Thiophene-modified iron porphyrin polymer, and preparation method and photocatalytic application thereof

Abstract

The present application relates to the technical field of photocatalysis, and particularly relates to a thiophene-modified iron porphyrin polymer and a preparation method and photocatalytic application thereof. The present application discloses a thiophene-modified iron porphyrin polymer, which comprises the following raw materials: iron thiophene-based porphyrin, mesoporous graphite phase carbon nitride and an auxiliary agent, and the weight ratio of the iron thiophene-based porphyrin, the mesoporous graphite phase carbon nitride and the auxiliary agent is (1-1.2):100:(3-4). The present application discloses a thiophene-modified iron porphyrin polymer, which is loaded on the surface of mesoporous graphite phase carbon nitride by an in-situ chemical polymerization method, thereby solving the problem of instability of a current molecular catalyst; as a photocatalyst, the thiophene-modified iron porphyrin polymer can catalytically reduce carbon dioxide into carbon monoxide under visible light (lambda=420nm) excitation, can realize 120-hour ultra-long time stable catalysis, and the selectivity of the product carbon monoxide is as high as 98%, thereby solving the problem of difficult product separation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photocatalysis, and in particular to a thienyl-modified iron porphyrin polymer, a preparation method thereof and photocatalytic application thereof. BACKGROUND

[0002] In recent years, with the improvement of social living standards and the acceleration of industrialization, global energy consumption continues to grow, and is expected to reach 27 terawatts by 2050. Moreover, over-reliance on non-renewable fossil fuels to meet the growing demand for energy not only reduces limited resources, but also leads to a sharp increase in the concentration of carbon dioxide (CO2) in the atmosphere. From 1750 to 2023, the concentration of carbon dioxide in the atmosphere rose rapidly from 280 ppm to 422 ppm, which is the main factor causing global warming. Energy crisis and environmental problems have begun to affect people's lives. Therefore, finding new green energy to replace fossil energy has become one of the hot topics of current scientific research. In nature, plants use light energy to convert carbon dioxide into glucose; inspired by this, we can use solar energy to reduce carbon dioxide (CO2RR) into some useful raw materials (such as carbon monoxide, methane, methanol, formic acid, etc.), and this idea can realize the concept of "carbon neutralization". This not only makes use of and converts CO2 in the atmosphere, but also converts intermittent solar energy into storable chemical energy, which is a promising new method to solve environmental pollution and energy crisis.

[0003] However, the current traditional CO2RR catalyst still has the shortcomings of difficult product separation, unstable catalytic performance, etc., which limits the development of photocatalytic reduction of carbon dioxide. Therefore, it is of great practical and theoretical significance to develop a CO2RR photocatalyst with high product selectivity and stability.

[0004] Currently, organic molecular catalysts have high catalytic performance and selectivity, but their stability is weak and they are difficult to recover. Therefore, combining molecular catalysts with solid carriers is a simple and effective strategy that can not only retain the high selectivity and activity of molecular catalysts, but also take advantage of the stability and recyclability of solid carriers.

[0005] There is no related prior art report on thienyl-modified iron porphyrin polymers, their preparation methods and photocatalytic applications. SUMMARY

[0006] In order to overcome the deficiencies of the prior art, the application provides a thiophene-modified iron porphyrin polymer, which is prepared by loading polythiophene porphyrin on the surface of mesoporous graphite phase carbon nitride through an in-situ chemical polymerization method, thereby solving the problem of instability of the current molecular catalyst; as a photocatalyst, the thiophene-modified iron porphyrin polymer can catalytically reduce carbon dioxide into carbon monoxide under visible light (λ = 420 nm) excitation, can realize 120-hour ultra-long time stable catalysis, and the selectivity of the product carbon monoxide is as high as 98%, thereby solving the problem of difficult product separation.

[0007] The technical scheme adopted by the application to solve the technical problems is:

[0008] The first object of the application is to provide a thiophene-modified iron porphyrin polymer, which comprises the following raw materials:

[0009] The weight ratio of the iron thiophene-based porphyrin, the mesoporous graphite phase carbon nitride and the additive is (1-1.2) : 100 : (3-4).

