A method for preparing a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material

Abstract

This invention discloses a method for preparing a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material. The method includes the following steps: first, a three-dimensional ordered polystyrene template is prepared; then, a three-dimensional ordered macroporous ZIF-67 framework is constructed using a hard template method combined with a solvent-induced heterogeneous nucleation strategy; finally, MnIn2S4 is grown in situ via sulfurization to obtain the hierarchical porous heterojunction photocatalytic material. This material possesses a hierarchical porous structure combining three-dimensional ordered macropores, micropores, and mesopores. The in-situ confined growth of MnIn2S4 within the pores and surface of the ZIF-67 framework is beneficial for improving light-harvesting ability, reactant mass transfer efficiency, and active site utilization, and promotes the separation and migration of photogenerated carriers. This material exhibits excellent performance in visible light photocatalytic water splitting and hydrogen evolution, with a maximum hydrogen evolution rate of 4.88 mmol·g⁻¹. ‑1 ·h ‑1 It also has good stability.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic hydrogen production materials technology, and relates to a method for preparing a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material. Background Technology

[0002] With the continued consumption of fossil fuels and the intensification of environmental pollution, the development of clean, efficient, and sustainable energy conversion technologies has become an important research direction. Hydrogen energy, due to its high energy density, clean combustion products, and zero carbon emissions, is considered a highly promising clean energy source. Photocatalytic water splitting driven by solar energy can directly convert solar energy into chemical energy under mild conditions, representing an important pathway for green hydrogen production. Metal-organic frameworks (MOFs) have attracted widespread attention in the field of photocatalytic hydrogen production due to their large specific surface area, designable structure, tunable function, and abundant active sites. Among them, ZIF-67 possesses advantages such as good framework stability, mild preparation conditions, and excellent interfacial compatibility, making it an ideal candidate for constructing MOF-based composite photocatalytic materials. However, existing MOF materials are mostly microporous with small pore sizes, which can lead to limited reactant mass transfer and insufficient accessibility to active sites. Furthermore, they suffer from low photogenerated electron-hole pair separation efficiency and severe carrier recombination, hindering further improvements in their photocatalytic hydrogen evolution performance.

[0003] To address the aforementioned shortcomings, constructing hierarchical porous structures, especially three-dimensional ordered macroporous (3DOM) structures, is considered an effective strategy for improving the mass transfer efficiency and light utilization capability of MOFs. 3DOM structures possess regularly interconnected macroporous channels, which not only promote the rapid diffusion of reactant and product molecules but also enhance light capture capabilities by increasing light scattering. However, relying solely on pore structure manipulation is insufficient to effectively address the problem of rapid carrier recombination. Heterostructure construction is an important method for improving charge separation efficiency. Among them, S-type heterojunctions can achieve directional migration of electrons and holes while retaining strong redox capabilities. MnIn2S4 possesses a suitable bandgap structure and good visible light response, making it an ideal semiconductor material for constructing highly efficient heterojunction photocatalysts. However, existing heterojunction systems still suffer from problems such as loose interfacial contact, weak built-in electric field, and insufficient charge transfer efficiency.

