A method for the preparation of a covalent triazine polymer

Abstract

The present disclosure provides a preparation method of a covalent triazine polymer, comprising: mixing and dissolving an aromatic aldehyde compound, ammonium iodide and a non-noble metal chloride catalyst in anhydrous organic solvent under oxygen-rich conditions to obtain a reactant mixed solution; heating the reactant mixed solution under oxygen-rich and a first temperature for a first time duration to obtain an intermediate mixed solution; heating the intermediate mixed solution under oxygen-rich and a second temperature for a second time duration to evaporate the solvent and obtain the covalent triazine polymer, wherein the second temperature is higher than the first temperature.

Description

Technical Field

[0001] This disclosure belongs to the field of organic semiconductor technology and relates to a method for preparing a covalent triazine polymer. Background Technology

[0002] Covalent triazine frameworks (CTFs) possess aromatic C=N bonds (i.e., triazine rings) and the absence of weak bonds, making them a promising class of organic polymer photocatalysts. The strong aromatic covalent bonds endow CTFs with chemical stability and abundant nitrogen content. Due to the heteroatom effect (HAE), covalent triazine frameworks exhibit unique advantages and significant value in practical applications such as separation and storage, energy storage, photocatalysis, and heterogeneous catalysis.

[0003] In related technologies, a series of synthetic strategies have been studied, including high-temperature ionothermal synthesis, phosphorus pentoxide (P2O5) catalysis, amidine polycondensation, superacid catalysis, and Friedel-Crafts reaction. However, many shortcomings still exist. For example, high-temperature ionothermal synthesis can damage the structure and cause partial carbonization of materials at temperatures exceeding 400℃. Furthermore, the large amount of ZnCl2 used as a catalyst and reaction medium introduces impurities that are difficult to remove completely. The covalent triazine polymers prepared by high-temperature phosphorus pentoxide catalysis have a certain degree of crystallinity, but the reaction is also carried out at 400℃, resulting in the same structural damage and carbonization drawback as the high-temperature ionothermal method. The aldehyde and amidine polycondensation methods use expensive precursors, making them unsuitable for large-scale synthesis. Superacid catalysis offers mild reaction temperatures (generally 0–100℃), but the use of strong acids still leads to acidic corrosion and limits the scalability of precursors; crystallinity is also limited and requires microwave assistance to be achieved. The Friedel-Crafts reaction is neither economical nor environmentally friendly, and severely lacks precursor scalability.

[0004] Therefore, it is of great significance to seek a method for preparing covalent triazine polymers that has mild reaction conditions, good crystal properties, and is economical and green. Summary of the Invention

[0005] In view of this, in order to solve the problem that the covalent triazine polymer is carbonized under preparation conditions such as high temperature and strong acid, which affects the yield and output of the covalent triazine polymer, this disclosure proposes a method for preparing covalent triazine polymer and its application.

[0006] In one aspect of this disclosure, a method for preparing a covalent triazine polymer is provided, comprising:

[0007] Under oxygen-rich conditions, aromatic aldehyde compounds, ammonium iodide, and non-precious metal chloride catalysts are mixed and dissolved in an anhydrous organic solvent to obtain a mixed solution of reactants.

[0008] Under oxygen-rich conditions and at a first temperature, the reactant mixture solution is heated for a first time to obtain an intermediate mixture solution.

[0009] The solvent was evaporated by heating, and the intermediate was heated for a second time under oxygen-rich and second temperature conditions to obtain a covalent triazine polymer.

[0010] The second temperature is higher than the first temperature.

[0011] According to embodiments of this disclosure, the non-precious metal chloride catalyst includes any one of FeCl3, CuCl2, ZnCl2, and CoCl2.

[0012] According to embodiments of this disclosure, the structure of the aromatic aldehyde compound includes:

[0013] Where n is an integer from 1 to 5.

[0014] According to embodiments of this disclosure, the structural formula of the covalent triazine polymer includes:

[0015] Where n takes the value of an integer from 1 to 5.

[0016] According to embodiments of this disclosure, the anhydrous organic solvent includes either anhydrous toluene or anhydrous chlorobenzene.

[0017] According to embodiments of this disclosure, the first temperature is 60–150°C, the first duration is 1–7 days, the second temperature is 150–200°C, and the second duration is 1–5 days.

[0018] According to embodiments of this disclosure, the molar ratio of aldehyde functional group to ammonium iodide in the aromatic aldehyde compound is 1:(1-5).

[0019] According to embodiments of this disclosure, the molar ratio of the aldehyde functional group to the non-precious metal chloride catalyst in the aromatic aldehyde compound is 1:(0.1~1).

[0020] According to embodiments of this disclosure, the preparation method further includes purifying and extracting the covalent triazine polymer using an organic solution and water, respectively.

[0021] According to embodiments of this disclosure, the organic solution includes ethyl acetate, dichloromethane, methanol, and tetrahydrofuran, which are used as purification and extraction reagents, respectively.

