A metalloporphyrin structure, a preparation method thereof and application thereof in preparation of a photocatalyst

Abstract

The application provides a metal porphyrin structure, a preparation method thereof and application in preparation of a photocatalyst, and belongs to the technical field of photocatalyst preparation; the application provides a metal porphyrin structure, which is an asymmetric metal porphyrin structure containing a lone pair of electrons; the application also loads the metal porphyrin structure on a semiconductor material to obtain a metal porphyrin / semiconductor composite photocatalyst; the metal porphyrin / semiconductor composite photocatalyst has the characteristics of simple synthesis and preparation method, low cost, high repeatability, green and environment-friendly production process and the like; the metal porphyrin / semiconductor composite photocatalyst can realize rapid and efficient reduction of organic pollutants in water.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photocatalyst preparation, and particularly relates to a metal porphyrin structure, a preparation method thereof and application thereof in photocatalyst preparation. BACKGROUND

[0002] Heterogeneous photocatalysis is an environmentally friendly water purification technology, and is expected to be applied to a new generation of water treatment technology. In the heterogeneous photocatalysis technology, pollutants in water can be converted, sterilized, disinfected and degraded through photocatalytic degradation. However, in the current research, the photocatalyst applied to the photodegradation of organic pollutants still has some shortcomings, such as ① the photocatalyst has a narrow ultraviolet light absorption range and low light energy utilization rate; ② the photocatalyst has low efficiency and can only degrade a small part of the pollutants; and ③ the photocatalyst has poor durability and its performance will decrease in a long-term use process. Therefore, it is still challenging to develop a photocatalyst with high activity, low cost, high selectivity and durability.

[0003] Semiconductor materials such as TiO2, ZnO and C3N4 have the characteristics of low cost, safety, stability and wide application, have strong ultraviolet absorption capacity, and are one of the key components for degrading harmful substances in wastewater in photocatalysts. However, the above semiconductor materials have the disadvantage of too narrow energy gap width, and therefore, a photosensitizer for enhancing the light trapping ability of the photocatalyst needs to be introduced in the preparation process of the photocatalyst. The ideal photosensitizer should meet the following requirements: ① wide visible light absorption; ② appropriate charge transfer interface energy level distribution; ③ long electron injection lifetime; and ④ uniform composite morphology. Porphyrin, which can be easily modified in structure and meets the above conditions, is a good photosensitizer and is therefore often used to construct photocatalysts.

[0004] The π-system heteroaromaticity of porphyrin endows the porphyrin molecule with efficient light absorption performance, ultrafast electron transfer properties and unique biological catalytic activity. The preparation of new metal porphyrin composite materials can further develop research in the fields of biology, chemistry, optoelectronics and medicine. Generally, metal porphyrin has better electron injection, dye regeneration level and better stability, and is more suitable for use in photocatalytic degradation than free radical porphyrin. Moreover, the porphyrin ring can be easily modified at the meso-position, β-position and central metal. Therefore, the electronic state and spatial form of the molecule can be reasonably designed to promote the transfer on the charge catalytic interface. At present, among the common photocatalytic metal porphyrins, zinc porphyrin, manganese porphyrin and copper porphyrin show considerable application potential in light trapping, stability and interface electron transfer dynamics.

[0005] Therefore, it is necessary to design a new photocatalyst with a wide light response range, efficient photo-generated carrier separation, low cost and no secondary pollution based on the metal porphyrin structure. SUMMARY

[0006] In order to solve the problems in the prior art, the application provides a metal porphyrin structure, a preparation method thereof and application thereof in preparation of a photocatalyst, and the metal porphyrin structure is an asymmetric metal porphyrin structure containing a lone pair of electrons.

[0007] In order to achieve the above object, the application adopts the following technical scheme.

[0008] The application provides a metal porphyrin structure, and the metal porphyrin structure is an asymmetric metal porphyrin structure containing a lone pair of electrons, and a structure formula of the metal porphyrin structure is shown as compound I.

[0009]

[0010] In the structure formula, R1 includes a group containing a lone pair of electrons.

[0011] R2, R3, R4, R5 and R6 include normal alkyl or isomeric alkyl containing 0-4 carbon atoms.

[0012] M includes zinc, manganese or copper.

[0013] Preferably, the group containing a lone pair of electrons includes any one of thiophene, pyridine, furan, pyrimidine and 2,1,3-benzothiadiazole or a derivative group of any one of the above.

[0014] The application further provides a synthesis method of the metal porphyrin structure, and the synthesis method specifically includes the following steps.