[0004] Therefore, there is an urgent need to develop a ZIF-67 / MnIn2S4 heterojunction photocatalytic material that combines a three-dimensional ordered hierarchical porous structure with efficient interfacial coupling characteristics to improve the visible light catalytic hydrogen evolution performance. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention aims to provide a method for preparing a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material. The method includes the following steps: first, a three-dimensional ordered polystyrene template is prepared; then, a three-dimensional ordered macroporous ZIF-67 framework is constructed using a hard template method combined with a solvent-induced heterogeneous nucleation strategy; finally, MnIn2S4 is grown in situ via sulfurization to obtain the hierarchical porous heterojunction photocatalytic material. This material possesses a hierarchical porous structure combining three-dimensional ordered macropores, micropores, and mesopores. The in-situ confined growth of MnIn2S4 within the pores and surface of the ZIF-67 framework is beneficial for improving light-harvesting ability, reactant mass transfer efficiency, and active site utilization, and promotes the separation and migration of photogenerated carriers. This material exhibits excellent performance in visible light photocatalytic water splitting and hydrogen evolution, with a maximum hydrogen evolution rate of 4.88 mmol·g⁻¹. -1 ·h -1 It also has good stability.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material, comprising the following steps in sequence: S1. Styrene monomer was washed with alkaline solution and deionized water respectively and then dispersed in deionized water. An initiator was added under nitrogen conditions to carry out a polymerization reaction to obtain a monodisperse polystyrene colloidal sphere dispersion. After centrifugation and drying, a three-dimensional ordered polystyrene template was obtained. The average particle size of the obtained polystyrene spheres was 200~500 nm. S2. The three-dimensional ordered polystyrene template obtained in step S1 is immersed in a methanol precursor solution containing cobalt salt and 2-methylimidazole, and vacuum degassed for 10-60 min to allow the precursor to enter the template pores. After removal and drying, it is immersed in a mixed solvent of ammonia and methanol for vacuum degassing for 10-60 min and allowed to stand for crystallization for 12-24 h. Subsequently, the polystyrene template is removed with an organic solvent. After centrifugation and drying, three-dimensional ordered macroporous ZIF-67 is obtained. S3. Add manganese salt and indium salt to anhydrous ethanol, mix evenly, add sulfur source, and carry out pre-reaction at 80 °C. Then add the three-dimensional ordered macroporous ZIF-67 obtained in step S2 to continue the reaction, so that MnIn2S4 grows in situ in the channels and surface of the three-dimensional ordered macroporous ZIF-67. After the reaction is completed, collect, wash and dry to obtain the three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material.

[0007] As a limitation of the present invention, in step S1, the alkaline solution is a sodium hydroxide aqueous solution with a mass fraction of 10 wt.%.

[0008] As another limitation of the present invention, in step S1, the initiator is potassium persulfate, and the mass-to-volume ratio of the initiator to the styrene monomer is 0.43:31 g / mL.

[0009] As a third limitation of the present invention, in step S1, the polymerization reaction temperature is 70~80 °C and the polymerization time is 24 h.

[0010] As a fourth limitation of the present invention, in step S2, the cobalt salt is cobalt nitrate hexahydrate, and the concentration of cobalt nitrate hexahydrate in the precursor solution is 0.4~0.8 g·mL. -1 The concentration of 2-methylimidazole is 1.0~2.0 g·mL. -1 .

[0011] As a fifth limitation of the present invention, in step S2, the immersion time is 5~15 min; the drying temperature is 50~60 ℃, and the drying time is 8~12 h.

[0012] As a sixth limitation of the present invention, in step S2, the volume ratio of ammonia to methanol in the mixed solvent of ammonia and methanol is 1:1; the organic solvent is tetrahydrofuran or N,N-dimethylformamide.

[0013] As a seventh limitation of the present invention, in step S3, the manganese salt is manganese chloride tetrahydrate, the indium salt is indium chloride tetrahydrate, and the sulfur source is thioacetamide; the molar ratio of manganese chloride tetrahydrate, indium chloride tetrahydrate and thioacetamide is 1:(1.5~2.5):(3~5).

[0014] As an eighth limitation of the present invention, in step S3, the pre-reaction time is 80~110 min, and the reaction time of adding the three-dimensional ordered macroporous ZIF-67 obtained in step S2 is 10~40 min.

[0015] As a final limitation of the present invention, the photocatalytic material has a hierarchical porous structure composed of three-dimensional ordered macropores, micropores and mesopores, and MnIn2S4 is grown in situ in confined within the pores and surface of the ZIF-67 framework.

