Preparation method and application of multifunctional organic-inorganic hybrid artificial photosynthetic heterojunction catalyst

Abstract

The invention discloses a preparation method of a multifunctional organic-inorganic hybrid artificial photosynthetic heterojunction catalyst, and belongs to the field of photochemical energy conversion and photocatalytic degradation. The invention aims to solve the technical problems of high-quality preparation of the artificial photosynthetic photocatalytic composite material and how to effectively improve the photochemical energy conversion efficiency. The method comprises the following steps: 1, dissolving zinc chloride, indium trichloride tetrahydrate and thioacetamide in deionized water, fully stirring and dissolving, transferring into a reaction kettle, heating, cooling to room temperature after the reaction is finished, taking out, washing and drying to obtain zinc indium sulfide (ZnIn2S4) solid powder; 2, ZnIn2S4 powder, ferric trichloride hexahydrate and 2-aminoterephthalic acid are dissolved in N, N-dimethylformamide, oil bath stirring is carried out, after the reaction is finished, cooling is carried out to the room temperature, washing and drying are carried out for multiple times, and the metal organic framework / indium zinc sulfide (MIL-101-NH2 (Fe) / ZnIn2S4) heterojunction composite material is obtained.

Description

Technical Field

[0001] The invention belongs to the field of water environment treatment and photocatalytic degradation. Background Art

[0002] Scientists began to look for new methods that can both utilize clean energy and achieve efficient chemical reactions. Photocatalytic technology came into being in this context, driving reactions by absorbing light energy through specific materials. Unlike traditional catalysis that requires high temperature and high pressure, photocatalytic reactions can be carried out at room temperature and pressure, and are particularly suitable for important applications such as treating pollutants and decomposing water to produce hydrogen. When a semiconductor is irradiated with light whose energy is greater than its band gap, the electrons in the valence band are excited by the energy of the photons and transition to the conduction band, leaving holes at the original position. The excited electrons can reduce the toxicity of heavy metal ions, and can also be used in clean energy generation, carbon dioxide reduction, etc. At the same time, electrons react with oxygen or water to produce strong oxidizing free radicals such as superoxide and hydroxyl. The generated oxidizing free radicals and holes react with pollutants, ultimately decomposing them into carbon dioxide and water.

[0003] Although semiconductor photocatalytic technology has shown significant application potential in the fields of environmental purification and energy conversion, single-component semiconductor photocatalytic systems are still limited by their own characteristics: narrow visible light absorption spectrum, high recombination rate of photogenerated carriers, and reduced surface active sites affected by the inherent agglomeration tendency of nanomaterials. Therefore, constructing different materials into heterojunctions has become a new strategy. After constructing the S-scheme heterojunction, when illuminated, electrons from the oxidized photocatalyst will migrate to the valence band of the reduced photocatalyst to recombine with holes, changing the movement path of photogenerated carriers, completing the separation of carriers, retaining electrons with high reduction potential and holes with high oxidation potential, and thus achieving the purpose of improving photocatalytic performance.

[0004] ZnIn 2 S 4 As a typical ternary layered sulfide, it is widely used in photocatalytic hydrogen production and pollutant degradation due to its narrow band gap, excellent visible light absorption ability and good chemical stability. 2 S 4 There are still problems such as high recombination rate of photogenerated electron-hole pairs and slow surface reaction kinetics. Metal-Organic Framework (MOFs) has a series of advantages, such as extremely high specific surface area, regular and neat structure, and adjustable porosity. In addition, MOFs have a band structure similar to that of inorganic semiconductors. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) correspond to the valence band and conduction band of the conductor, respectively, making MOFs applicable to the construction of organic-inorganic hybrid heterojunctions.

[0005] In summary, the present invention proposes a method for preparing a multifunctional organic-inorganic hybrid artificial photosynthetic heterojunction catalyst, which adopts a simple and mild co-precipitation method to prepare a three-dimensional nanoflower material ZnIn 2 S 4 In situ growth of metal organic framework (MIL-101-NH 2 ) particles to prepare and synthesize metal organic framework / indium zinc sulfide (MIL-101-NH 2 / ZnIn 2 S 4 ) Organic-inorganic hybrid heterojunction composite material. The S-scheme type heterojunction photocatalyst can effectively coordinate the efficiency of three aspects: solar light absorption range, photogenerated carrier separation efficiency and surface chemical reaction sites. Compared with the conventional preparation strategy of constructing heterojunctions by a two-step solvothermal method, the normal pressure, low temperature and rapid co-precipitation synthesis method proposed in the present invention does not require high temperature and high pressure hydrothermal reaction. It only needs oil bath heating and stirring at normal pressure for less than 5 hours. The composite material has a complete morphology, excellent heterojunction interface contact, stable bonding, and superior quantity and quality. At the same time, the method of the present invention is convenient and efficient, more green and energy-saving, and conforms to the development strategy of low carbon and low energy consumption. Summary of the invention

[0006] The present invention relates to solving the problems of high-quality and low-energy preparation of organic-inorganic hybrid artificial photosynthetic catalysts and improving and optimizing catalyst performance, thereby proposing a new strategy for energy-saving, simple and fast hybrid heterojunction catalyst synthesis. To solve the above problems, a preparation method of a multifunctional organic-inorganic hybrid artificial photosynthetic heterojunction catalyst and its application in the present invention are completed by the following steps.

