Methylated covalent triazine polymer as well as preparation method and application thereof

Abstract

The invention discloses a methylated covalent triazine polymer as well as a preparation method and application thereof. The preparation method comprises the following step: reacting a dimethylamino compound at least in the presence of an anhydride catalyst to prepare the methylated covalent triazine polymer. According to the method, the methylated covalent triazine polymer is prepared by catalyzing the cyclization of the amidinine compound by using the anhydride catalyst for the first time, and the method is simple in preparation process and mild in reaction conditions such as temperature and acid-base environment, so that the synthesis route of the covalent triazine polymer is expanded; meanwhile, the methylated covalent triazine polymer has good absorption in a visible light range and has good performance of photocatalytic reduction of carbon dioxide.

Description

Technical Field

[0001] The invention belongs to the technical field of organic compounds, and in particular relates to a methylated covalent triazine polymer and a preparation method and application thereof. Background Art

[0002] Carbon dioxide (CO2) is not only a greenhouse gas, but also a type of carbon resource that is abundant, cheap and easily available. Rational resource utilization of CO2 is one of the effective ways to achieve the dual carbon goals. The current serious energy crisis and environmental pollution problems have prompted more and more attention to the thermochemical, biological, electrochemical or photocatalytic conversion of CO2 to produce high-value-added carbon-containing chemicals or fuels. Using solar energy for artificial photosynthesis and photocatalytic conversion of CO2 are seen as a potential approach.

[0003] The essence of photocatalytic CO2 reduction (CO2 reduction reaction, CO2RR) is a redox process induced by light, which mainly includes two processes: (1) adsorption of CO2 molecules by the reaction sites of photocatalytic materials; (2) redox process between adsorbed CO2 and photogenerated electrons and holes. Therefore, improving the light absorption efficiency of photocatalytic materials, enhancing their adsorption and activation ability for CO2, and improving the separation efficiency of photogenerated electrons and holes are key factors in constructing efficient photoreduction catalysts. However, the catalysts currently developed are limited by factors such as narrow light absorption, slow charge transfer and limited catalytic active sites, resulting in serious photogenerated charge recombination problems, which in turn significantly limits their photocatalytic efficiency. Therefore, developing efficient, cheap and highly stable photocatalysts is a major challenge faced in improving the efficiency of photocatalytic CO2 reduction.

[0004] In recent years, regular and ordered crystalline covalent organic frameworks (COFs) have been regarded as a new type of organic semiconductor polymer materials due to their π-conjugated characteristics of the skeleton and the characteristics of easy regulation and functionalization of the pore structure, showing great application potential in the process of artificial synthetic photocatalysis. Among them, crystalline covalent triazine frameworks (CTFs) composed of triazine groups with excellent light absorption ability have attracted extensive research attention. Their excellent organic semiconductor properties have made them widely used in various photocatalytic processes, such as water decomposition to produce hydrogen and multiphase organic reactions. Some triazine organic polymer materials reported in the hydrolysis reaction showed photocatalytic activity comparable to or even better than that of inorganic semiconductors. However, due to the mismatch of energy band positions and the inability to meet high overpotentials, the application of triazine polymers in photocatalytic CO2 conversion is still relatively small. CTFs use covalent chemical bonds to link triazines and other organic structural units at the molecular scale to form periodic and ordered framework materials. For example, crystalline CTFs can be prepared by high-temperature (low-temperature) self-condensation reaction of aromatic cyano groups under the catalysis of Lewis acid (Brown acid). In addition, the condensation reaction between aromatic aldehydes / amines and diformamidine also provides an important way to create crystalline CTFs. However, it should be pointed out that there is an obvious shortcoming in the above preparation methods, that is, it is difficult to simply functionalize the skeleton structure of the prepared CTFs. It is usually necessary to design the organic building blocks of CTFs in a specific molecular structure to achieve secondary modification of CTFs or regulation of the pore structure. However, the multi-step and complex preparation process is often not conducive to further promoting its application in artificial synthetic photocatalytic processes. Therefore, it is an urgent problem to provide a simple method for preparing functionalized triazine polymers and use them for the reduction of carbon dioxide. Summary of the invention

[0005] The main purpose of the present invention is to provide a methylated covalent triazine polymer and a preparation method and application thereof, so as to overcome the deficiencies of the prior art.

