Metal organic framework composite material, preparation method and application thereof

Abstract

The application discloses a kind of metal organic framework composite material and its preparation method and application, preparation method is: metal source and the organic ligand source containing hydrazine hydrate are added to solvent, stirring uniformly, then 5-7h is reacted at 120-140 DEG C, separation, obtain metal organic framework material;Metal organic framework material after heating activation is immersed in SrTiO3:Al suspension, drying can be obtained.The metal organic framework composite material prepared in the application has excellent hydrophilicity and adsorption energy, rich water molecule adsorption site, unique pore structure in structure and large-area contact with air;Adsorbed water molecules are rapidly released under the driving of sunlight, flow through the surface of SrTiO3:Al, in gaseous form fills in closed environment, which opens up a sustainable way to produce green hydrogen in situ only using natural resources in extreme environment.

Description

Technical Field

[0001] This invention belongs to the field of catalytic hydrogen production technology, specifically relating to a metal-organic framework composite material, its preparation method, and its application in in-situ air hydrogen production. Background Technology

[0002] The energy shortage crisis caused by the consumption of traditional fossil fuels and the scarcity of liquid fuels, especially in remote areas, has prompted us to explore renewable and pollution-free alternative energy sources. Hydrogen, due to its high energy density, clean combustion products, excellent storage and transport performance, and high conversion and utilization efficiency, is an outstanding energy carrier and a superior clean and renewable energy source, considered a crucial bridge connecting fossil fuels to renewable energy. Solar energy, an inexhaustible and clean resource, makes solar-driven water splitting for hydrogen production an ideal energy conversion pathway. However, traditional photocatalytic water splitting systems are geographically limited by freshwater supply. Typically, their operation depends on the periodic replenishment of liquid water, resulting in additional resource consumption from transportation, which involves a series of complex environmental, economic, and regulatory issues. Furthermore, freshwater scarcity caused by climate change, global population growth, and industrial development has become a serious global challenge. Atmospheric water, approximately 13 trillion liters of continuously clean water, represents a vast untapped source of sustainable freshwater. Solar-driven adsorption-based atmospheric water harvesting (SAWH) can effectively address the global freshwater crisis by providing geographically unrestricted, decentralized water harvesting.

[0003] To address the current severe energy and freshwater crises, utilizing in-situ resources such as atmospheric water and solar energy to produce hydrogen through photocatalytic decomposition of atmospheric water is a green and scientific approach. Current reports on atmospheric hydrogen production primarily focus on using captured atmospheric water via electrocatalysis or photoelectrocatalysis. However, these methods all require the intervention of intermediate energy sources—electricity—resulting in waste after multiple energy conversions. Photocatalytic decomposition of atmospheric water not only eliminates the need for secondary energy supplies and enables hydrogen production without geographical limitations but also alleviates the water shortage crisis. Furthermore, this technology boasts advantages such as simple steps, mild reaction conditions, low cost, and ease of large-scale development, making it considered the most attractive renewable energy-based hydrogen production route. Therefore, pioneering and developing photocatalytic decomposition of atmospheric water for hydrogen production is urgently needed.

[0004] Considering the practicality of photocatalytic water splitting for hydrogen production in arid environments, its hydrogen production performance largely depends on material properties. Traditional adsorbents such as silica gel, zeolite, and activated carbon have a strong affinity for water, making their regeneration energy intensive. Metal-organic frameworks (MOFs), a new generation of porous materials composed of metal nodes and organic ligands assembled through self-assembly, are renowned for their unique porosity, tunable synthesis, and the resulting chemical and structural diversity, making them ideal materials for regulating water adsorption kinetics and thermodynamics. SrTiO3:Al, as a type of photocatalyst, has achieved breakthrough progress in the field of ultraviolet photocatalytic water splitting. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a metal-organic framework composite material, its preparation method and application. The metal-organic framework composite material prepared by this method can achieve in-situ air hydrogen production through air water capture coupled with photocatalytic hydrogen production.

[0006] The technical solution of this invention is as follows:

[0007] This invention relates to a method for preparing a metal-organic framework composite material, wherein a heated activated metal-organic framework material is impregnated in a suspension of SrTiO3:Al and dried to obtain a metal-organic framework composite material.

[0008] Preferably, the preparation method of metal-organic framework material (MOF-801(N)) is as follows: a metal source and an organic ligand source containing hydrazine hydrate are added to a solvent, stirred evenly, and then reacted at 120-140℃ for 5-7 hours, and separated to obtain the metal-organic framework material.

[0009] Preferably, the metal source is zirconium chloride octahydrate.

[0010] Preferably, the organic ligand source containing hydrazine hydrate is fumaric acid and hydrazine hydrate; the ratio of fumaric acid to hydrazine hydrate is 12.5 mmol: 0.1-0.5 mL, and the molar ratio of fumaric acid to the metal source is 1:1.