[0010] In some embodiments, the additive is anhydrous ferric chloride.

[0011] In some embodiments, the preparation process of the iron thiophene-based porphyrin is as follows: 2-thiophene formaldehyde and pyrrole are added to a mixed solution for reaction; after the reaction is completed, thiophene-based porphyrin is obtained; the thiophene-based porphyrin and an iron source are reacted to obtain iron thiophene-based porphyrin.

[0012] In some embodiments, the molar ratio of the 2-thiophene formaldehyde and the pyrrole is 1:1.

[0013] In some embodiments, the 2-thiophene formaldehyde and the pyrrole are added to a mixed solution, and the reaction is carried out under reflux for 50-60 min; the mixed solution comprises acetic acid, propionic acid and nitrobenzene.

[0014] In some embodiments, the thiophene-based porphyrin and the iron source are subjected to reflux reaction for 4-5 h, and the iron source is ferrous chloride.

[0015] In some embodiments, the preparation process of the mesoporous graphite phase carbon nitride is as follows: cyanamide and a silica-containing aqueous solution are mixed, heated to 550-560 DEG C and kept at 550-560 DEG C for 4-5 h, and then subjected to dispersion, filtration and washing to obtain the mesoporous graphite phase carbon nitride.

[0016] In some embodiments, the mass ratio of the cyanamide and the silica is 1:1.

[0017] The second object of the application is to provide a preparation method of a thiophene-modified iron porphyrin polymer, which comprises the following steps:

[0018] S1. Preparation of iron thienyl porphyrin

[0019] 2-thiophenecarboxaldehyde and pyrrole are added to the mixed solution to react, and after the reaction is completed, thienyl porphyrin is obtained; the thienyl porphyrin is reacted with an iron source to obtain iron thienyl porphyrin;

[0020] S2. Preparation of mesoporous graphite phase carbon nitride

[0021] The cyanamide and the aqueous solution containing silicon dioxide are mixed, heated to 550-560 DEG C and kept at 550-560 DEG C for 4-5 h, and then dispersed, filtered and washed to obtain mesoporous graphite phase carbon nitride;

[0022] S3. Thienyl modified iron porphyrin polymer

[0023] The mesoporous graphite phase carbon nitride is dispersed, iron thienyl porphyrin and an auxiliary agent are added, and reacted at 40-50 DEG C for 24-30 h to obtain a thienyl modified iron porphyrin polymer.

[0024] A third object of the present application is to provide a photocatalytic application of the thienyl modified iron porphyrin polymer, wherein the thienyl modified iron porphyrin polymer is used as a photocatalyst to catalytically reduce carbon dioxide to carbon monoxide under visible light irradiation.

[0025] The present application has the following advantages:

[0026] 1. The thienyl modified iron porphyrin polymer provided by the present application solves the problem of instability of current molecular catalysts by loading polythienyl porphyrin onto the surface of mesoporous graphite phase carbon nitride through in-situ chemical polymerization.

[0027] 2. The thienyl modified iron porphyrin polymer provided by the present application uses mesoporous graphite phase carbon nitride as a carrier, and the photo-generated electrons can be transferred to the metal catalytic site of thienyl porphyrin after being excited by visible light, thereby avoiding a large amount of electron-hole recombination and improving the catalytic activity.

[0028] 3. The thienyl modified iron porphyrin polymer provided by the present application is used as a photocatalyst, and can catalytically reduce carbon dioxide to carbon monoxide under visible light (λ = 420 nm) excitation, can realize 120-hour ultra-long time stable catalysis, and the selectivity of the product carbon monoxide is as high as 98%, thereby solving the problem of difficult product separation.

[0029] 4. The thienyl modified iron porphyrin polymer provided by the present application has good absorption in the visible light region when used as a catalyst, thereby solving the problem of needing to use ultraviolet light catalysis for traditional inorganic semiconductors, and greatly improving the light utilization rate. BRIEF DESCRIPTION OF DRAWINGS

[0030] The present application will be further described below in conjunction with the drawings and examples.

