Preparation method and application of MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution

Abstract

The present invention relates to the technical field of photocatalytic hydrogen evolution, and in particular to a preparation method and application of a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution, comprising: preparation of S1 and a MIL-68 precursor, preparation of S2 and In2O3, and preparation of S3 and an In2S3 / ZnIn2S4 composite material; the preparation operation process of the In2S3 / ZnIn2S4 composite material of the present invention is simple, and the simultaneous generation of In2S3 and ultrathin nanosheets In2S3 / ZnIn2S4 is successfully achieved; n2S3 and ZnI A heterojunction structure is constructed between n2S4; this heterojunction has unique structural characteristics, and through the synergistic effect of the built-in electric field, electrons and interface structure, it effectively enhances the photocatalytic hydrogen evolution activity; the retention of the MOF morphology leads to the high porosity of In2S3 / ZnIn2S4, and the ZnIn2S4 thin nanosheets shorten the charge diffusion path of the light hole in water, ensuring sufficient light absorption, thereby exposing more catalytic active centers; the preparation of metal organic framework-derived In2S3 / ZnIn2S4 composite materials has excellent performance advantages in the field of photocatalytic hydrogen evolution.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalytic hydrogen evolution, and in particular to a preparation method and application of a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution. Background Art

[0002] Metal-organic frameworks (MOFs) are considered promising materials for hydrogen evolution due to their high surface area, rich porous structure, and abundant metal sites. MOF derivatives fully inherit the high surface area and porous framework characteristics of MOFs, providing a large number of active sites for catalytic reactions, thereby enhancing the hydrogen evolution rate. Furthermore, In2S3 exhibits high photosensitivity and photoconductivity, making it an environmentally friendly semiconductor.

[0003] However, the photocatalytic performance of In2S3 remains unsatisfactory, primarily due to limitations in photogenerated charge separation, slow charge transfer kinetics, and photocorrosion. In2S3 not only serves as a co-catalyst but also possesses good catalytic activity on its own. Therefore, combining In2S3 with ZnIn2S4 is expected to further enhance their synergistic catalysis.

[0004] Patent application number CN201510212970.2 discloses a noble metal / ZnIn2S4 / TiO2 nanoheterostructure photocatalyst and its preparation method. Although the noble metal / ZnIn2S4 / TiO2 composite photocatalyst synthesized by this method has improved its photocatalytic performance, its economic and social benefits remain insufficient. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a preparation method and application of a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution.

[0006] The technical solution of the present invention is: a preparation method and application of a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution, comprising the following steps:

[0007] S1. Preparation of MIL-68 precursor:

[0008] 1.5-2.5 mmol of In(NO3)3 and 1.5-2.5 mmol of terephthalic acid are dissolved in 10-20 mL of N,N-dimethylformamide solution, and then 70-90 μL of crystalline sodium acetate aqueous solution is added to obtain a mixed solution; the mixed solution is heated in an oil bath at a temperature of 90-110°C for 30-40 minutes, and then naturally cooled to room temperature to obtain a mixed slurry; the mixed slurry is centrifuged and washed with an ethanol solution having a volume concentration of 95-99.9% to obtain a MIL-68 sample, and the MIL-68 sample is placed in a blast drying oven and dried at 50-80°C for 10-14 hours to obtain a MIL-68 precursor;

[0009] Preparation of S2 and In2O3:

[0010] The MIL-68 precursor prepared in S1 was placed in a tube furnace, calcined in air, heated to 500-600°C and kept at this temperature for 2-3 hours, and then cooled to room temperature to obtain In2O3;

[0011] Preparation of S3, In2S3 / ZnIn2S4 composite materials:

[0012] According to the mass percentage, 10-15% HCl aqueous solution, 5-8% propylene glycol and the rest deionized water are mixed evenly to obtain a mixed solution, and then the In2O3 prepared by the S2 is added and ultrasonically dissolved, and the amount of In2O3 added is 10-45wt% of the mixed solution; then, 0.1-0.2% zinc chloride, 0.4-0.6% indium chloride and 0.3-0.5% thioacetamide are added in sequence, and stirred until each additive is dissolved to obtain a stock solution; the stock solution is placed in an oil bath at a temperature of 75-85°C and heated for 5-7h until it is cooled to room temperature, and then centrifuged and washed with an ethanol solution with a volume concentration of 95-99.9% to obtain an In2S3 / ZnIn2S4 sample; finally, the In2S3 / ZnIn2S4 sample is placed in a drying oven and dried at a temperature of 55-65°C for 10-14h to obtain an In2S3 / ZnIn2S4 composite material.

[0013] Description: The preparation process of the In2S3 / ZnIn2S4 composite material of the present invention is simple, and the simultaneous generation of In2S3 and ultrathin nanosheets ZnIn2S4, the simultaneous generation of In2S3 and ultrathin nanosheets ZnIn2S4, and the construction of a heterojunction structure are successfully achieved. By precisely controlling the molar ratio of the reactants and the reaction conditions through the parameters of this method, materials with target structures and properties can be synthesized. The use of specific solvents and additives helps to form a uniform precursor and promote subsequent conversion; an appropriate In2O3 content is crucial for controlling the composition and structure of the final In2S3 / ZnIn2S4 composite material, which can optimize the light absorption performance, electron transport characteristics and catalytic activity of the composite material. Precisely controlling the amount of In2O3 added can also help avoid agglomeration or incomplete reaction caused by excessive In2O3, thereby improving the overall performance and stability of the composite material.

