Thiazolyl linear polyimide organic semiconductor and application in photocatalytic oxygen evolution

Abstract

The application discloses a novel thiazole-based linear polyimide organic semiconductor and a preparation and application thereof in photocatalytic decomposition of water to produce oxygen, and belongs to the field of material preparation. The linear polymer obtained by the application is a kind of crystalline polymer, which is a crystalline porous material with a periodic network structure connected by covalent bonds, has a clear void structure, an ordered pore structure, a large specific surface area, a high porosity, a low density, a semiconductor characteristic of absorbing certain band visible light and exciting photoelectrons, and can be loaded with Co on the semiconductor material by using a traditional stirring method, so that the material can be used for photocatalytic decomposition of water to produce O2 by taking water as a reactant and AgNO3 as an electron sacrificial agent, and therefore has great application potential.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of material preparation, and particularly relates to a novel thiazole-based linear polyimide organic semiconductor, a preparation method thereof and application thereof in photocatalytic decomposition of water to produce oxygen. BACKGROUND

[0002] Since the new century, along with the increasing awareness of energy demand and environmental protection, artificial photosynthesis has become a research hotspot, and the application of organic linear polymer materials in photocatalytic hydrogen production has been widely studied. However, one of the difficulties of artificial photosynthesis is the oxidation of water to produce oxygen.

[0003] The thiazole-based linear polyimide organic semiconductor material is a linear polymer with a crystal form connected by imine bonds formed by condensation of anhydride and amine groups, and has good solvent stability and thermal stability, unique photoelectric properties, good light absorption capacity, suitable band gap width and energy band structure, and can meet the thermodynamic conditions of photocatalytic decomposition of water to produce oxygen. The application provides a novel thiazole-based linear polyimide organic semiconductor material, which can be used for photocatalytic decomposition of water to produce oxygen, and has great significance for solving the energy problem of the earth. SUMMARY

[0004] The application utilizes a solvothermal method to prepare a novel thiazole-based linear polyimide organic semiconductor material under relatively mild conditions, the preparation method has repeatability, good economic and environmental benefits, and the obtained organic semiconductor can be catalytically decomposed to generate O2 in the visible light range after being modified by Co using AgNO3 as a sacrificial agent.

[0005] To achieve the above-mentioned purpose, the application adopts the following technical solutions:

[0006] A thiazole-based linear polyimide organic semiconductor is a linear polymer synthesized by using 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphenylamine (Bt) and pyromellitic dianhydride (PMDA) as reaction monomers, and the unit structure formula is:

[0007] , wherein n=10 3 ~10 6 .

[0008] Further, the specific surface area of the organic semiconductor is 77.1229 m 2 / g, and the pore size is 1.35 nm.

[0009] The preparation method of the thiazolyl linear polyimide organic semiconductor is that 4,4'- (benzo [c] [1,2,5] thiazole-4,7-diyl) diphenylamine and pyromellitic dianhydride are added into a mixed solution of mesitylene and N-methyl pyrrolidone, and isoquinoline is added as a catalyst, rapid freezing and thawing in a liquid nitrogen bath, vacuum extraction three times, flame sealing when the internal pressure is 0 mbar, then incubating at 200 DEG C for 5 days, and then washing, suction filtration and drying are carried out.

[0010] Further, the molar ratio of 4,4'- (benzo [c] [1,2,5] thiazole-4,7-diyl) diphenylamine and pyromellitic dianhydride used is 1:1.

[0011] Further, the volume ratio of mesitylene and N-methyl pyrrolidone in the mixed solution is 1:1.

[0012] Further, the amount of isoquinoline is 5% of the total volume of mesitylene and N-methyl pyrrolidone.

[0013] The thiazolyl linear polyimide organic semiconductor can be used for visible light driven photocatalytic water splitting oxygen production reaction, which is specifically that the thiazolyl linear polyimide organic semiconductor is post-functionally modified by using cobalt ions, and then photocatalytic water splitting oxygen production is carried out under the condition that AgNO3 is used as an electron sacrificial agent.

[0014] Further, the post-functional modification is that the thiazolyl linear polyimide organic semiconductor is dispersed in water, and then CoCl2•6H2O is added and uniformly mixed by ultrasonic.

[0015] Further, the mass ratio of CoCl2•6H2O to thiazolyl linear polyimide organic semiconductor used is 4:5.

