Triptycene modified beta-ketoenamine covalent organic framework as well as preparation method and application thereof

Abstract

The invention discloses a triptycene modified beta-ketoenamine covalent organic framework as well as a preparation method and application thereof, and the triptycene modified beta-ketoenamine covalent organic framework is prepared by polycondensation of a polyamino triptycene monomer, a 1, 3, 5-trialdehyde phloroglucinol monomer and an enamine monomer. The triptycene modified beta-ketoenamine covalent organic framework disclosed by the invention has excellent performance of photocatalytic decomposition of water to produce hydrogen, and can be repeatedly used. The preparation method provided by the invention is simple in process, mild in condition, short in time consumption, environment-friendly and easy for industrial production.

Description

Technical Field

[0001] The invention belongs to the technical field of photocatalytic materials, and in particular relates to a triptycene-modified beta-ketoenamine covalent organic framework, a preparation method thereof and uses thereof. Background Art

[0002] Energy crisis and environmental pollution are severe challenges facing countries around the world today. Solar energy and hydrogen energy, as renewable clean energy, are expected to become new energy sources to replace fossil fuels. Using sunlight to catalyze water decomposition to produce hydrogen is one of the important ways to convert solar energy into green hydrogen energy. Therefore, it is of great significance to find new green, efficient and inexpensive semiconductor catalysts.

[0003] Covalent organic framework materials (COFs) are a new type of organic polymer materials, composed of light elements such as C, H, N, O, and B. Their atoms are bonded together through covalent bonds to form an ordered porous framework structure. They are the frontier and hot spot in the field of photocatalysis research in recent years.

[0004] Among them, β-ketoenamine covalent organic framework has good thermal stability and chemical stability, strong visible light absorption ability, suitable band structure, porous structural characteristics and other advantages, showing great potential in the field of photocatalytic research and application. However, due to the large difference in electronegativity between carbon and nitrogen atoms in the COFs skeleton, the degree of electron delocalization in the conjugated system is low (easily enriched around nitrogen atoms), the conjugated system is not fully expanded, the photogenerated charge mobility is low, easy to recombine, and the quantum efficiency of the photocatalytic reaction is low. Summary of the invention

[0005] The present invention provides a triptycene-modified β-ketoenamine covalent organic framework, a preparation method and use thereof. The carriers in the triptycene-modified β-ketoenamine covalent organic framework provided by the present invention have higher migration and interface transfer efficiency, thereby improving the photocatalytic reaction efficiency.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A triptycene-modified β-ketoenamine covalent organic framework is prepared by polycondensation of polyaminotriptycene monomers, 1,3,5-trialdehyde phloroglucinol monomers and enamine monomers.

[0008] After the conjugated polymerization of β-ketoenamine covalent organic framework and triptycene, the increase in conjugated carbon content increases the degree of electron delocalization, accelerates the rapid transfer of photogenerated electrons on the β-ketoenamine covalent organic framework to triptycene, effectively improves the separation efficiency of photogenerated electron-hole pairs, and enhances the photocatalytic performance of the triptycene-modified β-ketoenamine covalent organic framework.

[0009] In order to further improve the hydrogen production activity, the mass ratio of polyaminotriptycene, 1,3,5-trialdehyde pyrogallol monomer and enamine monomer is (5-40): (30-60): (15-45), and more preferably (10-25): (45-55): (25-43).

[0010] The β-ketoenamine is used as a basic connecting unit of the covalent organic framework. The aldehyde group of the β-ketoenamine covalent organic framework and the amino group of the triaminotriptycene monomer are conjugated and polymerized through a Schiff base condensation reaction.

[0011] In order to further improve the hydrogen production activity, the enamine monomer is at least one of p-phenylenediamine (PDA), 2,5-diaminobenzonitrile (DBN) or 5,5'-diamino-2,2'-bipyridine (Bpy). The enamine monomer is more preferably 2,5-diaminobenzonitrile (DBN).

[0012] Preferably, the mass amount of the polyaminotriptycene monomer is 5 to 40% of the total mass of the polyaminotriptycene monomer, the 1,3,5-trialdehyde phloroglucinol monomer and the enamine monomer.