[0014] Furthermore, in S1, the concentration of the crystalline sodium acetate aqueous solution is 0.03 to 0.05 mol / L.

[0015] Description: Crystalline sodium acetate acts as a template or structure-directing agent in step S1, helping to control the morphology and pore structure of the MIL-68 material. The concentration of the prepared crystalline sodium acetate aqueous solution is 0.03 to 0.05 mol / L. This concentration ensures that an appropriate amount of acetate ions participate in the synthesis process, but is not too high to cause unnecessary side reactions or affect the purity and crystallinity of the final material. By precisely controlling the concentration of crystalline sodium acetate, the synthesis of the MIL-68 precursor can be optimized, thereby providing a better precursor for the subsequent conversion into In2O3 and In2S3 / ZnIn2S4 composite materials.

[0016] Furthermore, in S2, the heating rate of the MIL-68 precursor in the tube furnace is 4-6°C / min.

[0017] Note: In step S2, the heating rate of the MIL-68 precursor in the tube furnace is 4-6°C / min. Such a heating rate helps ensure that the material can be heated evenly during the calcination process, avoiding the generation of thermal stress and cracks caused by excessively rapid heating. Uniform heating helps maintain the crystal structure and morphology of the material, thereby obtaining In2O3 materials with better crystallinity and purity. The appropriate heating rate also helps promote the complete decomposition of organic ligands and the formation of metal oxides, which is crucial for the performance of the subsequent synthesis of In2S3 / ZnIn2S4 composite materials.

[0018] Furthermore, in S3, the pH value of the HCl aqueous solution is 2.4 to 2.6.

[0019] Description: Appropriate acidic conditions can accelerate the dissolution of In2O3 and promote the formation of In2S3 and ZnIn2S4. HCl can provide the necessary H+ ions to help convert In2O3 into soluble ions, thereby promoting the subsequent reaction with thioacetamide to form the target sulfide. Precise control of pH helps regulate the reaction rate, avoiding excessively fast or slow reactions, thereby ensuring the uniformity and quality of the material. Different pH values ​​affect the crystallinity and morphology of the final material. A specific pH range helps form In2S3 / ZnIn2S4 composites with ideal properties, such as higher specific surface area, more uniform particle size, and superior electrochemical performance.

[0020] Furthermore, in S1 and S3, the number of centrifugal washings is 3 times, the centrifugal speed of each time is 8000-8500 r / min, and the time of each centrifugation is 5-10 min.

[0021] Explanation: Higher centrifugal speeds can generate greater centrifugal force, helping to more effectively separate unreacted raw materials, by-products, and possible impurities from solid particles; multiple centrifugal washes can ensure that impurities on the surface and inside of the solid sample are fully removed, improving the purity of the final product; appropriate centrifugation time can achieve effective solid-liquid separation without destroying the material structure; by optimizing centrifugal washing conditions, higher quality MIL-68 and In2S3 / ZnIn2S4 composites can be obtained, which is crucial for subsequent application performance.

[0022] Furthermore, it also includes an impregnation treatment of S4 and In2S3 / ZnIn2S4 composite materials, and the impregnation treatment method is: immersing the In2S3 / ZnIn2S4 composite material prepared by S3 in a sodium polystyrene sulfonate solution with a concentration of 0.5-1 mg / mL, immersing and stirring for 0.2-3 hours, and then drying at 65-85°C to obtain a mixed material; the mass ratio of the In2S3 / ZnIn2S4 composite material and the sodium polystyrene sulfonate solution is 1:1.5-3, and the solvent of the sodium polystyrene sulfonate solution is deionized water; taking the doped microparticles and mixing them with water to prepare a treatment solution with a concentration of 0.01-0.05M, and the doped microparticles are Au(NO3)3 particles with a particle size of 2-5nm; then introducing the mixed material into the treatment solution, maintaining the reaction at a temperature of 50-100°C for 6-18 hours, controlling the pH value to 7-9, and after the reaction is completed, centrifugally drying to obtain the In2S3 / ZnIn2S4 composite doping material.

[0023] Description: Through the impregnation treatment of sodium polystyrene sulfonate, functional groups can be introduced on the surface of the composite material. These functional groups can enhance the interaction between the material and the solvent or reaction medium, thereby improving the dispersibility and stability of the composite material. The introduction of sodium polystyrene sulfonate can change the electronic structure of the composite material, help adjust its light absorption characteristics, and enable the composite material to absorb visible light more effectively, thereby improving the photocatalytic efficiency. By controlling the impregnation treatment conditions, such as solution concentration, reaction time and temperature, the surface properties of the composite material can be optimized, the number of active sites can be increased, and thus its catalytic activity can be improved. Doping treatment of the composite material helps to improve the separation efficiency of photogenerated electrons and holes, forming specific active sites on the surface or in the lattice of In2S3 / ZnIn2S4, improving the separation efficiency of photogenerated carriers, and enhancing the capture and utilization efficiency of photogenerated carriers by In2S3 / ZnIn2S4. Au(NO3)3 is used as a gold source to form gold nanoparticles on the surface or inside the composite material through thermal decomposition or reduction reaction. These gold nanoparticles can act as electron acceptors, effectively promoting the separation of electron-hole pairs, thereby enhancing the photocatalytic hydrogen evolution performance.