[0015] (1) mixing compound II, pyrrole and dilute hydrochloric acid, then performing a first condensation reaction under stirring, and obtaining a first intermediate A after the reaction is completed, for standby;

[0016] mixing compound III, neopentyl glycol, p-toluenesulfonic acid, anhydrous copper sulfate and toluene, then performing a second condensation reaction under stirring, and obtaining a second intermediate B after the reaction is completed;

[0017] The structure formula of the compound II is shown as follows: The structure formula of the first intermediate A is shown as follows:

[0018] The structure formula of the compound III is shown as follows: The structure formula of the second intermediate B is shown as follows:

[0019] (2) The first intermediate A, the second intermediate B, the compound IV and anhydrous dichloromethane are mixed uniformly under N2protection, then trifluoroacetic acid is added dropwise, after the end of dropwise addition, the first stirring reaction is carried out under light shielding condition, and a mixed solution is obtained after the reaction is completed;

[0020] The mixed solution is added with tetrachloroquinone under atmospheric condition, then the second stirring reaction is carried out under light shielding condition, and the third intermediate C is obtained after the reaction is completed;

[0021] The structural formula of the compound IV is The structural formula of the third intermediate C is

[0022]

[0023] (3) The third intermediate C, dichloromethane, water and trifluoroacetic acid are mixed uniformly for hydrolysis reaction, and the fourth intermediate D is obtained after the reaction is completed;

[0024] The structural formula of the fourth intermediate D is

[0025] (4) The fourth intermediate D, a metal salt, ammonium acetate, cyanoacetic acid, chloroform and glacial acetic acid are subjected to coordination reaction under heating condition, and the metal porphyrin structure is obtained after the reaction is completed;

[0026] The metal in the metal salt includes zinc, manganese or copper.

[0027] Preferably, in step (1), the use amount ratio of the compound II, the pyrrole and the dilute hydrochloric acid is 1-1.5 mmol: 6-9 mmol: 20-30 mL; wherein the concentration of the hydrochloric acid is 0.15M-0.20M;

[0028] The condition of the first condensation reaction is: stirring under N2protection and light shielding for 8-12h;

[0029] The use amount ratio of the compound III, neopentyl glycol, p-toluenesulfonic acid, anhydrous copper sulfate and toluene is 7.20-7.50 mmol: 10.00-11.00 mmol: 10-30 mg: 1-2 g: 20-30 mL;

[0030] The condition of the second condensation reaction is: heating to 110-130℃ to reflux, then stirring for 8-48h.

[0031] Preferably, the use amount ratio of the compound II, the pyrrole and the dilute hydrochloric acid is 1 mmol: 6 mmol: 20 mL;

[0032] The compound III, neopentyl glycol, p-toluenesulfonic acid, anhydrous copper sulfate and toluene are used in a ratio of 7.37 mmol: 10.60 mmol: 10 mg: 1.5 g: 20 mL;

[0033] The reaction time of the second condensation reaction is 23 h.

[0034] Preferably, in step (2), the first intermediate A, the second intermediate B, the compound IV, the tetrachlorobenzoquinone, the trifluoroacetic acid and the anhydrous dichloromethane are used in a ratio of 1-1.2 mmol: 0.5-0.6 mmol: 0.5-0.6 mmol: 1-1.5 mmol: 180-300 μL: 100 mL;

[0035] The time of the first stirring reaction is 1-1.5 h;

[0036] The time of the second stirring reaction is 1-1.5 h.

[0037] Preferably, the first intermediate A, the second intermediate B, the compound IV, the tetrachlorobenzoquinone, the trifluoroacetic acid and the anhydrous dichloromethane are used in a ratio of 1 mmol: 0.5 mmol: 0.5 mmol: 1.5 mmol: 180 μL: 100 mL;

[0038] The time of the first stirring reaction is 1 h;

[0039] The time of the second stirring reaction is 1 h.

[0040] Preferably, in step (3), the third intermediate C, dichloromethane, water, trifluoroacetic acid are used in a ratio of 0.1-0.15 mmol: 15-20 mL: 1-2 mL: 9-15 mL;

[0041] The condition of the hydrolysis reaction is stirring under N2 protection and avoiding light for 1-5 h.

[0042] Preferably, the third intermediate C, dichloromethane, water, trifluoroacetic acid are used in a ratio of 0.1 mmol: 15 mL: 1 mL: 9 mL.

[0043] Preferably, in step (4), the fourth intermediate D, the metal salt, ammonium acetate, cyanoacetic acid, chloroform and glacial acetic acid are used in a ratio of 0.05-0.08 mmol: 0.36-0.40 mmol: 1-1.2 mmol: 0.98-1.08 mmol: 9-15 mL: 9-15 mL;

[0044] The condition of the coordination reaction is refluxing after heating to 65-70 °C, and then reacting under stirring for 2-4 h.

[0045] Preferably, the fourth intermediate D, metal salt, ammonium acetate, cyanoacetic acid, chloroform and glacial acetic acid are used in a ratio of 0.05 mmol:0.36 mmol:1 mmol:0.98 mmol:9 mL:9 mL.

[0046] The coordination reaction time is 4 h.

[0047] Preferably, the metal porphyrin structure prepared by the above method includes but is not limited to the metal porphyrin structures shown in structural formulas 1-6:

[0048]

[0049] The application also provides a metal porphyrin / semiconductor composite photocatalyst, which is irregular spherical.