[0006] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention includes:

[0007] The embodiment of the present invention provides a method for preparing a methylated covalent triazine polymer, which comprises: reacting a dimethylamine compound at least in the presence of an acid anhydride catalyst to obtain a methylated covalent triazine polymer.

[0008] The embodiment of the present invention also provides a methylated covalent triazine polymer prepared by the aforementioned preparation method.

[0009] The embodiment of the present invention further provides a methylated covalent triazine polymer, wherein the methylated covalent triazine polymer comprises a plurality of repeating structural units, and the repeating structural units have a structure as shown in formula (II):

[0010]

[0011] Wherein, n=1-4, and the dotted lines represent the bond connection positions.

[0012] The embodiments of the present invention also provide the use of the aforementioned methylated covalent triazine polymer in the preparation of organic semiconductor materials or in the photocatalytic reduction of carbon dioxide.

[0013] An embodiment of the present invention further provides an organic semiconductor material, which at least includes the aforementioned methylated covalent triazine polymer.

[0014] The embodiment of the present invention also provides a method for photocatalytic reduction of carbon dioxide, which comprises:

[0015] Carbon dioxide is introduced into a reaction device equipped with a photocatalyst and a photocatalytic reaction is carried out under the condition of visible light irradiation, thereby reducing carbon dioxide to carbon monoxide; wherein the photocatalyst includes the aforementioned methylated covalent triazine polymer.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The methylated covalent triazine polymer prepared by the present invention has the characteristics of wide light absorption range, high stability, high CO2 adsorption performance and good recyclability; at the same time, the CO2 adsorption capacity of the methylated covalent triazine polymer in the present invention reaches 2.0 mmol·g -1 The introduced methyl structure extends its light absorption range to 800nm. Under visible light excitation, the methyl-modified covalent triazine framework catalytic system has basically no obvious activity loss in the photoreduction of CO2 for more than 4 rounds in the gas-solid mode, and achieves high yield and 100% CO selectivity under the test conditions without metal, photosensitizer or sacrificial reagent.

[0018] (2) The present invention uses anhydride catalysts to catalyze the cyclization of methylamine compounds to prepare methylated covalent triazine polymers for the first time. The preparation process of this method is simple, and the reaction conditions such as temperature and acid-base environment are relatively mild, which expands the synthesis route of covalent triazine polymers. It is very different from the traditional covalent triazine polymer synthesis method, and it can synthesize a triazine skeleton with functional methyl groups in situ in one step;

[0019] (3) The present invention provides a method for synthesizing a large amount of methylated covalent triazine polymers, and has good scalability for reaction monomers. The prepared methylated covalent triazine polymers have good absorption in the visible light range and good photocatalytic reduction of carbon dioxide performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 is a reaction mechanism diagram of a method for preparing a methyl-modified triazine structure in a typical embodiment of the present invention;

[0022] Figure 2 It is an infrared spectrum of the dimethylamino monomer terephthalamidine hydrochloride in Example 1 of the present invention, the methyl-modified covalent triazine polymer and the covalent triazine polymer material CTF synthesized by the traditional method;

[0023] Figure 3 The solid state carbon NMR spectra of CTF, methyl-CTF-1 and methyl-CTF-2 prepared in Examples 1-3 of the present invention are as follows:

[0024] Figure 4a-4b is a graph showing the catalytic performance of a methyl-modified covalent triazine polymer in a typical embodiment of the present invention;

[0025] Figure 5 Schematic diagram of the preparation of methylated covalent triazine polymers in a typical embodiment of the present invention. DETAILED DESCRIPTION

[0026] In view of the defects of the prior art, the inventors of this case have proposed the technical solution of the present invention after long-term research and extensive practice. The technical solution is mainly formed by condensing a dimethylamino compound into a ring under the catalysis of anhydride, and introducing methyl groups in situ on the triazine skeleton, thereby effectively regulating the CTF skeleton, shortening the photogenerated electron transmission distance between the methyl-modified CTF and CO2, and thus improving the photocatalytic efficiency.