[0011] Preferably, the solvent is a mixture of N,N'-dimethylformamide and formic acid; the volume ratio of N,N'-dimethylformamide to formic acid is 50:10-25.

[0012] Preferably, the SrTiO3:Al suspension is a methanol suspension of the SrTiO3:Al photocatalyst, and the mass ratio of the metal-organic framework material MOF-801(N) to the SrTiO3:Al photocatalyst is 100-60:0-40, and the amount of SrTiO3:Al photocatalyst does not include 0.

[0013] The preparation method of SrTiO3:Al photocatalyst includes the following steps:

[0014] 1) A mixture of SrTiO3, SrCl2·6H2O and Al2O3 was ground and mixed evenly, and then calcined in air at 1273-1473 K for 4-8 hours to obtain the SrTiO3:Al precursor; the molar ratio of SrTiO3, SrCl2·6H2O and Al2O3 was 1-2:9-11:0.01-0.04;

[0015] 2) Add the SrTiO3:Al precursor to a mixed solution of H2O and methanol, then add the Rh source and disperse it evenly with ultrasound.

[0016] 3) Subsequently, the mixed solution obtained in step 2) was transferred to the reactor, the air was first purged, and then the Cr source was added. The mixture was irradiated with an Xe lamp for 1-3 hours. After the reaction was completed, the reaction solution was centrifuged, washed, and dried to obtain the SrTiO3:Al photocatalyst.

[0017] Among them, the Rh source is Na3RhCl6, and the mass of Rh contained in the Rh source accounts for 0.6wt-0.8wt% of the mass of the SrTiO3:Al precursor; the Cr source is K2CrO4, and the mass of Cr contained in the Cr source accounts for 0.5-1wt% of the mass of the SrTiO3:Al precursor.

[0018] Preferably, the conditions for heat activation are: under vacuum, heat treatment at 50-80℃ for 10-14 hours, and then heat treatment at 130-170℃ for 22-26 hours.

[0019] Preferably, the drying conditions are: oil bath stirring, drying at 50-70℃ for 10-12 hours.

[0020] The present invention also relates to a metal-organic framework composite material, which is prepared by the above-described preparation method.

[0021] This invention also relates to the application of the above-mentioned metal-organic framework composite material in in-situ air hydrogen production, especially in in-situ air hydrogen production in arid environments. This material achieves in-situ air hydrogen production through air water capture coupled with photocatalytic hydrogen production. The humidity requirement for arid environments is 10-50% RH, preferably 20-30% RH. Although the metal-organic framework composite material of this invention can be used normally under very high or very low humidity conditions, it has more advantages in arid environments.

[0022] The beneficial effects of this invention are:

[0023] (1) The metal-organic framework composite material of the present invention can achieve in-situ air-based hydrogen production in arid environments by coupled photocatalytic water splitting through air water collection. Benefiting from its excellent hydrophilicity and adsorption energy, abundant water molecule adsorption sites, unique porous structure, and large-area contact with air, MOF-801(N) can rapidly adsorb atmospheric moisture in a 30% RH environment. Subsequently, the water molecules adsorbed in dry air by MOF-801(N) are rapidly released under sunlight, flowing over the surface of SrTiO3:Al and filling the sealed environment in gaseous form. Simultaneously, the metal-organic framework composite material produces hydrogen through photocatalytic decomposition of the adsorbed air water.

[0024] (2) The in-situ air hydrogen production process only requires the action of air, water and solar energy, eliminating the need for secondary energy supply, realizing hydrogen production without geographical restrictions, and also alleviating the water shortage crisis. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0026] Figure 1 The X-ray diffraction (XRD) patterns of MOF-801(N), SrTiO3:Al and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al(MS-20);

[0027] Figure 2 Fourier transform infrared (FTIR) spectra of MOF-801(N), SrTiO3:Al and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al(MS-20);

[0028] Figure 3 Raman spectra of MOF-801(N), SrTiO3:Al and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al(MS-20);

[0029] Figure 4 a is a scanning electron microscope (SEM) image of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0030] Figure 4 b is a transmission electron microscope (TEM) image of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0031] Figure 4 c is a high-magnification transmission electron microscope (TEM) image of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0032] Figure 4 d is a high-magnification transmission electron microscope (TEM) image of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0033] Figure 4 e is the elemental linear distribution diagram of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0034] Figure 4 f is the surface distribution diagram of C element in the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0035] Figure 4 g is the surface distribution diagram of O element in the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0036] Figure 4 h is the Zr element surface distribution diagram of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0037] Figure 4 i is the N element surface distribution diagram of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0038] Figure 4 g is the surface distribution map of Sr element in the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0039] Figure 4 k is the Ti element surface distribution diagram of the metal-organic framework composite material obtained in Example 3 of the present invention, namely MOF-801(N)@SrTiO3:Al(MS-20);