[0007] Step 1: Dissolve zinc chloride, indium trichloride tetrahydrate and thioacetamide in deionized water, stir and dissolve thoroughly, transfer to a reactor for hydrothermal reaction, cool to room temperature, wash and dry to obtain zinc indium sulfide (ZnIn 2 S 4 ) solid powder.

[0008] Step 2: Disperse the indium zinc sulfide obtained in step 1 in a mixed solution of ferric chloride hexahydrate, 2-aminoterephthalic acid and N,N-dimethylformamide, heat and stir, cool to room temperature after the reaction, wash and dry to obtain MIL-101-NH 2 (Fe) / ZnIn 2 S 4 Heterojunction composite materials.

[0009] Further defined, in step 1, 95.41-177.19 mg of zinc chloride, 410.54-762.42 mg of indium trichloride tetrahydrate, and 210.36-390.68 mg of thioacetamide are dissolved in 60 mL of deionized water.

[0010] It is further defined that the stirring and dissolving time in step 1 is 30 min.

[0011] It is further defined that the hydrothermal reaction temperature in step 1 is 100-120°C, and the reaction time is 1-4 h.

[0012] It is further defined that in step 1, the temperature in the vacuum drying oven is kept at 60°C for 12 h.

[0013] Further defined, in step 2, 350-650 mg of indium zinc sulfide powder, 13.52-121.64 mg of ferric chloride hexahydrate, and 4.53-40.76 mg of 2-aminoterephthalic acid are added to 60 mL of N,N-dimethylformamide in sequence.

[0014] It is further defined that the stirring and dissolving time in step 2 is 30 min.

[0015] It is further defined that in step 2, the heating temperature is 80-100°C and the insulation time is 1-4 h.

[0016] It is further defined that in step 2, the temperature in the vacuum drying oven is kept at 60°C for 12 h.

[0017] The preparation method of the multifunctional organic-inorganic hybrid artificial photosynthetic heterojunction catalyst prepared by the method of the present invention is to prepare the metal organic framework MIL-101-NH 2 (Fe) nanoparticles were grown in situ on ZnIn 2 S 4 The surface of three-dimensional nanoflower ball forms MIL-101-NH 2 (Fe) / ZnIn 2 S 4 Composite material. The present invention provides a novel method for preparing a fast, low-temperature, normal-pressure organic-inorganic hybrid artificial photosynthetic catalyst, so as to achieve close contact of heterogeneous interfaces, effective spatial separation of photogenerated carriers, and ultimately achieve the purpose of effectively improving photocatalytic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 ZnIn 2 S 4 、MIL-101-NH 2 (Fe) and each component MIL-101-NH 2 (Fe) / ZnIn2 S 4 (abbreviated as ZNM) XRD pattern of the composite material; Figure 2 is a scanning electron microscope photo of ZNM3; Figure 3 ZnIn 2 S 4 、MIL-101-NH 2 UV-visible absorption spectra of (Fe) and each composite material; Figure 4 ZnIn 2 S 4 and MIL-101-NH 2 Bandgap diagram of (Fe); Figure 5 ZnIn 2 S 4 With MIL-101-NH 2 (Fe) Mott-Schottky electrochemical test spectra of the two samples; Figure 6 ZnIn 2 S 4 、MIL-101-NH 2 Electrochemical impedance spectral lines of the three samples (Fe) and ZNM3; Figure 7 is the change curve of the photocatalytic reduction degradation of each sample to 100 mL of 80 mg / L potassium dichromate solution over time; Figure 8 This is the curve of the photocatalytic oxidation degradation of 50 mL of 60 mg / L tetracycline hydrochloride solution by each sample over time. Fig. 9 It is the hydrogen production rate diagram of ZIS and ZNM3. DETAILED DESCRIPTION

[0019] Example 1: This example uses ZnIn 2 S 4 The three-dimensional nanoflowers were prepared by the following steps: 136.30 mg zinc chloride (ZnCl 2 ), 586.48 mg indium trichloride tetrahydrate (InCl 3 ·4H 2 O), 300.52 mg thioacetamide (C 2 H 5 NS) was dissolved in 60 mL of deionized water, stirred for 30 min, transferred to a 100 mL reactor, heated at 90 °C for 2 h, and then cooled to room temperature. It was washed with deionized water and ethanol three times each, and vacuum dried at 60 °C for 12 h to obtain ZnIn 2 S 4 powder.

[0020] In this embodiment, a method for preparing a multifunctional organic-inorganic hybrid artificial photosynthetic heterojunction catalyst is completed by the following steps.