[0016] The beneficial effects of the present application are:

[0017] 1) The present application reacts 4,4'- (benzo [c] [1,2,5] thiazole-4,7-diyl) diphenylamine and pyromellitic dianhydride in a mixed solvent of mesitylene and N-methyl pyrrolidone by a solvothermal method to obtain a novel linear polyimide material, which has more microporous structure, narrower band gap width and suitable energy band structure, and can realize photocatalytic water splitting oxygen production under visible light after being modified by a metal.

[0018] 2) The synthesis process of the present application is simple and has strong repeatability; the chemical reagents and equipment used are reasonably priced, easy to obtain, have strong applicability, high industrial application value, and are easy to popularize and utilize. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1The images show a side view (a) and a top view (b) of the organic semiconductor material Bt-polymer structure prepared in Example 1.

[0020] Figure 2 The image shows the X-ray powder diffraction pattern of the organic semiconductor material Bt-polymer prepared in Example 1.

[0021] Figure 3 The Fourier transform infrared spectrum of the organic semiconductor material Bt-polymer prepared in Example 1 is shown.

[0022] Figure 4 The organic semiconductor material Bt-polymer prepared in Example 1 13 C10 NMR spectrum.

[0023] Figure 5 This is a scanning electron microscope image of the organic semiconductor material Bt-polymer prepared in Example 1.

[0024] Figure 6 This is a pore size distribution diagram of the organic semiconductor material Bt-polymer prepared in Example 1.

[0025] Figure 7 This is a band structure diagram of the organic semiconductor material Bt-polymer prepared in Example 1.

[0026] Figure 8 The graph shows the performance of the organic semiconductor material Bt-polymer in Example 2 in photocatalytic water splitting to produce oxygen. Detailed Implementation

[0027] The preparation steps of a thiazole-based polyimide organic semiconductor are as follows:

[0028] 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphenylamine and pyromellitic dianhydride were added to a mixed solution of mesitylene and N-methylpyrrolidone (1:1, v / v) at a molar ratio of 1:1. Isoquinoline was added as a catalyst at 5% of the total volume of the mixed solution. The mixture was rapidly frozen and thawed in a liquid nitrogen bath, and vacuumed three times until the internal pressure reached 0 mbar. Then, it was flame-sealed and reacted at 200°C for 5 days. After washing, filtration, and drying, a linear polymer material with crystalline structure, thiazolium-based polyimide (Bt-polymer), was obtained.

[0029] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0030] Example 1

[0031] A method for synthesizing a thiazole-based linear polyimide organic semiconductor material Bt-polymer, the specific synthesis steps are as follows:

[0032] 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diphenylamine (22.3 mg, 0.07 mmol) and pyromellitic dianhydride (15.3 mg, 0.07 mmol) were added into a Pyrex tube, followed by the addition of isoquinoline (50 μL), mesitylene (0.5 mL), N-methylpyrrolidone (0.5 mL) in sequence, and the tube was sealed with plastic wrap and placed in an ultrasonic machine for ultrasonic treatment for 20 minutes. Then the Pyrex tube was frozen in a liquid nitrogen bath at -196.15 ℃, and after freezing, the system was vacuumed for 10 seconds, then thawed, and the above operation was repeated three times. After the last vacuuming, the internal pressure was 0 mbar, and the Pyrex tube was sealed with a flame gun. Then the sealed Pyrex tube was placed at room temperature for 30 minutes, and then reacted at 200 ℃ for 5 days. After the reaction was completed, methanol, acetone, and tetrahydrofuran were used for washing in sequence, and the solid powder was collected by suction filtration, and then vacuum dried at 60 ℃ for 12 hours to obtain an orange-red solid powder Bt-polymer.

[0033] Figure 1 The structure of the prepared Bt-polymer is shown in the figure. As can be seen from the figure, the linear polymer is stacked in layers.

[0034] Figure 2 The X-ray powder diffraction pattern of the prepared Bt-polymer is shown in the figure. The figure proves that the obtained linear polymer has crystallinity.

[0035] Figure 3 The Fourier transform infrared spectrum of the prepared Bt-polymer is shown in the figure. From the figure, the disappearance of -NH2 (3340 cm -1 ) and the formation of a five-membered imide ring (~1720 cm -1 ) prove the synthesis of the polymer.

