A benzothiophene sulfone organic crystal, preparation and application as a photocatalyst

Abstract

The present invention relates to a benzothiophene sulfone organic crystal, preparation and application as a photocatalyst, and belongs to the technical field of new materials. The present invention conducts a sulfonation reaction on a biphenyl aromatic carboxylic acid compound and a sulfonating agent, wherein the meta-positioning property of the carboxylic acid on the biphenyl aromatic carboxylic acid compound enables the sulfonation reaction to occur at the meta-position of the carboxyl group, and at the same time, the biphenyl group causes the sulfonic acid group on the sulfonating agent to undergo an electrophilic reaction with the adjacent benzene ring to form a benzothiophene sulfone compound. The benzothiophene sulfone compound prepared by the present invention can be used as an efficient photocatalytic hydrogen production catalyst, and is suitable for low-cost, large-scale preparation and production of efficient organic photocatalytic hydrogen production catalysts.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and more specifically, relates to a benzothiophene sulfone organic crystal, and its preparation and application as a photocatalyst. Background Art

[0002] Clean energy includes wind energy, solar energy, hydrogen energy, nuclear energy, biomass energy, tidal energy, etc. Hydrogen energy is a green and low-carbon secondary energy source that can help large-scale consumption of renewable energy and accelerate the low-carbonization of industries, construction, transportation, etc. However, the low-cost and green preparation of hydrogen is still a great challenge. Hydrogen production from renewable energy is a key technology that needs to be solved to open up the hydrogen energy industry chain.

[0003] Existing hydrogen production technologies mainly include fossil fuel reforming, biomass fermentation, glycerol catalytic reforming and water decomposition. Among them, water decomposition technology (thermolysis, electrolysis and photolysis) is clean and effective, and is considered to be the most ideal method. The pyrolysis process requires a lot of heat, and the energy consumption and cost are high. Electrolysis technology is efficient and convenient, but it consumes a lot of clean electricity. Biophotolysis requires complex microbial screening and cultivation processes. Catalytic photolysis uses catalysts (mainly inorganic semiconductors and organic semiconductors) to decompose water into hydrogen and oxygen. It is conducive to the mass production of hydrogen with less pollution. However, it is difficult for most catalysts to produce catalytic effects in a continuous and stable manner, and the quantum efficiency is low.

[0004] In 2019, the U.S. Department of Energy (DOE) proposed that the standard for the practical application of catalytic photocatalytic water splitting technology is a solar-to-hydrogen (STH) conversion efficiency of 10%. This requires that the material has a quantum efficiency of 100% in the wavelength range of <500nm. Therefore, the development of catalysts that match the solar spectrum (ultraviolet light accounts for about 5% and visible light accounts for about 45%) is key. Limited by the absorption range, the STH of most inorganic photocatalysts is low. In 2020, Domen et al. conducted a 100m 2 Demonstration of photolysis water project, the STH of the system is 0.76%.

[0005] Organic semiconductor materials (carbonitride, conjugated polymers, etc.) with visible light absorption ability are a potential option for solving the light absorption problem. In 2009, Wang Xinchen et al. first proposed that carbon nitride, an organic material, can photocatalyze water decomposition to produce hydrogen. In 2020, Wang Xinchen et al. reported that carbon nitride can catalyze total hydrolysis, and the quantum efficiency at 365nm reached 8%, but the light absorption range of the material is still mainly in the ultraviolet region. In addition to carbon nitride, since 2014, conjugated polymer materials such as conjugated microporous polymers, covalent organic frameworks, and covalent triazine frameworks have been found to be used for photocatalysis. CN1059642965 discloses a method for preparing an organic photocatalyst, specifically disclosing the following steps, using acridine yellow and 2,4,6-tris (4-carboxyphenyl) -1,3,5-triazine as reactants, concentrated sulfuric acid as a dehydrating agent, and preparing an amide organic compound through an amidation reaction. The compound can be used as an organic photocatalyst for photocatalytic organic degradation. CN114570429 discloses a method for preparing a single-atom-loaded covalent organic framework material that can be used for photocatalytic hydrogen production. Specifically disclosed are the following steps: forming a covalent organic framework with sulfur-containing polyaldehyde groups and polyamino compounds, anchoring and stabilizing single atoms using sulfur-containing groups, and preparing a single-atom-loaded covalent organic photocatalyst with high catalytic efficiency and high stability. However, the STH of these materials is less than 0.1%, and most of them are complicated to prepare and have high costs.