[0027] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Specifically, as one aspect of the technical solution of the present invention, a method for preparing a methylated covalent triazine polymer includes:

[0029] The dimethylamine compound is reacted at least in the presence of an acid anhydride catalyst to obtain a methylated covalent triazine polymer.

[0030] The synthesis method of the methylated covalent triazine polymer in the present invention is simple, and only needs to be heated and stirred under nitrogen protection, and no high-temperature tube sealing is required. The reaction diagram of the methylated covalent triazine polymer is shown in Figure 5 shown.

[0031] In some preferred embodiments, the preparation method specifically includes: under a protective atmosphere, mixing a dimethylamino compound, an acid anhydride catalyst and an organic solvent and reacting them at a first temperature to form an intermediate; then heating the intermediate to a second temperature and continuing to react to obtain a methylated covalent triazine polymer; wherein the second temperature is higher than the first temperature.

[0032] Furthermore, the dimethylamino compound has a structure as shown in formula (I):

[0033]

[0034] Among them, n=1~4.

[0035] Furthermore, the acid anhydride catalyst includes any one or more combinations of trifluoromethanesulfonic anhydride, benzoic anhydride, acetic anhydride, and trifluoroacetic anhydride, but is not limited thereto.

[0036] Furthermore, the organic solvent is an anhydrous organic solvent, and the anhydrous organic solvent includes any one or more combinations of anhydrous dioxane, anhydrous mesitylene, o-dichlorobenzene, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, anhydrous toluene, anhydrous methanol, and N-methylpyrrolidone, and is not limited thereto.

[0037] Furthermore, the first temperature is 30-130°C.

[0038] Furthermore, the reaction time at the first temperature is 1 to 5 days.

[0039] Furthermore, the second temperature is 130-200°C.

[0040] Furthermore, the reaction time at the first temperature is 1 to 7 days.

[0041] Furthermore, the molar ratio of the amine functional group contained in the dimethylamino compound to the acid anhydride catalyst is 1:(1-100).

[0042] Furthermore, the preparation method further comprises: after the reaction is completed, purifying and extracting the obtained product.

[0043] Specifically, organic solution and water are used to purify and extract the methyl-modified covalent triazine polymer respectively; wherein, after the covalent triazine polymer is obtained by reaction, organic solution needs to be added in sequence to remove small molecule organic compound impurities and acetic anhydride impurities, and the organic solution includes N,N-dimethylformamide, dichloromethane, methanol and ethanol.

[0044] In some more specific embodiments, the method for preparing the methylated covalent triazine polymer comprises:

[0045] Under nitrogen protection, a series of dimethylamino compounds and anhydride catalysts are mixed and dissolved in an anhydrous organic solvent, and mixed evenly to obtain a reactant mixed solution; under the reaction conditions of nitrogen and a first temperature, the reactant mixed solution is stirred and heated for a first period of time to obtain an intermediate mixed solution; the temperature is increased to accelerate the reaction rate, and under the nitrogen protection and the heating conditions of a second temperature, the intermediate is heated for a second period of time to finally obtain a methyl-modified covalent triazine polymer (i.e., the aforementioned "methylated covalent triazine polymer"); wherein the second temperature is higher than the first temperature.

[0046] Furthermore, the methylated covalent triazine polymer is purified and extracted using an organic solution and high-purity water, respectively, wherein the organic solution includes N,N-dimethylformamide, dichloromethane, methanol and ethanol, which are respectively used as purification and extraction solvents for the material.

[0047] The present invention firstly carried out experimental experiments and obtained the mechanism of the preparation method disclosed in the present invention, such as Figure 1 As shown, Figure 1 The diagram is a reaction mechanism diagram of the preparation method of the methyl-modified triazine structure in the present invention, wherein the illustrated structure uses benzylamine as a schematic structure to demonstrate the reaction mechanism.

[0048] The present invention uses anhydride catalysts to catalyze the cyclization of dimethylamine compounds for the first time to prepare methylated covalent triazine polymers. The preparation process is simple, and the reaction conditions such as temperature and acid-base environment are mild, which expands the synthesis route of methylated covalent triazine polymers; at the same time, by regulating the amount of anhydride catalyst used and the polymerization temperature, the problem of difficult functionalization in the traditional CTFs preparation process is solved.