[0040] Figure 4 l is the Al elemental distribution diagram of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0041] Figure 4 m is the Rh element surface distribution diagram of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0042] Figure 4 n is the surface distribution diagram of Cr element in the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention;

[0043] Figure 5 N2 adsorption-desorption curves of MOF-801(N), SrTiO3:Al and the metal-organic framework composite material obtained in Example 3 of the present invention, namely MOF-801(N)@SrTiO3:Al(MS-20);

[0044] Figure 6 Thermogravimetric analysis (TGA) was performed on MOF-801(N), SrTiO3:Al and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al(MS-20);

[0045] Figure 7 The UV-Vis absorption spectra of MOF-801(N), SrTiO3:Al and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al(MS-20);

[0046] Figure 8 The photoluminescence (PL) spectra of MOF-801(N), SrTiO3:Al and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al(MS-20);

[0047] Figure 9 The water absorption curve of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention at 60 min (25℃, RH=30%).

[0048] Figure 10 The photocatalytic decomposition of atmospheric water to produce hydrogen and oxygen by the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of this invention under ultraviolet-visible light irradiation (λ>300nm);

[0049] Figure 11 The UV-Vis absorption spectrum and apparent quantum efficiency of hydrogen production of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of this invention are shown.

[0050] Figure 12 The X-ray diffraction (XRD) patterns of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention before and after air water absorption-desorption-hydrogen production;

[0051] Figure 13 The water absorption curve of the metal-organic framework composite material MOF-801(N) obtained in Comparative Example 1 of this invention at 60 min (25℃, RH=30%).

[0052] Figure 14 The photocatalytic decomposition of atmospheric water to produce hydrogen by the metal-organic framework composite material MOF-801(N) obtained in Comparative Example 1 of this invention is shown under ultraviolet-visible light irradiation (λ>300nm).

[0053] Figure 15 The water absorption curve of the photocatalytic material SrTiO3:Al obtained in Comparative Example 2 of this invention at 60 min (25℃, RH=30%) is shown.

[0054] Figure 16 This invention demonstrates the photocatalytic performance of the photocatalytic material SrTiO3:Al obtained in Comparative Example 2 of this invention in producing hydrogen through the photocatalytic decomposition of atmospheric water under ultraviolet-visible light irradiation (λ>300nm).

[0055] Figure 17 The water absorption curve of the metal-organic framework composite material obtained in Comparative Example 3 of the present invention at 60 min (25℃, RH=30%).

[0056] Figure 18 This invention demonstrates the photocatalytic decomposition of atmospheric water to produce hydrogen by the metal-organic framework composite material obtained in Comparative Example 3 under ultraviolet-visible light irradiation (λ>300nm). Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and the accompanying drawings. It should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0058] Metal-organic frameworks (MOFs) are a new generation of porous materials composed of metal nodes and organic ligands through self-assembly. They are known for their unique porosity, tunable synthesis, and the resulting chemical and structural diversity, making them ideal materials for modulating the adsorption kinetics and thermodynamics of water molecules.

[0059] Composite materials can be prepared by combining MOFs with a photocatalyst (SrTiO3:Al). The microstructure and physicochemical properties of the entire material can be adjusted by modifying the catalyst loading, particle size, and chemical properties of the matrix and filler. Based on this, this invention uses the stable MOF-801(N) as the matrix to construct a MOF-801(N)@SrTiO3:Al(MS) composite material to achieve in-situ air hydrogen production through air water capture coupled with photocatalytic hydrogen production. MOF-801(N) continuously captures water molecules from dry air. Subsequently, the water molecules adsorbed by MOF-801(N) in the dry air are rapidly released under sunlight, flowing over the surface of SrTiO3:Al and filling the sealed environment in gaseous form. Simultaneously, this metal-organic framework composite material produces hydrogen by photocatalytically decomposing the adsorbed water from the air. This process requires no additional water or secondary energy input, achieving in-situ hydrogen production.

[0060] The preparation method of the metal-based color-changing gel of the present invention includes the following steps:

[0061] 1) Using 12.5 mmol of zirconium chloride octahydrate (ZrOCl2·8H2O) as the metal source; 12.5 mmol of fumaric acid and 0.1-0.5 mL of hydrazine hydrate as the organic ligand source; and 50 mL of N,N'-dimethylformamide (DMF) and 10-25 mL of formic acid as the solvent, place all materials in a 250 mL single-necked flask and stir on a magnetic stirrer until transparent;

[0062] 2) Preheat the oil bath, place the reactants obtained in step 1) in the oil bath, heat at a constant temperature of 120-140℃ for 5-7 hours to allow for a full reaction, and then allow to cool naturally to room temperature;

[0063] 3) The pale yellow to white precipitate sample obtained in step 2) was separated by centrifugation and washed three times with DMF and methanol respectively. After centrifugation, the centrifuged sample was kept at 60℃ in an oven for 10 hours to obtain dried powder. The centrifugation speed was 5000 r / min and the centrifugation time was 5 min each time. The ultrasonic cleaning time was 5 min each time.