[0006] In summary, the prior art still lacks a method for preparing an organic photocatalyst that is simple to synthesize, low-cost and highly efficient. Summary of the invention

[0007] In view of the above defects of the prior art, the present invention provides a method for preparing an organic photocatalyst with simple synthesis, low cost and high efficiency. The preparation method of the present invention comprises using a biphenyl carboxylic acid compound as a raw material, using at least one of concentrated sulfuric acid, oleum, chlorosulfonic acid, sulfur trioxide and a sulfur trioxide-pyridine complex as a sulfonating agent, and converting the biphenyl carboxylic acid into a benzothiophene sulfone compound, which can efficiently catalyze photocatalytic hydrogen production.

[0008] According to a first aspect of the present invention, a method for preparing a benzothiophene sulfone organic crystal is provided, wherein a biphenyl aromatic carboxylic acid compound is subjected to a sulfonation reaction with a sulfonating agent, wherein the meta-positioning of the carboxylic acid group on the biphenyl aromatic carboxylic acid compound causes the sulfonation reaction to occur at the meta-position of the carboxyl group, and at the same time, the biphenyl group causes the sulfonic acid group on the sulfonating agent to undergo an electrophilic reaction with an adjacent benzene ring to form a benzothiophene sulfone compound.

[0009] Preferably, the biphenyl aromatic carboxylic acid compound is a diphenyl aromatic carboxylic acid compound, a polyphenyl aromatic carboxylic acid compound or a condensed ring compound.

[0010] Preferably, the polyphenyl aromatic carboxylic acid compound is a terphenyl aromatic carboxylic acid compound or a quaterphenyl aromatic carboxylic acid compound; and the condensed ring compound is a phenanthrene compound or a perylene compound.

[0011] Preferably, the sulfonating agent is at least one of concentrated sulfuric acid, oleum, chlorosulfonic acid, sulfur trioxide and a sulfur trioxide-pyridine complex.

[0012] Preferably, the molar ratio of the biphenyl aromatic carboxylic acid compound to the sulfonating agent is (1-0.01):1.

[0013] Preferably, the temperature of the sulfonation reaction is lower than the boiling point of the sulfonating agent.

[0014] Preferably, the temperature of the sulfonation reaction is 120-160°C.

[0015] According to another aspect of the present invention, a benzothiophene sulfone organic crystal prepared by any one of the methods is provided.

[0016] According to another aspect of the present invention, there is provided a use of the benzothiophene sulfone organic crystal as a photocatalyst.

[0017] Preferably, the photocatalyst is used for photocatalytic hydrogen production, photocatalytic oxygen production or organic conversion reaction;

[0018] Preferably, the organic conversion reaction is an organic pollutant degradation reaction.

[0019] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0020] (1) The present invention provides a universal method for synthesizing an aromatic carboxylic acid compound containing a benzothiophene sulfone group. The method has high yield and purity of the target product and is easy to operate.

[0021] (2) The synthesis method of the aromatic carboxylic acid compound containing benzothiophene sulfone group proposed in the present invention is flexible and controllable, and can be applied to introduce benzothiophene sulfone group into aromatic carboxylic acids with different structures, thereby providing the possibility for adjusting the energy band structure and light absorption range of the target product.

[0022] (3) The preparation method of the present invention has mild reaction conditions, a reaction temperature not exceeding 200°C, low cost, and a wide variety of raw material options. It can prepare target compounds with different redox abilities according to different needs to meet the energy requirements of special redox reactions.

[0023] (4) The aromatic carboxylic acid compound containing benzothiophene sulfone group proposed in the present invention has a large degree of conjugation and light absorption ability, as well as good water wettability, and is particularly suitable for photocatalytic related applications in water systems.