[0024] Furthermore, the In2S3 / ZnIn2S4 composite material described in S4 is applied to photocatalytic hydrogen production, and the method for hydrogen production is: by mass percentage, 15-45% of the In2S3 / ZnIn2S4 composite material, 0.1-10% of the photocatalytic sacrificial agent, 0.01-6% of the zinc phthalocyanine and the remainder of the distilled water or ethanol solution are mixed, stirred to form a uniform suspension, and a 300W xenon lamp is used to carry out photoreduction water decomposition reaction to produce hydrogen. The temperature of the suspension is controlled at 50-70°C, and the pH value is controlled at 10-12. During the reaction, samples are measured at the same time interval, and the hydrogen production of each sample is analyzed continuously for 3-5 times. Qualitative analysis is performed by gas chromatography, and hydrogen evolution information is obtained by computational analysis.

[0025] Description: By precisely controlling the preparation conditions of the composite doped material, the material's light absorption and charge separation capabilities can be optimized, thereby improving the photocatalytic efficiency and enhancing the yield of hydrogen production from photocatalytic water splitting; zinc phthalocyanine, as a co-catalyst, can improve the stability of the photocatalyst, prevent the photocatalyst from decomposing under long-term light, and ensure the long-term operation of the catalytic system; the addition of a photocatalytic sacrificial agent can improve the selectivity of hydrogen production, reduce the occurrence of side reactions, and ensure the purity of hydrogen; by controlling the temperature, pH value, and light intensity of the suspension, the efficiency of photocatalytic hydrogen production can be further optimized and energy consumption can be reduced; qualitative analysis by gas chromatography can accurately determine the amount of hydrogen produced, providing a scientific basis for optimizing reaction conditions and evaluating catalyst performance.

[0026] Furthermore, the photocatalytic sacrificial agent comprises, by mass percentage, 10-40% cytochrome c, 0-30% peroxidase, 1-20% polypeptide, 0.1-10% hydrogenase, and the remainder polyphenol.

[0027] Description: The components of a photocatalytic sacrificial agent contribute to improved photocatalytic efficiency and stability. Cytochrome c, as a sacrificial agent, effectively donates electrons, promoting the separation of photogenerated charge carriers; peroxidase and hydrogenase participate in redox reactions, further enhancing hydrogen generation efficiency; peptides act as stabilizers or promoters, enhancing photocatalytic activity; and polyphenols coordinate with metal ions to form a metallophenol network, activating photocatalytic activity and improving photocatalytic efficiency. Improving the synergistic effect of these components optimizes the photocatalytic hydrogen production process, increasing hydrogen production rate and overall system performance.

[0028] The beneficial effects of the present invention are:

[0029] (1) In the In2S3 / ZnIn2S4 composite material of the present invention, the retention of the MOF morphology results in a high porosity of the In2S3 / ZnIn2S4, and the MOF morphology can be well inherited. At the same time, the ZnIn2S4 thin nanosheets shorten the charge diffusion path of the photohole in water, ensuring sufficient light absorption, thereby exposing more catalytic active centers, resulting in excellent performance advantages for the preparation of the metal organic framework-derived In2S3 / ZnIn2S4 composite material in the field of photocatalytic hydrogen evolution.

[0030] (2) The present invention has simple steps for preparing the In2S3 / ZnIn2S4 composite material. In2S3 and ultrathin nanosheets ZnIn2S4 are generated simultaneously, and a heterojunction structure is constructed. The heterojunction has unique structural characteristics and effectively improves the photocatalytic hydrogen evolution activity through the synergistic effect of the built-in electric field, electrons, and interface structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 1 is an XRD test result diagram of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention;

[0032] Figure 2 This is a standard comparison diagram of the SEM test results of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention;

[0033] Figure 3 TEM test results of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention;

[0034] Figure 41 is an XPS test result diagram of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention;

[0035] Figure 5 This is the UV-visible diffuse reflectance spectrum test result of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention

[0036] Figure 6 1 is a graph showing the transient photocurrent test results of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention;

[0037] Figure 7 1 is a graph showing the electrochemical impedance spectroscopy test results of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention;

[0038] Figure 8 is a Mott-Schottky curve diagram of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention;

[0039] Figure 9 This is a test chart of the photocatalytic hydrogen evolution activity of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention.

[0040] Figure 10 This is a diagram of the photocatalytic reaction mechanism of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0041] In order to further illustrate the approach and effects achieved by the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with experiments.

[0042] Example 1: A method for preparing a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution, comprising the following steps:

[0043] S1. Preparation of MIL-68 precursor:

[0044] 2 mmol of In(NO3)3 and 2 mmol of terephthalic acid were dissolved in 15 mL of N,N-dimethylformamide solution, and then 80 μL of crystalline sodium acetate aqueous solution was added to obtain a mixed solution; the mixed solution was heated in an oil bath at a temperature of 100°C for 35 minutes, and then naturally cooled to room temperature to obtain a mixed slurry; the mixed slurry was centrifuged and washed with an ethanol solution having a volume concentration of 97% to obtain a MIL-68 sample, and then the MIL-68 sample was placed in a blast drying oven and dried at 65°C for 12 hours to obtain a MIL-68 precursor; the concentration of the crystalline sodium acetate aqueous solution was 0.04 mol / L;

[0045] Preparation of S2 and In2O3:

[0046] The MIL-68 precursor prepared in S1 was placed in a tube furnace, calcined in air, heated to 550°C and kept at this temperature for 2.5 hours, and then cooled to room temperature to obtain In2O3; the heating rate of the MIL-68 precursor in the tube furnace was 5°C / min;

[0047] Preparation of S3, In2S3 / ZnIn2S4 composite materials:

[0048] According to the mass percentage, 12.5% ​​HCl aqueous solution, 6.5% glycerol and the rest deionized water are mixed uniformly to obtain a mixed solution, and then the In2O3 prepared by the S2 is added and ultrasonically dissolved, and the amount of In2O3 added is 25wt% of the mixed solution; then 0.15% zinc chloride, 0.5% indium chloride and 0.4% thioacetamide are added in sequence with a mass ratio of deionized water, and stirred uniformly until each additive is dissolved to obtain a stock solution; the stock solution is placed in an oil bath at a temperature of 80°C and heated for 6 hours until it is cooled to room temperature, and then centrifuged and washed with a volume concentration of 97% ethanol solution to obtain an In2S3 / ZnIn2S4 sample; finally, the In2S3 / ZnIn2S4 sample is placed in a drying oven and dried at a temperature of 60°C for 12 hours to obtain an In2S3 / ZnIn2S4 composite material; the pH value of the HCl aqueous solution is 2.5;

[0049] In S1 and S3, the number of centrifugal washings was 3 times, the centrifugal speed of each time was 8250 r / min, and the time of each centrifugation was 7.5 min;

[0050] An application method of a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution is:

[0051] The invention discloses a method for preparing a photocatalytic sacrificial agent comprising mixing 30% of an In2S3 / ZnIn2S4 composite material, 5.05% of a photocatalytic sacrificial agent, 3% of zinc phthalocyanine, and the balance of distilled water or ethanol solution, stirring the mixture to form a uniform suspension, and performing a photoreduction water decomposition reaction to produce hydrogen using a 300W xenon lamp. The temperature of the suspension is controlled at 60°C, and the pH value is controlled at 11. The photocatalytic sacrificial agent comprises, by mass percentage, 25% of cytochrome c, 15% of peroxidase, 10% of polypeptide, 5% of hydrogenase, and the balance of polyphenol.

[0052] Example 2: This embodiment differs from Example 1 in that it also includes an impregnation treatment of S4 and an In2S3 / ZnIn2S4 composite material, and the impregnation treatment method is as follows: the In2S3 / ZnIn2S4 composite material prepared by S3 is immersed in a sodium polystyrene sulfonate solution with a concentration of 0.75 mg / mL, immersed and stirred for 1.6 hours, and then dried at 75°C to obtain a mixed material; the mass ratio of the In2S3 / ZnIn2S4 composite material to the sodium polystyrene sulfonate solution is 1:2.25, and the solvent of the sodium polystyrene sulfonate solution is deionized water; the doped microparticles are mixed with water to prepare a treatment solution with a concentration of 0.03M, and then the mixed material is introduced into the treatment solution, and the reaction is maintained at a temperature of 75°C for 12 hours, and the pH value is controlled to be 8. After the reaction is completed, it is centrifuged and dried to obtain an In2S3 / ZnIn2S4 composite doping material; the doped microparticles are Au(NO3)3 particles with a particle size of 2.5 to 3 nm;

[0053] A method for applying a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution is as follows: the In2S3 / ZnIn2S4 composite doping material is applied to photocatalytic hydrogen production, and the hydrogen production method is as follows: 30% of the In2S3 / ZnIn2S4 composite doping material, 5% of a photocatalytic sacrificial agent, 3% of zinc phthalocyanine and the remainder of distilled water or ethanol solution are mixed by mass percentage, stirred to form a uniform suspension, and a 300W xenon lamp is used to perform a photoreduction water decomposition reaction to produce hydrogen, wherein the suspension temperature is controlled at 60°C and the pH value is controlled at 11; the components of the photocatalytic sacrificial agent are, by mass percentage, 25% of cytochrome c, 15% of peroxidase, 10% of polypeptide, 5% of hydrogenase and the remainder of polyphenol.

[0054] Example 3: The difference between this example and Example 2 is that: the In2S3 / ZnIn2S4 composite material prepared by S3 is immersed in a sodium polystyrene sulfonate solution with a concentration of 0.5 mg / mL, immersed and stirred for 0.2 h, and then dried at 65°C to obtain a mixed material; the mass ratio of the In2S3 / ZnIn2S4 composite material and the sodium polystyrene sulfonate solution is 1:1.5, and the solvent of the sodium polystyrene sulfonate solution is deionized water; the doped microparticles are mixed with water to prepare a treatment solution with a concentration of 0.01 M, and then the mixed material is introduced into the treatment solution, maintained at a temperature of 50°C for 6 h, and the pH value is controlled to 7. After the reaction is completed, it is centrifuged and dried to obtain an In2S3 / ZnIn2S4 composite doped material.