[0016] This invention constructs a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material. First, a three-dimensional ordered colloidal crystal template is constructed using regularly self-assembled polystyrene microspheres. Then, a ZIF-67 precursor undergoes heterogeneous nucleation and growth within the template interstices. After removing the template, a three-dimensional ordered macroporous ZIF-67 with a periodically interconnected framework is obtained. This structure retains the inherent microporous active sites of ZIF-67 while providing open and ordered pore spaces for the in-situ confined growth of MnIn2S4. Furthermore, mesopores are introduced during the growth process, forming a hierarchical porous structure with interconnected macropores, micropores, and mesopores. Specifically, the three-dimensional ordered macroporous framework enhances multiple scattering and reflection of incident light within the material, improving light capture capability; macropores and mesopores facilitate the rapid diffusion and transport of water molecules, sacrificial agents, and reaction intermediates, and promote the timely escape of generated hydrogen, improving mass transfer efficiency; micropores provide abundant active sites and adsorb and enrich reactants, which is beneficial for improving the utilization rate of active sites and surface reaction efficiency. Meanwhile, MnIn2S4 is grown in situ on the surface and within the pores of the framework, forming a tightly coupled heterojunction interface with the three-dimensionally ordered macroporous ZIF-67. Furthermore, the Co-S bonds at the interface enhance electron coupling and interfacial charge transport, thereby promoting the directional separation and migration of photogenerated carriers and reducing the electron-hole recombination rate. This achieves a synergistic enhancement of light absorption, mass transport, surface reaction, and interfacial charge separation, significantly improving the material's photocatalytic hydrogen evolution performance.

[0017] The above-mentioned technical solution of the present invention is a whole in which each step is closely related and mutually influential, and together they determine the morphological characteristics and performance of the product.

[0018] The above technical solution has the following advantages or beneficial effects: 1. This invention constructs a three-dimensional ordered hierarchical porous structure and grows MnIn2S4 in situ within the channels and surface of the three-dimensional ordered macroporous ZIF-67 framework, forming a heterojunction structure with tight interfacial contact and Co-S bond interaction at the interface. This improves the light-harvesting ability, reactant mass transfer efficiency, active site utilization, and separation and migration efficiency of photogenerated carriers, thereby enhancing its visible light photocatalytic water splitting hydrogen production performance. 2. The three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material prepared by this invention exhibits excellent visible light photocatalytic hydrogen production performance, with a hydrogen evolution rate reaching up to 4.88 mmol·g under visible light irradiation. -1 ·h -1 The activity was 4.8 times and 13.5 times that of single-component ZIF-67 and MnIn2S4, respectively; at the same time, the material maintained high hydrogen evolution activity after multiple cycles of reaction, showing good photocatalytic stability. 3. The preparation method of this invention is simple, the process is easy to control, and it is suitable for large-scale industrial production.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0020] Figure 1 The images shown are scanning electron microscope (SEM) images of the photocatalytic materials prepared in Example 1 and Comparative Examples 2-4 of the present invention, wherein: (a) and (b) are SEM images of the 3DOM ZIF-67 photocatalytic material prepared in Comparative Example 4 at different magnifications, (c) and (d) are SEM images of the 3DOM ZIF-67 / MnIn2S4-20 photocatalytic material prepared in Example 1 at different magnifications, (e) and (f) are SEM images of the ZIF-67 photocatalytic material prepared in Comparative Example 2 at different magnifications, and (g) and (h) are SEM images of the ZIF-67 / MnIn2S4-20 photocatalytic material prepared in Comparative Example 3 at different magnifications; Figure 2 The X-ray diffraction patterns of the photocatalytic materials prepared in Example 1 and Comparative Examples 1-4 of this invention are shown below. Figure 3 The Fourier transform infrared spectra of the photocatalytic materials prepared in Examples 1-4, Comparative Examples 1-2, and Comparative Example 4 of the present invention are shown below. Figure 4 The nitrogen adsorption-desorption isotherms and pore size distribution diagrams of the photocatalytic materials prepared in Example 1 and Comparative Examples 1-4 of the present invention are shown, wherein: (a) is a nitrogen adsorption-desorption isotherm diagram; (b) is a pore size distribution diagram. Figure 5 These are test graphs showing the photocatalytic hydrogen evolution performance of the photocatalytic materials prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention. Figure 6 This is a test diagram of the cyclic photocatalytic hydrogen evolution stability of the 3DOM ZIF-67 / MIS-20 photocatalytic material prepared in Example 1 of the present invention. Detailed Implementation

[0021] The following embodiments are merely some, not all, of the embodiments of the present invention. Therefore, the detailed descriptions of the embodiments provided below are not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] In this invention, unless otherwise specified, all equipment and raw materials are commercially available or commonly used in the industry. The methods described in the following embodiments are conventional methods in the art, unless otherwise specified. Example 1

