Preparation and application of a sulfur-indium-zinc-azine-based covalent organic framework composite material

Abstract

The application discloses a kind of sulfur indium zinc azine-based covalent organic framework composite materials and its preparation and application in photocatalytic reduction carbon dioxide.The application combines in-situ growth strategy with inorganic semiconductor ZnIn2S4 and COFs with large π conjugated system and excellent chemical stability to form a composite catalytic material.The composite catalytic material can realize the full reaction of carbon dioxide photocatalytic reduction without sacrificial agent and cocatalyst, and thus has great application potential in the field of photocatalysis.

Description

Technical Field

[0001] The present invention belongs to the field of material preparation, and in particular relates to a sulfur-indium-zinc-azine-based covalent organic framework composite material for photocatalytic reduction of carbon dioxide and a preparation method thereof. Background Art

[0002] Since the turn of the century, with increasing awareness of energy demands and environmental protection, covalent organic frameworks (COFs) have become a hot topic of research in modern science. These materials, a class of periodic, crystalline organic porous polymers linked by covalent bonds, have become a hot topic of research in recent years due to their excellent thermal and chemical stability, ordered pore structure, excellent crystallinity, and designable unit structures.

[0003] The application of covalent organic frameworks (COFs) in the photocatalytic reduction of carbon dioxide has been widely studied, but research on photocatalytic reduction of carbon dioxide that does not require sacrificial agents or co-catalysts is limited. The present invention provides a novel sulfur-indium zinc azine-based COF composite material. This heterojunction catalyst combines the inorganic semiconductor ZnIn2S4 with COFs (COFs) with a large π-conjugated system and excellent chemical stability. This catalyst can be used in the photocatalytic reduction of carbon dioxide to produce pollution-free clean energy, which has far-reaching significance for the development of environmental energy. Summary of the Invention

[0004] In order to solve the problems of fast recombination rate of photogenerated electron-hole pairs, short carrier lifetime, and low light absorption capacity in single semiconductor materials, the present invention proposes a catalyst composed of an inorganic semiconductor ZnIn2S4 and an azine-based covalent organic framework material with a large π conjugated system and good chemical stability. The catalyst can be used for the photocatalytic reduction of carbon dioxide, exploring a new path for the development of the field of photocatalytic technology.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A sulfur-indium-zinc-azine-based covalent organic framework composite material, the preparation method of which comprises the following steps:

[0007] (1) 2,4,6-Tris(4-formylphenyl)-1,3,5-triazine (TFPT) and hydrazine hydrate were added to a mixture of mesitylene and 1,4-dioxane containing acetic acid, and after three freeze-thaw cycles of degassing, an azine-based covalent organic framework material TAZ-COF was obtained by solvothermal reaction.

[0008] (2) Anhydrous zinc chloride, thioacetamide, and indium chloride are used as zinc source, sulfur source, and indium source, respectively, and are added to a hydrochloric acid aqueous solution with a pH of 2.5 and stirred to dissolve to obtain a mixed system;

[0009] (3) ultrasonic dispersion of the TAz-COF obtained in step (1) in acetonitrile solution for 20 min, then added into the mixed system obtained in step (2), stirred for 30 min to mix, then in-situ growth of ZnIn2S4 on the TAz-COF in the oil bath under stirring to obtain the sulfur-indium-zinc azine-based covalent organic framework composite material TAz-COF / ZnIn2S4.

[0010] Further, the volume ratio of mesitylene and 1,4-dioxane in the mixed system in step (1) is 1:1, and the content of acetic acid is 6 mol / L.

[0011] Further, the molar ratio of 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and hydrazine hydrate added in step (1) is 2:3.

[0012] Further, the temperature of the solvothermal reaction in step (1) is 120℃, and the time is 3 days.

[0013] Further, the molar ratio of anhydrous zinc chloride, thioacetamide and indium chloride used in step (2) is 1:1:2.

[0014] Further, the temperature of the reaction in step (2) is 80℃, and the time is 12h.

[0015] Further, the volume ratio of acetonitrile and water in the acetonitrile solution in step (3) is 3:1.

[0016] Further, the temperature of the reaction in step (3) is 80℃, and the time is 12h.

[0017] Further, the mass ratio of TAz-COF and ZnIn2S4 in the sulfur-indium-zinc azine-based covalent organic framework composite material obtained in step (3) is 15%.

[0018] The application of the sulfur-indium-zinc azine-based covalent organic framework composite material in photocatalytic reduction of carbon dioxide.

