A hydrophilic covalent triazine framework and its preparation method and application

Abstract

The present invention discloses a hydrophilic covalent triazine framework, which is characterized in that the structure of the hydrophilic covalent triazine framework is shown in formula (I): wherein the structure of R is shown in formula (II); represents that the structure extends infinitely; the hydrophilic covalent triazine framework prepared by the present invention has a water contact angle of 0 to 60°, and the material has strong hydrophilicity and is used as a photocatalytic water splitting hydrogen production catalyst with high hydrogen production efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of advanced materials, relates to photocatalysts and photocatalytic hydrogen production, and particularly relates to a hydrophilic covalent triazine framework, a preparation method thereof, and an application thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the understanding of the overall background of the present invention, and it is not necessarily regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Since covalent triazine frameworks (CTFs) were reported, they have received extensive attention from researchers. Due to the electron-rich property of the triazine group, CTFs have good development prospects in the optoelectronic field, especially in the field of photocatalysis. However, since the backbone of CTFs belongs to an aromatic structure and exhibits obvious hydrophobicity, it directly affects the mass transfer efficiency in photocatalytic reactions with water as the guest molecule, thereby limiting its photocatalytic reaction efficiency. The commonly used methods for improving the hydrophilicity of organic polymers are two methods: "top-down" and "bottom-up". The former is also called the post-modification method. After the organic polymer is polymerized, hydrophilic groups are grafted to improve the hydrophilicity of the organic polymer. However, one of the disadvantages of this method is that the uniformity of grafting cannot be guaranteed. The "bottom-up" method starts from hydrophilic monomers and polymerizes to form hydrophilic polymers, which can ensure the uniformity of the structure of the obtained hydrophilic polymers. Compared with the "top-down" method, the "bottom-up" method has a more obvious improvement effect on hydrophilicity. Summary of the Invention

[0004] In order to overcome the above problems, the present invention provides a hydrophilic covalent triazine framework, a preparation method thereof, and an application thereof. Dibenzoyl-dibenzothiophene sulfone and p-phenylenediamidine hydrochloride are prepared under the catalysis of a catalyst to obtain a hydrophilic covalent triazine framework material, and this material is used as a photocatalyst for water splitting to hydrogen, solving the technical problem of low efficiency of water splitting to hydrogen due to the hydrophobicity of the covalent triazine framework material.

[0005] To achieve the above technical objectives, the present invention adopts the following technical solutions:

[0006] In the first aspect of the present invention, a hydrophilic covalent triazine framework is provided, and the structure of the hydrophilic covalent triazine framework is shown in formula (I):

[0007]

[0008] Wherein, the structure of R is shown in formula (Ⅱ); Represents an infinitely extended structure;

[0009]

[0010] In the second aspect of the present invention, a method for preparing the above hydrophilic covalent triazine framework is provided. The method includes: putting dibenzoyl-dibenzothiophene sulfone, p-phenylenediamidine hydrochloride, and cesium carbonate catalyst into a solvent, reacting at 60 °C to 200 °C for 24 to 240 h, and obtaining the hydrophilic covalent triazine framework after washing and drying.

[0011] In the third aspect of the present invention, a catalyst for photocatalytic water splitting to produce hydrogen is provided, and the catalyst is the above hydrophilic covalent triazine framework.

[0012] In the fourth aspect of the present invention, the application of the above hydrophilic covalent triazine framework in photocatalytic water splitting to produce hydrogen is provided.

[0013] The beneficial effects of the present invention are as follows:

[0014] (1) By selecting appropriate polymerization monomers, catalysts, solvents, reaction temperatures, and reaction times, and through the synergistic cooperation of various process parameters, the overall technical solution is formed, and finally, a hydrophilic covalent triazine framework material is prepared. This material has strong hydrophilicity and, when used as a photocatalytic water splitting to produce hydrogen catalyst, has a high hydrogen production efficiency.

[0015] (2) For the hydrophilic covalent triazine framework prepared in the present invention, the water contact angle is 0 to 60°. This material has strong hydrophilicity and, when used as a photocatalytic water splitting to produce hydrogen catalyst, has a high hydrogen production efficiency. Description of the Drawings

[0016] The attached drawings forming a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0017] Figure 1 is the static water contact angle of the hydrophilic covalent triazine ring framework obtained in Example 1 of the present invention;

[0018] Figure 2 is the photocatalytic water splitting to produce hydrogen diagram of the covalent triazine framework obtained in Example 1 of the present invention under visible light;

[0019] Figure 3 is the static water contact angle of the hydrophilic covalent triazine ring framework obtained in Example 2 of the present invention;