[0024] (5) The photocatalytic hydrogen production rate of the benzothiophene sulfone organic crystals proposed in the present invention reaches 60000 μmol g - 1 h -1 , STH reached 1%. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a schematic diagram of the process of preparing 3,7-dibenzothiophenedicarboxylic acid, 5,5-dioxide by concentrated sulfuric acid in the present invention.

[0026] Figure 2 The present invention is a schematic diagram of the process of preparing 3,7-dibenzothiophenedicarboxylic acid, 5,5-dioxide by fuming sulfuric acid.

[0027] Figure 3 The figure is a schematic diagram of the process of preparing 3,7-dibenzothiophenedicarboxylic acid, 5,5-dioxide by using chlorosulfonic acid in the present invention.

[0028] Figure 4 The present invention is a schematic diagram of the process of preparing benzo[1,2-b:4,5-b']bis[1]benzothiophene-3,9-dicarboxylic acid, 5,5,11,11-tetraoxide by using fuming sulfuric acid.

[0029] Figure 5 The schematic diagram of the process of preparing benzo[1,2-b:4,5-b']bis[1]benzothiophene-3,9-dicarboxylic acid, 5,5,11,11-tetraoxide by using chlorosulfonic acid in the present invention.

[0030] Figure 6 This is the NMR spectrum of benzo[1,2-b:4,5-b']bis[1]benzothiophene-3,9-dicarboxylic acid, 5,5,11,11-tetraoxide prepared in Example 5 of the present invention.

[0031] Figure 7 The powder X-ray diffraction pattern of 3,7-dibenzothiophenedicarboxylic acid, 5,5-dioxide prepared in the present invention.

[0032] Figure 8 This is the powder X-ray diffraction pattern of benzo[1,2-b:4,5-b′]bis[1]benzothiophene-3,9-dicarboxylic acid, 5,5,11,11-tetraoxide prepared in Example 5 of the present invention.

[0033] Fig. 9 This is a photocatalytic hydrogen production performance diagram in Example 1 of the present invention.

[0034] Fig.10 This is a photocatalytic hydrogen production performance diagram in Example 2 of the present invention.

[0035] Fig.11 This is a photocatalytic hydrogen production performance diagram in comparative example 1 of the present invention.

[0036] Fig.12 This is a photocatalytic hydrogen production performance diagram in comparative example 2 of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0038] The invention provides a method for preparing an organic crystal containing a benzothiophene sulfone group, wherein a biphenyl carboxylic acid compound is used as a raw material, concentrated sulfuric acid or fuming sulfuric acid or chlorosulfonic acid is used as a sulfonation reagent, and the biphenyl carboxylic acid compound is converted into an aromatic carboxylic acid compound containing a benzothiophene sulfone group through a sulfonation reaction.

[0039] The raw material of the invention is a biphenyl aromatic carboxylic acid compound. The carboxylic acid group in the aromatic carboxylic acid is an electron-withdrawing meta-positioning group. Its electron-withdrawing effect causes an electrophilic reaction to occur at the meta-position. The sulfonation reaction is a typical electrophilic reaction. The meta-positioning property of the carboxyl group causes the sulfonation reaction to occur at the meta-position of the carboxyl group. Meanwhile, the presence of the biphenyl group causes the sulfonic acid group to further undergo an electrophilic reaction with an adjacent benzene ring to form a benzothiophene sulfone compound.

[0040] Preferably, the biphenyl aromatic carboxylic acid compound should contain polyphenyls (such as biphenyl, terphenyl, quaterphenyl) or condensed ring groups (such as phenanthrene, perylene), etc., to meet the requirement of a wider light absorption range.

[0041] As preferred, the sulfonating agent described in the present invention includes but is not limited to concentrated sulfuric acid, oleum and chlorosulfonic acid, etc., and should also include other types of sulfonating agents, such as sulfur trioxide, sulfur trioxide-pyridine complex, etc. Preferred sulfonating agents are concentrated sulfuric acid, 20% oleum, 50% oleum and chlorosulfonic acid. The sulfonating agent can electrophilically attack benzene ring compounds and introduce sulfonic acid groups on the benzene ring.