[0055] Example 4: The difference between this example and Example 2 is that: the In2S3 / ZnIn2S4 composite material prepared by S3 is immersed in a sodium polystyrene sulfonate solution with a concentration of 1 mg / mL, immersed and stirred for 3 hours, and then dried at 85°C to obtain a mixed material; the mass ratio of the In2S3 / ZnIn2S4 composite material and the sodium polystyrene sulfonate solution is 1:3, and the solvent of the sodium polystyrene sulfonate solution is deionized water; the doped microparticles are mixed with water to prepare a treatment solution with a concentration of 0.05M, and then the mixed material is introduced into the treatment solution, maintained at a temperature of 100°C for 18 hours, and the pH value is controlled to be 9. After the reaction is completed, it is centrifuged and dried to obtain an In2S3 / ZnIn2S4 composite doped material.

[0056] Example 5: The difference between this example and Example 2 is that: 15% of the In2S3 / ZnIn2S4 composite material, 0.1% of the photocatalytic sacrificial agent, 0.01% of the zinc phthalocyanine and the remainder of the distilled water or ethanol solution are mixed and stirred to form a uniform suspension, and a 300W xenon lamp is used to carry out the photoreduction water decomposition reaction to produce hydrogen. The temperature of the suspension is controlled at 50°C and the pH value is controlled at 10. The components of the photocatalytic sacrificial agent are, by mass percentage, 10% of cytochrome c, 1% of polypeptide, 0.1% of hydrogenase and the remainder of polyphenols.

[0057] Example 6: The difference between this example and Example 2 is that: 45% of the In2S3 / ZnIn2S4 composite material, 10% of the photocatalytic sacrificial agent, 6% of the zinc phthalocyanine and the remainder of the distilled water or ethanol solution are mixed and stirred to form a uniform suspension, and a 300W xenon lamp is used to carry out the photoreduction water decomposition reaction to produce hydrogen. The temperature of the suspension is controlled at 70°C and the pH value is controlled at 12. The components of the photocatalytic sacrificial agent are, by mass percentage, 40% of cytochrome c, 30% of peroxidase, 20% of polypeptide, 10% of hydrogenase and the remainder of polyphenols.

[0058] Example 7: The difference between this example and Example 1 is that: 1.5 mmol of In(NO3)3 and 1.5 mmol of terephthalic acid are dissolved in 10 mL of N,N-dimethylformamide solution, and then 70 μL of crystalline sodium acetate aqueous solution is added to obtain a mixed solution; the mixed solution is heated in an oil bath at a temperature of 90°C for 30 minutes, and then naturally cooled to room temperature to obtain a mixed slurry; the mixed slurry is centrifuged and washed with an ethanol solution with a volume concentration of 95% to obtain a MIL-68 sample, and then the MIL-68 sample is placed in a blast drying oven and dried at 50°C for 10 hours to obtain a MIL-68 precursor; the concentration of the crystalline sodium acetate aqueous solution is 0.03 mol / L.

[0059] Example 8: The difference between this example and Example 1 is that: 2.5 mmol of In(NO3)3 and 2.5 mmol of terephthalic acid are dissolved in 20 mL of N,N-dimethylformamide solution, and then 90 μL of crystalline sodium acetate aqueous solution is added to obtain a mixed solution; the mixed solution is heated in an oil bath at a temperature of 110°C for 40 minutes, and then naturally cooled to room temperature to obtain a mixed slurry; the mixed slurry is centrifuged and washed with an ethanol solution with a volume concentration of 99% to obtain a MIL-68 sample, and then the MIL-68 sample is placed in a blast drying oven and dried at 80°C for 14 hours to obtain a MIL-68 precursor; the concentration of the crystalline sodium acetate aqueous solution is 0.05 mol / L.

[0060] Example 9: This example differs from Example 1 in that the MIL-68 precursor prepared in S1 is placed in a tube furnace, calcined in air, heated to 500°C and kept warm for 2 hours, and then cooled to room temperature to obtain In2O3; the heating rate of the MIL-68 precursor in the tube furnace is 4°C / min.

[0061] Example 10: This example differs from Example 1 in that the MIL-68 precursor prepared in S1 is placed in a tube furnace, calcined in air, heated to 600°C and kept warm for 3 hours, and then cooled to room temperature to obtain In2O3; the heating rate of the MIL-68 precursor in the tube furnace is 6°C / min.

[0062] Example 11: The difference between this embodiment and Example 1 is that: 10% HCl aqueous solution, 5% glycerol and the remainder deionized water are mixed uniformly by mass percentage to obtain a mixed solution, and then the In2O3 prepared by S2 is added and ultrasonically dissolved, and the amount of In2O3 added is 10wt% of the mixed solution; then 0.1% zinc chloride, 0.4% indium chloride and 0.3% thioacetamide are added in sequence by mass ratio of deionized water, and stirred until each additive is dissolved to obtain a stock solution; the stock solution is placed in an oil bath at a temperature of 75°C and heated for 5h, until it is cooled to room temperature, and then centrifuged and washed with a volume concentration of 95% ethanol solution to obtain an In2S3 / ZnIn2S4 sample; finally, the In2S3 / ZnIn2S4 sample is placed in a drying oven and dried at a temperature of 55°C for 10h to obtain an In2S3 / ZnIn2S4 composite material; the pH value of the HCl aqueous solution is 2.4.