[0031] Figure 1 NMR chart of thienyl porphyrin prepared for Example 1;

[0032] Figure 2 X-ray powder diffraction (XRD) chart of mpg-CN and p-FeTThP|mpg-CN prepared for Example 1;

[0033] Figure 3 UV-visible absorption spectrum of p-FeTThP|mpg-CN catalyst prepared for Example 1;

[0034] Figure 4 TEM chart of p-FeTThP|mpg-CN catalyst prepared for Example 1;

[0035] Figure 5 Chart of the amount of CO produced by photocatalysis of CO2 under visible light conditions with respect to time for p-FeTThP|mpg-CN catalyst prepared for Example 1;

[0036] Figure 6 Chart of the amount of CO and selectivity produced by photocatalysis of CO2 under visible light conditions for p-FeTThP|mpg-CN catalyst prepared for Example 1;

[0037] Figure 7 Chart of the amount of CO produced by photocatalysis of CO2 under visible light conditions with respect to time for p-FeTThP|mpg-CN catalyst prepared for Example 1, in which the ratio of FeTThP is 1.2;

[0038] Figure 8 Chart of the amount of CO produced when FeTThP prepared for Comparative Example 1 and p-FeTThP|mpg-CN prepared for Example 1 are irradiated with visible light for 24 hours;

[0039] Figure 9 Chart of the amount of CO and H2 produced when mpg-CN prepared for Comparative Example 2 and p-FeTThP|mpg-CN prepared for Example 1 are irradiated with visible light for 24 hours. DETAILED DESCRIPTION

[0040] In order to facilitate the understanding of those skilled in the art, the present application is further described below in conjunction with examples, and the content mentioned in the embodiments is not a limitation of the present application.

[0041] As used herein, “and / or” includes all combinations of any and one or more of the associated listed items. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a,” “an,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. Further understanding is needed; when used in this specification, “comprising” designates the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof.

[0042] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Further understanding is that terms, such as those defined in common dictionaries, are interpreted in accordance with their meaning in the context of the relevant field and are not idealized or overly formal, unless expressly defined herein.

[0043] The exemplary invention described herein may suitably omit any one or more limiting elements, which are not specifically disclosed herein. Therefore, terms such as “comprising,” “including,” “containing,” etc., should be interpreted broadly and non-limitingly. Furthermore, the terminology used herein is for descriptive purposes without limitation, and it is unintentional to use terms that do not include any equivalent characteristics, but only to describe a portion of their characteristics; however, various modifications are possible within the scope of the invention according to the claims. Therefore, while the invention has been specifically disclosed through preferred embodiments and optional features, variations of the invention embodied by the modifications disclosed herein may be noted by those skilled in the art, and such modifications and variations are considered to be within the scope of the invention.

[0044] All raw materials or reagents used in the embodiments and comparative examples of this invention were purchased from mainstream manufacturers on the market. Those without specified manufacturers or concentrations are all analytical grade raw materials or reagents that are routinely available. There are no particular restrictions as long as they achieve the expected effect. The instruments and equipment used in this embodiment were all purchased from major manufacturers on the market. There are no particular limitations as long as they achieve the expected effect. Where specific techniques or conditions are not specified in this embodiment, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions.

[0045] The activity of the current photocatalyst is prone to decrease after long-term use, resulting in reduced catalytic efficiency; and many inorganic semiconductor photocatalysts need to be excited by ultraviolet light, but the proportion of ultraviolet light in sunlight is low, which limits the practical application of the catalyst. Therefore, the application provides a thiophene modified iron porphyrin polymer for a photocatalyst, which comprises the following raw materials: iron thiophene-based porphyrin, mesoporous graphite phase carbon nitride, and an auxiliary agent, and the weight ratio of the iron thiophene-based porphyrin, mesoporous graphite phase carbon nitride, and auxiliary agent is (1-1.2):100:(3-4).