[0022] According to the embodiments of this disclosure, for the first time, ammonium iodide is used as the nitrogen source in the triazine ring structural unit of the covalent triazine polymer, and aromatic aldehydes are used as the sole aromatic precursor of the covalent triazine polymer. The covalent triazine polymer material is prepared by cyclization of the aromatic aldehyde group using non-precious metal chloride catalysis. The preparation process is simple, low-cost, and uses mild reaction conditions such as temperature and acid / alkali environments, thus expanding the synthetic route for covalent triazine polymers. Furthermore, the preparation method proposed in this disclosure uses low-toxicity and inexpensive raw materials, making it more eco-friendly.

[0023] According to embodiments of this disclosure, the polymerization mechanism of the preparation method of this disclosure was verified and studied through experimental small molecule template reaction examples and control experiments. This disclosure is expected to be a new method for the large-scale synthesis of covalent triazine polymers, and it has good scalability for monomers. Furthermore, the prepared covalent triazine framework material has good absorption in the visible light range and good photocatalytic hydrogen production performance. Attached Figure Description

[0024] Figure 1 This is a reaction mechanism diagram of the method for preparing covalent triazine polymers disclosed in this paper;

[0025] Figure 2 This is a flowchart of the method for preparing covalent triazine polymers disclosed herein;

[0026] Figure 3 These are the liquid phase nuclear magnetic resonance hydrogen and carbon spectra of the triazine small molecule obtained in Example 1 of this disclosure;

[0027] Figure 4 These are the infrared spectra of the covalent triazine polymers obtained in Examples 2, 3, and 4 of this disclosure;

[0028] Figure 5 These are the solid-state carbon NMR spectra of the covalent triazine polymers obtained in Examples 2, 3, and 4 of this disclosure;

[0029] Figure 6 These are the photoelectron spectra of the covalent triazine polymers obtained in Examples 2, 3, and 4 of this disclosure;

[0030] Figure 7 This is a graph showing the photocatalytic hydrogen production performance of the covalent triazine polymers obtained in Examples 2, 3, and 4 of this disclosure in pure water. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0032] The endpoints and any values ​​of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this disclosure.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0034] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0035] It should be noted that, unless otherwise defined, the technical or scientific terms used in this disclosure should have the ordinary meaning understood by a person with ordinary skill in the art to which this disclosure pertains. Where the terms "first," "second," etc., are used throughout, they are used only to distinguish similar objects and should not be construed as indicating or implying their relative importance, order of precedence, or implicitly specifying the number of technical features indicated. It should be understood that the data described by "first," "second," etc., can be interchanged where appropriate.

[0036] Covalent triazine polymers (CTFs) possess chemical stability and abundant nitrogen content due to their unique C=N bond (triazine ring) structure, which has profound significance in practical applications and the application of heteroatom effects. In this disclosure, the term "heteroatom effect" refers to the modification of the electron distribution on the carbon plane, thereby altering the surface chemical properties of the material.

[0037] Before implementing the preparation method of the covalent triazine polymer proposed in this disclosure, experimental experiments were first conducted and the mechanism of the preparation method of this disclosure was obtained.

[0038] Figure 1 This is a reaction mechanism diagram of the preparation method of the covalent triazine polymer disclosed herein, wherein the schematic structure uses terephthalaldehyde as a schematic structure to demonstrate the reaction mechanism.

[0039] like Figure 1As shown, under an oxygen atmosphere and a non-precious metal chloride catalyst, the aldehyde group in an aromatic aldehyde first reacts with ammonium iodide to generate an imine-containing intermediate A. Simultaneously, under oxygen-promoted conditions, iron ions convert iodide ions into elemental iodine, which then reacts with imine intermediate A to yield intermediate B. The lone pair of electrons in nitrogen in imine intermediate A attacks the carbon atom on intermediate B, resulting in a condensation reaction to yield intermediate C. Based on a similar principle, imine intermediate A continues to attack the carbon atom on intermediate C under oxygen-promoted conditions, further undergoing a condensation reaction to yield intermediate D. Based on a similar principle, it further cyclizes to yield intermediate E. Furthermore, an oxygen-rich atmosphere and increased temperature promote the conversion of intermediate E to a covalent triazine polymer, increasing the yield of the covalent triazine polymer and promoting the formation of its planar two-dimensional structure.

[0040] According to embodiments of this disclosure, the reaction mechanism of the method for preparing covalent triazine polymers in this disclosure is inferred from experimental small molecule template reaction examples.

[0041] Figure 2 This is a flowchart of the method for preparing covalent triazine polymers disclosed herein.

[0042] In one aspect of this disclosure, a method for preparing a covalent triazine polymer is provided, such as... Figure 2 As shown, it mainly includes:

[0043] S1: Under oxygen-rich conditions, aromatic aldehyde compounds, ammonium iodide, and non-precious metal chloride catalysts are mixed and dissolved in an anhydrous organic solvent to obtain a mixed solution of reactants.

[0044] S2: Under oxygen-rich conditions and at a first temperature, the reactant mixture solution is heated for a first duration to obtain an intermediate mixture solution;

[0045] S3: Evaporate the solvent by heating, and heat the intermediate for a second time under oxygen-rich and second temperature conditions to obtain a covalent triazine polymer, wherein the second temperature is higher than the first temperature.