[0050] The metal porphyrin / semiconductor composite photocatalyst takes a semiconductor as a carrier, and the above metal porphyrin structure is compounded on the semiconductor; the loading amount of the metal porphyrin structure is 0.5-5 wt%; and the semiconductor includes titanium dioxide, zinc oxide and carbon nitride.

[0051] The application also provides a synthesis method of the above metal porphyrin / semiconductor composite photocatalyst, which specifically includes the following steps:

[0052] The semiconductor and the metal porphyrin structure are respectively uniformly dispersed in dichloromethane to obtain a dichloromethane solution of the semiconductor and a dichloromethane solution of the metal porphyrin under magnetic stirring, for standby use;

[0053] The dichloromethane solution of the metal porphyrin is added to the dichloromethane solution of the semiconductor, and a stirring reaction is carried out at room temperature in the dark; after the reaction is completed, centrifugation, washing and drying are carried out to obtain the metal porphyrin / semiconductor composite photocatalyst.

[0054] Preferably, the semiconductor and the metal porphyrin structure are used in a ratio of 200 mg:1-10 mg, and preferably 200 mg:1 mg; and the stirring reaction time is 8-12 h.

[0055] The application also provides application of the above metal porphyrin structure or metal porphyrin / semiconductor composite photocatalyst in photocatalytic degradation of organic pollutants.

[0056] Compared with the prior art, the application has the following beneficial effects:

[0057] The interface charge separation and migration ability of the metal porphyrin structure of the metal porphyrin are related to the electron-donating ability of the substituent group, and the metal porphyrin structure is an asymmetric metal porphyrin structure containing a lone pair of electrons compared with the metal porphyrin structure in the prior art, and the special structure can greatly enhance the light trapping ability of the semiconductor and effectively improve the performance of the semiconductor and promote the interface charge separation of the catalyst, thereby improving the photocatalytic degradation performance.

[0058] The metal porphyrin / semiconductor composite photocatalyst is synthesized based on the metal porphyrin structure, and in the metal porphyrin / semiconductor composite photocatalyst, the metal porphyrin structure is connected to a long-chain alkane through an anchor group, so that the angle between the porphyrin and the carrier is a right angle or an obtuse angle (preferably a right angle). The metal porphyrin exposes more active sites to the semiconductor, and can improve the utilization rate of the photosensitizer porphyrin molecule. The metal porphyrin / semiconductor composite photocatalyst can better promote the separation of the electron-hole pairs at the porphyrin interface, not only broaden the light response range of the semiconductor particles, but also promote the separation of the photo-generated carriers and prolong the photoelectron lifetime, so that the organic pollutants in water are quickly and efficiently reduced, and the degradation efficiency is about 90%, which is much higher than that of the existing metal porphyrin / semiconductor composite photocatalyst.

[0059] The metal porphyrin in the metal porphyrin / semiconductor composite photocatalyst is loaded on TiO2 through ordinary mixing, and the main morphology of TiO2 does not change obviously, and the morphology structure also has no obvious influence on the photocatalytic performance. The metal porphyrin structure and the metal porphyrin / semiconductor composite photocatalyst have the characteristics of simple synthesis and preparation method, low cost, high repeatability, green and environmentally friendly production process and the like. BRIEF DESCRIPTION OF DRAWINGS

[0060] Figure 1 It is a preparation flowchart of the metal porphyrin / semiconductor composite photocatalyst.

[0061] Figure 2 It is a SEM image of the metal porphyrin / semiconductor composite photocatalyst in Example 1 under different magnifications, and the scale of A in the figure is 5 μm, and the scale of B is 5 μm.

[0062] Figure 3 It is a SEM image of the metal porphyrin / semiconductor composite photocatalyst in Example 2 under different magnifications, and the scale of A in the figure is 5 μm, and the scale of B is 5 μm.

[0063] Figure 4 It is a SEM image of the metal porphyrin / semiconductor composite photocatalyst in Example 4 under different magnifications, and the scale of A in the figure is 2 μm, and the scale of B is 5 μm.

[0064] Figure 5Figure showing the degradation activity of the metalloporphyrin / semiconductor composite photocatalyst prepared in Example 1-3 on AB1 under visible light.

[0065] Figure 6 Figure showing the degradation activity of the metalloporphyrin / semiconductor composite photocatalyst prepared in Example 1-3 on TC under visible light. DETAILED DESCRIPTION

[0066] The present application is further described in conjunction with the accompanying drawings and specific examples, but the scope of the present application is not limited thereto.

[0067] Example 1: Synthesis of metalloporphyrin structure and metalloporphyrin / semiconductor composite photocatalyst

[0068] I. Synthesis of metalloporphyrin structure:

[0069] The flow chart for synthesizing the metalloporphyrin structure in this example is shown below:

[0070]

[0071] The specific synthesis steps are as follows:

[0072] (1) Synthesis of the first intermediate A:

[0073] Into a 500 mL two-necked flask was added 60 mmol (4.2 mL) of pyrrole, 200 mL of freshly prepared 0.18 M HC1, and 10 mmol (1.47 mL) of 2,4,6-trimethylbenzaldehyde, and the mixture was stirred at room temperature for 12 h under nitrogen protection. After the reaction was completed, the reaction solution was extracted with dichloromethane, and the lower organic phase was collected. Anhydrous sodium sulfate was added to the organic phase to dry it, and the mixture was filtered and dried with silica gel powder. The obtained crude product was purified by silica gel column chromatography (dichloromethane: petroleum ether = 1:1). Finally, the purified product was recrystallized to obtain white solid, which was the first intermediate A.