[0013] When the enamine monomer is p-phenylenediamine (PDA), the mass amount of the polyaminotriptycene monomer is 10-40% of the mass of the polyaminotriptycene monomer, the 1,3,5-trialdehyde phloroglucinol monomer and the enamine monomer, and more preferably 10-30%.

[0014] When the enamine monomer is 2,5-diaminobenzonitrile (DBN), the mass amount of the polyaminotriptycene monomer is 10-40% of the mass of the polyaminotriptycene monomer, 1,3,5-trialdehyde phloroglucinol monomer and the enamine monomer, and more preferably 10-30%.

[0015] When the enamine monomer is 5,5'-diamino-2,2'-bipyridine (Bpy), the mass amount of the polyaminotriptycene monomer is 5-30% of the mass of the polyaminotriptycene monomer, 1,3,5-trialdehyde phloroglucinol monomer and the enamine monomer, more preferably 5-20%.

[0016] When the enamine monomer is p-phenylenediamine (PDA), the obtained triptycene-modified β-ketoenamine covalent organic framework is abbreviated as Tp-PDA-TATP; when the enamine monomer is 2,5-diaminobenzonitrile (DBN), the obtained triptycene-modified β-ketoenamine covalent organic framework is abbreviated as Tp-DBN-TATP; when the enamine monomer is 5,5'-diamino-2,2'-bipyridine (Bpy), the obtained triptycene-modified β-ketoenamine covalent organic framework is abbreviated as Tp-Bpy-TATP.

[0017] The polyaminotriptycene monomer contains three or more amino groups, preferably, three amino groups or six amino groups.

[0018] In order to further improve the catalytic activity, the above-mentioned polyaminotriptycene monomer includes at least one of 2,6,14-triaminotriptycene, 2,7,14-triaminotriptycene, 1,7,13-triaminotriptycene, 2,7,13-triaminotriptycene or 2,3,6,7,14,15-hexaaminotriptycene, and more preferably 2,6,14-triaminotriptycene (TATP).

[0019] In the present invention, unless otherwise specified, the raw materials used are conventional commercially available products.

[0020] The above-mentioned triptycene-modified β-ketoenamine covalent organic framework has a preferred structural formula:

[0021]

[0022] At least one of .

[0023] The above structural formula represents the smallest structural unit, and the wavy lines represent omitted repeated structural units. The structure extends infinitely.

[0024] The synthetic route of the above-mentioned triptycene-modified β-ketoenamine covalent organic framework is as follows:

[0025]

[0026] The above-mentioned triptycene-modified β-ketoenamine covalent organic framework is prepared by polycondensation reaction of polyaminotriptycene monomer, 1,3,5-trialdehyde phloroglucinol monomer and enamine monomer at room temperature for 8 to 12 hours;

[0027] The mass dosage of the polyaminotriptycene monomer is 5-40% of the total mass of the polyaminotriptycene monomer, the 1,3,5-trialdehyde phloroglucinol monomer and the enamine monomer.

[0028] When the enamine monomer is p-phenylenediamine (PDA), the mass amount of the polyaminotriptycene monomer is 10-40% of the mass of the polyaminotriptycene monomer, the 1,3,5-trialdehyde phloroglucinol monomer and the enamine monomer, and more preferably 10-30%.

[0029] When the enamine monomer is 2,5-diaminobenzonitrile (DBN), the mass amount of the polyaminotriptycene monomer is 10-40% of the mass of the polyaminotriptycene monomer, 1,3,5-trialdehyde phloroglucinol monomer and the enamine monomer, and more preferably 10-30%.

[0030] When the enamine monomer is 5,5'-diamino-2,2'-bipyridine (Bpy), the mass amount of the polyaminotriptycene monomer is 5-30% of the mass of the polyaminotriptycene monomer, 1,3,5-trialdehyde phloroglucinol monomer and the enamine monomer, more preferably 5-20%.

[0031] The preparation method is simple, mild and controllable, and time-saving. After the β-ketoenamine covalent organic framework is conjugated with triptycene, the delocalization degree of the π electrons on the β-ketoenamine covalent organic framework skeleton increases, which improves the separation, migration and interface transfer efficiency of the carriers in the bulk phase of the β-ketoenamine covalent organic framework, significantly improves the charge separation degree, and enhances the photocatalytic performance of the triptycene-modified β-ketoenamine covalent organic framework.