[0049] Another aspect of the embodiments of the present invention further provides a methylated covalent triazine polymer prepared by the aforementioned preparation method.

[0050] Furthermore, the specific surface area of ​​the methylated covalent triazine polymer is 60 to 560 m 2 / g, pore size is 0.5~10nm.

[0051] The skeleton of the methylated covalent triazine polymer in the present invention is composed of a methyl-modified triazine π-conjugated system. The specific methyl triazine structure not only broadens the light absorption range of the catalyst, but also provides an ideal model platform for the elucidation of the structure-activity relationship in photocatalytic CO2RR.

[0052] Another aspect of the embodiments of the present invention further provides a methylated covalent triazine polymer, wherein the methylated covalent triazine polymer comprises a plurality of repeating structural units, and the repeating structural units have a structure as shown in formula (II):

[0053]

[0054] Wherein, n=1-4, and the dotted lines represent the bond connection positions.

[0055] Furthermore, the specific surface area of ​​the methylated covalent triazine polymer is 60 to 560 m 2 / g, pore size is 0.5~10nm.

[0056] Furthermore, the number average molecular weight of the methylated covalent triazine polymer is 15-25 kDa.

[0057] The skeleton of the methylated covalent triazine polymer in the present invention is composed of a methyl-modified triazine π-conjugated system. The specific methyl triazine structure not only broadens the light absorption range of the catalyst, but also promotes the transfer of photogenerated electrons, thereby accelerating the carbon dioxide reduction reaction.

[0058] Another aspect of the embodiments of the present invention further provides use of the aforementioned methylated covalent triazine polymer in preparing organic semiconductor materials or photocatalytic reduction of carbon dioxide.

[0059] Another aspect of the embodiments of the present invention further provides an organic semiconductor material, which at least includes the aforementioned methylated covalent triazine polymer.

[0060] Another aspect of the embodiments of the present invention further provides a method for photocatalytic reduction of carbon dioxide, comprising:

[0061] Carbon dioxide is introduced into a reaction device equipped with a photocatalyst and a photocatalytic reaction is carried out under the condition of visible light irradiation, thereby reducing carbon dioxide to carbon monoxide; wherein the photocatalyst includes the aforementioned methylated covalent triazine polymer.

[0062] Furthermore, when the photocatalyst dosage was 5 mg and the photocatalyst was excited by visible light (>420 nm) at room temperature, the CO yield was 524.5 μmol·h -1 There was no significant change in the activity of the catalytic system after four cycles of reaction.

[0063] The technical solution of the present invention is further described in detail below in conjunction with several preferred embodiments and drawings. This embodiment is implemented on the premise of the technical solution of the invention, and a detailed implementation method and specific operation process are given, but the protection scope of the present invention is not limited to the following embodiments.

[0064] Unless otherwise specified, the experimental materials used in the following examples can be purchased from conventional biochemical reagent companies.

[0065] Example 1

[0066] In a protective atmosphere, 1 mmol of terephthalamidine hydrochloride is first heated to 120° C. in a DMAC solvent (3-10 mL) under the catalysis of anhydride catalysts (trifluoromethanesulfonic anhydride) for a reaction time of 1-3 days, and then heated to 150° C. for a reaction of 1-5 days to finally prepare a methyl-modified covalent triazine polymer (methylated covalent triazine polymer). The solid powder obtained after the reaction is soaked in DMF, CH2Cl2, and EtOH, and then Soxhlet extracted in a MeOH solvent for 24 hours to obtain a brown powder with a yield of 159.9 mg. The relative molecular mass of the structural unit corresponding to terephthalamidine hydrochloride is 235.1 g / mol, and the yield is 68.1%, recorded as methyl-CTF-1.