[0046] According to embodiments of this disclosure, the intermediate is an insoluble solid product with incomplete reaction, which needs to be heated to initiate further polymerization and obtain a covalent triazine polymer with a planar two-dimensional structure.

[0047] According to the embodiments of this disclosure, for the first time, ammonium iodide is used as the nitrogen source in the triazine ring structural unit of the covalent triazine polymer, and aromatic aldehydes are used as the sole aromatic precursor of the covalent triazine polymer. The covalent triazine polymer material is prepared by cyclization of the aromatic aldehyde group using non-precious metal chloride catalysis. The preparation process is simple, low-cost, and uses mild reaction conditions such as temperature and acid / alkali environments, thus expanding the synthetic route for covalent triazine polymers. Furthermore, the covalent triazine polymer preparation method proposed in this disclosure uses low-toxicity and inexpensive raw materials, making it more eco-friendly.

[0048] According to the embodiments of this disclosure, the method for preparing covalent triazine polymers proposed in this disclosure has the prospect of large-scale preparation, with a yield of up to 30%. For example, taking terephthalaldehyde as an example, if 2 mmol of terephthalaldehyde is added, 62 mg of the covalent triazine polymer is obtained. If the relative molecular mass of the structural unit corresponding to terephthalaldehyde is 102 g / mol, then the yield is 30.4%.

[0049] According to embodiments of this disclosure, the non-precious metal chloride catalyst includes any one of FeCl3, CuCl2, ZnCl2, and CoCl2.

[0050] According to embodiments of this disclosure, a non-precious metal chloride catalyst is used to introduce oxidizing metal ions to oxidize iodide ions in the reaction to generate elemental iodine, while no other impurity anions are introduced.

[0051] According to embodiments of this disclosure, the structure of the aromatic aldehyde compound includes:

[0052] Where n is an integer from 1 to 5.

[0053] According to embodiments of this disclosure, this disclosure is the first to use aromatic aldehydes as the sole aromatic precursor for synthesizing covalent triazine polymers.

[0054] According to embodiments of this disclosure, the structural formula of the covalent triazine polymer includes:

[0055] Where n takes the value of an integer from 1 to 5.

[0056] According to the embodiments of this disclosure, the covalent triazine polymer prepared by this disclosure is yellow or orange in color and has a planar two-dimensional structure.

[0057] According to embodiments of this disclosure, the anhydrous organic solvent includes either anhydrous toluene or anhydrous chlorobenzene.

[0058] According to the embodiments of this disclosure, the anhydrous organic solvent selected in the preparation method of this disclosure does not produce side reactions, and the solvent is removed by evaporation at a boiling point below a second temperature.

[0059] According to embodiments of this disclosure, the first temperature is 60–150°C, the first duration is 1–7 days, the second temperature is 150–200°C, and the second duration is 1–5 days.

[0060] According to embodiments of this disclosure, the first temperature can be selected as 60℃, 100℃, 150℃, etc., the first duration can be selected as 1 day, 4 days, 7 days, etc., the second temperature can be selected as 150℃, 180℃, 200℃, etc., and the second duration can be selected as 1 day, 3 days, 5 days, etc.

[0061] According to embodiments of this disclosure, an oxygen-rich atmosphere and increased temperature can promote the conversion of intermediates into covalent triazine polymers, forming covalent triazine polymers with planar two-dimensional structures.

[0062] According to embodiments of this disclosure, the molar ratio of aldehyde functional group to ammonium iodide in the aromatic aldehyde compound is 1:(1-5).

[0063] According to embodiments of this disclosure, the molar ratio of aldehyde functional group to ammonium iodide in aromatic aldehyde compounds can be selected as 1:1, 1:3, 1:5, etc.

[0064] According to embodiments of this disclosure, the molar ratio of the aldehyde functional group to the non-precious metal chloride catalyst in the aromatic aldehyde compound is 1:(0.1~1).

[0065] According to embodiments of this disclosure, the molar ratio of the aldehyde functional group to the non-precious metal chloride catalyst in the aromatic aldehyde compound can be selected as 1:0.1, 1:0.5, 1:1, etc.

[0066] According to embodiments of this disclosure, the amount of non-precious metal chloride catalyst used is small, and no new impurities are introduced.

[0067] According to embodiments of this disclosure, such as Figure 2 As shown, the above preparation method also includes,

[0068] S4: The covalent triazine polymer was purified and extracted using organic solvents and water, respectively.

[0069] According to the embodiments of this disclosure, after obtaining the covalent triazine polymer in step S3, an organic solution is added sequentially to remove small molecule organic compound impurities, and ammonium iodide and water are added to remove inorganic impurities. At the same time, the temperature is rapidly lowered to quench the reaction, thereby obtaining the covalent triazine polymer.

[0070] According to embodiments of this disclosure, the organic solution includes ethyl acetate, dichloromethane, methanol, and tetrahydrofuran, which are used as purification and extraction reagents, respectively.

