2) sealing the mixture, ultrasonically dispersing and oscillating to obtain uniform dispersion liquid;

(3) heating the dispersion to 95 ℃, and reacting for 72 hours;

(4) washing the reaction product with acetone, drying the product in vacuum, introducing argon protective gas, and performing heat treatment on the product at 200 ℃ for 3h to obtain the COF-5 two-dimensional flaky crystal material.

< example two >

The preparation method of the COF-5 two-dimensional sheet crystal material provided in this embodiment two includes the following steps:

(1) mixing 2,3,6,7,10, 11-hexahydroxy triphenyl, 1, 4-phenyl diboronic acid, 1,3, 5-trimethylbenzene and 1, 4-dioxane in a ratio of 0.5mmol to 0.9mmol to 12mL to 13mL in a glove box;

(3) heating the dispersion to 85 ℃, and reacting for 84 h;

(4) washing the reaction product with acetone, drying the product in vacuum, introducing argon protective gas, and performing heat treatment on the product at 220 ℃ for 1h to obtain the COF-5 two-dimensional flaky crystal material.

< example three >

The preparation method of the COF-5 two-dimensional sheet crystal material provided by the third embodiment includes the following steps:

(1) mixing 2,3,6,7,10, 11-hexahydroxy triphenyl, 1, 4-phenyl diboronic acid, 1,3, 5-trimethylbenzene and 1, 4-dioxane in a ratio of 0.6mmol to 1.0mmol to 10mL to 15mL in a glove box;

(3) heating the dispersion to 100 ℃, and reacting for 72 hours;

(4) washing the reaction product with acetone, drying the product in vacuum, introducing argon protective gas, and performing heat treatment on the product at 250 ℃ for 2h to obtain the COF-5 two-dimensional flaky crystal material.

< example four >

The fourth embodiment provides a method for preparing a COF-5 two-dimensional sheet crystal material, which comprises the following steps:

(1) mixing 2,3,6,7,10, 11-hexahydroxy triphenyl, 1, 4-phenyl diboronic acid, 1,3, 5-trimethylbenzene and 1, 4-dioxane in a ratio of 0.7mmol to 1.3mmol to 15mL to 10mL in a glove box;

(3) heating the dispersion to 80 ℃, and reacting for 120 h;

(4) washing the reaction product with acetone, drying the product in vacuum, introducing argon protective gas, and performing heat treatment on the product at 300 ℃ for 2h to obtain the COF-5 two-dimensional flaky crystal material.

< example five >

(1) mixing 2,3,6,7,10, 11-hexahydroxy triphenyl, 1, 4-phenyl diboronic acid, 1,3, 5-trimethylbenzene and 1, 4-dioxane in a ratio of 0.8mmol to 1.4mmol to 13mL to 12mL in a glove box;

(3) heating the dispersion to 85 ℃, and reacting for 120 h;

(4) washing the reaction product with acetone, drying the product in vacuum, introducing argon protective gas, and performing heat treatment on the product at 250 ℃ for 1h to obtain the COF-5 two-dimensional flaky crystal material.

Further, characterization and performance tests were performed on the COF-5 two-dimensional plate-like crystal material prepared in the above example:

as shown in fig. 1, in the XRD spectrum, the matching degree of the position and relative intensity of each diffraction peak obtained by actual test (experimental value) and theoretical calculation (simulated value) is high; as shown in FIG. 2, each infrared absorption peak in the FT-IR spectrum corresponds one-to-one to the characteristic absorption peak of the functional group contained in the COF-5 crystal material. These map data all indicate that the product synthesized by the present invention is a COF-5 crystalline material.

As shown in fig. 3 and 4, the COF-5 crystal materials obtained in different embodiments of the present invention are in a sheet shape, have slight wrinkles, are stacked with each other, have uniform size, and have no significant difference in the shape and size of the COF-5 sheet crystal under different experimental conditions. In order to observe the morphology of the material more clearly, the material is subjected to ultrasonic wave to be fully dispersed and is configured into a dilute dispersion liquid to be subjected to a low-power TEM test, as shown in FIG. 5, a small number of thin two-dimensional flaky crystal structures can be seen, and the stacking relationship between sheets shows that the material is formed by stacking a plurality of flaky crystals, and a certain interaction force exists between the sheets, so that a single layer of flaky crystals are difficult to obtain.

As shown in FIGS. 6 and 7, gas-sensitive performance tests of the material show that the material has good gas-sensitive response to 5-25 ppm high-concentration and 100-1000 ppb low-concentration ammonia gas at 50 ℃.

In addition, in the above embodiments: step 2, the ultrasonic treatment frequency is 70Hz, and the ultrasonic time is 5-10 min; the oscillation treatment adopts a vortex mixing instrument, and the oscillation time is about 1 min; step 4, drying under vacuum at 60-90 ℃ for 24-36 h; and, step 2 and step 3 are both performed under sealed conditions.

The above embodiments are merely illustrative of the technical solutions of the present invention. The COF-5 two-dimensional plate-like crystalline material and the method for preparing the same according to the present invention are not limited to the description in the above embodiments, but are subject to the scope defined by the claims. Any modification or supplement or equivalent replacement made by a person skilled in the art on the basis of this embodiment is within the scope of the invention as claimed in the claims.

Claims

A preparation method of a COF-5 two-dimensional flaky crystal material is characterized by comprising the following steps:

step 1, adding 2,3,6,7,10, 11-hexahydroxy triphenyl, 1, 4-benzene diboronic acid, 1,3, 5-trimethylbenzene and 1, 4-dioxane into a mixed solution of 1,3, 5-trimethylbenzene and 1, 4-dioxane to form a mixture according to the addition ratio of 0.4mmol:0.6mmol: 10-15 mL of 2,3,6,7,10, 11-hexahydroxy triphenyl and 1, 4-benzene diboronic acid in an anhydrous and oxygen-free environment;

step 2, sealing the mixture, ultrasonically dispersing and oscillating to obtain uniform dispersion liquid;

step 3, heating the dispersion liquid to 80-100 ℃, and reacting for 72-120 h;

and 4, washing the reaction product, then carrying out vacuum drying, finally introducing protective gas, and carrying out heat treatment on the product at the temperature of 200-300 ℃ for 1-3 h to obtain the COF-5 two-dimensional flaky crystal material, wherein the crystal material is flaky in appearance and uniform in size.
2. The method for preparing a COF-5 two-dimensional plate-like crystalline material according to claim 1, characterized in that:

wherein, in the step 4, the washing reagent is any one of acetone, methanol, benzene, diethyl ether and DMF.
3. The method for preparing a COF-5 two-dimensional plate-like crystalline material according to claim 1, characterized in that:

in step 4, the protective gas is any one of nitrogen, argon and helium.
A COF-5 two-dimensional plate-like crystalline material characterized by:

the COF-5 two-dimensional plate-like crystalline material according to any one of claims 1 to 3.