[0023] This embodiment prepares a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material. The preparation process and steps are as follows: S1. Take 31 mL of styrene monomer, wash it first with a 10 wt.% sodium hydroxide aqueous solution, and then wash it thoroughly with deionized water to remove residual stabilizer; transfer the washed styrene monomer to a round-bottom flask containing 240 mL of deionized water, bubble it under nitrogen for 30 min to remove dissolved oxygen from the system, then quickly add 0.43 g of potassium persulfate as an initiator, and stir continuously at 80 ℃ for 24 h to obtain a monodisperse polystyrene colloidal sphere dispersion; centrifuge the obtained dispersion at 2000 rpm for 24 h, collect the precipitate and dry it at 50 ℃ overnight to obtain a three-dimensional ordered polystyrene template, and the average particle size of the obtained polystyrene spheres is about 500 nm; S2. The above-mentioned three-dimensional ordered polystyrene template was immersed in a methanol precursor solution containing cobalt nitrate hexahydrate and 2-methylimidazole for 10 min, wherein the concentration of cobalt nitrate hexahydrate was 0.4 g·mL. -1 The concentration of 2-methylimidazole was 1.0 g·mL. -1 To ensure uniform infiltration of the precursor into the template pores, the system was degassed under vacuum for 30 min. The impregnated sample was then removed, dried at 60 °C for 12 h, and then immersed in a 1:1 mixture of ammonia and methanol for 10 min, followed by degassed under vacuum for 10 min. The sample was then allowed to crystallize at room temperature for 24 h. The resulting product was centrifuged at 9000 rpm for 2 min, and the precipitate was collected and dried at 60 °C for 12 h. Sufficient tetrahydrofuran was added to dissolve and remove the polystyrene template. The sample was then washed with dichloromethane to remove residual tetrahydrofuran. Finally, after centrifugation and drying at 60 °C for 12 h, three-dimensional ordered macroporous ZIF-67 was obtained, denoted as 3DOMZIF-67. S3. Add 0.05 mmol of manganese chloride tetrahydrate and 0.10 mmol of indium chloride tetrahydrate to a round-bottom flask containing 30 mL of anhydrous ethanol. Stir vigorously for 30 min, then add 0.20 mmol of thioacetamide and pre-react at 80 °C for 100 min. Then add 0.5 mmol of the above 3DOM ZIF-67 powder and continue to react at 80 °C for 20 min. After the reaction is complete, collect the product and wash it. After drying at 60 °C for 12 h, a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material is obtained, denoted as 3DOM ZIF-67 / MIS-20. Example 2

[0024] This embodiment prepares a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material. The preparation process and steps are as follows: S1. Take 31 mL of styrene monomer, wash it first with a 10 wt.% sodium hydroxide aqueous solution, and then wash it thoroughly with deionized water to remove residual stabilizer; transfer the washed styrene monomer to a round-bottom flask containing 240 mL of deionized water, bubble it under nitrogen for 30 min to remove dissolved oxygen from the system, then quickly add 0.43 g of potassium persulfate as an initiator, and stir continuously at 75 ℃ for 24 h to obtain a monodisperse polystyrene colloidal sphere dispersion; centrifuge the obtained dispersion at 2000 rpm for 24 h, collect the precipitate and dry it at 50 ℃ overnight to obtain a three-dimensional ordered polystyrene template, and the average particle size of the obtained polystyrene spheres is about 200 nm; S2. The above-mentioned three-dimensional ordered polystyrene template was immersed in a methanol precursor solution containing cobalt nitrate hexahydrate and 2-methylimidazole for 5 min, wherein the concentration of cobalt nitrate hexahydrate was 0.6 g·mL. -1 The concentration of 2-methylimidazole was 1.5 g·mL. -1 To ensure uniform infiltration of the precursor into the template pores, the system was degassed under vacuum for 10 min. The impregnated sample was then removed, dried at 55 °C for 10 h, and then immersed in a 1:1 mixture of ammonia and methanol for 5 min, followed by degassed under vacuum for 30 min. The sample was then allowed to crystallize at room temperature for 18 h. The resulting product was centrifuged at 9000 rpm for 2 min, and the precipitate was collected and dried at 55 °C for 10 h. Sufficient tetrahydrofuran was added to dissolve and remove the polystyrene template. The sample was then washed with dichloromethane to remove residual tetrahydrofuran. Finally, after centrifugation and drying at 55 °C for 10 h, three-dimensional ordered macroporous ZIF-67 was obtained, denoted as 3DOMZIF-67. S3. Add 0.05 mmol manganese chloride tetrahydrate and 0.075 mmol indium chloride tetrahydrate to a round-bottom flask containing 30 mL of anhydrous ethanol. After stirring vigorously for 30 min, add 0.15 mmol thioacetamide and pre-react at 80 °C for 110 min. Then add 0.5 mmol of the above 3DOM ZIF-67 powder and continue to react at 80 °C for 10 min. After the reaction is complete, collect the product and wash it. After drying at 55 °C for 10 h, a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material is obtained, denoted as 3DOM ZIF-67 / MIS-10. Example 3