[0074] The first intermediate A was 2,2'-(2,4,6-trimethylphenylmethylene)dipyrrole, and 1.12 g of the product was obtained after purification, with a yield of 42%.

[0075] (2) Synthesis of the second intermediate B:

[0076] In a 100 mL three-necked flask, 7.37 mmol (0.9882 g) of 2,5-diethylterephthalaldehyde, 10.60 mmol (1.4164 g), 20 mg of p-toluenesulfonic acid hydrate and 2 g of anhydrous copper sulfate were added, 30 mL of toluene solution was added under nitrogen protection, and then the second condensation reaction was carried out by stirring and refluxing at 115°C for 24 h. After the reaction was completed, the anhydrous copper sulfate was removed by suction filtration, and an appropriate amount of silica gel powder was added, and then dried by rotary evaporation instrument. The obtained crude product was purified by silica gel column chromatography (ethyl acetate: petroleum ether = 1:5) to obtain a white solid, which was the second intermediate B.

[0077] The second intermediate B was 4-(5,5-dimethyl-1,3-dioxan-2-yl)-2,5-diethylbenzaldehyde, and the purified yield was 1.5009 g, and the yield was 92.9%.

[0078] (3) Synthesis of the third intermediate C:

[0079] In a three-necked flask, 0.5 mmol (136.67 mg) of 4-pyridylbenzaldehyde, 1 mmol (264.37 mg) of the first intermediate A, 0.5 mmol (110.14 mg) of the second intermediate B and 100 mL of anhydrous dichloromethane were added, and the mixture was stirred uniformly under nitrogen protection and light protection. Then 180 μL of trifluoroacetic acid was slowly added dropwise, and the reaction was continued under light protection and stirring for 1 h to generate porphyrinogen.

[0080] The three-necked flask containing the mixed solution was exposed to air, 1 mmol (227 mg) of chloranil was added, and the reaction was stirred under light protection for 1 h to oxidize the porphyrinogen into free radical porphyrin. Then 0.337 mL of triethylamine was added to neutralize the trifluoroacetic acid in the mixed solution, silica gel powder was added, and then dried by rotary evaporation instrument. The obtained crude product was purified by silica gel column chromatography (dichloromethane: petroleum ether = 1:2) to obtain a purple solid, which was the second intermediate C.

[0081] The third intermediate C was 5-(pyridin-4-yl)-15-(4-(5,5-dimethyl-1,3-dioxan-2-yl)-2,5-diethylphenyl)-10,20-bis(2,4,6-trimethylphenyl)porphyrin, and the purified yield was 112.70 mg, and the yield was 11.49%.

[0082] (4) Synthesis of metalloporphyrin structure:

[0083] Into a 100 mL three-necked flask was added 0.1 mmol (82 mg) of the third intermediate, 15 mL of dichloromethane, 1 mL of water, 9 mL of trifluoroacetic acid, and the mixture was stirred at room temperature under nitrogen protection for 1 h in the dark. After stirring was completed, an appropriate amount of silica gel powder was added, and the mixture was spin-dried using a rotary evaporator to obtain a crude product. The crude product was purified by silica gel column chromatography (dichloromethane: petroleum ether = 1:2) to obtain the fourth intermediate D.

[0084] Into a 100 mL three-necked flask was added 0.05 mmol (36.6 mg) of the fourth intermediate D, 0.36 mmol (79.02 mg) of zinc acetate, 1 mmol (77.08 mg) of ammonium acetate, 0.98 mmol (85.06 mg) of cyanoacetic acid, 9 mL of chloroform, and 9 mL of glacial acetic acid, and the mixture was stirred at 68°C for 4 h under nitrogen protection in the dark. After stirring was completed, an appropriate amount of silica gel powder was added, and the mixture was spin-dried using a rotary evaporator to obtain a crude product. The crude product was purified by silica gel column chromatography (dichloromethane: petroleum ether = 1:2) to obtain a purple-red solid, i.e., a metalloporphyrin structure.

[0085] The metalloporphyrin structure was 5-(pyridin-4-yl)-15-(4-cyanoacetoxy-2,5-diethylphenyl)-10,20-di(2,4,6-trimethylphenyl)porphyrin zinc (II), denoted as porphyrin 1. The yield of the porphyrin 1 was 40.5 mg, and the yield was 93.8%.