[0032] As one specific implementation scheme, the preparation method of the above-mentioned triptycene-modified β-ketoenamine covalent organic framework comprises the following steps:

[0033] 1) placing 1,3,5-trialdehyde-trisphenol monomer and p-toluenesulfonic acid in a mixture of trimethylbenzene, 1,4-dioxane and acetic acid solution in a volume ratio of (2-3):(2-3):1, and ultrasonically dispersing to obtain a liquid 1; the mass amount of p-toluenesulfonic acid is 0.5-0.7 times the mass of 1,3,5-trialdehyde-trisphenol;

[0034] 2) placing the polyaminotriptycene monomer in a tetrahydrofuran solution and dispersing it by ultrasonication to obtain a liquid II;

[0035] 3) placing liquid 1 and liquid 2 in a ball mill, adding enamine monomer, introducing argon protective gas, ball milling for 8 to 12 hours at room temperature at a rotation speed of 300 to 500 rpm, centrifuging, washing and drying the obtained product to obtain a triptycene-modified β-ketoenamine covalent organic framework.

[0036] In the above step 1), p-toluenesulfonic acid is used as a catalyst and a dehydrating agent.

[0037] In the above step 3), the drying temperature is 50-60° C. and the drying time is 8-12 hours.

[0038] The polycondensation reaction is carried out under a protective atmosphere, which may be argon, nitrogen or other inert gases, to prevent the reactants and products from being decomposed by moisture and oxidation.

[0039] In the above step 3), the centrifugal speed is 11000 rpm and the centrifugal time is 5 minutes, and then the product is washed with anhydrous tetrahydrofuran, and the centrifugation and washing steps are repeated 3 times (the centrifugation after washing with tetrahydrofuran is repeated once, and this is repeated 3 times). Finally, the obtained product is dried in a vacuum drying oven at 60°C for 12 hours.

[0040] The above-mentioned triptycene-modified β-ketoenamine covalent organic framework is used for photocatalytic water decomposition to produce hydrogen.

[0041] Photocatalytic decomposition of water to produce hydrogen preferably comprises the following steps:

[0042] (1) mixing a triptycene-modified β-ketoenamine covalent organic framework, sodium ascorbate, chloroplatinic acid and water to obtain a reaction solution; the mass amount of the triptycene-modified β-ketoenamine covalent organic framework is 0.1-0.2‰ of the mass of water; the mass ratio of the triptycene-modified β-ketoenamine covalent organic framework, sodium ascorbate and chloroplatinic acid is 20:(90-100):(0.04-0.06);

[0043] (2) The reaction solution is subjected to a photocatalytic reaction under vacuum conditions. The temperature of the photocatalytic reaction is preferably 5 to 8° C., more preferably 6° C.

[0044] In the above step 1), the triptycene-modified β-ketoenamine covalent organic framework, sodium ascorbate, chloroplatinic acid and water are mixed and ultrasonicated at a power of 50 to 150 W for 5 to 10 min to obtain a reaction solution; the power of the above ultrasound is more preferably 90 to 110 W.

[0045] The present invention has no particular limitation on the dissolution, as long as the dissolution is complete.

[0046] In the above step (2), before the photocatalytic reaction, it is preferably also included: passing high-purity argon gas into the reaction solution, the purity of the high-purity argon gas is preferably above 99.999%; the flow rate of the high-purity argon gas is preferably 10 to 30 mL / min, more preferably 20 mL / min; the time for passing the high-purity argon gas is preferably 0.5 to 1.5 hours, more preferably 1 hour.

[0047] The purpose of introducing high-purity argon into the reaction solution in the present invention is to remove dissolved oxygen in the reaction solution.

[0048] In the above step (2), the light source for the photocatalytic reaction is preferably a xenon lamp, and the xenon lamp is preferably a CEL-HXUV300 model produced by Beijing Zhongjiao Jinyuan Company; when the xenon lamp is used as the light source in the present invention, a high-pass filter is preferably used to filter out light with a wavelength less than 420nm.