[0025] This embodiment prepares a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material. The preparation process and steps are as follows: S1. Take 31 mL of styrene monomer, wash it first with a 10 wt.% sodium hydroxide aqueous solution, and then wash it thoroughly with deionized water to remove residual stabilizer; transfer the washed styrene monomer to a round-bottom flask containing 240 mL of deionized water, bubble it under nitrogen for 30 min to remove dissolved oxygen from the system, then quickly add 0.43 g of potassium persulfate as an initiator, and stir continuously at 70 ℃ for 24 h to obtain a monodisperse polystyrene colloidal sphere dispersion; centrifuge the obtained dispersion at 2000 rpm for 24 h, collect the precipitate and dry it at 50 ℃ overnight to obtain a three-dimensional ordered polystyrene template, and the average particle size of the obtained polystyrene spheres is about 300 nm; S2. The above-mentioned three-dimensional ordered polystyrene template was immersed in a methanol precursor solution containing cobalt nitrate hexahydrate and 2-methylimidazole for 15 min, wherein the concentration of cobalt nitrate hexahydrate was 0.8 g·mL. -1 The concentration of 2-methylimidazole was 2.0 g·mL. -1 To ensure uniform penetration of the precursor into the template pores, the system was degassed under vacuum for 60 min. The impregnated sample was then removed, dried at 50 °C for 8 h, and then immersed in a 1:1 mixture of ammonia and methanol for 15 min, followed by degassed under vacuum for 60 min. Subsequently, the sample was allowed to crystallize at room temperature for 12 h. The resulting product was centrifuged at 9000 rpm for 2 min, and the precipitate was collected and dried at 50 °C for 8 h. Sufficient tetrahydrofuran was added to dissolve and remove the polystyrene template. The sample was then washed with dichloromethane to remove residual tetrahydrofuran. Finally, after centrifugation and drying at 50 °C for 8 h, three-dimensional ordered macroporous ZIF-67 was obtained, denoted as 3DOMZIF-67. S3. Add 0.05 mmol manganese chloride tetrahydrate and 0.125 mmol indium chloride tetrahydrate to a round-bottom flask containing 30 mL of anhydrous ethanol. After stirring vigorously for 30 min, add 0.25 mmol thioacetamide and pre-react at 80 °C for 90 min. Then add 0.5 mmol of the above 3DOM ZIF-67 powder and continue to react at 80 °C for 30 min. After the reaction is completed, collect the product and wash it. After drying at 50 °C for 8 h, a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material is obtained, denoted as 3DOM ZIF-67 / MIS-30. Example 4

[0026] This embodiment prepares a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material. The preparation process is similar to that in Example 1, except that in step S3, the pre-reaction time is 80 min, and after adding 3DOM ZIF-67 powder, the reaction continues for 40 min. The resulting sample is denoted as 3DOM ZIF-67 / MIS-40.