[0020] Figure 4 is the photocatalytic water splitting to produce hydrogen diagram of the hydrophilic covalent triazine framework obtained in Example 2 of the present invention under visible light;

[0021] Figure 5 is the static water contact angle of the covalent triazine ring framework obtained in Comparative Example 1 of the present invention;

[0022] Figure 6It is the diagram of hydrogen production by water photolysis of the triazine ring framework obtained in Comparative Example 1 of the present invention under visible light. Detailed implementation mode

[0023] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanations for the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0024] It should be noted that the terms used herein are only for describing specific implementation modes and are not intended to limit the exemplary implementation modes according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should also be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0025] The first typical implementation mode of the present invention provides a hydrophilic covalent triazine framework, and the structure of the hydrophilic covalent triazine framework is shown in formula (I):

[0026]

[0027] Among them, the structure of R is shown in formula (Ⅱ); Indicates that the structure extends infinitely;

[0028]

[0029] The second typical implementation mode of the present invention provides a preparation method for the above-mentioned hydrophilic covalent triazine framework. The method includes: putting dibenzoyl-dibenzothiophene sulfone, p-phenylenediamidine hydrochloride, and cesium carbonate catalyst into a solvent, reacting at 60°C to 200°C for 24 to 240 hours, and obtaining the hydrophilic covalent triazine framework after washing and drying.

[0030] In one or more implementation modes, the solvent is a mixed solvent of dimethyl sulfoxide (DMSO) and water. Preferably, the volume ratio of dimethyl sulfoxide to water is 15 to 30:1.

[0031] In one or more implementation modes, the molar ratio of dibenzoyl-dibenzothiophene sulfone, p-phenylenediamidine hydrochloride, and cesium carbonate catalyst is 0.2 to 5:1:2 to 4, preferably 0.5:1:2 to 4.

[0032] In one or more implementation modes, the reaction temperature is 100 to 100°C, further preferably 150°C; the reaction time is 36 to 120°C, further preferably 36 hours.

[0033] In one or more embodiments, the method of washing is to wash the reaction product with one or more of water, ethanol, and N,N-dimethylformamide.

[0034] In one or more embodiments, the method of drying is freeze-drying or heat drying; preferably, the time of freeze-drying is 12 to 24 h, more preferably 10 h; preferably, the temperature of vacuum heat drying is 75°C to 5°C, and the time is 12 to 24 h, and more preferably the temperature of vacuum heat drying is 0°C, and the time is 10 h.

[0035] In the third typical embodiment of the present invention, a catalyst for photocatalytic water splitting to hydrogen is provided, and the catalyst is the above-mentioned hydrophilic covalent triazine framework.

[0036] In the fourth typical embodiment of the present invention, the application of the above-mentioned hydrophilic covalent triazine framework in photocatalytic water splitting to hydrogen is provided.

[0037] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with specific examples.

[0038] Example 1

[0039] Benzoyl-dibenzothiophene sulfone (0.159 g, 0.375 mmol), p-phenylenediamidine dihydrochloride (0.176 g, 0.75 mmol) and cesium carbonate (0.400 g, 1.5 mmol) were added to 15 mL of DMSO and 1 mL of aqueous solution, and reacted at 150°C for 36 h with stirring. After the reaction was completed and naturally cooled to room temperature, it was washed with water, ethanol, and DMF respectively, and the product hydrophilic covalent triazine framework was obtained by freeze-drying for 10 h, and the yield was 75%.

[0040] The product of this example was subjected to a static water contact angle test, and the results are as Figure 1 shown. From Figure 1 the results, it is shown that the contact angle of the hydrophilic covalent triazine framework prepared in this example is 34.07°, showing good hydrophilic performance.

[0041] The hydrophilic covalent triazine framework prepared in this example was taken for a photocatalytic water splitting to hydrogen performance test. The test conditions are as follows: 20 mg of hydrophilic covalent triazine framework, 90 mL of water, 10 mL of triethanolamine, and 3 wt% Pt was loaded as a co-catalyst, and the photocatalytic water splitting test was carried out under visible light (λ≥420 nm) irradiation. The result graph is shown in Figure 2. From the results, it can be seen that the hydrophilic covalent triazine framework has good photocatalytic water splitting hydrogen production activity.

[0042] Example 2

[0043] Dibenzoyl-dibenzothiophene sulfone (0.159 g, 0.375 mmol), p-phthalimidohydrochloride (0.176 g, 0.75 mmol) and cesium carbonate (0.976 g, 3.0 mmol) were added to 30 mL of DMSO and 1 mL of aqueous solution, and the reaction was carried out at 150 °C for 36 h with stirring. After the reaction was completed and cooled to room temperature naturally, it was washed with water, ethanol and DMF respectively, and dried by vacuum heating at 0 °C for 10 h to obtain the product hydrophilic covalent triazine framework with a yield of 69%.