[0086] II. Synthesis of metalloporphyrin / semiconductor composite photocatalyst:

[0087] In this example, a metalloporphyrin / semiconductor composite photocatalyst was also synthesized based on the porphyrin 1 prepared in (I), and the preparation process is shown in Figure 1 The specific synthesis steps are as follows:

[0088] (1) Synthesis of TiO2:

[0089] TiO2 was obtained by a sol-gel method: 12.5 mL of tetrabutyl titanate was added to 100 mL of isopropanol, and the mixture was uniformly dispersed by ultrasonic treatment. Then, 4 mL of water was added dropwise to obtain a colloidal suspension, and the mixture was stirred at room temperature for 8 h. After the reaction, the mixture was suction-filtered, washed with water 3 times, washed with ethanol 3 times, and the solid was dried in an oven at 90°C for 6 h, and then further calcined in a muffle furnace at 450°C for 6 h to obtain a white TiO2 solid.

[0090] (2) Synthesis of metalloporphyrin / semiconductor composite photocatalyst

[0091] 100 mg of TiO2 was uniformly dispersed in 10 mL of dichloromethane, and 0.5 mg of porphyrin 1 was dispersed in 5 mL of dichloromethane, both under magnetic stirring to form a uniform solution. The dichloromethane solution of porphyrin 1 was poured into the titanium dioxide suspension, stirred at room temperature for 10 h in the dark, and after the reaction was completed, centrifuged, washed with ethanol for 3 times, and then dried in an oven at 60°C for 12 h to obtain the metalloporphyrin / semiconductor composite photocatalyst, denoted as porphyrin 1 / TiO2.

[0092] Figure 2 The SEM images of porphyrin 1 / TiO2 at different magnifications are shown in the figure, and it can be seen from the figure that the photocatalyst is irregular spherical, and its morphology has no obvious change compared with pure TiO2, that is, after TiO2 is doped with 0.5wt% of metalloporphyrin, no significant change in the morphology of TiO2 is caused, and it is still irregular spherical.

[0093] Example 2: Synthesis of metalloporphyrin structure and metalloporphyrin / semiconductor composite photocatalyst

[0094] I. Synthesis of metalloporphyrin structure:

[0095] The flowchart for synthesizing the metalloporphyrin structure in this example is shown as follows:

[0096]

[0097] According to the flowchart, the synthesis steps of the metalloporphyrin structure in this example are basically the same as those of porphyrin 1 in Example 1, and the only difference is that the zinc acetate in step (4) is replaced by copper acetate, and the third intermediate C is replaced by 5-(furan-2-yl)-15-(4-(5,5-dimethyl-1,3-dioxan-2-yl)-2,5-diethylphenyl)-10,20-di(2,4,6-trimethylphenyl)porphyrin, and the obtained metalloporphyrin structure is 5-(furan-2-yl)-15-(4-cyanoacetic acid-2,5-diethylphenyl)-10,20-di(2,4,6-trimethylphenyl)porphyrin copper(II), denoted as porphyrin 2. The yield of the porphyrin 2 is 93%.

[0098] II. Synthesis of metalloporphyrin / semiconductor composite photocatalyst:

[0099] In this example, a metalloporphyrin / semiconductor composite photocatalyst was also synthesized based on the porphyrin 2 prepared in (I), and the synthesis steps are shown as follows:

[0100] 100 mg ZnO was uniformly dispersed in 10 mL dichloromethane, and 0.5 mg porphyrin 2 was dispersed in 5 mL dichloromethane, both under magnetic stirring to form a uniform solution. The dichloromethane solution of porphyrin 2 was poured into the ZnO suspension, and the reaction was stirred at room temperature for 10 h in the dark. After the reaction, the product was centrifuged, washed with ethanol for 3 times, and then dried in an oven at 60°C for 12 h to obtain the metalloporphyrin / semiconductor composite photocatalyst, denoted as porphyrin 2 / ZnO.

[0101] Figure 3 The SEM images of porphyrin 2 / ZnO at different magnifications are shown in FIG. 2, from which it can be seen that the photocatalyst is irregularly spherical, and its morphology has no obvious change compared with pure ZnO, i.e. the ZnO doped with 0.5wt% metalloporphyrin does not cause significant change in the morphology of ZnO, and still presents irregularly spherical shape. Figure 3 The SEM images of porphyrin 2 / ZnO at different magnifications are shown in FIG. 2, from which it can be seen that the photocatalyst is irregularly spherical, and its morphology has no obvious change compared with pure ZnO, i.e. the ZnO doped with 0.5wt% metalloporphyrin does not cause significant change in the morphology of ZnO, and still presents irregularly spherical shape.

[0102] Example 3: Synthesis of metalloporphyrin structure and metalloporphyrin / semiconductor composite photocatalyst

[0103] I. Synthesis of metalloporphyrin structure:

[0104] The flowchart for synthesizing the metalloporphyrin structure in this example is shown below:

[0105]

[0106] According to the flowchart, the synthesis steps of the metalloporphyrin structure in this example are basically the same as those of porphyrin 1 in Example 1, except that the zinc acetate in step (4) is replaced by manganese chloride, and the third intermediate C is replaced by 5-(thiophene-2-yl)-15-(4-(5,5-dimethyl-1,3-dioxane-2-yl)-2,5-diethylphenyl)-10,20-di(4-methylphenyl) porphyrin. The final metalloporphyrin structure is 5-(thiophene-2-yl)-15-(4-cyanoacetic acid phenyl)-10,20-di(4-methylphenyl) porphyrin manganese (II), denoted as porphyrin 3. The yield of porphyrin 3 is 91.6%.