[0027] Comparative Example To investigate the influence of different reactants on the performance of the product during the preparation process of this invention, the following comparative experiments were conducted. Different photocatalytic materials were prepared in the following comparative examples: Comparative Example 1 In this comparative example, a pure MnIn2S4 photocatalytic material was prepared. The preparation process and steps are as follows: 0.05 mmol manganese chloride tetrahydrate and 0.10 mmol indium chloride tetrahydrate were added to a round-bottom flask containing 30 mL of ethanol. After stirring vigorously for 30 min, 0.20 mmol thioacetamide was added, and the mixture was reacted at 80 °C for 120 min. After the reaction was completed, the product was collected, washed, and dried to obtain pure MnIn2S4, denoted as MIS.

[0028] Comparative Example 2 In this comparative example, a ZIF-67 photocatalytic material was prepared. The preparation process and steps are as follows: 2 mmol of cobalt nitrate hexahydrate and 0.50 g of polyvinylpyrrolidone were dispersed together in 50 mL of methanol to obtain solution A; 8 mmol of 2-methylimidazole was dissolved in 50 mL of methanol to obtain solution B; solution A was poured into solution B under stirring and stirred vigorously for 5 min, and then allowed to stand at room temperature for 12 h; the resulting purple precipitate was collected by centrifugation, washed thoroughly with ethanol, and dried overnight at 60 °C to obtain ZIF-67.

[0029] Comparative Example 3 This comparative example prepares a ZIF-67 / MnIn2S4 photocatalytic material. The preparation process is similar to that of Example 1, except that steps S1 and S2 are omitted, and the 3DOM ZIF-67 in step S3 is replaced with an equimolar amount of ZIF-67 prepared in Comparative Example 2, resulting in ZIF-67 / MnIn2S4, denoted as ZIF-67 / MIS-20.

[0030] Comparative Example 4 This comparative example prepares a 3DOM ZIF-67 photocatalytic material. The preparation process is similar to that of Example 1, except that step S3 is omitted. That is, the 3DOM ZIF-67 obtained in step S2 is directly used as a photocatalyst.

[0031] Structural characterization test A series of structural characterization tests were performed on Examples 1-4 and Comparative Examples 1-4 of the present invention, as detailed below: The morphology of the photocatalytic materials prepared in Example 1 and Comparative Examples 2-4 were observed using a scanning electron microscope, and the results are as follows: Figure 1 As shown. Figure 1 (a) and Figure 1 (b) shows that 3DOM ZIF-67 has a regular tetrahedral morphology and a highly ordered three-dimensional interconnected macroporous structure with an average pore diameter of about 410 nm, thin pore walls and interconnected channels. Figure 1 (c) and Figure 1 (d) indicates that 3DOM ZIF-67 / MnIn2S4-20 basically maintains its original three-dimensional ordered macroporous framework after vulcanization, indicating that the framework structure is stable and MnIn2S4 has been successfully introduced into it. Figure 1 (e) and Figure 1 (f) shows that conventional ZIF-67 exhibits a dense polyhedral morphology. Figure 1 (g) and Figure 1 (h) indicates that MnIn2S4 is unevenly distributed and aggregated in conventional ZIF-67 / MnIn2S4-20. In contrast, the 3DOM framework is more conducive to the confined growth and uniform dispersion of MnIn2S4, thus facilitating the formation of heterojunction structures with tight interfacial contacts.

[0032] X-ray diffraction was used to analyze the crystal phases of the photocatalytic materials prepared in Example 1 and Comparative Examples 1-4 of this invention. The results are as follows: Figure 2 As shown. 3DOM ZIF-67 in 7.4 ° 10.4 ° 12.7 ° 16.5 ° and 18.1 °The diffraction peaks at approximately 48.0°C correspond to the (011), (002), (112), (013), and (222) crystal planes, respectively, and are largely consistent with those of conventional ZIF-67, indicating that a highly crystalline ZIF-67 framework has been successfully prepared. The diffraction peaks of pure MnIn2S4 are consistent with the standard card (JCPDS No. 85-1229) for cubic MnIn2S4. The 3DOM ZIF-67 / MnIn2S4-20 and ZIF-67 / MnIn2S4-20 composite samples show diffraction peaks at approximately 48.0°C. ° The presence of the (440) crystal plane characteristic peak of MnIn2S4 and the retention of the ZIF-67 characteristic peak indicate that MnIn2S4 has been successfully introduced into the composite system and the ZIF-67 framework remains basically intact.