[0046] Specifically, the weight ratio of the iron thiophene-based porphyrin, mesoporous graphite phase carbon nitride, and auxiliary agent is 1:100:3, for example, the weight ratio of the iron thiophene-based porphyrin, mesoporous graphite phase carbon nitride, and auxiliary agent can be 1.2:100:4, or the weight ratio of the iron thiophene-based porphyrin, mesoporous graphite phase carbon nitride, and auxiliary agent can be 1.1:100:3.5, or the weight ratio of the iron thiophene-based porphyrin, mesoporous graphite phase carbon nitride, and auxiliary agent can be 1:100:4.

[0047] The current traditional molecular catalysts such as iron porphyrin have high catalytic activity, but often have poor stability. The above technical solution combines iron thiophene-based porphyrin with mesoporous graphite phase carbon nitride, utilizes the stability and carrier effect of mpg-CN, and significantly improves the overall stability of the catalyst. Even under long-term light and reaction conditions, the catalyst can maintain high catalytic performance.

[0048] As a metal-free organic photosensitizer, mesoporous graphite phase carbon nitride (mpg-CN) has excellent stability and visible light response capability. The mesoporous structure not only increases the specific surface area and improves the adsorption performance of the catalyst, but also provides abundant sites for the loading of iron thiophene-based porphyrin. Under visible light irradiation, mpg-CN can generate photo-generated electrons and holes, and these photo-generated electrons can be rapidly transferred to the catalytic site of FeTThP through the conduction band of mpg-CN to participate in the reduction reaction of carbon dioxide.

[0049] Therefore, in the application, iron thiophene-based porphyrin (FeTThP) is polymerized on the surface of mesoporous graphite phase carbon nitride (mpg-CN) by in-situ chemical polymerization, which not only realizes the close combination of molecular catalyst and solid carrier, but also promotes the effective separation and transfer of photo-generated electrons and holes; this method avoids the rapid recombination of electrons and holes in traditional catalysts, improves the catalytic efficiency. At the same time, the polymerization process enhances the structural stability of the catalyst, so that it can maintain high catalytic performance for a long time.

[0050] The preparation method of the above-mentioned thiophene modified iron porphyrin polymer comprises the following steps:

[0051] S1. Preparation of iron thiophene-based porphyrin

[0052] 2-thiophenecarboxaldehyde, pyrrole are added to the mixed solution, and the reaction is carried out under reflux for 50-60 min; after the reaction is completed, a thiophene-based porphyrin (TThP) is obtained; the thiophene-based porphyrin and an iron source are reacted under reflux for 4-5 h to obtain an iron thiophene-based porphyrin (FeTThP);

[0053] S2. Preparation of mesoporous graphite phase carbon nitride

[0054] The cyanamide and the aqueous solution containing silicon dioxide are mixed, heated to 550-560℃ and kept at 550-560℃ for 4-5 h, and then dispersed, filtered and washed to obtain mesoporous graphite phase carbon nitride;

[0055] S3. Thiophene-modified iron porphyrin polymer

[0056] The mesoporous graphite phase carbon nitride is dispersed, the iron thiophene-based porphyrin and an auxiliary agent are added, and the reaction is carried out at 40-50℃ for 24-30 h to obtain a thiophene-modified iron porphyrin polymer.

[0057] Specifically, in step S1, the molar ratio of 2-thiophenecarboxaldehyde and pyrrole is 1:1, and the volume of the mixed solution added is 10 times the volume of pyrrole; the volume ratio of acetic acid, propionic acid and nitrobenzene in the mixed solution is 4:4:1; and the iron source is ferrous chloride;

[0058] It can be understood that the preparation of TThP is to further introduce iron ions through metallization reaction (reaction with FeCl2·4H2O) to obtain FeTThP with higher catalytic activity and selectivity; in addition, the introduction of TThP can also enhance the electronic conductivity and stability of the material, which is crucial for improving the performance of the final photocatalyst in the photocatalytic reduction of carbon dioxide.