[0021] Step 1: Dissolve 136.30 mg zinc chloride, 586.48 mg indium trichloride tetrahydrate, and 300.52 mg thioacetamide in 60 mL deionized water, stir for 30 min, transfer to a 100 mL reactor, and heat at 90 °C for 2 h. Wash the product with deionized water and ethanol three times each, and dry it in a vacuum oven at 60 °C for 12 h to obtain ZnIn 2 S 4 powder.

[0022] Step 2: Disperse 500 mg of ZnIn in 5 beakers containing 60 mL of N,N-dimethylformamide. 2 S 4 Powder, then add 13.52, 40.55, 67.58, 94.61 and 121.64 mg of ferric chloride hexahydrate and 4.53, 13.59, 22.64, 31.70 and 40.76 mg of 2-aminoterephthalic acid in sequence, stir for 30 min to fully dissolve, stir in an oil bath at 110 ° C for 2 h. After the reaction is completed and cooled to room temperature, wash with anhydrous ethanol 5 times, and vacuum dry at 60 ° C for 12 h to obtain MIL-101-NH 2 (Fe) / ZnIn 2 S 4 powder, and based on ZnIn 2 S 4 With MIL-101-NH 2 The composite samples were named ZNM1, ZNM2, ZNM3, ZNM4 and ZNM5.

[0023] The photocatalytic degradation indicator reaction uses a 300 W xenon lamp to simulate the sunlight light source. In a 250 mL beaker, 10 mg of the catalyst to be tested and 100 mL of potassium dichromate solution with a concentration of 80 mg / L were placed as a reduction degradation test. In a 100 mL beaker, 10 mg of the catalyst to be tested and 50 mL of tetracycline hydrochloride solution with a concentration of 60 mg / L were placed as an oxidation degradation test. The beaker was fixed 5 cm below the light source, and uniform magnetic stirring was maintained during the degradation reaction. The absorbance of the reaction solution was detected at the same time interval, and the concentration of the reaction solution was calculated to make a curve of the degradation rate changing with the illumination time, thereby analyzing and comparing the photocatalytic activity of the samples, such as Figure 7 and Figure 8 shown.

[0024] from Figure 7It can be seen that the performance of the five composite photocatalysts ZNM1~ZNM5 in the photocatalytic reduction reaction is higher than that of the reference photocatalyst. Among them, the degradation rate of the ZNM3 sample is the fastest, and it took 24 minutes to degrade 89% of the potassium dichromate solution. Figure 8 It can also be seen that the ZNM3 sample has the fastest degradation rate, and can degrade 92% of the tetracycline hydrochloride solution in 50 minutes. Fig. 9 It can be seen that the hydrogen production and efficiency of ZNM3 are higher than those of ZIS. 2 (Fe) / ZnIn 2 S 4 The unique photogenerated electron migration path of organic-inorganic hybrid artificial catalysts creates favorable conditions for the separation of carriers, which not only prolongs the lifetime of photogenerated electrons, but also effectively increases the reaction thermodynamic potential energy of photogenerated electrons, which is manifested macroscopically as a significant improvement in the photocatalytic oxidation and reduction performance of the material.

Claims

1. A method for preparing a multifunctional organic-inorganic hybrid artificial photosynthetic heterojunction catalyst and its application, characterized in that The preparation method is completed by the following steps: step 1, dissolving zinc chloride, indium trichloride tetrahydrate and thioacetamide in deionized water, stirring and dissolving them fully, transferring them to a reactor for hydrothermal reaction, cooling them to room temperature, washing and drying them, and obtaining indium zinc sulfide (ZnIn2S4) solid powder; step 2, dispersing the indium zinc sulfide powder obtained in step 1 in a mixed solution of ferric trichloride hexahydrate, 2-aminoterephthalic acid and N,N-dimethylformamide, heating and stirring them, cooling them to room temperature after the reaction, washing and drying them, and obtaining the MIL-101-NH2(Fe) / ZnIn2S4 artificial photosynthetic heterojunction catalyst.

2. The method according to claim 1, characterized in that In step 1, 95.41-177.19 mg of zinc chloride, 410.54-762.42 mg of indium trichloride tetrahydrate, and 210.36-390.68 mg of thioacetamide were dissolved in 60 mL of deionized water.

3. The method according to claim 1, characterized in that The stirring and dissolving time in step 1 is 30 min.

4. The method according to claim 1, characterized in that In step 1, the hydrothermal reaction temperature is 100-120°C, and the reaction time is 1-4 h.

5. The method according to claim 1, characterized in that Step 1: Keep in a vacuum drying oven at 60 °C for 12 h.

6. The method according to claim 1, characterized in that Step 2: Add 350-650 mg of indium zinc sulfide powder, 13.52-121.64 mg of ferric chloride hexahydrate, and 4.53-40.76 mg of 2-aminoterephthalic acid into 60 mL of N,N-dimethylformamide.

7. The method according to claim 1, characterized in that The stirring time in step 2 is 30 min.

8. The method according to claim 1, characterized in that Step 2: The heating temperature is 80~100℃ and the insulation time is 1~4h.

9. The method according to claim 1, characterized in that Step 2: Keep in a vacuum drying oven at 60 °C for 12 h.

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