[0019] The beneficial effects of the present application are:

[0020] 1) ZnIn2S4 is a flower-like microspherical ternary metal sulfide compound, which has a series of advantages such as wide light absorption range and adjustable band gap, and TAz-COF has the characteristics of low density, regular pore, large specific surface area, good chemical stability and easy to control structure. The TAz-COF / ZnIn2S4 sulfide-indium-zinc azine-based covalent organic framework composite material is prepared by synthesizing TAz-COF through a solvothermal method and then in-situ growing ZnIn2S4 on the TAz-COF. The prepared TAz-COF / ZnIn2S4 organic-inorganic semiconductor material can exhibit good photocatalytic CO2 reduction performance under the condition of not adding any cocatalyst and sacrificial agent, which provides more theoretical basis for designing and synthesizing the composite material for this application.

[0021] 2) The Z-type heterojunction is constructed by in-situ growing ZnIn2S4 on the TAz-COF, which can solve the problems of single semiconductor material such as fast recombination of photo-generated electron-hole pairs, short carrier lifetime and low light absorption capacity.

[0022] 3) The synthesis process condition and operation of the present application are simple, and the repeatability is strong; the chemical reagents and equipment used are reasonable in price, easy to obtain, and have strong applicability, the obtained composite catalyst has high industrial application value, and is easy to popularize and utilize. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 It is a flowchart for synthesizing TAz-COF / ZnIn2S4 of the present application.

[0024] Figure 2 It is an X-ray powder diffraction pattern of TAz-COF, ZnIn2S4 and TAz-COF / ZnIn2S4 prepared in Example 1.

[0025] Figure 3 It is a Fourier transform infrared spectrum of TFPT, TAz-COF, ZnIn2S4 and TAz-COF / ZnIn2S4 prepared in Example 1.

[0026] Figure 4 It is a SEM diagram of TAz-COF, ZnIn2S4 and TAz-COF / ZnIn2S4 prepared in Example 1.

[0027] Figure 5 It is a graph of the yield of carbon monoxide generated by photocatalytic reduction of carbon dioxide by TAz-COF, ZnIn2S4 and TAz-COF / ZnIn2S4 in Example 2 under visible light, without adding any sacrificial agent and cocatalyst. DETAILED DESCRIPTION

[0028] As Figure 1A sulfur-indium-zinc-azine-based covalent organic framework composite material, the preparation method of which comprises the following steps:

[0029] (1) To a mixed system of mesitylene and 1,4-dioxane containing acetic acid (the volume ratio of mesitylene to 1,4-dioxane is 1:1, and the content of acetic acid is 6 mol / L), 2,4,6-tris(4-formylphenyl)-1,3,5-triazine (TFPT) and hydrazine hydrate at a molar ratio of 2:3 were added respectively. After degassing by freeze-thaw cycles three times, the mixture was heated to 120°C and kept warm for 3 days to obtain the azine-based covalent organic framework material TAZ-COF.

[0030] (2) Anhydrous zinc chloride, thioacetamide, and indium chloride were used as zinc source, sulfur source, and indium source, respectively, and added to a hydrochloric acid aqueous solution with a pH of 2.5 in a molar ratio of 1:1:2, and stirred to dissolve to obtain a mixed system;

[0031] (3) The TAZ-COF obtained in step (1) was ultrasonically dispersed in an acetonitrile solution (acetonitrile: water = 3:1, v / v) for 20 min, and then added to the mixed system obtained in step (2), stirred for 30 min to mix it evenly, and then reacted in an oil bath at 80°C for 12 h under stirring conditions to allow ZnIn2S4 to grow in situ on the TAZ-COF, thereby obtaining a sulfur indium zinc azine-based covalent organic framework composite material TAZ-COF / ZnIn2S4, wherein the mass ratio of TAZ-COF to ZnIn2S4 is 15%.

[0032] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0033] Example 1

[0034] A mixture of 2,4,6-tris(4-formylphenyl)-1,3,5-triazine (23.6 mg, 0.06 mmol), hydrazine hydrate (4.8 μL, 0.09 mmol), and 1 mL of mesitylene / 1,4-dioxane (1:1, v / v) was placed in a Pyrex tube and sonicated for 10 minutes to obtain a uniform dispersion. Acetic acid solution (0.1 mL, 6 M) was then added and mixed thoroughly. The mixture was then rapidly frozen in a liquid nitrogen bath at -196°C and degassed by freeze-thaw cycles three times. The Pyrex tube was then evacuated, flame-sealed, and placed in an oven at 120°C for 3 days before cooling to room temperature. The product was collected by filtration and washed three times with methanol, dichloromethane, N,N-dimethylformamide (DMF), and acetone, respectively. The resulting powder was dried overnight in a vacuum oven at 60°C to obtain a yellow powder of TAZ–COF.

[0035] Anhydrous zinc chloride (1 mmol), thioacetamide (1 mmol), indium chloride (2 mmol) were added into 30 ml aqueous hydrochloric acid solution (pH = 2.5) and stirred to dissolve, obtaining a mixed system.