[0071] According to an embodiment of this disclosure, the purification and extraction process in step S4 includes acid washing and filtration with dilute hydrochloric acid, followed by washing with ethyl acetate, dichloromethane, methanol, tetrahydrofuran and water in sequence to remove impurities, and finally Soxhlet extraction and purification with water, methanol and tetrahydrofuran as solvents.

[0072] According to the embodiments of this disclosure, the concentration of dilute hydrochloric acid during pickling is (0.1~1) mol / L, which can be selected as 0.1 mol / L, 0.5 mol / L, 1 mol / L, etc.; the pickling time is 1~3 days, which can be selected as 1 day, 2 days, 3 days, etc.

[0073] According to embodiments of this disclosure, the covalent triazine framework semiconductor material prepared using the method of this disclosure has the application of catalytic water reduction to produce hydrogen under visible light.

[0074] It should be noted that the described embodiments are merely some, not all, of the embodiments disclosed herein. Other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without inventive effort are all within the scope of protection of this disclosure.

[0075] Example 1: Experimental Experiment

[0076] Before implementing the preparation method of the covalent triazine polymer proposed in this disclosure, experimental comparisons were first conducted to determine the mechanism of the preparation method of this disclosure.

[0077] S1: Under air or oxygen conditions, 4 mmol of benzaldehyde, 4 mmol of ammonium iodide and 0.8 mmol of FeCl3 catalyst were added to a reaction flask containing 20 ml of anhydrous toluene to obtain a mixed solution of reactants.

[0078] S2: The reactant mixture was heated in an oil bath at 130°C for 3 days to obtain a triphenyltriazine polymer mixture;

[0079] S3: After the reaction stopped, the triphenyltriazine polymer mixture was diluted with 50 ml of ethyl acetate, washed with 25 ml of water, extracted three times with 25 ml of ethyl acetate, dried with anhydrous sodium sulfate, and then concentrated under vacuum. The crude product was purified by column chromatography (diethyl ether / petroleum ether) to obtain the triphenyltriazine polymer.

[0080] Figure 3 The figures show the liquid phase NMR 1H and 1C spectra of the template small molecule prepared in Example 1. The characteristic peaks in the figures indicate that the small molecule triazine compound was synthesized by the experimental method in Example 1, thus verifying the possibility of synthesizing covalent triazine polymers using this method.

[0081] Using the experimental method in Example 1 as the basic experimental framework, a control group experiment was set up to infer and verify the mechanism and reaction conditions in the preparation method of the covalent triazine polymer disclosed herein. The results and experimental conclusions are shown in the table below:

[0082]

[0083] Example 2

[0084] S1: Under air or oxygen conditions, 2 mmol of terephthalaldehyde, 4 mmol of ammonium iodide and 0.8 mmol of FeCl3 catalyst were added to a round-bottom flask containing 20 ml of anhydrous toluene to obtain a mixed solution of reactants.

[0085] S2: The reactant mixture is reacted in an oil bath at 130°C for 3 days to generate a covalent triazine polymer and an intermediate, resulting in a covalent triazine polymer mixture.

[0086] S3: Continue heating to remove the reaction solvent anhydrous toluene, and heat to 200℃ to remove excess ammonium iodide and allow the intermediate to react fully to generate a covalent triazine polymer.

[0087] S4: After the reaction stopped, ethyl acetate and water were added sequentially to quench the reaction. The mixture was then sonicated for 10 minutes and filtered and washed. Next, ethyl acetate, dichloromethane, methanol, tetrahydrofuran, and dilute hydrochloric acid were used for further filtration and washing to remove impurities. Finally, the product was purified by extraction with water, methanol, and tetrahydrofuran as extraction solvents for 3 days. After purification, the product was dried in a vacuum oven at 60°C for 24 hours. The obtained product was then ground into powder using a mortar and pestle to obtain a pure covalent triazine polymer, denoted as CTF-1.

[0088] Example 3

[0089] S1: Under air or oxygen conditions, 2 mmol of biphenyl dicarboxaldehyde, 4 mmol of ammonium iodide and 0.8 mmol of FeCl3 catalyst were added to a round-bottom flask containing 20 ml of anhydrous toluene to obtain a mixed solution of reactants.

[0090] S2: The reactant mixture is reacted in an oil bath at 130°C for 3 days to generate a covalent triazine polymer and an intermediate, resulting in a covalent triazine polymer mixture.

[0091] S3: Continue heating to remove the reaction solvent anhydrous toluene, and heat to 200℃ to remove excess ammonium iodide and allow the intermediate to react fully to generate a covalent triazine polymer.

[0092] S4: After the reaction stopped, ethyl acetate and water were added sequentially to quench the reaction. The mixture was then sonicated for 10 minutes and filtered and washed. Next, ethyl acetate, dichloromethane, methanol, tetrahydrofuran, and dilute hydrochloric acid were used for further filtration and washing to remove impurities. Finally, the product was purified by extraction with water, methanol, and tetrahydrofuran as extraction solvents for 3 days. After purification, the product was dried in a vacuum oven at 60°C for 24 hours. The obtained product was then ground into powder using a mortar and pestle to obtain a pure covalent triazine polymer, denoted as CTF-2.