[0064] 4) Transfer the powder product obtained in step 3) to a vacuum drying oven. Keep it at 50-80℃ in a vacuum for 10-14h, and then keep it at 130-170℃ for 22-26h to perform thermal activation of the sample, and obtain the metal-organic framework MOF-801(N) adsorbent.

[0065] 5) Disperse the MOF-801(N) obtained in step 4) in 25 mL of a methanol suspension of SrTiO3:Al, wherein the ratio of MOF-801(N) to SrTiO3:Al is 100-60 mg: 0-40 mg. Then, stir and react in an oil bath at 50-70 °C for 10-12 h to finally obtain the MOF-801(N)@SrTiO3:Al(MS) composite material.

[0066] Comparative Example 1

[0067] The preparation method of the metal-organic framework material, MOF-801(N), of the present invention includes the following steps:

[0068] 1) Using 12.5 mmol of zirconium chloride octahydrate (ZrOCl2·8H2O) as the metal source; 12.5 mmol of fumaric acid and 0.5 mL of hydrazine hydrate as the organic ligand source; and 50 mL of N,N'-dimethylformamide (DMF) and 25 mL of formic acid as the solvent, the materials were placed in a 250 mL single-necked flask and stirred on a magnetic stirrer until transparent.

[0069] 2) Preheat the oil bath to 130°C, place the reactants obtained in step 1) in the oil bath, heat at 130°C for 6 hours to allow for full reaction, and then allow to cool naturally to room temperature.

[0070] 3) The pale yellow to white precipitate sample obtained in step 2) was separated by centrifugation and washed three times with DMF and methanol respectively. After centrifugation, the centrifuged sample was kept at 60℃ in an oven for 10 hours to obtain dried powder. The centrifugation speed was 5000 r / min and the centrifugation time was 5 min each time. The ultrasonic cleaning time was 5 min each time.

[0071] 4) Transfer the powder product obtained in step 3) to a vacuum drying oven. Keep it at 70°C for 12 hours in a vacuum, and then keep it at 150°C for 24 hours to perform thermal activation of the sample, thereby obtaining the metal-organic framework MOF-801(N) adsorbent.

[0072] Comparative Example 2

[0073] The preparation method of the photocatalytic material, namely SrTiO3:Al photocatalyst, of the present invention includes the following steps:

[0074] 1) A mixture of SrTiO3, SrCl2·6H2O and Al2O3 was ground to a uniform molar ratio of 1:10:0.02 and calcined in an alumina crucible in air at 1373 K for 5 hours to obtain the SrTiO3:Al precursor.

[0075] 2) Add SrTiO3:Al precursor (100mg) to a mixed solution of H2O (64mL) and methanol (16mL), and use ultrasound to disperse 0.6wt% Rh (Na3RhCl6) evenly.

[0076] 3) Subsequently, the mixed solution obtained in step 2) was transferred to a 105 mL Pyrex glass photocatalytic reactor with a circulating water jacket. Before irradiation with a 300 W Xe lamp for 1 hour, the solution was bubbled with argon gas for 15 minutes to remove air. Then, 1 wt% Cr (K2CrO4) was added to the solution, and irradiation was carried out for another hour. After the reaction was completed, the reaction solution was centrifuged, washed three times with deionized water, and dried overnight at 60 °C to obtain the SrTiO3:Al photocatalyst.

[0077] Wherein, 0.6 wt% Rh (Na3RhCl6) represents the mass of Rh contained in the added Na3RhCl6 being 0.6 wt% of the mass of the SrTiO3:Al precursor, and 1 wt% Cr (K2CrO4) represents the mass of Cr contained in the added K2CrO4 being 1 wt% of the mass of the SrTiO3:Al precursor.

[0078] The SrTiO3:Al used in Examples 1-9 and Comparative Example 3 to prepare the SrTiO3:Al methanol suspension was prepared according to the method of Comparative Example 2.

[0079] Example 1

[0080] The preparation method of the metal-organic framework composite material, namely MOF-801(N)@SrTiO3:Al(MS-3) composite material of the present invention includes the following steps:

[0081] 1) Using 12.5 mmol of zirconium chloride octahydrate (ZrOCl2·8H2O) as the metal source; 12.5 mmol of fumaric acid and 0.5 mL of hydrazine hydrate as the organic ligand source; and 50 mL of N,N'-dimethylformamide (DMF) and 25 mL of formic acid as the solvent, the materials were placed in a 250 mL single-necked flask and stirred on a magnetic stirrer until transparent.