[0036] A certain amount of TAz-COF was ultrasonically dispersed in acetonitrile solution (acetonitrile: water = 3:1, v / v) for 20 min, and then added into the prepared mixed system, stirred for 30 min to mix, and then in-situ growth of ZnIn2S4 on TAz-COF was carried out under 80°C oil bath condition with continuous stirring for 12 h, obtaining TAz-COF / ZnIn2S4 composite material, wherein the mass ratio of TAz-COF to ZnIn2S4 was 15%.

[0037] Figure 2 X-ray powder diffraction patterns of the prepared TAz-COF, ZnIn2S4 and TAz-COF / ZnIn2S4. The characteristic peaks given by XRD proved the successful synthesis of the composite material.

[0038] Figure 3 Fourier transform infrared spectra of the prepared TFPT, TAz-COF, ZnIn2S4 and TAz-COF / ZnIn2S4. The characteristic peaks of FT-IR further proved the successful synthesis of the composite material.

[0039] Figure 4 SEM images of the prepared TAz-COF, ZnIn2S4 and TAz-COF / ZnIn2S4. From the figure, it can be seen that TAz-COF is nanobelt (a), ZnIn2S4 is nanoflower (b), and the morphology of TAz-COF / ZnIn2S4 is nanoflower formed on nanobelt, which proves that ZnIn2S4 is successfully attached to TAz-COF (c).

[0040] Example 2

[0041] Weigh 10 mg of TAz-COF / ZnIn2S4 and spread it flat in a quartz dish. Add 10 mL of deionized water to the lower layer of a special glass reactor to generate water vapor for the photocatalytic reaction process. Place the quartz dish containing the catalyst on the upper layer of the reactor to separate it from the water. No sacrificial agent, co-catalyst, or other substances are added during the reaction. After evacuating the reactor, pass CO2 gas for 15 minutes to ensure that no other impurity gases remain in the reaction system. Then use a 300 W xenon lamp equipped with a 420 nm cutoff filter to irradiate the reaction system for 4 hours. During the photocatalytic reaction, pass condensed water outside the reactor to keep the reaction system temperature constant at 303~323K. Take 0.2 mL of the gas from the catalytic system with a gastight syringe every 1 hour. Use a gas chromatograph to detect the gas after the photocatalytic reaction and perform component analysis. The results are as follows: Figure 5 shown.

[0042] The performance of TAZ-COF / ZnIn2S4 photocatalytic reduction of carbon dioxide was explained based on the detected CO content. Figure 5 The results show that the CO yield of the composite TAZ-COF / ZnIn2S4 reached 12.625 μmol·g -1 ·h -1 , while the yield of pure ZnIn2S4 is 2.25 μmol·g -1 ·h -1 The yield of pure TAZ-COF was 1.525 μmol·g -1 ·h -1 It can be seen that the photocatalytic performance of the composite material is significantly improved, which proves that the composite material obtained by the present invention has good catalytic activity for photocatalytic reduction of carbon dioxide.

[0043] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. Application of a sulfur-indium zinc azine-based covalent organic framework composite material in photocatalytic reduction of carbon dioxide, characterized by: The preparation of the sulfur-indium-zinc-azine-based covalent organic framework composite material comprises the following steps: (1) 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and hydrazine hydrate were added to a mixture of mesitylene and 1,4-dioxane containing acetic acid, and after three freeze-thaw cycles of degassing, an azine-based covalent organic framework material TAZ-COF was obtained by solvothermal reaction. (2) Anhydrous zinc chloride, thioacetamide, and indium chloride are used as zinc source, sulfur source, and indium source, respectively, and are added to a hydrochloric acid aqueous solution with a pH of 2.5 and stirred to dissolve to obtain a mixed system; (3) The TAZ-COF obtained in step (1) is ultrasonically dispersed in an acetonitrile solution for 20 minutes, and then added to the mixed system obtained in step (2), stirred for 30 minutes to mix, and then reacted in an oil bath under stirring conditions to allow ZnIn2S4 to grow in situ on the TAZ-COF to obtain the sulfur-indium-zinc-azine-based covalent organic framework composite material; The reaction temperature in step (3) is 80° C. and the reaction time is 12 h. The mass ratio of TAZ-COF to ZnIn2S4 in the obtained sulfur indium zinc azine-based covalent organic framework composite material is 15%.

2. The use according to claim 1, characterized in that: The volume ratio of mesitylene to 1,4-dioxane in the mixed system of step (1) is 1:1, and the content of acetic acid is 6 mol / L; The molar ratio of the added 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and hydrazine hydrate is 2:

3.

3. The use according to claim 1, characterized in that: The temperature of the solvent thermal reaction in step (1) is 120° C. and the time is 3 days.

4. The use according to claim 1, characterized in that: The molar ratio of anhydrous zinc chloride, thioacetamide and indium chloride used in step (2) is 1:1:

2.

5. The use according to claim 1, characterized in that: The volume ratio of acetonitrile to water in the acetonitrile solution of step (3) is 3:1.

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