[0044] The product of this example was subjected to a static water contact angle test, and the results are as Figure 3 shown. From Figure 3 the results, it is shown that the contact angle of the hydrophilic covalent triazine framework prepared in this example is 26.40°, showing good hydrophilic performance.

[0045] The hydrophilic covalent triazine framework prepared in this example was taken for the photocatalytic water splitting for hydrogen production performance test. The test conditions were as follows: 20 mg of hydrophilic covalent triazine framework, 90 mL of water, 10 mL of triethanolamine, and 3 wt% Pt was loaded as a co-catalyst, and the photocatalytic water splitting test was carried out under visible light (λ≥420 nm) irradiation. The result graph is shown in Figure 4. It can be seen from the results that the hydrophilic covalent triazine framework has good photocatalytic water splitting hydrogen production activity.

[0046] Comparative Example 1

[0047] Compared with Example 1, the aldehyde monomer was replaced with dibenzoyl-fluorene. Dibenzoyl-fluorene (0.140 g, 0.375 mmol), p-phthalimidohydrochloride (0.176 g, 0.75 mmol) and cesium carbonate (0.400 g, 1.5 mmol) were added to 15 mL of DMSO and 1 mL of aqueous solution, and the reaction was carried out at 150 °C for 36 h with stirring. After the reaction was completed and cooled to room temperature naturally, it was washed with water, ethanol and DMF respectively, and dried by freeze-drying to obtain the product with a yield of 75%.

[0048] The covalent triazine framework prepared in Comparative Example 1 was subjected to a static water contact angle test, and the results are as Figure 5 shown. From Figure 5 the results, it is shown that the static water contact angle of the covalent triazine framework in Comparative Example 1 is 124.90°, showing obvious hydrophobicity.

[0049] The covalent triazine framework prepared in Comparative Example 1 was taken for the photocatalytic water splitting for hydrogen production performance test. The test conditions were as follows: 20 mg of hydrophilic covalent triazine framework, 90 mL of water, 10 mL of triethanolamine, and 3 wt% Pt was loaded as a co-catalyst, and the photocatalytic water splitting test was carried out under visible light (λ≥420 nm) irradiation. The result graph is shown in Figure 6. It can be seen from the results that the photocatalytic water splitting hydrogen production activity of the covalent triazine framework in Comparative Example 1 is significantly reduced.

[0050] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A hydrophilic covalent triazine framework, characterized in that, The structure of the hydrophilic covalent triazine framework is shown in Formula (I): Formula (I); Among them, the structure of R is shown in formula (II); indicating that the structure extends infinitely; Formula (II).

2. A preparation method of the hydrophilic covalent triazine framework according to claim 1, characterized in that, The method includes: putting dibenzoyl-dibenzothiophene sulfone, p-phthalimidobenzamidine hydrochloride, and cesium carbonate catalyst into a solvent, reacting at 100-180 °C for 36-120 h, and obtaining the hydrophilic covalent triazine framework after washing and drying.

3. The preparation method according to claim 2, characterized in that, The solvent is a mixed solvent of dimethyl sulfoxide and water.

4. The preparation method according to claim 3, characterized in that The volume ratio of dimethyl sulfoxide to water is (15-30):

1.

5. The preparation method according to claim 2, characterized in that, The molar ratio of dibenzoyl-dibenzothiophene sulfone, p-phthalimidobenzamidine hydrochloride, and cesium carbonate catalyst is (0.2-5):1:(2-4).

6. The preparation method according to claim 5, characterized in that, The molar ratio of dibenzoyl-dibenzothiophene sulfone, p-phthalimidobenzamidine hydrochloride, and cesium carbonate catalyst is 0.5:1:(2-4).

7. The preparation method according to claim 2, characterized in that, The reaction temperature is 150 °C.

8. The preparation method according to claim 2, characterized in that, The reaction time is 36 h.

9. The preparation method according to claim 2, wherein The washing method is: washing the reaction product with one or more of water, ethanol, and N,N-dimethylformamide.

10. The preparation method according to claim 2, characterized in that, The drying method is freeze-drying or vacuum heating drying.

11. A catalyst for photocatalytic water splitting to produce hydrogen, characterized in that, The catalyst is the hydrophilic covalent triazine framework described in Claim 1 or the hydrophilic covalent triazine framework prepared by the preparation method according to any one of Claims 2-10.

12. Application of the hydrophilic covalent triazine framework described in Claim 1 or the hydrophilic covalent triazine framework prepared by the preparation method according to any one of Claims 2-10 in photocatalytic water splitting for hydrogen production.

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