[0042] Preferably, the concentration of the sulfonating agent is concentrated sulfuric acid (80wt% to 100wt%), oleum (20wt% to 60wt%), chlorosulfonic acid (1wt% to 100wt%);

[0043] Preferably, the ratio of the amount of the biphenyl aromatic carboxylic acid to the amount of the sulfonating agent is (0.01-1.0):1.0, preferably (0.25-1.0):1.0.

[0044] Preferably, the reaction temperature is 25-160°C. Considering the boiling point of the sulfonating agent and the difficulty of the sulfonation reaction of different raw materials, increasing the reaction temperature or extending the reaction time is conducive to improving the reaction efficiency, but the reaction temperature should not be higher than the boiling point of the sulfonating agent. The preferred reaction temperature is 120-160°C. The occurrence of the sulfonation reaction requires crossing a certain reaction barrier, especially the formation of sulfone needs to occur at a higher reaction temperature.

[0045] According to another aspect of the present invention, a method for synthesizing an aromatic carboxylic acid compound containing a benzothiophene sulfone group is provided, which is prepared according to the above-mentioned preparation method.

[0046] The present invention can adjust the spectral absorption range of the target product by adjusting the structure of the selected biphenyl aromatic carboxylic acid.

[0047] The present invention can adjust the photocatalytic hydrogen production performance of the product by selecting a target product with a suitable light absorption range and a suitable energy band structure.

[0048] According to another aspect of the present invention, there is provided an application of an aromatic carboxylic acid compound containing a benzothiophene sulfone group, wherein the application includes serving as a photocatalyst to catalyze water decomposition to produce hydrogen, water decomposition to produce oxygen, dye degradation, organic oxidation reaction, etc.

[0049] The present invention provides a method for preparing an aromatic carboxylic acid containing a benzothiophene sulfone group, wherein the biphenyl aromatic carboxylic acid is dispersed in a sulfonating agent such as concentrated sulfuric acid, fuming sulfuric acid or chlorosulfonic acid, and stirred for reaction at 25°C to 160°C for 12 to 72 hours. After the reaction is completed, the mixture is cooled to room temperature, poured onto crushed ice, filtered, washed with a large amount of water, and dried to obtain a yellow powder. The biphenyl aromatic carboxylic acid compound is one or more aromatic compounds containing a carboxylic acid functional group.

[0050] The preferred biphenyl aromatic carboxylic acid compounds in the present invention are divalent or polyvalent carboxyl-containing aromatic compounds, such as 4,4'-biphenyldicarboxylic acid, 4,4-dicarboxy-p-terphenyl, 3,4,9,10-pyrenetetracarboxylic acid, and the like.

[0051] According to the preparation method, aromatic carboxylic acid compounds containing different numbers of benzothiophene sulfone groups can be prepared.

[0052] The following are specific embodiments.

[0053] Example 1: Synthesis of 3,7-dibenzothiophenedicarboxylic acid, 5,5-dioxide

[0054] 1.0g of 4,4'-biphenyldicarboxylic acid was added to a 10mL round-bottom flask, and 3.0mL of concentrated sulfuric acid was added. The mixture was reacted at 120℃ for 12h to obtain a black mixed solution. The mixed solution was cooled to room temperature and poured into 100g of crushed ice. After stirring for 1h, it was allowed to stand for 1h. The white suspension was filtered to obtain a white solid. After washing with a large amount of water and drying, 1.1g of white product was collected, with a yield of about 87%. The obtained product is 3,7-dibenzothiophene dicarboxylic acid, 5,5-dioxide (such as Figure 1 ). 1 H-NMR (600MHz, DMSO-d6): 8.53 (d, J = 8.0 Hz, 2H), 8.50 (s, 2H), 8.46 (d, J = 8.0, 2H).