[0067] Figure 2 : is the infrared spectra of the dimethylamine monomer terephthalamidine hydrochloride, the methyl-modified covalent triazine polymer and the covalent triazine polymer material CTF without methyl structure synthesized by the traditional method in Example 1; Figure 2 As shown, at 1700cm -1 The characteristic signal peak of benzene ring skeleton vibration was detected at 1520 cm -1 The characteristic signal peak of CN stretching vibration was detected at 1361cm -1 The characteristic signal peak of the triazine ring breathing vibration was detected at 1423 cm -1 The characteristic signal peak of the stretching vibration of the methyl group was detected at , verifying the existence of the methyl structure in the methyl-modified CTF structure, indicating that the methyl-modified covalent triazine polymer was successfully synthesized in situ in this example.

[0068] Example 2

[0069] Weigh 0.1mmol [1,1′-biphenyl]-4,4′-bis(carboxylic acid imide) dihydrochloride, 0.05mmol 1,1,1-biphenyl-4,4-diylbis(N-phenylmethylamine) anhydrous carbonate, benzaldehyde (0.05mL-0.5mL), DMF solvent (1-10mL) and place them in a 50mL two-necked round-bottom flask equipped with a reflux condenser and a stirrer, and protect with nitrogen, and then heat at 80°C for 24 hours, 120°C for 48 hours, and 150°C for 72 hours. After cooling the reaction system to room temperature, filter it and treat it with 5% dilute hydrochloric acid, DMF, ethanol and dichloromethane in sequence to remove excess metal salts (carbonates) and incompletely reacted oligomers or monomers, and then place the product in a vacuum drying oven at 100°C for 12 hours to obtain a methyl-free covalent triazine polymer material CTF, which is recorded as CTF. The carbonate catalyst in this embodiment can be any one of cesium carbonate, sodium carbonate, lithium carbonate, and potassium carbonate.

[0070] Example 3

[0071] In a protective atmosphere, 1 mmol of [1,1′-biphenyl]-4,4′-bis(carboxylic acid imide) dihydrochloride is first heated to 120° C. in DMAC and mesitylene solvent (5-10 mL) under the catalysis of anhydride catalyst (benzoic anhydride) for 1-5 days, then heated to 150° C. and reacted for 2-7 days to finally prepare a brown product methyl-modified covalent triazine polymer (methyl-CTF-2). After the reaction, the solid powder obtained by filtration is soaked in DMF, CH2Cl2, and EtOH, respectively, and then Soxhlet extracted in MeOH solvent for 24 hours to obtain a brown powder. The relative molecular mass of the structural unit corresponding to [1,1′-biphenyl]-4,4′-bis(carboxylic acid imide) dihydrochloride is 311.3 g / mol, and the yield of methyl-CTF-2 is 74.5%.

[0072] Figure 3 It is the solid state carbon nuclear magnetic resonance spectrum of CTF, methyl-CTF-1 and methyl-CTF-2 prepared in Examples 1-3.

[0073] Example 4

[0074] In a protective atmosphere, 1 mmol of 1,1:4,1-terphenyl-4,4-dicarboximidamide is first heated to 120°C in DMAC and o-dichlorobenzene solvent (5-10 mL) under the catalysis of anhydride catalysts (acetic anhydride 0.5 mL-3 mL) for a reaction time of 1-5 days, then heated to 150 degrees Celsius for a reaction of 1-7 days to finally prepare a methyl-modified covalent triazine polymer product (methyl-CTF-3). After the reaction, the solid powder obtained by filtration is soaked in DMF, CH2Cl2, and EtOH, respectively, and then Soxhlet extracted in MeOH solvent for 24 hours to obtain a dark brown powder. The relative molecular mass of the structural unit corresponding to 1,1:4,1-terphenyl-4,4-dicarboximidamide is 314.39 g / mol, and the yield of methyl-CTF-3 is 81.3%.

[0075] Application Examples

[0076] The methylated covalent triazine polymer (methyl-modified CTF prepared in Example 1) and the methyl-free CTF prepared in Example 2 were respectively irradiated with visible light for 4 hours. Before irradiation, the above covalent triazine polymer materials were evenly dispersed in the reactor, the reaction system was evacuated, carbon dioxide was introduced, and after standing for 30 minutes, ultrapure water saturated with carbon dioxide was added thereto.