[0049] In step (2), the photocatalytic reaction is preferably carried out under vacuum conditions, and the vacuum degree of the vacuum conditions is preferably -0.08 to -0.12 MPa, more preferably -0.1 MPa.

[0050] In the present invention, the photocatalytic reaction is preferably accompanied by stirring; the stirring is preferably magnetic stirring; the stirring speed is preferably 100 to 500 rpm, more preferably 300 rpm.

[0051] The present invention has no special limitation on the device for photocatalytic reaction. In the embodiment of the present invention, the CEL-SPH2N photocatalytic water decomposition hydrogen production system produced by Beijing Zhongjiao Jinyuan Company is used to perform photocatalytic water decomposition hydrogen production.

[0052] From the composition and structure of the β-ketoenamine covalent organic framework, the C atoms in the structure are sp 2 Hybrid form, N with sp 2 or sp 3 The hybrid forms together form a stable two-dimensional porous conjugated system. Due to the difference in electronegativity between carbon and nitrogen atoms, most of the delocalized π electrons are enriched around nitrogen atoms (i.e., the electron cloud density near nitrogen atoms is high), the π electron conjugated system is not fully expanded, and the charge mobility is low, which is the fundamental reason for the low quantum yield of the photocatalytic reaction of the β-ketoenamine covalent organic framework. In the present invention, the aldehyde group of the β-ketoenamine covalent organic framework is doped with triaminotriptycene through a Schiff base condensation reaction, so that the delocalization degree of the π electrons on the β-ketoenamine covalent organic framework is increased, the separation, migration and interface transfer efficiency of the carriers in the bulk phase of the β-ketoenamine covalent organic framework are improved, and the photocatalytic performance of the triptycene-modified β-ketoenamine covalent organic framework is enhanced.

[0053] The technologies not mentioned in the present invention are all referred to the prior art.

[0054] The triptycene-modified β-ketoenamine covalent organic framework of the present invention has excellent photocatalytic water decomposition and hydrogen production performance and can be reused. The preparation method provided by the present invention has a simple process, mild conditions, short time consumption, environmental friendliness, and is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 The SEM images of the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3 are shown;

[0056] Figure 2 The samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3 are 13 C NMR spectrum;

[0057] Figure 3 The transient fluorescence spectra of the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3 are shown;

[0058] Figure 4 The transient photocurrent diagrams of the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3;

[0059] Figure 5 This is a comparison chart of the photocatalytic hydrogen production activities of the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3. DETAILED DESCRIPTION

[0060] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0061] In each example, polyaminotriptycene and 1,3,5-trialdehyde phloroglucinol were of analytical grade; ball milling was performed using a planetary ball mill; the purity of the protective atmosphere argon was 99.999%; and water was deionized water.

[0062] Example 1

[0063] 190 mg 1,3,5-trialdehyde-triphenylene, 130 mg p-toluenesulfonic acid, 3 mL mesitylene, 3 mL 1,4-dioxane and 1 mL acetic acid solution (6M) were added to a centrifuge tube, and ultrasonicated for 10 minutes at room temperature to obtain a uniformly dispersed suspension; 72 mg 2,6,14-triaminotriphenylene was dissolved in 2 mL tetrahydrofuran solution, and ultrasonicated for 10 minutes at room temperature to obtain a uniformly dispersed suspension; the above two solutions were added to a ball mill, and 98 mg p-phenylenediamine was added, and argon protective gas (20 mL / min) was introduced, and ball milling was performed for 12 hours to obtain the product. The product was collected by centrifugation (11000 rpm, 5 min) and washed with anhydrous tetrahydrofuran, and the centrifugation and washing steps were repeated 3 times. Finally, the obtained product was placed in a 60°C vacuum drying oven and dried for 12 hours to obtain a red powder, referred to as Tp-PDA-TATP. 0.2 .