[0063] Example 12: The difference between this embodiment and Example 1 is that: 15% HCl aqueous solution, 8% glycerol and the remainder deionized water are mixed uniformly by mass percentage to obtain a mixed solution, and then the In2O3 prepared by the S2 is added and ultrasonically dissolved, and the amount of In2O3 added is 45wt% of the mixed solution; then 0.2% zinc chloride, 0.6% indium chloride and 0.5% thioacetamide are added in sequence with a mass ratio of deionized water, and stirred until each additive is dissolved to obtain a stock solution; the stock solution is placed in an oil bath at a temperature of 85°C and heated for 7h until it is cooled to room temperature, and then centrifuged and washed with a volume concentration of 99% ethanol solution to obtain an In2S3 / ZnIn2S4 sample; finally, the In2S3 / ZnIn2S4 sample is placed in a drying oven and dried at a temperature of 65°C for 14h to obtain an In2S3 / ZnIn2S4 composite material; the pH value of the HCl aqueous solution is 2.6.

[0064] Experimental Example 1: The description of this experimental example is based on the scheme described in Example 1, and is intended to illustrate the practical application effect of the present invention.

[0065] 1. XRD test was performed on the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention. Figure 1 As shown:

[0066] The diffraction peaks of the composite In2S3 / ZnIn2S4 at 21.5°, 27.6°, and 47.1° correspond to the (006), (102), and (110) crystal planes in the ZnIn2S4 PDF standard card (JCPDS.65-2023). No obvious characteristic peaks of In2S3 were detected in the prepared In2S3 / ZnIn2S4 composite. The absence of characteristic peaks of In2S3 may be due to the similar crystal structures of In2S3 and ZnIn2S4, or it may be due to the low In2S3 loading and the high dispersion of In2S3 on ZnIn2S4.

[0067] 2. The In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention was subjected to SEM testing. Figure 2 (a) shows:

[0068] A single ZnIn2S4 is in the form of a two-dimensional nanosheet. Figure 2 (b) It can be seen that due to the small amount of In2O3 added, the morphology of In2S3 / ZnIn2S4 after one-step sulfurization is consistent with that of ZnIn2S4, and the diameter size is almost unchanged.

[0069] 3. The In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention was subjected to TEM test. Figure 3(a) shows:

[0070] There are a large number of ZnIn2S4 nanosheets in In2S3 / ZnIn2S4. Figure 3 (b) The A and B areas are enlarged to obtain Figure 3 (c, d). HRTEM shows that the interplanar spacing of 0.189nm and 0.203nm corresponds to the (440) and (511) planes of In2S3 respectively. Figure 3 The C and D areas in (e) are enlarged to obtain Figure 3 (f, g). The interplanar spacings of 0.192 nm and 0.175 nm correspond to the (110) and (1112) planes of ZnIn2S4, respectively.

[0071] 4. The In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention was subjected to XPS testing. By observing the measurement spectrum of In2S3 / ZnIn2S4 (such as Figure 4 (a) as shown):

[0072] The presence of In, S, and Zn elements can be clearly seen, and this result is consistent with the elemental analysis results of the element mapping diagram, further confirming the accuracy of its composition. Figure 4 (b) shows the Zn 2p spectrum of In2S3 / ZnIn2S4 photocatalyst. The peaks at 1022.2eV and 1045.3eV correspond to Zn 2p 3 / 2 and Zn 2p 1 / 2 , indicating that Zn 2+ formation. Figure 4 (c) S2p 3 / 2 and S2p 1 / 2 The characteristic binding energies of S are 161.7 eV and 162.9 eV, respectively. 2- formation. Figure 4 (d) shows the In 3d spectrum of the In2S3 / ZnIn2S4 photocatalyst. The peaks at 445 eV and 452.5 eV correspond to the In3d 5 / 2 and In 3d 3 / 2 , indicating that In 3+ formation.

[0073] 5. The In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention was tested by UV-visible diffuse reflectance spectroscopy. Figure 5 (a) It can be seen that:

[0074] ZnIn2S4 has an absorption edge at about 600nm. After coupling with In2S3, the absorption edge of In2S3 / ZnIn2S4 does not change significantly, but the light response ability between 600-800nm ​​wavelength is slightly improved, which may be due to the small amount of In2S3 added. The band gap values ​​of In2S3 and ZnIn2S4 ( Figure 5 (b)) are 1.95eV and 2.0eV, respectively.

[0075] 6. The transient photocurrent test of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention was carried out. Figure 6 As shown:

[0076] The In2S3 / ZnIn2S4 photocatalyst exhibited good photocurrent response and excellent stability. This result indicates that the introduction of In2S3 can significantly enhance the separation and transfer of charge carriers and improve the efficiency of hydrogen evolution.

[0077] 7. Electrochemical impedance spectroscopy was performed on the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention. Figure 7 As shown:

[0078] The In2S3 / ZnIn2S4 photocatalyst exhibits the smallest arc radius, which reflects that the charge transfer resistance of In2S3 / ZnIn2S4 at the solid-liquid interface is extremely low, and further suggests that the separation and transfer efficiency of photogenerated carriers has been significantly improved.

[0079] 8. The Mott-Schottky curve test of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention was carried out. Figure 8 As shown:

[0080] The slopes of the curves for In2S3 and ZnIn2S4 are both positive, indicating that they are both n-type semiconductors. Using the formula to create tangent lines, we obtain a flat-band potential of -0.2 eV for In2S3 and -0.27 eV for ZnIn2S4, corresponding to -0.4 eV and -0.47 eV vs. NHE, respectively.