[0082] 2) Preheat the oil bath to 130°C, place the reactants obtained in step 1) in the oil bath, heat at 130°C for 6 hours to allow for full reaction, and then allow to cool naturally to room temperature.

[0083] 3) The pale yellow to white precipitate sample obtained in step 2) was separated by centrifugation and washed three times with DMF and methanol respectively. After centrifugation, the centrifuged sample was kept at 60℃ in an oven for 10 hours to obtain dried powder. The centrifugation speed was 5000 r / min and the centrifugation time was 5 min each time. The ultrasonic cleaning time was 5 min each time.

[0084] 4) Transfer the powder product obtained in step 3) to a vacuum drying oven. Keep it at 70°C for 12 hours in a vacuum, and then keep it at 150°C for 24 hours to perform thermal activation of the sample, thereby obtaining the metal-organic framework MOF-801(N) adsorbent.

[0085] 5) The MOF-801(N) obtained in step 4) was dispersed in 25 mL of a methanol suspension of SrTiO3:Al, wherein the amounts of MOF-801(N) and SrTiO3:Al were 97 mg and 3 mg, respectively. The mixture was then stirred and reacted in an oil bath at 60 °C for 12 h to finally obtain the MOF-801(N)@SrTiO3:Al(MS-3) composite material.

[0086] Example 2

[0087] The preparation method of the metal-organic framework composite material, namely MOF-801(N)@SrTiO3:Al(MS-10) composite material of the present invention includes the following steps:

[0088] 1) Using 12.5 mmol of zirconium chloride octahydrate (ZrOCl2·8H2O) as the metal source; 12.5 mmol of fumaric acid and 0.5 mL of hydrazine hydrate as the organic ligand source; and 50 mL of N,N'-dimethylformamide (DMF) and 25 mL of formic acid as the solvent, the materials were placed in a 250 mL single-necked flask and stirred on a magnetic stirrer until transparent.

[0089] 2) Preheat the oil bath to 130°C, place the reactants obtained in step 1) in the oil bath, heat at 130°C for 6 hours to allow for full reaction, and then allow to cool naturally to room temperature.

[0090] 3) The pale yellow to white precipitate sample obtained in step 2) was separated by centrifugation and washed three times with DMF and methanol respectively. After centrifugation, the centrifuged sample was kept at 60℃ in an oven for 10 hours to obtain dried powder. The centrifugation speed was 5000 r / min and the centrifugation time was 5 min each time. The ultrasonic cleaning time was 5 min each time.

[0091] 4) Transfer the powder product obtained in step 3) to a vacuum drying oven. Keep it at 70°C for 12 hours in a vacuum, and then keep it at 150°C for 24 hours to perform thermal activation of the sample, thereby obtaining the metal-organic framework MOF-801(N) adsorbent.

[0092] 5) The MOF-801(N) obtained in step 4) was dispersed in 25 mL of a methanol suspension of SrTiO3:Al, wherein the amounts of MOF-801(N) and SrTiO3:Al were 90 mg and 10 mg, respectively. The mixture was then stirred and reacted in an oil bath at 60 °C for 12 h to finally obtain the MOF-801(N)@SrTiO3:Al(MS-10) composite material.

[0093] Example 3

[0094] The preparation method of the metal-organic framework composite material, namely MOF-801(N)@SrTiO3:Al(MS-20) composite material of the present invention includes the following steps:

[0095] 1) Using 12.5 mmol of zirconium chloride octahydrate (ZrOCl2·8H2O) as the metal source; 12.5 mmol of fumaric acid and 0.5 mL of hydrazine hydrate as the organic ligand source; and 50 mL of N,N'-dimethylformamide (DMF) and 25 mL of formic acid as the solvent, the materials were placed in a 250 mL single-necked flask and stirred on a magnetic stirrer until transparent.

[0096] 2) Preheat the oil bath to 130°C, place the reactants obtained in step 1) in the oil bath, heat at 130°C for 6 hours to allow for full reaction, and then allow to cool naturally to room temperature.

[0097] 3) The pale yellow to white precipitate sample obtained in step 2) was separated by centrifugation and washed three times with DMF and methanol respectively. After centrifugation, the centrifuged sample was kept at 60℃ in an oven for 10 hours to obtain dried powder. The centrifugation speed was 5000 r / min and the centrifugation time was 5 min each time. The ultrasonic cleaning time was 5 min each time.

[0098] 4) Transfer the powder product obtained in step 3) to a vacuum drying oven. Keep it at 70°C for 12 hours in a vacuum, and then keep it at 150°C for 24 hours to perform thermal activation of the sample, thereby obtaining the metal-organic framework MOF-801(N) adsorbent.