[0055] Example 2: Synthesis of 3,7-dibenzothiophenedicarboxylic acid, 5,5-dioxide

[0056] 1.0g of 4,4'-biphenyldicarboxylic acid was added to a 10mL round-bottom flask, and 3.0mL of 20% fuming sulfuric acid was added. The mixture was reacted at 140℃ for 12h to obtain a black mixed solution. After the mixed solution was cooled to room temperature, it was poured into 100g of crushed ice, stirred for 1h and then allowed to stand for 1h. The white suspension was filtered to obtain a white solid. After washing with a large amount of water and drying, 1.2g of white product was collected, with a yield of about 95%. The obtained product is 3,7-dibenzothiophene dicarboxylic acid, 5,5-dioxide (such as Figure 2 ). 1 H-NMR (600MHz, DMSO-d6): 8.53 (d, J = 8.0 Hz, 2H), 8.50 (s, 2H), 8.46 (d, J = 8.0, 2H). The powder X-ray diffraction pattern of the obtained organic crystal is as follows: Figure 7 .

[0057] Example 3: Synthesis of 3,7-dibenzothiophenedicarboxylic acid, 5,5-dioxide

[0058] 1.0g of 4,4'-biphenyldicarboxylic acid was added to a 10mL round-bottom flask, and 3.0mL of 50% fuming sulfuric acid was added. The mixture was reacted at 120℃ for 12h to obtain a black mixed solution. After the mixed solution was cooled to room temperature, it was poured into 100g of crushed ice, stirred for 1h and then allowed to stand for 1h. The white suspension was filtered to obtain a white solid. After washing with a large amount of water and drying, 1.2g of white product was collected, with a yield of about 95%. The obtained product is 3,7-dibenzothiophene dicarboxylic acid, 5,5-dioxide (such as Figure 2 ). 1 H-NMR (600MHz, DMSO-d6): 8.53 (d, J = 8.0 Hz, 2H), 8.50 (s, 2H), 8.46 (d, J = 8.0, 2H).

[0059] Example 4: Synthesis of 3,7-dibenzothiophenedicarboxylic acid, 5,5-dioxide

[0060] 1.0g 4,4'-biphenyldicarboxylic acid was added to a 10mL round-bottom flask, and 10.0mL chlorosulfonic acid was added. The mixture was reacted at 140℃ for 12h to obtain a black mixed solution. The mixed solution was cooled to room temperature and poured into 100g crushed ice. After stirring for 1h, it was allowed to stand for 1h. The white suspension was filtered to obtain a white solid. After washing with a large amount of water and drying, 1.2g of white product was collected. The yield was about 95%. The obtained product was 3,7-dibenzothiophene dicarboxylic acid, 5,5-dioxide (such as Figure 3 ). 1 H-NMR (600MHz, DMSO-d6): 8.53 (d, J = 8.0 Hz, 2H), 8.50 (s, 2H), 8.46 (d, J = 8.0, 2H).

[0061] Example 5: Synthesis of benzo[1,2-b:4,5-b']bis[1]benzothiophene-3,9-dicarboxylic acid, 5,5,11,11-tetraoxide

[0062] 1.0g of [p-terphenyl]-4,4'-dicarboxylic acid was added to a 10mL round-bottom flask, and 3.0mL of 20% fuming sulfuric acid was added. The mixture was reacted at 120℃ for 12h to obtain a black mixed solution. After the mixed solution was cooled to room temperature, it was poured into 100g of crushed ice, stirred for 1h and then allowed to stand for 1h. The yellow mixed solution was filtered to obtain a yellow solid. After washing with a large amount of water and drying, 1.3g of yellow product was collected, with a yield of about 93%. The obtained product is benzo[1,2-b:4,5-b']bis[1]benzothiophene-3,9-dicarboxylic acid, 5,5,11,11-tetraoxide (such as Figure 4 ). The organic crystal was characterized by NMR, and the obtained NMR spectrum was as follows Figure 6 As shown: 1 H-NMR (600 MHz, DMSO-d6): 9.07 (s, 2H), 8.35 (d, J = 8.0 Hz, 2H), 8.01-8.30 (t, 4H). The crystal structure of the organic crystal was characterized by powder X-ray diffraction. The PXRD curve of the obtained product is shown in Figure 8 shown.