[0093] Example 4

[0094] S1: Under air or oxygen conditions, 2 mmol of pyromellitic aldehyde, 4 mmol of ammonium iodide and 0.8 mmol of FeCl3 catalyst were added to a round-bottom flask containing 20 ml of anhydrous toluene to obtain a mixed solution of reactants.

[0095] S2: The reactant mixture is reacted in an oil bath at 130°C for 3 days to generate a covalent triazine polymer and an intermediate, resulting in a covalent triazine polymer mixture.

[0096] S3: Continue heating to remove the reaction solvent anhydrous toluene, and heat to 200℃ to remove excess ammonium iodide and allow the intermediate to react fully to generate a covalent triazine polymer.

[0097] S4: After the reaction stopped, ethyl acetate and water were added sequentially to quench the reaction. The mixture was then sonicated for 10 minutes and filtered and washed. Next, ethyl acetate, dichloromethane, methanol, tetrahydrofuran, and dilute hydrochloric acid were used for further filtration and washing to remove impurities. Finally, the product was purified by extraction with water, methanol, and tetrahydrofuran as extraction solvents for 3 days. After purification, the product was dried in a vacuum oven at 60°C for 24 hours. The obtained product was then ground into powder using a mortar and pestle to obtain a pure covalent triazine polymer, denoted as CTF-0.

[0098] Example 5

[0099] S1: Under air or oxygen conditions, 4 mmol of terephthalaldehyde, 8 mmol of ammonium iodide and 0.8 mmol of FeCl3 catalyst were added to a round-bottom flask containing 20 ml of anhydrous toluene to obtain a mixed solution of reactants.

[0100] S2: The reactant mixture is reacted in an oil bath at 130°C for 3 days to generate a covalent triazine polymer and an intermediate, resulting in a covalent triazine polymer mixture.

[0101] S3: Continue heating to remove the reaction solvent anhydrous toluene, and heat to 200℃ to remove excess ammonium iodide and allow the intermediate to react fully to generate a covalent triazine polymer.

[0102] S4: After the reaction stopped, ethyl acetate and water were added sequentially to quench the reaction. The mixture was then sonicated for 10 minutes and filtered and washed. Next, ethyl acetate, dichloromethane, methanol, tetrahydrofuran, and dilute hydrochloric acid were used for further filtration and washing to remove impurities. Finally, the product was purified by extraction with water, methanol, and tetrahydrofuran as extraction solvents for 3 days. After purification, the product was dried in a vacuum drying oven at 60°C for 24 hours. The obtained product was then ground into powder using a mortar and pestle to obtain a pure covalent triazine polymer.

[0103] Example 6

[0104] S1: Under air or oxygen conditions, 1 mmol of terephthalaldehyde, 2 mmol of ammonium iodide and 0.8 mmol of FeCl3 catalyst were added to a round-bottom flask containing 20 ml of anhydrous toluene to obtain a mixed solution of reactants.

[0105] S2: The reactant mixture is reacted in an oil bath at 130°C for 3 days to generate a covalent triazine polymer and an intermediate, resulting in a covalent triazine polymer mixture.

[0106] S3: Continue heating to remove the reaction solvent anhydrous toluene, and heat to 200℃ to remove excess ammonium iodide and allow the intermediate to react fully to generate a covalent triazine polymer.

[0107] S4: After the reaction stopped, ethyl acetate and water were added sequentially to quench the reaction. The mixture was then sonicated for 10 minutes and filtered and washed. Next, ethyl acetate, dichloromethane, methanol, tetrahydrofuran, and dilute hydrochloric acid were used for further filtration and washing to remove impurities. Finally, the product was purified by extraction with water, methanol, and tetrahydrofuran as extraction solvents for 3 days. After purification, the product was dried in a vacuum drying oven at 60°C for 24 hours. The obtained product was then ground into powder using a mortar and pestle to obtain a pure covalent triazine polymer.

[0108] Example 7

[0109] S1: Under air or oxygen conditions, 2 mmol of terephthalaldehyde, 4 mmol of ammonium iodide and 0.8 mmol of FeCl3 catalyst were added to a round-bottom flask containing 20 ml of toluene to obtain a mixed solution of reactants.

[0110] S2: The reactant mixture is reacted in an oil bath at 130°C for 3 days to generate a covalent triazine polymer and an intermediate, resulting in a covalent triazine polymer mixture.

[0111] S3: Continue heating to remove the reaction solvent anhydrous toluene, and heat to 200℃ to remove excess ammonium iodide and allow the intermediate to react fully to generate a covalent triazine polymer.

[0112] S4: After the reaction stopped, ethyl acetate and water were added sequentially to quench the reaction. The mixture was then sonicated for 10 minutes and filtered and washed. Next, ethyl acetate, dichloromethane, methanol, tetrahydrofuran, and dilute hydrochloric acid were used for further filtration and washing to remove impurities. Finally, the product was purified by extraction with water, methanol, and tetrahydrofuran as extraction solvents for 3 days. After purification, the product was dried in a vacuum drying oven at 60°C for 24 hours. The obtained product was then ground into powder using a mortar and pestle to obtain a pure covalent triazine polymer.