[0107] II. Synthesis of metalloporphyrin / semiconductor composite photocatalyst:

[0108] In this example, a metalloporphyrin / semiconductor composite photocatalyst was also synthesized based on the porphyrin 3 prepared in (I), and the synthesis steps are shown below:

[0109] 100 mg of C3N4 was uniformly dispersed in 10 mL of dichloromethane, and 0.5 mg of porphyrin 3 was dispersed in 5 mL of dichloromethane, both forming a uniform solution under magnetic stirring. The dichloromethane solution of porphyrin 3 was poured into the C3N4 suspension, and the reaction was stirred at room temperature for 10 h in the dark. After the reaction, centrifugation, ethanol washing for 3 times, and drying in an oven at 60°C for 12 h, the metal porphyrin / semiconductor composite photocatalyst was obtained, denoted as porphyrin 3 / C3N4.

[0110] Example 4: Synthesis of metal porphyrin structure and metal porphyrin / semiconductor composite photocatalyst

[0111] I. Synthesis of metal porphyrin structure:

[0112] The flowchart for synthesizing the metal porphyrin structure in this example is shown below:

[0113]

[0114] According to the flowchart, the synthesis steps of the metal porphyrin structure in this example are basically the same as those of porphyrin 1 in Example 1, with the only difference being that the third intermediate C is adjusted to 5-(pyrimidin-2-yl)-15-(4-(5,5-dimethyl-1,3-dioxan-2-yl)-2,5-diethylphenyl)-10,20-diphenylporphyrin. The final metal porphyrin structure obtained is 5-(pyrimidin-4-yl)-15-(4-cyanoacetic acid-2,5-diethylphenyl)-10,20-diphenylporphyrin zinc(II), denoted as porphyrin 4. The yield of porphyrin 4 is 93.3%.

[0115] II. Synthesis of metal porphyrin / semiconductor composite photocatalyst:

[0116] In this example, porphyrin 4 / TiO2 was synthesized according to the method shown in (II) of Example 1.

[0117] Figure 4 The SEM images of porphyrin 4 / ZnO at different magnifications are shown in the figure, from which it can be observed that TiO2 is in irregular spherical shape.

[0118] Example 5: Synthesis of metal porphyrin structure and metal porphyrin / semiconductor composite photocatalyst

[0119] I. Synthesis of metal porphyrin structure:

[0120] The flowchart for synthesizing the metal porphyrin structure in this example is shown below:

[0121]

[0122] As shown in the flowchart, the synthesis steps of the metalloporphyrin structure in this embodiment are basically the same as those of porphyrin 1 in Example 1, except that: zinc acetate in step (4) is replaced with copper acetate, and the third intermediate C is replaced with 5-(pyridin-2-yl)-15-(4-(5,5-dimethyl-1,3-dioxane-2-yl)-2,5-diethylphenyl)-10,20-diphenylporphyrin; the final metalloporphyrin structure is 5-(pyridin-2-yl)-15-(4-cyanoacetyl-2,5-diethylphenyl)-10,20-diphenylporphyrin copper (II), denoted as porphyrin 5. The yield of porphyrin 5 is 93.7%.

[0123] II. Synthesis of metalloporphyrin / semiconductor composite photocatalysts:

[0124] In this embodiment, porphyrin 5 / ZnO was synthesized according to the method shown in Example 2 (II).

[0125] Example 6: Synthesis of metalloporphyrin structure and metalloporphyrin / semiconductor composite photocatalyst

[0126] I. Synthesis of metalloporphyrin structures:

[0127] The process for synthesizing the metalloporphyrin structure in this embodiment is shown below:

[0128]

[0129] According to the flowchart, the synthesis steps of the metalloporphyrin structure in this embodiment are basically the same as those of porphyrin 1 in Example 1, except that: zinc acetate in step (4) is replaced with manganese chloride, and the third intermediate C is replaced with 5-(2,1,3-benzothiadiazol-4-yl)-15-(4-(5,5-dimethyl-1,3-dioxane-2-yl)-2,5-diethylphenyl)-10,20-di(4-methylphenyl)porphyrin; the final metalloporphyrin structure is 5-(2,1,3-benzothiadiazol-4-yl)-15-(4-cyanoacetyl-2,5-diethylphenyl)-10,20-di(4-methylphenyl)porphyrin manganese (II), denoted as porphyrin 6. The yield of porphyrin 6 is 92.4%.

[0130] II. Synthesis of metalloporphyrin / semiconductor composite photocatalysts:

[0131] In this embodiment, porphyrin 6 / C3N4 was synthesized according to the method shown in Example 3 (II).