[0033] The chemical bond structures of the photocatalytic materials prepared in Examples 1-4, Comparative Examples 1-2, and Comparative Example 4 of this invention were analyzed using Fourier transform infrared spectroscopy. The results are as follows: Figure 3 As shown, both 3DOM ZIF-67 and its composite samples retain the characteristic absorption peaks of the ZIF-67 framework, with the peak at 428 cm⁻¹. -1 The peak for Co-N stretching vibration is located at 689 cm⁻¹. -1 and 755 cm -1 The peak at 1109 cm⁻¹ represents the out-of-plane bending vibration of the 2-methylimidazole ring. -1 1139 cm -1 and 1173 cm -1 The peak at 1696 cm⁻¹ represents the in-plane bending vibration of the imidazole ring. The peak at 1696 cm⁻¹ is also observed in the MnIn₂S₄ sample. -1 and 1420 cm -1 The corresponding vibrational peaks at 590 cm⁻¹ correspond to S-In and S-Mn, respectively. The composite sample exhibits characteristic absorption peaks of both ZIF-67 and MnIn₂S₄, with a peak at 590 cm⁻¹. -1 The vibration occurs at 1059 cm⁻¹, representing a metal-oxygen bond vibration. -1 The new absorption peak that appears can be attributed to Co-S bond vibration, indicating that there is Co-S bond interaction at the heterojunction interface.

[0034] The specific surface area and pore structure of the photocatalytic materials prepared in Example 1 and Comparative Examples 1-4 of this invention were analyzed using nitrogen adsorption-desorption tests. The results are as follows: Figure 4As shown, the MnIn2S4 sample exhibits typical mesoporous adsorption-desorption characteristics. Both 3DOM ZIF-67 and ZIF-67 show adsorption isotherms dominated by micropores, with the main peak of the pore size distribution at approximately 0.66 nm, indicating that the introduction of the 3DOM structure did not disrupt the intrinsic microporous framework of ZIF-67. Compared with ZIF-67, the specific surface area of ​​3DOM ZIF-67 is reduced, but the average pore size is increased, indicating that some micropores are transformed into a hierarchical pore structure of interconnected macropores / micropores. After constructing the heterojunction, the specific surface area of ​​3DOM ZIF-67 / MnIn2S4-20 is significantly higher than that of pure MnIn2S4, while retaining micropore, macropore, and mesopore characteristics simultaneously, indicating that it constructs a hierarchical porous channel structure with macropores, micropores, and mesopores coexisting.

[0035] Performance testing A series of relevant performance tests were conducted on Embodiments 1-4 and Comparative Examples 1-4 of the present invention, as detailed below: 10 mg of the photocatalytic materials prepared in Examples 1-4 and Comparative Examples 1-4 of this invention were dispersed in 50 mL of aqueous solutions containing triethanolamine and eosin Y. After purging with argon gas to remove air, photocatalytic hydrogen evolution tests were performed under visible light irradiation. The evolved hydrogen gas was quantitatively analyzed by gas chromatography. The results are as follows: Figure 5 As shown, the hydrogen evolution rates of pure MnIn2S4 and ZIF-67 were 0.36 mmol·g⁻¹, respectively. -1 ·h -1 and 1.00 mmol·g -1 ·h -1 The ZIF-67 / MnIn2S4-20 ratio was increased to 1.54 mmol·g. -1 ·h -1 3DOM ZIF-67 reached 2.65 mmol·g -1 ·h -1 After further constructing a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 heterojunction, 3DOM ZIF-67 / MnIn2S4-20 exhibited the best hydrogen evolution performance, with a hydrogen evolution rate reaching 4.88 mmol·g. -1 ·h -1 The hydrogen evolution performance of the samples was approximately 4.8 times that of ZIF-67 and 13.5 times that of MnIn2S4, respectively, indicating that the coupling of the three-dimensional ordered macroporous structure and the heterostructure has a significant synergistic effect. After further extending the sulfidation time, the hydrogen evolution performance of the samples decreased, indicating that 20 min is the optimal reaction time.