[0064] Example 2

[0065] 190 mg 1,3,5-trialdehyde-triphenylene, 130 mg p-toluenesulfonic acid, 3 mL mesitylene, 3 mL 1,4-dioxane and 1 mL acetic acid solution (6M) were added to a centrifuge tube, and ultrasonicated for 10 minutes at room temperature to obtain a uniformly dispersed suspension; 77.5 mg 2,6,14-triaminotriphenylene was dissolved in 2 mL tetrahydrofuran solution, and ultrasonicated for 10 minutes at room temperature to obtain a uniformly dispersed suspension; the above two solutions were added to a ball mill, and then 120 mg 2,5-diaminobenzonitrile was added, and argon protective gas (20 mL / min) was introduced, and ball milled for 12 hours to obtain the product. The product was collected by centrifugation (11000 rpm, 5 min) and washed with anhydrous tetrahydrofuran, and the centrifugation and washing steps were repeated 3 times. Finally, the obtained product was placed in a 60°C vacuum drying oven and dried for 12 hours to obtain a red powder, referred to as Tp-DBN-TATP. 0.2 .

[0066] Example 3

[0067] 190 mg 1,3,5-trialdehyde-triphenylphenol, 130 mg p-toluenesulfonic acid, 3 mL mesitylene, 3 mL 1,4-dioxane and 1 mL acetic acid solution (6M) were added to a centrifuge tube, and ultrasonicated for 10 minutes at room temperature to obtain a uniformly dispersed suspension; 39.8 mg 2,6,14-triaminotriptycene was dissolved in 2 mL tetrahydrofuran solution, and ultrasonicated for 10 minutes at room temperature to obtain a uniformly dispersed suspension; the above two solutions were added to a ball mill, and then 168 mg 5,5'-diamino-2,2'-bipyridine was added, and argon protective gas (20 mL / min) was introduced, and ball milled for 12 hours to obtain the product. The product was collected by centrifugation (11000 rpm, 5 min) and washed with anhydrous tetrahydrofuran, and the centrifugation and washing steps were repeated 3 times. Finally, the obtained product was placed in a 60°C vacuum drying oven and dried for 12 hours to obtain a red powder, referred to as Tp-Bpy-TATP. 0.1 .

[0068] Comparative Example 1

[0069] The only difference from Example 1 is that 2,6,14-triaminotriptycene is not added during the preparation process, and the rest is the same as Example 1. Tp-PDA is obtained.

[0070] Comparative Example 2

[0071] The only difference from Example 2 is that 2,6,14-triaminotriptycene is not added during the preparation process, and the rest is the same as Example 2. Tp-DBN is obtained.

[0072] Comparative Example 3

[0073] The only difference from Example 3 is that 2,6,14-triaminotriptycene is not added during the preparation process, and the rest is the same as Example 3. Tp-Bpy is obtained.

[0074] The morphology of the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was observed using a S-3500N scanning electron microscope (SEM) produced by Hitachi, Japan. The operating voltage of the instrument was 20 kV, and the vacuum degree of the sample chamber was less than 3.0×10 - 5 Pa. Get SEM pictures, such as Figure 1 As shown, after the modification of triptycene, the particle size of the samples of Examples 1 to 3 is reduced, and many fine spherical particles are added to the samples, indicating that the polycondensation doping of triptycene can significantly inhibit the orderly growth of the β-ketoenamine covalent organic framework structural unit, and the obtained triptycene-modified β-ketoenamine covalent organic framework has a smaller particle size, and the fine spherical particles attached to the surface are mainly caused by the grafting of triptycene on the surface of the β-ketoenamine covalent organic framework. This is conducive to more complete contact between the catalyst and the reactant, thereby promoting the catalytic effect.