[0132] Example 7: Photocatalytic Testing of Metalporphyrin / Semiconductor Composite Photocatalyst

[0133] The metalloporphyrin / semiconductor composite photocatalysts prepared in Examples 1-3 were tested for photocatalytic degradation performance, and the specific testing process is shown below:

[0134] The photodegradation performance test was carried out at room temperature, and a 300W xenon lamp equipped with a 420nm filter was used as the light source to degrade 10ppm of acid black (AB1) and 20mg L -1 of tetracycline (TC). In order to detect the photocatalytic activity of the metalloporphyrin / semiconductor composite photocatalysts prepared in Examples 1-3 on AB1 and TC, 5mg of photocatalyst was added to 50mL of AB1 or TC solution, and stirred in the dark for 60 minutes to ensure adsorption and desorption equilibrium on the surface of the catalyst. After turning on the light, 4mL of suspension was extracted from the AB1 and TC solutions at 15 minute intervals. All samples were centrifuged to remove photocatalyst particles, and the UV-vis absorption spectrum of the supernatant was recorded at 620nm and 357nm, respectively.

[0135] Figure 5 The degradation activity of the metalloporphyrin / semiconductor composite photocatalysts prepared in Examples 1-3 on AB1 under visible light is shown in the graph, from which it can be seen that the concentration of pollutants changes with the light exposure time after the addition of the metalloporphyrin / semiconductor composite photocatalysts prepared in Examples 1-3. In the suspension with the addition of photocatalyst, the concentration of pollutants will decrease significantly with the increase of time. As can be seen from the graph, the metalloporphyrin / semiconductor composite photocatalysts prepared in Examples 1-3 have good photodegradation performance, with a total degradation rate of AB1 of about 90% within 60 minutes, which is much higher than that of existing metalloporphyrin / semiconductor composite photocatalysts.

[0136] Figure 6 The degradation activity of the metalloporphyrin / semiconductor composite photocatalysts prepared in Examples 1-3 on TC under visible light is shown in the graph, from which it can be seen that the concentration of pollutants changes with the light exposure time after the addition of the metalloporphyrin / semiconductor composite photocatalysts prepared in Examples 1-3. In the suspension with the addition of photocatalyst, the concentration of pollutants will decrease significantly with the increase of time. As can be seen from the graph, the metalloporphyrin / semiconductor composite photocatalysts prepared in Examples 1-3 have good photodegradation performance on TC, with a total degradation efficiency of TC of about 90% within 60 minutes, which is higher than that of existing metalloporphyrin / semiconductor composite photocatalysts.

[0137] Based on the metal porphyrin structure, the metal porphyrin / semiconductor composite photocatalyst is synthesized, in the metal porphyrin / semiconductor composite photocatalyst, the metal porphyrin structure is connected with long-chain alkane through an anchoring group, and the angle between the porphyrin and the carrier is a right angle or an obtuse angle (preferably a right angle). The metal porphyrin exposes more active sites to the semiconductor, and the utilization rate of the photosensitizer porphyrin molecule can be improved. The metal porphyrin / semiconductor composite photocatalyst can better promote the separation of the electron-hole pairs at the porphyrin interface, not only widens the light response range of the semiconductor particles, but also promotes the separation of photo-generated carriers and prolongs the photoelectron lifetime, and realizes rapid and efficient reduction of organic pollutants in water.

[0138] Based on the metal porphyrin structure, the metal porphyrin / semiconductor composite photocatalyst is synthesized, in the metal porphyrin / semiconductor composite photocatalyst, the metal porphyrin structure is connected with long-chain alkane through an anchoring group, and the angle between the porphyrin and the carrier is a right angle or an obtuse angle (preferably a right angle). The metal porphyrin exposes more active sites to the semiconductor, and the utilization rate of the photosensitizer porphyrin molecule can be improved. The metal porphyrin / semiconductor composite photocatalyst can better promote the separation of the electron-hole pairs at the porphyrin interface, not only widens the light response range of the semiconductor particles, but also promotes the separation of photo-generated carriers and prolongs the photoelectron lifetime, and realizes rapid and efficient reduction of organic pollutants in water.

[0139] The embodiments are preferred embodiments of the present application, but the present application is not limited to the above embodiments, and any obvious improvement, replacement or modification made by those skilled in the art without departing from the essential content of the present application shall fall within the protection scope of the present application.

Claims

1. A metalloporphyrin structure, characterized by, The metalloporphyrin structure is an asymmetric metalloporphyrin structure containing a lone pair of electrons, and its structural formula is as shown below: ； In the structural formula, R1 is a group containing a lone pair of electrons; the group containing a lone pair of electrons is selected from any one of thiophene, pyridine, furan, pyrimidine, 2,1,3-benzothiadiazole; R2, R3, R4, R5 and R6 are: C0-4 and not 0 normal alkyl or isomeric alkyl; M is zinc, manganese or copper.