[0036] The 3DOM ZIF-67 / MIS-20 photocatalyst material prepared in Example 1 of this invention was subjected to a 6-cycle hydrogen evolution test, and the results are as follows: Figure 6As shown, the material maintains high hydrogen evolution activity after cyclic reaction, and the hydrogen evolution efficiency only slightly decreases after continuous visible light irradiation for 8 hours; the hydrogen evolution activity can be restored after the addition of eosin Y, indicating that its deactivation process is reversible, and the material has good structural stability and photocatalytic stability.

[0037] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A preparation method of a three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material, characterized in that, Follow these steps in sequence: S1. Styrene monomers were washed with alkaline solution and deionized water respectively, and then dispersed in deionized water. An initiator was added under nitrogen conditions to carry out a polymerization reaction to obtain a monodisperse polystyrene colloidal sphere dispersion. After centrifugation and drying, the resulting dispersion was used to obtain a three-dimensional ordered polystyrene template. S2. The three-dimensional ordered polystyrene template obtained in step S1 is immersed in a methanol precursor solution containing cobalt salt and 2-methylimidazole and degassed under vacuum for 10-60 min. After being removed and dried, it is immersed in a mixed solvent of ammonia and methanol for vacuum degassed for 10-60 min and allowed to stand for crystallization for 12-24 h. Subsequently, the polystyrene template is removed with an organic solvent. After centrifugation and drying, three-dimensional ordered macroporous ZIF-67 is obtained. S3. Add manganese salt and indium salt to anhydrous ethanol, mix well, add sulfur source, and carry out pre-reaction at 80 °C. Then add the three-dimensional ordered macroporous ZIF-67 obtained in step S2 to continue the reaction. After the reaction is completed, collect, wash and dry to obtain the three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material.

2. The preparation method of the three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material according to claim 1, characterized in that, In step S1, the alkaline solution is a sodium hydroxide aqueous solution with a mass fraction of 10 wt.%.

3. The preparation method of the three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material according to claim 1, characterized in that, In step S1, the initiator is potassium persulfate, and the mass-to-volume ratio of the initiator to the styrene monomer is 0.43:31 g / mL.

4. The preparation method of the three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material according to claim 1, characterized in that, In step S1, the polymerization reaction temperature is 70~80 ℃ and the polymerization time is 24 h.

5. The preparation method of the three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material according to claim 1, characterized in that, In step S2, the cobalt salt is cobalt nitrate hexahydrate; the concentration of cobalt nitrate hexahydrate in the precursor solution is 0.4-0.8 g·mL -1 , and the concentration of 2-methylimidazole is 1.0-2.0 g·mL -1 .

6. The preparation method of the three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material according to claim 1, characterized in that, In step S2, the soaking time is 5~15 min; the drying temperature is 50~60℃, and the drying time is 8~12 h.

7. The preparation method of the three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material according to claim 1, characterized in that, In step S2, the volume ratio of ammonia to methanol in the mixed solvent of ammonia and methanol is 1:1; the organic solvent is tetrahydrofuran or N,N-dimethylformamide.

8. The preparation method of the three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material according to claim 1, characterized in that, In step S3, the manganese salt is manganese chloride tetrahydrate, the indium salt is indium chloride tetrahydrate, and the sulfur source is thioacetamide; the molar ratio of manganese chloride tetrahydrate, indium chloride tetrahydrate, and thioacetamide is 1:(1.5~2.5):(3~5).

9. The preparation method of the three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material according to claim 1, characterized in that, In step S3, the pre-reaction time is 80-110 min, and the reaction time after adding the three-dimensional ordered macroporous ZIF-67 obtained in step S2 is 10-40 min.

10. The preparation method of the three-dimensional ordered macroporous ZIF-67 / MnIn2S4 hierarchical porous heterojunction photocatalytic material according to claim 1, characterized in that, The photocatalytic material has a hierarchical porous structure composed of three-dimensional ordered macropores, micropores and mesopores, and MnIn2S4 is grown in situ in confined within the pores and surface of the ZIF-67 framework.

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