[0063] Example 6: Synthesis of benzo[1,2-b:4,5-b']bis[1]benzothiophene-3,9-dicarboxylic acid, 5,5,11,11-tetraoxide

[0064] 1.0g of [p-terphenyl]-4,4'-dicarboxylic acid was added to a 10mL round-bottom flask, and 10.0mL of chlorosulfonic acid was added. The mixture was reacted at 140℃ for 12h to obtain a black mixed solution. The mixed solution was cooled to room temperature and poured into 100g of crushed ice. After stirring for 1h, it was allowed to stand for 1h. The yellow mixed solution was filtered to obtain a yellow solid. After washing with a large amount of water and drying, 1.2g of yellow product was collected. The yield was about 88%. The obtained product was benzo[1,2-b:4,5-b']bis[1]benzothiophene-3,9-dicarboxylic acid, 5,5,11,11-tetraoxide (such as Figure 5 ). 1 H-NMR (600MHz, DMSO-d6): 9.07 (s, 2H), 8.45 (d, J = 8.0Hz, 2H), 8.34 (t, 4H).

[0065] In order to test the photocatalytic hydrogen production effect of the organic photocatalyst prepared in the above examples, two comparative examples are combined to conduct practical application tests (photocatalytic water decomposition hydrogen production). Test Examples 1 and 2 are photocatalytic tests of organic crystals after sulfonation, and Comparative Examples 1 and Comparative Examples 2 are photocatalytic tests of raw materials before sulfonation.

[0066] Test Example 1: Weigh 10 mg of photocatalyst 3,7-dibenzothiophenedicarboxylic acid, 5,5-dioxide and add it to 100 mL of 1 mol / L ascorbic acid aqueous solution. After ultrasonic dispersion for 10 minutes, add 80 uL of 1% mass fraction chloroplatinic acid aqueous solution. Transfer to the online continuous photocatalytic system, turn on the light source for photocatalysis, take 100 uL of gas every 60 minutes, and analyze the gas composition through the online chromatography system. Calculate the hydrogen production rate based on the chromatographic area and concentration of the corresponding hydrogen. Among them, the light source of the reaction is a 300W xenon lamp light source with a wavelength of 300-720nm. The photocatalytic hydrogen production and time curve of the organic crystal is as shown in the figure. Fig. 9 As shown in Figure 2, after 5 h of illumination, the total hydrogen production was 12 μmol, and the calculated hydrogen production rate was 240 μmol g -1 h -1 .

[0067] Test Example 2: Weigh 10 mg of the photocatalyst benzo[1,2-b:4,5-b']bis[1]benzothiophene-3,9-dicarboxylic acid, 5,5,11,11-tetraoxide and add it to 100 mL of 1.0 mol / L ascorbic acid aqueous solution. After ultrasonic dispersion for 10 minutes, add 80 uL of 1% mass fraction chloroplatinic acid aqueous solution. Transfer to the online continuous photocatalytic system, turn on the light source for photocatalysis, take 100 uL of gas every 60 minutes, and analyze the gas composition through the online chromatography system. Calculate the hydrogen production rate based on the chromatographic area and concentration of the corresponding hydrogen. Among them, the light source of the reaction is a 300W xenon lamp light source with a wavelength of 300-720nm. The photocatalytic hydrogen production and time curve of the organic crystal is as shown in the figure. Fig.10 As shown in Figure 2, after 5 h of illumination, the total hydrogen production was 3000 μmol, and the calculated hydrogen production rate was 60000 μmol g -1 h -1 .

[0068] The following is a comparative example

[0069] Comparative Example 1

[0070] Weigh 10 mg of photocatalyst 4,4'-biphenyldicarboxylic acid and add it to 100 mL of 1 mol / L ascorbic acid aqueous solution. After ultrasonic dispersion for 10 minutes, add 80 uL of 1% mass fraction chloroplatinic acid aqueous solution. Transfer to the online continuous photocatalytic system, turn on the light source for photocatalysis, take 100 uL of gas every 60 minutes, and analyze the gas composition through the online chromatography system. Calculate the hydrogen production rate based on the chromatographic area and concentration of the corresponding hydrogen. Among them, the light source of the reaction is a 300W xenon lamp light source with a wavelength of 300-720nm. The photocatalytic hydrogen production of 4,4'-biphenyldicarboxylic acid versus time curve is shown in the figure. Fig.11 As shown in Figure 2, no hydrogen release was observed after 5 h of illumination. The calculated hydrogen production rate was 0 μmol g -1 h -1 .