2. The method of synthesis of metalloporphyrin structures according to claim 1, characterized by that, Specifically comprising the following steps: (1) mixing the compound , pyrrole and dilute hydrochloric acid, and then performing a first condensation reaction under stirring, to obtain a first intermediate A after the reaction is completed, for standby; The compound , neopentyl glycol, p-toluenesulfonic acid, anhydrous copper sulfate and toluene were mixed, and then a second condensation reaction was carried out under stirring. After the reaction was completed, a second intermediate B was obtained. The compound having the structural formula The first intermediate A has the structural formula ; The compound having the structural formula ; the second intermediate B has the structural formula ; Compound pyrrole and dilute hydrochloric acid in a ratio of 1-1.5 mmol: 6-9 mmol: 20-30 mL; wherein the concentration of dilute hydrochloric acid is 0.15 M - 0.20 M; Compound The use ratio of p-toluenesulfonic acid, anhydrous copper sulfate and toluene is 7.20~7.50 mmol: 10.00~11.00 mmol: 10~30 mg: 1~2 g: 20~30 mL. (2) mixing the first intermediate A, the second intermediate B, the compound and anhydrous dichloromethane under N2protection, then adding trifluoroacetic acid dropwise, after the end of the dropwise addition, carrying out the first stirring reaction under light shielding conditions, and obtaining a mixed solution after the reaction is completed; The mixed solution is added to tetrachlorobenzoquinone under atmospheric conditions, and then subjected to a second stirring reaction under light shielding conditions, and after the reaction is completed, a third intermediate C is obtained; The compound having the structural formula ; and the third intermediate C has the structural formula ; the first intermediate A, the second intermediate B, the compound chloranil, trifluoroacetic acid and anhydrous dichloromethane in the amount ratio of 1~1.2 mmol: 0.5~0.6 mmol: 0.5~0.6 mmol: 1~1.5 mmol: 180~300 μL: 100 mL; (3) The third intermediate C, dichloromethane, water and trifluoroacetic acid are uniformly mixed to carry out a hydrolysis reaction, and after the reaction is completed, a fourth intermediate D is obtained; The structural formula of the fourth intermediate D is ; The use amount ratio of the third intermediate C, dichloromethane, water, and trifluoroacetic acid is 0.1-0.15 mmol: 15-20 mL: 1-2 mL: 9-15 mL; (4) The fourth intermediate D, a metal salt, ammonium acetate, cyanoacetic acid, chloroform and glacial acetic acid are subjected to a coordination reaction under heating conditions, and after the reaction is completed, the metalloporphyrin structure is obtained; The use amount ratio of the fourth intermediate D, the metal salt, ammonium acetate, cyanoacetic acid, chloroform and glacial acetic acid is 0.05-0.08 mmol: 0.36-0.40 mmol: 1-1.2 mmol: 0.98-1.08 mmol: 9-15 mL: 9-15 mL; The metal in the metal salt is selected from zinc, manganese or copper.

3. The method of synthesis of metalloporphyrin structures according to claim 2, characterized by that, In step (1), the first condensation reaction is under the conditions of N2 protection, light shielding and stirring for 8-12 h; The second condensation reaction is under the conditions of heating to 110-130°C to reflux, and then stirring for 8-48 h.

4. The method of synthesis of metalloporphyrin structures according to claim 2, characterized by that, In step (2), The time of the first stirring reaction is 1-1.5 h; The time of the second stirring reaction is 1-1.5 h.

5. The method of synthesis of metalloporphyrin structures according to claim 2, characterized by that, In step (3), The hydrolysis reaction is under the conditions of N2 protection, light shielding and stirring for 1-1.5 h; In step (4), the coordination reaction is under the conditions of heating to 65-70°C to reflux, and then stirring for 2-4 h.

6. A metalloporphyrin / semiconductor composite photocatalyst, characterized by, The metalloporphyrin / semiconductor composite photocatalyst is in an irregular spherical shape; The metalloporphyrin / semiconductor composite photocatalyst takes a semiconductor as a carrier, and the metalloporphyrin structure of claim 1 is compounded on the semiconductor; the loading amount of the metalloporphyrin structure is 0.5-5 wt%; and the semiconductor is selected from titanium dioxide, zinc oxide and carbon nitride.

7. The method for synthesizing the metalloporphyrin / semiconductor composite photocatalyst according to claim 6, characterized by, Specifically comprising the following steps: The semiconductor and the metalloporphyrin structure are uniformly dispersed in dichloromethane respectively to obtain a dichloromethane solution of the semiconductor and a dichloromethane solution of the metalloporphyrin respectively under magnetic stirring, for standby; The dichloromethane solution of the metalloporphyrin is added to the dichloromethane solution of the semiconductor, and a stirring reaction is carried out under light shielding at room temperature, and after the reaction is completed, centrifugation, washing and drying are carried out to obtain the metalloporphyrin / semiconductor composite photocatalyst.

8. The method of synthesis of claim 7, wherein, The use amount ratio of the semiconductor and the metalloporphyrin structure is 200 mg: 1-10 mg; The reaction time of the stirring reaction is 8-12 h.

9. Use of the metalloporphyrin structure of claim 1 or the metalloporphyrin / semiconductor composite photocatalyst of claim 6 in photocatalytic degradation of organic pollutants.

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