[0099] 5) The MOF-801(N) obtained in step 4) was dispersed in 25 mL of a methanol suspension of SrTiO3:Al, wherein the amounts of MOF-801(N) and SrTiO3:Al were 80 mg and 20 mg, respectively. The mixture was then stirred and reacted in an oil bath at 60 °C for 12 h to finally obtain the MOF-801(N)@SrTiO3:Al(MS-20) composite material.

[0100] Example 4

[0101] The preparation method of the metal-organic framework composite material, namely MOF-801(N)@SrTiO3:Al(MS-40) composite material of the present invention includes the following steps:

[0102] 1) Using 12.5 mmol of zirconium chloride octahydrate (ZrOCl2·8H2O) as the metal source; 12.5 mmol of fumaric acid and 0.5 mL of hydrazine hydrate as the organic ligand source; and 50 mL of N,N'-dimethylformamide (DMF) and 25 mL of formic acid as the solvent, the materials were placed in a 250 mL single-necked flask and stirred on a magnetic stirrer until transparent.

[0103] 2) Preheat the oil bath to 130°C, place the reactants obtained in step 1) in the oil bath, heat at 130°C for 6 hours to allow for full reaction, and then allow to cool naturally to room temperature.

[0104] 3) The pale yellow to white precipitate sample obtained in step 2) was separated by centrifugation and washed three times with DMF and methanol respectively. After centrifugation, the centrifuged sample was kept at 60℃ in an oven for 10 hours to obtain dried powder. The centrifugation speed was 5000 r / min and the centrifugation time was 5 min each time. The ultrasonic cleaning time was 5 min each time.

[0105] 4) Transfer the powder product obtained in step 3) to a vacuum drying oven. Keep it at 70°C for 12 hours in a vacuum, and then keep it at 150°C for 24 hours to perform thermal activation of the sample, thereby obtaining the metal-organic framework MOF-801(N) adsorbent.

[0106] 5) The MOF-801(N) obtained in step 4) was dispersed in 25 mL of a methanol suspension of SrTiO3:Al, wherein the amounts of MOF-801(N) and SrTiO3:Al were 60 mg and 40 mg, respectively. The mixture was then stirred and reacted in an oil bath at 60 °C for 12 h to finally obtain the MOF-801(N)@SrTiO3:Al (MS-40) composite material.

[0107] Example 5

[0108] The preparation method of the metal-organic framework composite material, namely MOF-801(N)@SrTiO3:Al(MS-20) composite material of the present invention includes the following steps:

[0109] 1) Using 12.5 mmol of zirconium chloride octahydrate (ZrOCl2·8H2O) as the metal source; 12.5 mmol of fumaric acid and 0.5 mL of hydrazine hydrate as the organic ligand source; and 50 mL of N,N'-dimethylformamide (DMF) and 10 mL of formic acid as the solvent, the materials were placed in a 250 mL single-necked flask and stirred on a magnetic stirrer until transparent.

[0110] 2) Preheat the oil bath to 130°C, place the reactants obtained in step 1) in the oil bath, heat at 130°C for 6 hours to allow for full reaction, and then allow to cool naturally to room temperature.

[0111] 3) The pale yellow to white precipitate sample obtained in step 2) was separated by centrifugation and washed three times with DMF and methanol respectively. After centrifugation, the centrifuged sample was kept at 60℃ in an oven for 10 hours to obtain dried powder. The centrifugation speed was 5000 r / min and the centrifugation time was 5 min each time. The ultrasonic cleaning time was 5 min each time.

[0112] 4) Transfer the powder product obtained in step 3) to a vacuum drying oven. Keep it at 70°C for 12 hours in a vacuum, and then keep it at 150°C for 24 hours to perform thermal activation of the sample, thereby obtaining the metal-organic framework MOF-801(N) adsorbent.

[0113] 5) The MOF-801(N) obtained in step 4) was dispersed in 25 mL of a methanol suspension of SrTiO3:Al, wherein the amounts of MOF-801(N) and SrTiO3:Al were 80 mg and 20 mg, respectively. The mixture was then stirred and reacted in an oil bath at 60 °C for 12 h to finally obtain the MOF-801(N)@SrTiO3:Al(MS-20) composite material.

[0114] Example 6

[0115] The preparation method of the metal-organic framework composite material, namely MOF-801(N)@SrTiO3:Al(MS-20) composite material of the present invention includes the following steps:

[0116] 1) Using 12.5 mmol of zirconium chloride octahydrate (ZrOCl2·8H2O) as the metal source; 12.5 mmol of fumaric acid and 0.5 mL of hydrazine hydrate as the organic ligand source; and 50 mL of N,N'-dimethylformamide (DMF) and 25 mL of formic acid as the solvent, the materials were placed in a 250 mL single-necked flask and stirred on a magnetic stirrer until transparent.