[0113] Example 8

[0114] S1: Under air or oxygen conditions, 2 mmol of terephthalaldehyde, 8 mmol of ammonium iodide and 0.8 mmol of FeCl3 catalyst were added to a round-bottom flask containing 20 ml of anhydrous toluene to obtain a mixed solution of reactants.

[0115] S2: The reactant mixture is reacted in an oil bath at 130°C for 3 days to generate a covalent triazine polymer and an intermediate, resulting in a covalent triazine polymer mixture.

[0116] S3: Continue heating to remove the reaction solvent anhydrous toluene, and heat to 200℃ to remove excess ammonium iodide and allow the intermediate to react fully to generate a covalent triazine polymer.

[0117] S4: After the reaction stopped, ethyl acetate and water were added sequentially to quench the reaction. The mixture was then sonicated for 10 minutes and filtered and washed. Next, ethyl acetate, dichloromethane, methanol, tetrahydrofuran, and dilute hydrochloric acid were used for further filtration and washing to remove impurities. Finally, the product was purified by extraction with water, methanol, and tetrahydrofuran as extraction solvents for 3 days. After purification, the product was dried in a vacuum drying oven at 60°C for 24 hours. The obtained product was then ground into powder using a mortar and pestle to obtain a pure covalent triazine polymer.

[0118] Example 9

[0119] S1: Under air or oxygen conditions, 2 mmol of terephthalaldehyde, 4 mmol of ammonium iodide and 1.6 mmol of FeCl3 catalyst were added to a round-bottom flask containing 20 ml of anhydrous toluene to obtain a mixed solution of reactants.

[0120] S2: The reactant mixture is reacted in an oil bath at 130°C for 3 days to generate a covalent triazine polymer and an intermediate, resulting in a covalent triazine polymer mixture.

[0121] S3: Continue heating to remove the reaction solvent anhydrous toluene, and heat to 200℃ to remove excess ammonium iodide and allow the intermediate to react fully to generate a covalent triazine polymer.

[0122] S4: After the reaction stopped, ethyl acetate and water were added sequentially to quench the reaction. The mixture was then sonicated for 10 minutes and filtered and washed. Next, ethyl acetate, dichloromethane, methanol, tetrahydrofuran, and dilute hydrochloric acid were used for further filtration and washing to remove impurities. Finally, the product was purified by extraction with water, methanol, and tetrahydrofuran as extraction solvents for 3 days. After purification, the product was dried in a vacuum drying oven at 60°C for 24 hours. The obtained product was then ground into powder using a mortar and pestle to obtain a pure covalent triazine polymer.

[0123] Example 10

[0124] S1: Under air or oxygen conditions, 2 mmol of terephthalaldehyde, 4 mmol of ammonium iodide and 0.8 mmol of FeCl3 catalyst were added to a round-bottom flask containing 20 ml of anhydrous chlorobenzene to obtain a mixed solution of reactants.

[0125] S2: The reactant mixture is reacted in an oil bath at 130°C for 3 days to generate a covalent triazine polymer and an intermediate, resulting in a covalent triazine polymer mixture.

[0126] S3: Continue heating to remove the reaction solvent anhydrous toluene, and heat to 200℃ to remove excess ammonium iodide and allow the intermediate to react fully to generate a covalent triazine polymer.

[0127] S4: After the reaction stopped, ethyl acetate and water were added sequentially to quench the reaction. The mixture was then sonicated for 10 minutes and filtered and washed. Next, ethyl acetate, dichloromethane, methanol, tetrahydrofuran, and dilute hydrochloric acid were used for further filtration and washing to remove impurities. Finally, the product was purified by extraction with water, methanol, and tetrahydrofuran as extraction solvents for 3 days. After purification, the product was dried in a vacuum drying oven at 60°C for 24 hours. The obtained product was then ground into powder using a mortar and pestle to obtain a pure covalent triazine polymer.

[0128] Example 11

[0129] S1: Under air or oxygen conditions, 2 mmol of terephthalaldehyde, 4 mmol of ammonium iodide and 0.8 mmol of ZnCl2 catalyst were added to a round-bottom flask containing 20 ml of anhydrous toluene to obtain a mixed solution of reactants.

[0130] S2: The reactant mixture is reacted in an oil bath at 130°C for 3 days to generate a covalent triazine polymer and an intermediate, resulting in a covalent triazine polymer mixture.

[0131] S3: Continue heating to remove the reaction solvent anhydrous toluene, and heat to 200℃ to remove excess ammonium iodide and allow the intermediate to react fully to generate a covalent triazine polymer.

[0132] S4: After the reaction stopped, ethyl acetate and water were added sequentially to quench the reaction. The mixture was then sonicated for 10 minutes and filtered and washed. Next, ethyl acetate, dichloromethane, methanol, tetrahydrofuran, and dilute hydrochloric acid were used for further filtration and washing to remove impurities. Finally, the product was purified by extraction with water, methanol, and tetrahydrofuran as extraction solvents for 3 days. After purification, the product was dried in a vacuum drying oven at 60°C for 24 hours. The obtained product was then ground into powder using a mortar and pestle to obtain a pure covalent triazine polymer.