[0075] The samples prepared in Examples 1 to 3 were analyzed using an Avance III 500 solid-state nuclear magnetic resonance spectrometer (NMR) produced by Bruker, Germany. 13 C NMR test, the obtained spectrum is as follows Figure 2 As shown. Analysis of the sample of Example 1 shows that the chemical shift values ​​of δ = 205.6ppm (a), δ = 141.6ppm (b) and δ = 126.1ppm (f) correspond to the carbon atom signals of the carbonyl group, carbon-nitrogen single bond and carbon-carbon double bond in the six-membered ring, respectively, and the chemical shift values ​​of δ = 140.4ppm (c), δ = 131.5ppm (d) and δ = 19.7ppm (e) are the signals of the substituted, meta and ortho carbon atoms on the benzene ring. The chemical shifts of the above carbon atoms are consistent with Tp-PDA-TATP 0.2 In addition, a tertiary carbon atom peak also appeared at δ = 51.9ppm (h), which is a carbon characteristic peak of triptycene; compared with the sample of Example 1, the sample of Example 2 showed characteristic peaks of cyano and triptycene tertiary carbon at δ = 104.0ppm (g) and δ = 53.0ppm (h), respectively, Tp-DBN-TATP 0.2 The peaks of other carbon atoms are relative to Tp-PDA-TATP 0.2 There is a slight shift, indicating that there is a strong electronic conjugation between cyano and triptycene and the main framework, which affects the chemical shift of adjacent carbon atoms; similarly, the analysis of the sample in Example 3 shows that in addition to the characteristic peaks of carbon atoms containing Tp and Bpy motifs, Tp-Bpy-TATP 0.1 The sample also exhibits a characteristic peak of tertiary carbon of conjugated triptycene at δ=51.5ppm(h), indicating that triptycene is conjugated with the above-mentioned β-ketoenamine covalent organic framework through covalent bonds, forming a good electron transmission channel.

[0076] The transient fluorescence lifetime of the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was measured using a FLS920 fluorescence spectrometer produced by Edinburgh, UK (excitation wavelength was 402.8 nm, scanning step length was 1 nm), and a transient fluorescence spectrum was obtained, as shown in FIG. Figure 3 As shown. Figure 3 It can be seen that compared with Tp-PDA, Tp-DBN and Tp-Bpy, Tp-PDA-TATP 0.2 , Tp-DBN-TATP 0.2 and Tp-Bpy-TATP 0.1The transient fluorescence decay changes more slowly, and its fluorescence lifetime is significantly prolonged. The fluorescence lifetime curve is fitted by the double exponential decay kinetics method. The fitting results are shown in Table 1. There are short-lived and long-lived fluorescence emissions on the surface of the β-ketoenamine covalent organic framework, which correspond to the bulk recombination and surface recombination of photogenerated carriers, respectively. After conjugation with triptycene, the lifetimes of these two types of fluorescence are prolonged, and the proportion of short-lived fluorescence is reduced, while the proportion of long-lived fluorescence is increased, indicating that the introduction of triptycene effectively inhibits the bulk recombination of photogenerated carriers. The conjugation between triptycene and the β-ketoenamine covalent organic framework increases the degree of delocalization of electrons on the β-ketoenamine covalent organic framework, accelerates the separation, migration and interface transfer rate of photogenerated electrons, effectively reduces the recombination probability of photogenerated carriers, and is beneficial to improving the photocatalytic activity of the triptycene-modified β-ketoenamine covalent organic framework.

[0077] Table 1 Fitting results of fluorescence lifetime test using samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3

[0078]

[0079] Photocatalytic hydrolysis hydrogen production performance test:

[0080] The amount of 2,6,14-triaminotriptycene in Example 1 was changed, and the rest was referred to Example 1 to obtain Tp-PDA-TATP. 0.1 , Tp-PDA-TATP 0.3 and Tp-PDA-TATP 0.4 Among them, Tp-PDA-TATP 0.1 It means that the mass dosage of polyaminotriptycene is 10% of the sum of the mass of polyaminotriptycene, 1,3,5-trialdehyde pyrogallol monomer and enamine monomer. The rest are similarly expressed and have similar meanings.

[0081] The amount of 2,6,14-triaminotriptycene in Example 2 was changed, and the rest was referred to Example 2 to obtain Tp-DBN-TATP. 0.1 , Tp-DBN-TATP 0.3 and Tp-DBN-TATP 0.4 Among them, Tp-DBN-TATP 0.1 It means that the mass dosage of polyaminotriptycene is 10% of the total mass of polyaminotriptycene, 1,3,5-trialdehyde pyrogallol monomer and enamine monomer. The rest are similarly expressed and have similar meanings.

[0082] The amount of 2,6,14-triaminotriptycene in Example 3 was changed, and the rest was referred to Example 3 to obtain Tp-Bpy-TATP. 0.05 , Tp-Bpy-TATP 0.2and Tp-Bpy-TATP 0.3 Among them, Tp-Bpy-TATP 0.1 It means that the mass dosage of polyaminotriptycene is 10% of the total mass of polyaminotriptycene, 1,3,5-trialdehyde pyrogallol monomer and enamine monomer. The rest are similarly expressed and have similar meanings.