[0071] Comparative Example 2

[0072] Weigh 10 mg of the photocatalyst [p-terphenyl]-4,4'-dicarboxylic acid and add it to 100 mL of 1 mol / L ascorbic acid aqueous solution. After ultrasonic dispersion for 10 minutes, add 80 uL of 1% mass fraction chloroplatinic acid aqueous solution. Transfer to the online continuous photocatalytic system, turn on the light source for photocatalysis, take 100 uL of gas every 60 minutes, and analyze the gas composition through the online chromatography system. Calculate the hydrogen production rate based on the chromatographic area and concentration of the corresponding hydrogen. Among them, the light source of the reaction is a 300W xenon lamp light source with a wavelength of 300-720nm. The photocatalytic hydrogen production of [p-terphenyl]-4,4'-dicarboxylic acid and time curve is shown in the figure. Fig.12As shown in Figure 2, after 5 h of illumination, the total amount of hydrogen produced was 5.4 μmol. The calculated hydrogen production rate was 110 μmol g -1 h -1 .

[0073] From the results of Example 1 and Comparative Example 1, it can be seen that after sulfonation, the photocatalytic hydrogen production performance was improved from 0 to 240 μmol g -1 h -1 That is, aromatic carboxylic acids that originally did not have photocatalytic properties, in the organic crystals prepared by sulfonation, have photocatalytic hydrogen production properties.

[0074] From the results of Example 2 and Comparative Example 2, it can be seen that after sulfonation, the photocatalytic hydrogen production performance increased from 110 μmol g -1 h -1 Increased to 60000 μmol g -1 h -1 That is, the photocatalytic hydrogen production performance of the organic crystals prepared by sulfonation was improved by 545 times.

[0075] These results fully demonstrate that the low-cost, simple organic crystals containing benzothiophene sulfone groups proposed in the present invention exhibit better photocatalytic performance. The photocatalytic performance before and after sulfonation, the photocatalytic performance of the target product after sulfonation is improved by 545 times. Compared with the previous polymer photocatalytic materials, the advantages of the photocatalyst proposed in the present invention are self-evident (such as high photocatalytic performance, simple synthesis, rich raw material sources, etc.), these advantages are expected to promote the application of such materials in the field of photoelectrocatalysis.

[0076] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. Application of benzothiophene sulfone organic crystals for photocatalytic hydrogen production, characterized in that: The benzothiophene sulfone organic crystal is prepared by the following method: A biphenyl aromatic carboxylic acid compound is subjected to a sulfonation reaction with a sulfonating agent, wherein the meta-positioning of the carboxylic acid group on the biphenyl aromatic carboxylic acid compound causes the sulfonation reaction to occur at the meta-position of the carboxyl group, and the biphenyl aromatic carboxylic acid compound is 4,4'-biphenyldicarboxylic acid and 4,4-dicarboxyl-p-terphenyl; at the same time, the biphenyl group causes the sulfonic acid group on the sulfonating agent to undergo an electrophilic reaction with an adjacent benzene ring to form a benzothiophene sulfone compound; The benzothiophene sulfone is:

2. The use according to claim 1, characterized in that The sulfonating agent is at least one of concentrated sulfuric acid, fuming sulfuric acid, chlorosulfonic acid, sulfur trioxide and a sulfur trioxide-pyridine complex.

3. The use according to claim 1, characterized in that The molar ratio of the biphenyl aromatic carboxylic acid compound to the sulfonating agent is (1-0.01):

1.

4. The use according to claim 1, characterized in that The temperature of the sulfonation reaction is lower than the boiling point of the sulfonating agent.

5. The use according to claim 1, characterized in that The temperature of the sulfonation reaction is 120-160°C.

Images