[0133] Example 12

[0134] S1: Under air or oxygen conditions, 2 mmol of terephthalaldehyde, 4 mmol of ammonium iodide and 0.8 mmol of CoCl2 catalyst were added to a round-bottom flask containing 20 ml of anhydrous toluene to obtain a mixed solution of reactants.

[0135] S2: The reactant mixture is reacted in an oil bath at 130°C for 3 days to generate a covalent triazine polymer and an intermediate, resulting in a covalent triazine polymer mixture.

[0136] S3: Continue heating to remove the reaction solvent anhydrous toluene, and heat to 200℃ to remove excess ammonium iodide and allow the intermediate to react fully to generate a covalent triazine polymer.

[0137] S4: After the reaction stopped, ethyl acetate and water were added sequentially to quench the reaction. The mixture was then sonicated for 10 minutes and filtered and washed. Next, ethyl acetate, dichloromethane, methanol, tetrahydrofuran, and dilute hydrochloric acid were used for further filtration and washing to remove impurities. Finally, the product was purified by extraction with water, methanol, and tetrahydrofuran as extraction solvents for 3 days. After purification, the product was dried in a vacuum drying oven at 60°C for 24 hours. The obtained product was then ground into powder using a mortar and pestle to obtain a pure covalent triazine polymer.

[0138] Example 13

[0139] S1: Under air or oxygen conditions, 2 mmol of terephthalaldehyde, 4 mmol of ammonium iodide and 0.8 mmol of CuCl2 catalyst were added to a round-bottom flask containing 20 ml of anhydrous toluene to obtain a mixed solution of reactants.

[0140] S2: The reactant mixture is reacted in an oil bath at 130°C for 3 days to generate a covalent triazine polymer and an intermediate, resulting in a covalent triazine polymer mixture.

[0141] S3: Continue heating to remove the reaction solvent anhydrous toluene, and heat to 200℃ to remove excess ammonium iodide and allow the intermediate to react fully to generate a covalent triazine polymer.

[0142] S4: After the reaction stopped, ethyl acetate and water were added sequentially to quench the reaction. The mixture was then sonicated for 10 minutes and filtered and washed. Next, ethyl acetate, dichloromethane, methanol, tetrahydrofuran, and dilute hydrochloric acid were used for further filtration and washing to remove impurities. Finally, the product was purified by extraction with water, methanol, and tetrahydrofuran as extraction solvents for 3 days. After purification, the product was dried in a vacuum drying oven at 60°C for 24 hours. The obtained product was then ground into powder using a mortar and pestle to obtain a pure covalent triazine polymer.

[0143] Test Example 1

[0144] The specific structure and electronic state of the covalent triazine polymer materials CTF-1, CTF-2, and CTF-0 prepared in Examples 2, 3, and 4 of this disclosure were verified by infrared spectroscopy, nuclear magnetic resonance spectroscopy, and photoelectron spectroscopy.

[0145] Figure 4 This is the infrared spectrum of the covalent triazine polymer obtained in Examples 2, 3, and 4 of this disclosure.

[0146] like Figure 4 As shown, at 1700cm -1 Characteristic signal peaks of benzene ring skeletal vibration were detected at 1510 cm⁻¹, confirming the presence of the benzene ring. CTF-1 and CTF-2 showed characteristic signal peaks at 1510 cm⁻¹. -1 The characteristic signal peak of CN stretching vibration was detected at 1360 cm. -1 The characteristic signal peak of the triazine ring respiratory vibration was detected at 810 cm⁻¹. -1 Characteristic signal peaks of triazine ring skeletal vibration were detected at 1525 cm⁻¹, verifying the existence of triazine ring structures in CTF-1 and CTF-2. CTF-0 showed a peak at 1525 cm⁻¹. -1 The characteristic signal peak of CN stretching vibration was detected at 1330 cm. -1 The characteristic signal peak of the triazine ring respiratory vibration was detected at 810 cm⁻¹. -1 Characteristic signal peaks of triazine ring skeletal vibration were detected at the site, indicating that the embodiments of this disclosure successfully synthesized covalent triazine polymers.

[0147] Figure 5 This is the solid-state carbon NMR spectrum of the covalent triazine polymers obtained in Examples 2, 3, and 4 of this disclosure.

[0148] like Figure 5 As shown, in the solid-state carbon NMR spectrum of CTF-1, a characteristic peak corresponding to component a was found at 164 ppm, a characteristic peak corresponding to component b was found at 133 ppm, and a characteristic peak corresponding to component c was found at 124 ppm. In the solid-state carbon NMR spectrum of CTF-2, a characteristic peak corresponding to component a was found at 164 ppm, characteristic peaks corresponding to components b and e were found at 133 ppm, and characteristic peaks corresponding to components c and d were found at 121 ppm. In the solid-state carbon NMR spectrum of CTF-0, a characteristic peak corresponding to component a was found at 171 ppm, a characteristic peak corresponding to component b was found at 138 ppm, and a characteristic peak corresponding to component c was found at 117 ppm. This demonstrates that the embodiments of this disclosure successfully synthesized the covalent triazine polymer.