[0036] Figure 4 The 13 C nuclear magnetic resonance spectrum of the prepared Bt-polymer is shown in the figure. From the figure, the signal of the carbonyl carbon on the imide ring corresponding to 165 ppm can be observed, which further proves the synthesis of the polymer.

[0037] Figure 5 The scanning electron microscope image of the prepared Bt-polymer is shown in the figure. As can be seen from the figure, the prepared Bt-polymer is a honeycomb structure with a large number of long strips stacked and intertwined together, and this stacking can provide more adsorption sites.

[0038] Figure 6 The figure is the pore size distribution of the prepared Bt-polymer. It can be seen from the figure that the pore size of the polymer is mainly ~1.35 nm.

[0039] Figure 7 The figure is the band structure of the prepared Bt-polymer. It can be seen from the figure that the polymer can meet the energy requirement of water oxidation to produce oxygen.

[0040] Example 2

[0041] The application of the thiazole-based linear polyimide material Bt-polymer in photocatalytic decomposition of water to produce oxygen is as follows:

[0042] 10 mg of the Bt-polymer prepared in Example 1 was weighed, 50 mL of deionized water was added, and then 8 mg of CoCl2·6H2O and 17 mg of AgNO3 were added. The mixture was uniformly mixed by ultrasonic for 10 minutes. The reactor was connected to a glass closed gas system (Labsolar-6A, Perfect Light), and a stirring rod was added. The system was stirred while being vacuumed until the pressure in the system was 0.0-0.5 Kpa. Then the light (300 W xenon lamp with a 420 nm cutoff filter) was turned on to run the program. The sample was taken every 0.5 h, and the vacuum was pumped every hour (until the pressure in the system was 0.0-0.5 Kpa) to produce oxygen under light. The oxygen content was detected by gas chromatography to evaluate the performance of the Bt-polymer in decomposition of water to produce oxygen. The results are shown in Figure 8 .

[0043] Figure 8 The figure is the performance of the Bt-polymer in photocatalytic decomposition of water to produce oxygen. It can be seen from the figure that the average yield of one hour is 554 µmol g -1 h -1 , which is outstanding in the field of single organic matter oxygen production.

[0044] The above only describes the preferred embodiments of the present application, and any equivalent changes and modifications made within the scope of the patent application of the present application shall be included in the scope of the present application.

Claims

1. Application of thiazole-based linear polyimide organic semiconductor in photocatalytic decomposition of water oxygen evolution reaction driven by visible light, characterized in that: The thiazole-based linear polyimide organic semiconductor is a linear polymer synthesized by using 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dianiline and pyromellitic dianhydride as reaction monomers, and the unit structural formula is as follows: wherein n = 10 3 ~10 6 ; In application, the thiazole-based linear polyimide organic semiconductor is post-functionally modified by using cobalt ions, and then, under the condition that AgNO3 is used as an electron sacrificial agent, the photocatalytic decomposition of water is carried out to produce oxygen. The post-functional modification is that the thiazole-based linear polyimide organic semiconductor is dispersed in water, and then, CoCl2•6H2O is added and ultrasonically mixed.

2. Use according to claim 1, characterized in that: The specific surface area of the organic semiconductor is 77.1229 m 2 / g with a pore size of 1.35 nm.

3. Use according to claim 1, characterized in that: The preparation of the thiazole-based linear polyimide organic semiconductor is that 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dianiline and pyromellitic dianhydride are added into a mixed solution of mesitylene and N-methylpyrrolidone, and isoquinoline is added as a catalyst, and then, the mixture is rapidly frozen and thawed in a liquid nitrogen bath, and vacuumized three times, and then, flame sealed when the internal pressure is 0 mbar, and then, incubated at 200℃ for 5 days, and then, washed, filtered and dried to obtain the thiazole-based linear polyimide organic semiconductor.

4. Use according to claim 3, characterized in that: The molar ratio of 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dianiline to pyromellitic dianhydride used is 1:

1.

5. Use according to claim 3, characterized in that: The volume ratio of mesitylene to N-methylpyrrolidone in the mixed solution is 1:

1.

6. Use according to claim 3, characterized in that: The amount of isoquinoline used is 5% of the total volume of mesitylene and N-methylpyrrolidone.

7. The use according to claim 1, characterized in that: The mass ratio of CoCl2•6H2O to the thiazole-based linear polyimide organic semiconductor used is 4:5.

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