[0059] In this application, 2-thiophenecarboxaldehyde is selected as the aldehyde compound, which contains a thiophene ring, a heterocyclic ring with a conjugated structure, which can effectively enhance the stability and electronic conductivity of the molecule;

[0060] Mixed solvent selection: a mixed solution of acetic acid, propionic acid and nitrobenzene is used as the reaction solvent. The selection of these solvents is based on their solubility to the reactants, control of the reaction process and convenience of subsequent processing; acetic acid and propionic acid act as protic solvents, which help the condensation reaction of pyrrole and aldehyde compounds; nitrobenzene acts as an aprotic solvent, which can adjust the polarity of the reaction system and promote the precipitation of the product.

[0061] Reaction condition control: the reaction is carried out under heating and reflux conditions, and by controlling the reaction time and temperature, the reaction is ensured to proceed fully and avoid the generation of by-products. After the reaction is completed, the product is precipitated by natural cooling and methanol standing.

[0062] Post-processing and purification: high-purity TThP is obtained by vacuum filtration, hot water and ethanol washing, and silica gel column chromatography. The key of this step is to remove impurities to ensure the purity of the product and the smooth progress of the subsequent reaction.

[0063] Specifically, in step S2, the mass ratio of cyanamide to silicon dioxide is 1:1, the dispersion liquid is NH4HF2 solution, and the mass fraction of NH4HF2 solution is 15%.

[0064] Specifically, in step S3, the weight ratio of iron thiophene-based porphyrin, mesoporous graphite phase carbon nitride, and adjuvant is (1-1.2):100:(3-4)

[0065] On the other hand, the application also provides a photocatalytic application of thiophene-modified iron porphyrin polymer. The thiophene-modified iron porphyrin polymer described above is used as a photocatalyst to catalytically reduce carbon dioxide to carbon monoxide under visible light irradiation. That is, the thiophene-modified iron porphyrin polymer can realize the reduction of CO2 to CO with high selectivity and for a long time under visible light, and has a wide application prospect.

[0066] Specifically, the application method is to use acetonitrile as the solvent, 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole (BIH) as the sacrificial agent, and add thiophene-modified iron porphyrin polymer to realize the reduction of CO2 to CO under visible light without adding any cocatalyst.

[0067] Moreover, the traditional photocatalytic reduction of carbon dioxide often accompanies the generation of multiple by-products, resulting in low selectivity of the target product. In the present application, by optimizing the structure of iron thiophene-based porphyrin and the reaction conditions, high selectivity of CO generation is realized; experimental results show that under visible light irradiation, the p-FeTThP|mpg-CN catalyst can efficiently reduce CO2 to CO with a selectivity as high as 98%.

[0068] Example 1

[0069] A preparation method of a thiophene-modified iron porphyrin polymer, comprising the following steps:

[0070] S1. Preparation of iron thiophene-based porphyrin

[0071] To a mixture of 2.8 mL (0.03 mol) of 2-thiophenecarboxaldehyde and 2.07 mL (0.03 mol) of freshly distilled pyrrole in 60 mL of acetic acid, 60 mL of propionic acid and 15 mL of nitrobenzene, reflux for 55 min, then cool to room temperature naturally, add 25 mL of methanol and stand overnight. After filtration under reduced pressure, the precipitate is washed with hot water and ethanol respectively until the filtrate is colorless. The crude product is purified by silica gel column chromatography (dichloromethane as eluent) to obtain a purple-black powder.

[0072] 100 mg of thiophene porphyrin and 94 mg of FeCl2·4H2O are added to 100 mL of N,N-dimethylformamide (DMF) and refluxed for 4 h. After the reaction is completed, the organic solvent is removed by distillation under reduced pressure. The obtained solid is washed with water until it is colorless to obtain a purple-black solid (iron thiophene porphyrin FeTThP).

[0073] S2. Preparation of mpg-CN

[0074] A 40% aqueous solution of 4 g of SiO2particles is mixed with 4 g of cyanamide and stirred at 60°C overnight to obtain a white mixture. The white mixture is heated to 550°C at a temperature of 2.3°C / min, and kept at this temperature for 4 h. The obtained powder is dispersed in a 15% aqueous solution of NH4HF2and stirred overnight, and then filtered and washed with distilled water and ethanol respectively until the filtrate is neutral. After drying, a yellow powder of mpg-CN is obtained.