[0077] A 300W xenon lamp was used as the light source, and a 420nm cutoff filter was configured to obtain a visible light photocatalytic device.

[0078] Every 30 minutes, a portion of the gas in the system was taken from the photocatalytic device using a syringe, and the carbon monoxide concentration in the syringe was obtained using gas chromatography, and the carbon monoxide production was calculated based on the gas volume in the photocatalytic device.

[0079] Figure 4a-4b 3 is a performance graph of the photocatalytic reduction of carbon dioxide in pure water by the methyl-modified covalent triazine polymer in this example.

[0080] As shown in Figure 4, within 2 hours, CTF, methyl-CTF-1, and methyl-CTF-2 achieved carbon monoxide yields of 89.3 μmol / g / h, 236.8 μmol / g / h, and 524.5 μmol / g / h, respectively, and had good catalytic stability.

[0081] In addition, the inventors of this case also referred to the aforementioned embodiments and conducted experiments with other raw materials, process operations, and process conditions described in this specification, and obtained relatively ideal results.

[0082] It should be understood that the technical solution of the present invention is not limited to the above-mentioned specific implementation cases. Any technical deformation made according to the technical solution of the present invention without departing from the scope of protection of the purpose of the present invention and the claims shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a methylated covalent triazine polymer, characterized in that: include: The dimethylamine compound is reacted at least in the presence of an acid anhydride catalyst to obtain a methylated covalent triazine polymer.

2. The preparation method according to claim 1, characterized in that: Specifically include: Under a protective atmosphere, a dimethylamino compound, an anhydride catalyst and an organic solvent are mixed and reacted at a first temperature to form an intermediate; then the intermediate is heated to a second temperature and continues to react to obtain a methylated covalent triazine polymer; wherein the second temperature is higher than the first temperature.

3. The preparation method according to claim 2, characterized in that: The dimethylamino compound has a structure as shown in formula (I): Wherein, n=1 to 4; And / or, the acid anhydride catalyst includes any one or more combinations of trifluoromethanesulfonic anhydride, benzoic anhydride, acetic anhydride, and trifluoroacetic anhydride; And / or, the organic solvent is an anhydrous organic solvent, and the anhydrous organic solvent includes any one or more combinations of anhydrous dioxane, anhydrous mesitylene, o-dichlorobenzene, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, anhydrous toluene, anhydrous methanol, and N-methylpyrrolidone.

4. The preparation method according to claim 2, characterized in that: The first temperature is 30 to 130° C.; and / or the reaction time at the first temperature is 1 to 5 days; and / or, the second temperature is 130-200° C.; and / or, the reaction time at the first temperature is 1-7 days; And / or, the molar ratio of the amine functional group contained in the dimethylamino compound to the acid anhydride catalyst is 1:(1-100).

5. The preparation method according to claim 2, characterized in that: Also includes: After the reaction is completed, the obtained product is purified and extracted.

6. A methylated covalent triazine polymer prepared by the preparation method according to any one of claims 1 to 5; preferably, the specific surface area of ​​the methylated covalent triazine polymer is 60 to 560 m 2 / g, pore size is 0.5~10nm.

7. A methylated covalent triazine polymer, characterized in that: The methylated covalent triazine polymer comprises a plurality of repeating structural units, wherein the repeating structural units have a structure as shown in formula (II): Where n = 1 to 4, and the dotted lines represent the bond connection positions; Preferably, the specific surface area of ​​the methylated covalent triazine polymer is 60 to 560 m 2 / g, pore size is 0.5~10nm.

8. Use of the methylated covalent triazine polymer according to claim 6 or 7 in the preparation of organic semiconductor materials or photocatalytic reduction of carbon dioxide.

9. An organic semiconductor material, characterized in that: At least comprises the methylated covalent triazine polymer described in claim 6 or 7.

10. A method for photocatalytic reduction of carbon dioxide, characterized in that: include: The carbon dioxide is introduced into a reaction device provided with a photocatalyst and a photocatalytic reaction is carried out under the condition of visible light irradiation, thereby reducing the carbon dioxide to carbon monoxide; Wherein, the photocatalyst comprises the methylated covalent triazine polymer as described in claim 6 or 7.

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