[0117] 2) Preheat the oil bath to 140°C, place the reactants obtained in step 1) in the oil bath, heat at 140°C for 7 hours to allow for full reaction, and then allow to cool naturally to room temperature.

[0118] 3) The pale yellow to white precipitate sample obtained in step 2) was separated by centrifugation and washed three times with DMF and methanol respectively. After centrifugation, the sample was dried and kept in an oven at 70°C for 10 hours to obtain dried powder. The centrifugation speed was 5000 r / min and the centrifugation time was 5 min each time. The ultrasonic cleaning time was 5 min each time.

[0119] 4) Transfer the powder product obtained in step 3) to a vacuum drying oven. Keep it at 80°C for 12 hours in a vacuum, and then keep it at 130°C for 24 hours to perform thermal activation of the sample, thereby obtaining the metal-organic framework MOF-801(N) adsorbent.

[0120] 5) The MOF-801(N) obtained in step 4) was dispersed in 25 mL of a methanol suspension of SrTiO3:Al, wherein the amounts of MOF-801(N) and SrTiO3:Al were 80 mg and 20 mg, respectively. The mixture was then stirred and reacted in an oil bath at 60 °C for 12 h to finally obtain the MOF-801(N)@SrTiO3:Al(MS-20) composite material.

[0121] Example 7

[0122] The preparation method of the metal-organic framework composite material, namely MOF-801(N)@SrTiO3:Al(MS-20) composite material of the present invention includes the following steps:

[0123] 1) Using 12.5 mmol of zirconium chloride octahydrate (ZrOCl2·8H2O) as the metal source; 12.5 mmol of fumaric acid and 0.1 mL of hydrazine hydrate as the organic ligand source; and 50 mL of N,N'-dimethylformamide (DMF) and 25 mL of formic acid as the solvent, the materials were placed in a 250 mL single-necked flask and stirred on a magnetic stirrer until transparent.

[0124] 2) Preheat the oil bath to 130°C, place the reactants obtained in step 1) in the oil bath, heat at 130°C for 6 hours to allow for full reaction, and then allow to cool naturally to room temperature.

[0125] 3) The pale yellow to white precipitate sample obtained in step 2) was separated by centrifugation and washed three times with DMF and methanol respectively. After centrifugation, the centrifuged sample was kept at 60℃ in an oven for 10 hours to obtain dried powder. The centrifugation speed was 5000 r / min and the centrifugation time was 5 min each time. The ultrasonic cleaning time was 5 min each time.

[0126] 4) Transfer the powder product obtained in step 3) to a vacuum drying oven. Keep it at 50°C for 12 hours in a vacuum, and then keep it at 130°C for 24 hours to perform thermal activation of the sample, thereby obtaining the metal-organic framework MOF-801(N) adsorbent.

[0127] 5) The MOF-801(N) obtained in step 4) was dispersed in 25 mL of a methanol suspension of SrTiO3:Al, wherein the amounts of MOF-801(N) and SrTiO3:Al were 80 mg and 20 mg, respectively. The mixture was then stirred and reacted in an oil bath at 60 °C for 12 h to finally obtain the MOF-801(N)@SrTiO3:Al(MS-20) composite material.

[0128] Example 8

[0129] The preparation method of the metal-organic framework composite material, namely MOF-801(N)@SrTiO3:Al(MS-20) composite material of the present invention includes the following steps:

[0130] 1) Using 12.5 mmol of zirconium chloride octahydrate (ZrOCl2·8H2O) as the metal source; 12.5 mmol of fumaric acid and 0.5 mL of hydrazine hydrate as the organic ligand source; and 50 mL of N,N'-dimethylformamide (DMF) and 25 mL of formic acid as the solvent, the materials were placed in a 250 mL single-necked flask and stirred on a magnetic stirrer until transparent.

[0131] 2) Preheat the oil bath to 130°C, place the reactants obtained in step 1) in the oil bath, heat at 130°C for 6 hours to allow for full reaction, and then allow to cool naturally to room temperature.

[0132] 3) The pale yellow to white precipitate sample obtained in step 2) was separated by centrifugation and washed three times with DMF and methanol respectively. After centrifugation, the centrifuged sample was kept at 60℃ in an oven for 10 hours to obtain dried powder. The centrifugation speed was 5000 r / min and the centrifugation time was 5 min each time. The ultrasonic cleaning time was 5 min each time.

[0133] 4) Transfer the powder product obtained in step 3) to a vacuum drying oven. Keep it at 70°C for 12 hours in a vacuum, and then keep it at 150°C for 24 hours to perform thermal activation of the sample, thereby obtaining the metal-organic framework MOF-801(N) adsorbent.