[0075] S3. Preparation of iron thiophene porphyrin polymer modified mpg-CN composite photocatalyst (p-FeTThP|mpg-CN)

[0076] The above prepared 100 mg of mpg-CN is dispersed in 40 mL of CHCl3for 30 min to obtain a dispersion of mpg-CN; 1 mg of FeTThP is dissolved in 10 mL of CHCl3to obtain a dispersion of FeTThP, and the dispersion of FeTThP is added to the above dispersion of mpg-CN, and ultrasonic treatment is performed for 30 min to obtain a mixed solution;

[0077] A CHCl3solution containing 3 mg of anhydrous FeCl3is added to the mixed solution, and the reaction is carried out at 40°C for 24 h under Ar protection. During the reaction, the suspension changes from yellow to dark gray. After the reaction is completed, it is cooled to room temperature and filtered. The filter cake is washed with CHCl3and distilled water respectively until the filtrate is colorless. After drying, a composite photocatalyst is obtained.

[0078] Example 2

[0079] A preparation method of a thiophene modified iron porphyrin polymer, comprising the following steps:

[0080] In S3. Preparation of iron thiophene porphyrin polymer modified mpg-CN composite photocatalyst (p-FeTThP|mpg-CN), the weight ratio of FeTThP, mpg-CN, anhydrous FeCl3 is 1.2:100:4, and the rest of the conditions are consistent with Example 1.

[0081] Example 3

[0082] A preparation method of a thiophene modified iron porphyrin polymer, comprising the following steps:

[0083] In S3. Preparation of iron thiophene porphyrin polymer modified mpg-CN composite photocatalyst (p-FeTThP|mpg-CN), the weight ratio of FeTThP, mpg-CN, anhydrous FeCl3 is 1.1:100:3.5, and the rest of the conditions are consistent with Example 1.

[0084] Example 4

[0085] A preparation method of a thiophene modified iron porphyrin polymer, comprising the following steps:

[0086] In S3. Preparation of iron thiophene porphyrin polymer modified mpg-CN composite photocatalyst (p-FeTThP|mpg-CN), the weight ratio of FeTThP, mpg-CN, anhydrous FeCl3 is 1:100:4, and the rest of the conditions are consistent with Example 1.

[0087] Comparative Example 1

[0088] A preparation method of a thiophene modified iron porphyrin polymer, comprising the following steps:

[0089] S1. Preparation of iron thiophene porphyrin polymer

[0090] 2.8 mL (0.03 mol) of 2-thiophene formaldehyde and 2.07 mL (0.03 mol) of freshly distilled pyrrole were simultaneously added to a mixed solution of 60 ml of acetic acid, 60 ml of propionic acid and 15 ml of nitrobenzene, and after refluxing for 55 minutes, the reaction was naturally cooled to room temperature, 25 ml of methanol was added and left overnight. After filtration under reduced pressure, the precipitate was washed with hot water and ethanol respectively until the filtrate was colorless, and the crude product was purified by silica gel column chromatography (dichloromethane as eluent) to obtain a purple black powder.

[0091] 100 mg of thiophene porphyrin and 94 mg of FeCl2·4H2O were added to 100 mL of N,N-dimethylformamide (DMF), and refluxed for 4 hours. After the reaction was completed, the organic solvent was removed by distillation under reduced pressure. The obtained solid was washed with water until it was colorless to obtain a purple black solid (iron thiophene porphyrin FeTThP).

[0092] Comparative Example 2

[0093] Preparation of mesoporous graphite phase carbon nitride, comprising the following steps:

[0094] After mixing 4 g of cyanamide with 4 g of SiO2 particles in a 40% aqueous solution, a white mixture was obtained by stirring overnight at 60°C. The white mixture was heated to 550°C at a temperature of 2.3°C / min, and the temperature was maintained for 4 h. The obtained powder was dispersed in a 15% aqueous NH4HF2 solution and stirred overnight, and then washed with distilled water and ethanol until neutral, and dried to obtain a yellow powder of mpg-CN.