[0081] 9. The photocatalytic hydrogen evolution activity of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention was tested. Figure 9 (a) It can be seen that:

[0082] After In2S3 is loaded on Znln2S4 two-dimensional nanosheets to form a heterojunction, the hydrogen evolution rate is significantly improved. At this time, the establishment of the heterojunction suppresses the recombination of photoinduced charge-hole pairs and promotes the transfer of photogenerated electrons within the heterojunction. In addition, the chemical composition ratio has a significant effect on the photocatalytic efficiency. As shown in Figure 3-8(b), when 5mg In2S3 is added, the hydrogen evolution rate of the In2S3 / ZnIn2S4 composite material is the highest, which is 2478.62μmol g -1 h -1 , which is lower than the hydrogen evolution rate of single ZnIn2S4 (847.24 μmol g -1 h -1 The photocatalytic hydrogen evolution rates of the composite photocatalyst In2S3 / ZnIn2S4 with different chemical composition ratios (the addition amount of In2O3 is 5mg, 10mg and 15mg respectively) are 2478.62μmol g -1 h -1 、2279.54μmol g -1 h -1 and 1320.11 μmol g -1 h -1 With the increase of In2S3 addition, the photocatalytic hydrogen evolution rate of In2S3 / ZnIn2S4 composite material shows a gradually decreasing trend. This may be because the excessive In2S3 acts as a recombination center for photoinduced carriers or blocks the large surface area coverage of active sites on ZnIn2S4, inhibiting the internal light penetration and affecting the photocatalytic hydrogen evolution rate.

[0083] 10. The photocatalytic hydrogen evolution activity of the In2S3 / ZnIn2S4 composite material prepared in Example 1 of the present invention was tested. Figure 10 As shown:

[0084] Under light, both In2S3 and ZnIn2S4 can effectively absorb light energy and be excited, thereby generating electrons and holes. Under the influence of visible light irradiation and the internal electric field, since the conduction band potential of ZnIn2S4 is more negative than that of In2S3, photoelectrons may migrate from the conduction band of ZnIn2S4 to the conduction band of In2S3, further enhancing the electric field effect. Due to the blocking effect of the potential barrier, these electrons that move to In2S3 cannot flow back to ZnIn2S4, thereby achieving effective separation of electrons and holes. Subsequently, the photogenerated electrons gathered on the surface of In2S3 will react with the H adsorbed on the surface. +The reaction releases H2. Simultaneously, photogenerated holes may migrate from the valence band of In2S3 to the valence band of ZnIn2S4. By adding a sacrificial agent, TEOA, which reacts with holes in the valence band of ZnIn2S4, photocorrosion is reduced. Therefore, during the In2S3 / ZnIn2S4 photocatalytic process, the construction of the heterojunction significantly enhances the separation efficiency of electrons and holes, making the photocatalytic activity of In2S3 / ZnIn2S4 more outstanding than that of single In2S3 and ZnIn2S4 materials.

[0085] In order to explore the performance of the In2S3 / ZnIn2S4 composite materials produced in Examples 1 to 12, the main materials were determined according to the experimental formula and 12 groups of samples were prepared for testing. The specific exploration is as follows:

[0086] 1. Investigate the influence of preparation parameters of In2S3 / ZnIn2S4 composite materials on their hydrogen evolution performance.

[0087] Table 2 Hydrogen production rate of In2S3 / ZnIn2S4 composite materials in Examples 1-4, 7-12 (μmol g -1 h -1 )

[0088]

[0089] From the results in Table 2, it can be seen that in Examples 1 to 12, the hydrogen production rate of the composite material is 2682.35 μmol g - 1 h -1 to 3357.63 μmol g -1 h -1 It fluctuates between 0.05 and 0.17, indicating that the change of preparation parameters has a significant effect on the hydrogen production rate;

[0090] The hydrogen production rates of Examples 4 and 2 were significantly higher than those of the other examples, while the hydrogen production rate of Example 11 was the lowest. The hydrogen production rates of Examples 1 to 4 and 7 to 12 were concentrated at 2491.54 μmol g -1 h -1 to 3357.63 μmol g -1 h -1 between them, showing higher hydrogen evolution activity;

[0091] Comparing Example 1 with Examples 2 to 4, it can be seen that the impregnation and doping treatment of the In2S3 / ZnIn2S4 composite material has a certain positive effect on the hydrogen production rate. Comparing Examples 2 to 4, it can be seen that changing the process parameters of the impregnation and doping treatment has a certain effect on the hydrogen production rate, and the sample tested with the process parameters of Example 4 has the best hydrogen production rate.

[0092] Comparing Example 2 with Examples 7 and 8, it can be seen that the process parameters used in preparing the MIL-68 precursor have a certain influence on the hydrogen production rate, and the sample tested with the process parameters of Example 2 has the best hydrogen production rate;

[0093] Comparing Example 2 with Examples 9 and 10, it can be seen that the process parameters used in preparing In2O3 have a certain influence on the hydrogen production rate. The difference between Example 9 and Example 10 is not obvious, and the sample tested with the process parameters of Example 2 has the best hydrogen production rate.

[0094] Comparing Example 2 with Examples 11 and 12, it can be seen that the process parameters used in step S3 to prepare In2S3 / ZnIn2S4 have a certain influence on the hydrogen production rate. The hydrogen production rate of Example 12 is higher than that of Example 11. The sample test using the process parameters of Example 2 has the best hydrogen production rate.

[0095] 2. Investigate the influence of application methods of In2S3 / ZnIn2S4 composite materials on their hydrogen evolution performance.