[0083] 20 mg of the samples prepared in Examples 1 to 3 and Comparative Examples 1 to 3, 0.1 g of sodium ascorbate, 60 μL of a 1 mg / mL aqueous solution of chloroplatinic acid, and 100 mL of deionized water were ultrasonically treated at a power of 100 W for 5 min to obtain a reaction solution;

[0084] Each reaction solution was added to the reaction bottle of the photocatalytic water decomposition hydrogen production system (CEL-SPH2N photocatalytic water decomposition hydrogen production system produced by Beijing Zhongjiao Jinyuan Company), the circulating condenser of the reaction system was turned on to stabilize the system temperature at 5°C, argon gas with a purity of 99.999% was introduced into the reaction solution at a flow rate of 20mL / min for 1 hour, the sealing cover of the reactor was covered, and the reaction system was evacuated to a vacuum degree of -0.1MPa. A CEL-HXUV300 xenon lamp produced by Beijing Zhongjiao Jinyuan Company was used as the light source, and a high-pass filter was used to filter out light with a wavelength less than 420nm, and the photocatalytic water decomposition hydrogen production reaction was carried out under magnetic stirring. Every 1 hour, the concentration of the prepared hydrogen was automatically sampled and analyzed using a 2014C online gas chromatograph produced by Shimadzu Corporation of Japan. The results are as follows: Figure 5 shown.

[0085] like Figure 5 As shown in a, after a certain proportion of triptycene is added to the raw material for modification, the hydrogen production activity of the β-ketoenamine covalent organic framework is significantly improved. 0.2 The optimal hydrogen production rate of the sample is 5.77 mmol·h -1 ·g -1 , which is 9.3 times the activity of the Tp-PDA sample prepared in Example 1; Tp-DBN-TATP prepared in Example 2 0.2 The optimal hydrogen production rate of the sample is 17.81 mmol·h -1 ·g -1 , which is 5.6 times the activity of the Tp-DBN sample prepared in Example 2; Tp-Bpy-TATP prepared in Example 3 0.1 The optimal hydrogen production rate of the sample is 13.55 mmol·h -1 ·g -1 , which is 2.1 times the activity of the Tp-Bpy sample prepared in Example 3.

[0086] The triptycene-modified β-ketoenamine covalent organic framework prepared in Examples 1 to 3 was subjected to a cycle activity stability test according to the above-mentioned photocatalytic hydrolysis hydrogen production performance evaluation scheme. After each reaction, the sample was centrifuged 3 times (12000rpm) and washed with deionized water, then dried at 110°C, 20 mg of sample (the insufficient amount was supplemented by the sample prepared in the corresponding Examples 1 to 3 and Comparative Examples 1 to 3), 0.1 g of sodium ascorbate and 100 mL of deionized water were ultrasonicated for 5 min at a power of 100 W to obtain a reaction solution, and the illumination, vacuum degree and cycle condensation conditions were referred to the above-mentioned photocatalytic hydrolysis hydrogen production performance evaluation scheme, and the hydrogen production rate was detected every 1 hour, and the reaction was 5 hours each time, and the cycle was performed 4 times, and the results are listed in Table 2.

[0087] According to Table 2, a dotted line graph of the hydrogen production rate of the photocatalytic hydrolysis hydrogen production using the triptycene-modified β-ketoenamine covalent organic framework prepared in Examples 1 to 3 is drawn, as shown in FIG. Figure 5 As shown in b.

[0088] Combining Table 2 and Figure 5 b It can be seen that the photocatalytic hydrogen production activity of the triptycene-modified β-ketoenamine covalent organic framework provided by the present invention is significantly improved compared with the β-ketoenamine covalent organic framework, and the hydrogen production activity is stable. In the 20-hour cycle test, the triptycene-modified β-ketoenamine covalent organic framework has no obvious deactivation.