[0095] Application Example

[0096] 2 mg of p-FeTThP|mpg-CN of any one of Examples 1-4 and Comparative Examples 1-2 was weighed, 28 mg of BIH and 10 ml of acetonitrile were added, and ultrasonic treatment was performed for 10 minutes. It was put into a 35 ml quartz glass reactor. The reactor was purged with 25 minutes of ultra-pure CO2 gas, and was irradiated with 10 W LED simulated visible light (λ = 420 nm). During the photocatalytic reaction, the gas composition after photocatalytic reaction was detected at intervals until the end of 120 hours.

[0097] wherein, Figure 1 is the thienyl porphyrin nuclear magnetic resonance chart prepared in Example 1; from Figure 1 As can be seen in the figure, there are seven groups of peaks in total, of which the single peak at 7.26 ppm is the deuterated reagent chloroform, and the single peak at 1.6 ppm is the solvent peak remaining during the experiment; the remaining five groups of peaks are all attributed to thienyl porphyrin, of which the single peak at 9.04 ppm corresponds to the peripheral hydrogen of the pyrrole in the porphyrin, and the multiple peaks at 7.91-7.93, 7.86-7.88, 7.51-7.53 ppm are attributed to the three hydrogens of the thienyl group in the porphyrin, and the single peak at -2.65 ppm is the two uncoordinated hydrogens in the inner ring of the porphyrin; and their peak area ratio is 4:2:2:2:1, proving that the thienyl porphyrin is successfully synthesized.

[0098] Figure 2 is the X-ray powder diffraction (XRD) chart of mpg-CN and p-FeTThP|mpg-CN prepared in Example 1; from Figure 2 As can be seen in the figure, compared with mpg-CN, the 002 crystal face peak of the p-FeTThP|mpg-CN catalyst is obviously decreased, indicating that the iron thienyl porphyrin is successfully polymerized on the surface of mpg-CN, causing the periodic structure of mpg-CN to be destroyed;

[0099] Figure 3 is the ultraviolet-visible absorption spectrum of the p-FeTThP|mpg-CN catalyst prepared in Example 1; from Figure 3 As can be seen in the figure, it is indicated that the p-FeTThP|mpg-CN has obvious visible light response;

[0100] Figure 4 TEM image of p-FeTThP|mpg-CN catalyst prepared in Example 1;

[0101] Figure 5 The graph of the yield of CO2 photocatalytic reduction to CO by p-FeTThP|mpg-CN catalyst prepared in Example 1 under visible light condition over time; it can be seen from the graph that the yield of CO increases steadily over time within 120 hours, indicating that the catalyst has catalytic stability, which meets the actual application;

[0102] Figure 6 The graph of the yield and selectivity of CO2 photocatalytic reduction to CO by p-FeTThP|mpg-CN catalyst prepared in Example 1 under visible light condition; it can be seen from the graph that the turnover number (TON) of CO production is 1033 and the selectivity is as high as 98% at 120 hours.

[0103] Figure 7 The graph of the yield of CO2 photocatalytic reduction to CO by p-FeTThP|mpg-CN catalyst prepared in Example 1 with FeTThP ratio of 1.2 under visible light condition over time; it can be seen from the graph that the yield of CO also increases steadily over time within 120 hours, but the TON of CO production is 835 at 120 hours, which is less than that of p-FeTThP|mpg-CN photocatalyst with FeTThP ratio of 1.

[0104] Figure 8 The graph of the yield of CO by FeTThP prepared in Comparative Example 1 and p-FeTThP|mpg-CN prepared in Example 1 under visible light irradiation for 24 hours; it can be seen from the graph that the TON of CO production by FeTThP is only 2.65 in 24 hours, which is much less than 37.87 of p-FeTThP|mpg-CN, indicating that the addition of carrier mpg-CN accelerates electron transfer and improves catalytic activity.

[0105] Figure 9 The graph of the yield of CO and H2 by mpg-CN prepared in Comparative Example 2 and p-FeTThP|mpg-CN prepared in Example 1 under visible light irradiation for 24 hours; it can be seen from the graph that the yield of CO by mpg-CN is 99 μmol / g in 24 hours, but the selectivity of CO is only 50%; when FeTThP is introduced in situ, the yield of CO reaches 280 μmol / g and the selectivity of CO is improved to more than 90%; it indicates that FeTThP as the reaction center of CO2 reduction reduces the energy barrier and improves the catalytic performance.