[0096] Table 3 Hydrogen production rate of In2S3 / ZnIn2S4 composite materials in Examples 5 and 6 (μmol g -1 h -1 )

[0097]

[0098] As can be seen from the results in Tables 2 and 3, there is a slight difference in the hydrogen production rate between Example 5 and Example 6. The hydrogen production rate of Example 6 is slightly higher than that of Example 5. Both show high hydrogen evolution activity. The hydrogen production rate of the sample tested using the application method of Example 4 is the best.

Claims

1. A method for preparing a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution, characterized in that: The following steps are involved: S1. Preparation of MIL-68 precursor: 1.5-2.5 mmol of In(NO3)3 and 1.5-2.5 mmol of terephthalic acid are dissolved in 10-20 mL of N,N-dimethylformamide solution, and then 70-90 μL of crystalline sodium acetate aqueous solution is added to obtain a mixed solution; the mixed solution is heated in an oil bath at a temperature of 90-110°C for 30-40 minutes, and then naturally cooled to room temperature to obtain a mixed slurry; the mixed slurry is centrifuged and washed with an ethanol solution having a volume concentration of 95-99.9% to obtain a MIL-68 sample, and the MIL-68 sample is placed in a blast drying oven and dried at 50-80°C for 10-14 hours to obtain a MIL-68 precursor; Preparation of S2 and In2O3: The MIL-68 precursor prepared in S1 was placed in a tube furnace, calcined in air, heated to 500-600°C and kept at this temperature for 2-3 hours, and then cooled to room temperature to obtain In2O3; Preparation of S3, In2S3 / ZnIn2S4 composite materials: According to the mass percentage, 10-15% HCl aqueous solution, 5-8% propylene glycol and the rest deionized water are mixed uniformly to obtain a mixed solution, and then In2O3 prepared by S2 is added and ultrasonically dissolved, and the amount of In2O3 added is 10-45wt% of the mixed solution; then, 0.1-0.2% zinc chloride, 0.4-0.6% indium chloride and 0.3-0.5% thioacetamide are added in sequence, and stirred uniformly until each additive is dissolved to obtain a stock solution; the stock solution is placed in an oil bath at a temperature of 75-85°C and heated for 5-7h until it is cooled to room temperature, and then centrifuged and washed with an ethanol solution with a volume concentration of 95-99.9% to obtain an In2S3 / ZnIn2S4 sample; finally, the In2S3 / ZnIn2S4 sample is placed in a drying oven and dried at a temperature of 55-65°C for 10-14h to obtain an In2S3 / ZnIn2S4 composite material.

2. A method for preparing a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution according to claim 1, characterized in that: In S1, the concentration of the crystalline sodium acetate aqueous solution is 0.03 to 0.05 mol / L.

3. The method for preparing a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution according to claim 1, characterized in that: In S2, the heating rate of the MIL-68 precursor in the tube furnace is 4-6°C / min.

4. The method for preparing a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution according to claim 1, characterized in that: In S3, the pH value of the HCl aqueous solution is 2.4 to 2.

6.

5. The method for preparing a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution according to claim 1, characterized in that: In S1 and S3, the number of centrifugal washings is 3 times, the centrifugal speed of each time is 8000-8500 r / min, and the time of each centrifugation is 5-10 minutes.

6. The method for preparing a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution according to claim 1, characterized in that: It also includes an impregnation treatment of S4 and In2S3 / ZnIn2S4 composite materials, and the impregnation treatment method is: immersing the In2S3 / ZnIn2S4 composite material prepared by S3 in a sodium polystyrene sulfonate solution with a concentration of 0.5-1 mg / mL, immersing and stirring for 0.2-3 hours, and then drying at 65-85°C to obtain a mixed material; the mass ratio of the In2S3 / ZnIn2S4 composite material and the sodium polystyrene sulfonate solution is 1:1.5-3, and the solvent of the sodium polystyrene sulfonate solution is deionized water; taking doped microparticles and mixing them with water to prepare a treatment solution with a concentration of 0.01-0.05M, and the doped microparticles are Au(NO3)3 particles with a particle size of 2-5nm; then introducing the mixed material into the treatment solution, maintaining the reaction at a temperature of 50-100°C for 6-18 hours, controlling the pH value to 7-9, and after the reaction is completed, centrifuging and drying to obtain an In2S3 / ZnIn2S4 composite doping material.

7. Use of a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution prepared by the method according to any one of claims 1 to 6, characterized in that: The In2S3 / ZnIn2S4 composite material is applied to photocatalytic hydrogen production. The hydrogen production method is as follows: 15-45% of the In2S3 / ZnIn2S4 composite material, 0.1-10% of a photocatalytic sacrificial agent, 0.01-6% of zinc phthalocyanine and the remainder of distilled water or ethanol solution are mixed by mass percentage, stirred to form a uniform suspension, and a 300W xenon lamp is used to perform a photoreduction water decomposition reaction to produce hydrogen. The temperature of the suspension is controlled at 50-70°C, and the pH value is controlled at 10-12.

8. The use of a MOF-derived In2S3 / ZnIn2S4 composite material for photocatalytic hydrogen evolution according to claim 7, characterized in that: Calculated by mass percentage, the components of the photocatalytic sacrificial agent are: 10-40% cytochrome c, 0-30% peroxidase, 1-20% polypeptide, 0.1-10% hydrogenase and the balance polyphenol.

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