[0149] Figure 6 This is the photoelectron spectrum of the covalent triazine polymer obtained in Examples 2, 3, and 4 of this disclosure.

[0150] like Figure 6As shown, in the C1s spectrum, the binding energy of the C=N structure is 288.4 eV, the binding energy of the CN structure is 286.3 eV, and the binding energy of the C=C structure is 284.8 eV; in the N1s spectrum, the binding energy of the CN structure is 399.9 eV, and the binding energy of the C=N structure is 398.9 eV. It can be seen that the intensity of the CN peak in the figure is very weak, indicating that only a small number of CN bonds in the structure have not completely reacted to form C=N, demonstrating that the correctly structured covalent triazine polymer was obtained through the embodiments of this disclosure.

[0151] Test Example 2: Photocatalytic production of hydrogen from pure water under visible light.

[0152] 40 mg of the covalent triazine polymer materials CTF-1, CTF-2, and CTF-0 prepared in Examples 2, 3, and 4 of this disclosure were added to quartz bottles containing 20 ml of deionized water, and then 200 μL of 4 mg / ml chloroplatinic acid aqueous solution was added dropwise. The dispersion was sonicated for 5 minutes to allow the materials to be well dispersed in the water. Then, argon gas was continuously introduced for 20 minutes, and the bottle mouth was sealed with a rubber stopper.

[0153] Covalent triazine polymer materials CTF-1, CTF-2, and CTF-0 were irradiated with visible light and loaded with platinum for 12 hours. After adding 5 ml of triethanolamine as a sacrificial agent, the platinum-loaded covalent triazine polymer materials were dispersed in water, and argon gas was continuously introduced for 20 minutes before the bottle was sealed with a rubber stopper.

[0154] Photocatalytic experiments were conducted using covalent triazine polymer materials CTF-1, CTF-2, and CTF-0 as photocatalysts. A 300W xenon lamp was used as the light source, and a 420nm cutoff filter was configured to obtain visible light for photocatalytic effects.

[0155] Every 2 hours, a portion of the gas in the bottle is taken from the photocatalytic device using a syringe. The hydrogen concentration in the syringe is obtained using gas chromatography, and the hydrogen production is calculated in combination with the gas volume in the photocatalytic device.

[0156] Figure 7 This is a graph showing the photocatalytic hydrogen production performance of the covalent triazine polymers obtained in Examples 2, 3, and 4 of this disclosure in pure water.

[0157] like Figure 7 As shown, CTF-1, CTF-2, and CTF-0 achieved hydrogen concentrations of 610 μmol / g·h, 550 μmol / g·h, and 1120 μmol / g·h, respectively, within 6 hours, and exhibited good catalytic stability.

[0158] Test results show that the covalent triazine polymer prepared by the method proposed in this disclosure has good absorption in the visible light range, and its band structure can meet the requirements for reducing water to produce hydrogen under visible light conditions, thus achieving high photocatalytic hydrogen production performance.

[0159] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A method for preparing a covalent triazine polymer, comprising: Under oxygen-rich conditions, aromatic aldehyde compounds, ammonium iodide, and non-precious metal chloride catalysts are mixed and dissolved in an anhydrous organic solvent to obtain a reactant mixture solution. The non-precious metal chloride catalyst includes any one of FeCl3, CuCl2, ZnCl2, and CoCl2. The structure of the aromatic aldehyde compound includes: Where n is an integer from 1 to 5; Under oxygen-rich conditions and at a first temperature, the reactant mixture solution is heated for a first duration to obtain an intermediate mixture solution. The solvent is evaporated by heating, and the intermediate is heated for a second time under oxygen-rich and second temperature conditions to obtain the covalent triazine polymer. The first temperature is 60–150°C, and the second temperature is 150–200°C.

2. The preparation method according to claim 1, wherein, The structural formula of the covalent triazine polymer includes: , where n is an integer from 1 to 5.

3. The preparation method according to claim 1, wherein, The anhydrous organic solvent includes either anhydrous toluene or anhydrous chlorobenzene.

4. The preparation method according to claim 1, wherein, The duration is 1 to 7 days; The second duration is 1 to 5 days.

5. The preparation method according to claim 1, wherein, The molar ratio of aldehyde functional group to ammonium iodide in the aromatic aldehyde compound is 1:(1~5).

6. The preparation method according to claim 1, wherein, The molar ratio of the aldehyde functional group in the aromatic aldehyde compound to the non-precious metal chloride catalyst is 1:(0.1~1).

7. The preparation method according to claim 1 further includes purifying and extracting the covalent triazine polymer using an organic solvent and water, respectively.

8. The preparation method according to claim 7, wherein, The organic solution includes ethyl acetate, dichloromethane, methanol, and tetrahydrofuran, which are used as purification and extraction reagents, respectively.

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