[0089] Table 2 Hydrogen production rate of the samples prepared by Examples 1 to 3 and Comparative Examples 1 to 3 for photocatalytic water decomposition

[0090]

[0091]

[0092] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A triptycene-modified β-ketoenamine covalent organic framework, characterized in that: It is prepared by polycondensation of polyaminotriptycene monomer, 1,3,5-trialdehyde phloroglucinol monomer and enamine monomer.

2. The triptycene-modified β-ketoenamine covalent organic framework according to claim 1, characterized in that: The mass ratio of polyaminotriptycene, 1,3,5-trialdehyde phloroglucinol monomer and enamine monomer is (5-40): (30-60): (15-45).

3. The triptycene-modified β-ketoenamine covalent organic framework according to claim 1 or 2, characterized in that: The enamine monomer is at least one of p-phenylenediamine, 2,5-diaminobenzonitrile or 5,5'-diamino-2,2'-bipyridine.

4. The triptycene-modified β-ketoenamine covalent organic framework according to claim 1 or 2, characterized in that: The polyaminotriptycene monomer includes at least one of 2,6,14-triaminotriptycene, 2,7,14-triaminotriptycene, 1,7,13-triaminotriptycene, 2,7,13-triaminotriptycene or 2,3,6,7,14,15-hexaaminotriptycene.

5. The triptycene-modified β-ketoenamine covalent organic framework according to claim 1 or 2, characterized in that: Its structural formula is: At least one of .

6. A method for preparing a triptycene-modified β-ketoenamine covalent organic framework according to any one of claims 1 to 5, characterized in that: The following steps are involved: It is prepared by polycondensation reaction of polyaminotriptycene monomer, 1,3,5-trialdehyde phloroglucinol monomer and enamine monomer at room temperature for 8 to 12 hours; The mass dosage of the polyaminotriptycene monomer is 5-40% of the total mass of the polyaminotriptycene monomer, the 1,3,5-trialdehyde phloroglucinol monomer and the enamine monomer.

7. The preparation method according to claim 6, characterized in that: The steps include: 1) placing 1,3,5-trialdehyde-trisphenol monomer and p-toluenesulfonic acid in a mixture of trimethylbenzene, 1,4-dioxane and acetic acid solution in a volume ratio of (2-3):(2-3):1, and ultrasonically dispersing to obtain a liquid 1; the mass amount of p-toluenesulfonic acid is 0.5-0.7 times the mass of 1,3,5-trialdehyde-trisphenol; 2) placing the polyaminotriptycene monomer in a tetrahydrofuran solution and dispersing it by ultrasonication to obtain a liquid II; 3) Liquid 1 and liquid 2 are placed in a ball mill, enamine monomer is added, protective gas is introduced, and ball milling is performed at room temperature at a rotation speed of 300 to 500 rpm for 8 to 12 hours. The obtained product is centrifuged, washed, and dried to obtain a triptycene-modified β-ketoenamine covalent organic framework.

8. Use of the triptycene-modified β-ketoenamine covalent organic framework according to any one of claims 1 to 5, characterized in that: Used for photocatalytic decomposition of water to produce hydrogen.

9. The use according to claim 8, characterized in that: Photocatalytic decomposition of water to produce hydrogen includes the following steps: 1) mixing a triptycene-modified β-ketoenamine covalent organic framework, sodium ascorbate, chloroplatinic acid and water to obtain a reaction solution; the mass amount of the triptycene-modified β-ketoenamine covalent organic framework is 0.1-0.2‰ of the mass of water; the mass ratio of the triptycene-modified β-ketoenamine covalent organic framework, sodium ascorbate and chloroplatinic acid is 20:(90-100):(0.04-0.06); 2) The reaction solution is subjected to a photocatalytic reaction under vacuum conditions, and the temperature of the photocatalytic reaction is 5 to 8°C.

10. The use according to claim 9, characterized in that: In step 2), before the photocatalytic reaction, it also includes: introducing high-purity argon gas into the reaction solution, the purity of the high-purity argon gas is above 99.999%; the flow rate of the high-purity argon gas is 10 to 30 mL / min; the time of introducing the high-purity argon gas is 0.5 to 1.5 hours; the light source for the photocatalytic reaction is preferably a xenon lamp, and a high-pass filter is used to filter out light with a wavelength less than 420 nm.

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