[0106] The above embodiments are the preferred implementation of the present application, in addition to this, the present application can be implemented in other ways, any obvious replacement without departing from the concept of the present application is within the protection scope of the present application.

Claims

1. A thienyl-modified iron porphyrin polymer, characterized by, It comprises the following raw materials: Iron thiophene-based porphyrin, mesoporous graphite phase carbon nitride, and an auxiliary agent, the weight ratio of the iron thiophene-based porphyrin, mesoporous graphite phase carbon nitride, and auxiliary agent being (1-1.2):100:(3-4); The auxiliary agent is anhydrous ferric chloride; The preparation process of the thiophene-modified iron porphyrin polymer comprises dispersing mesoporous graphite phase carbon nitride, adding iron thiophene-based porphyrin and an auxiliary agent, and reacting at 40-50°C for 24-30 hours to obtain a thiophene-modified iron porphyrin polymer.

2. The thienyl-modified iron porphyrin polymer of claim 1, wherein, The preparation process of the iron thiophene-based porphyrin comprises adding 2-thiophene formaldehyde and pyrrole into a mixed solution and reacting; after the reaction is completed, thiophene-based porphyrin is obtained; and the thiophene-based porphyrin is reacted with an iron source to obtain iron thiophene-based porphyrin.

3. A thienyl-modified iron porphyrin polymer according to claim 2, wherein The molar ratio of the 2-thiophene formaldehyde and pyrrole is 1:

1.

4. The thienyl-modified iron porphyrin polymer of claim 2, wherein, The 2-thiophene formaldehyde and pyrrole are added into a mixed solution and reacted under reflux for 50-60 minutes; the mixed solution comprises acetic acid, propionic acid, and nitrobenzene.

5. The thienyl-modified iron porphyrin polymer of claim 2, wherein, The thiophene-based porphyrin is refluxed with the iron source for 4-5 hours, and the iron source is ferrous chloride.

6. The thienyl-modified iron porphyrin polymer of claim 1, wherein, The preparation process of the mesoporous graphite phase carbon nitride comprises mixing cyanamide and a silica-containing aqueous solution, heating to 550-560°C and maintaining at 550-560°C for 4-5 hours, and then dispersing, filtering, and washing to obtain mesoporous graphite phase carbon nitride; In the dispersing process, a dispersing solution NH4HF2 solution is used.

7. A thienyl-modified iron porphyrin polymer according to claim 6, wherein The mass ratio of the cyanamide and silica is 1:

1.

8. A process for the preparation of a thienyl-modified iron porphyrin polymer according to any one of claims 1 to 7, characterized in that, It comprises the following steps: S1. Preparation of iron thiophene-based porphyrin 2-thiophene formaldehyde and pyrrole are added into a mixed solution and reacted; after the reaction is completed, thiophene-based porphyrin is obtained; and the thiophene-based porphyrin is reacted with an iron source to obtain iron thiophene-based porphyrin; S2. Preparation of mesoporous graphite phase carbon nitride Cyanamide and a silica-containing aqueous solution are mixed, heated to 550-560°C and maintained at 550-560°C for 4-5 hours, and then dispersed, filtered, and washed to obtain mesoporous graphite phase carbon nitride; in the dispersing process, a dispersing solution NH4HF2 solution is used; S3. Thiophene-modified iron porphyrin polymer Mesoporous graphite phase carbon nitride is dispersed, iron thiophene-based porphyrin and an auxiliary agent are added, and the mixture is reacted at 40-50°C for 24-30 hours to obtain a thiophene-modified iron porphyrin polymer.

9. Photocatalytic applications of thienyl-modified iron porphyrin polymers characterized in that, The thiophene-modified iron porphyrin polymer of any one of claims 1-7 or prepared by the preparation method of claim 8 is used as a photocatalyst, Carbon dioxide is catalytically reduced to carbon monoxide under visible light irradiation.

Images