[0134] 5) The MOF-801(N) obtained in step 4) was dispersed in 25 mL of a methanol suspension of SrTiO3:Al, wherein the amounts of MOF-801(N) and SrTiO3:Al were 80 mg and 20 mg, respectively. The mixture was then stirred and reacted in an oil bath at 50 °C for 10 h to finally obtain the MOF-801(N)@SrTiO3:Al(MS-20) composite material.

[0135] Example 9

[0136] The preparation method of the metal-organic framework composite material, namely MOF-801(N)@SrTiO3:Al(MS-20) composite material of the present invention includes the following steps:

[0137] 1) Using 12.5 mmol of zirconium chloride octahydrate (ZrOCl2·8H2O) as the metal source; 12.5 mmol of fumaric acid and 0.5 mL of hydrazine hydrate as the organic ligand source; and 50 mL of N,N'-dimethylformamide (DMF) and 25 mL of formic acid as the solvent, the materials were placed in a 250 mL single-necked flask and stirred on a magnetic stirrer until transparent.

[0138] 2) Preheat the oil bath to 130°C, place the reactants obtained in step 1) in the oil bath, heat at 130°C for 6 hours to allow for full reaction, and then allow to cool naturally to room temperature.

[0139] 3) The pale yellow to white precipitate sample obtained in step 2) was separated by centrifugation and washed three times with DMF and methanol respectively. After centrifugation, the centrifuged sample was kept at 60℃ in an oven for 10 hours to obtain dried powder. The centrifugation speed was 5000 r / min and the centrifugation time was 5 min each time. The ultrasonic cleaning time was 5 min each time.

[0140] 4) Transfer the powder product obtained in step 3) to a vacuum drying oven. Keep it at 70°C for 12 hours in a vacuum, and then keep it at 150°C for 24 hours to perform thermal activation of the sample, thereby obtaining the metal-organic framework MOF-801(N) adsorbent.

[0141] 5) The MOF-801(N) obtained in step 4) was dispersed in 25 mL of a methanol suspension of SrTiO3:Al, wherein the amounts of MOF-801(N) and SrTiO3:Al were 80 mg and 20 mg, respectively. The mixture was then stirred and reacted in an oil bath at 70 °C for 12 h to finally obtain the MOF-801(N)@SrTiO3:Al(MS-20) composite material.

[0142] Comparative Example 3

[0143] The preparation method of the metal-organic framework composite material of the present invention includes the following steps:

[0144] 1) Using 12.5 mmol of zirconium chloride octahydrate (ZrOCl2·8H2O) as the metal source; 12.5 mmol of fumaric acid and 0.5 mL of hydrazine hydrate as the organic ligand source; and 50 mL of N,N'-dimethylformamide (DMF) and 25 mL of formic acid as the solvent, the materials were placed in a 250 mL single-necked flask and stirred on a magnetic stirrer until transparent.

[0145] 2) Preheat the oil bath to 130°C, place the reactants obtained in step 1) in the oil bath, heat at 130°C for 6 hours to allow for full reaction, and then allow to cool naturally to room temperature.

[0146] 3) The pale yellow to white precipitate sample obtained in step 2) was separated by centrifugation and washed three times with DMF and methanol respectively. After centrifugation, the centrifuged sample was kept at 60℃ in an oven for 10 hours to obtain dried powder. The centrifugation speed was 5000 r / min and the centrifugation time was 5 min each time. The ultrasonic cleaning time was 5 min each time.

[0147] 4) Transfer the powder product obtained in step 3) to a vacuum drying oven. Keep it at 70°C for 12 hours in a vacuum, and then keep it at 150°C for 24 hours to perform thermal activation of the sample, thereby obtaining the metal-organic framework MOF-801(N) adsorbent.

[0148] 5) Grind and mix MOF-801(N) obtained in step 4) with SrTiO3:Al until homogeneous, wherein the mass ratio of MOF-801(N) to SrTiO3:Al is 80:20, and finally obtain the composite material.

[0149] The phase structure morphology, component distribution, and in-situ air hydrogen production performance of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) prepared in Example 3 were characterized using X-ray diffraction, infrared spectroscopy, Raman spectroscopy, UV-Vis spectrophotometer, fluorescence spectroscopy, fully automated physical adsorption analyzer, scanning electron microscope, transmission electron microscope, and energy-dispersive X-ray detector. The in-situ air hydrogen production performance of the samples prepared in Comparative Examples 1, 2, and 3 were also tested. The results are as follows:

[0150] Figure 1 The X-ray diffraction (XRD) patterns of MOF-801(N), SrTiO3:Al, and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al (MS-20), are shown. It can be seen that in the XRD pattern of MOF-801(N), there are two strong diffraction peaks at 2θ = 8.6° and 9.9°, corresponding to (111) and (200), respectively. SrTiO3:Al exhibits characteristic diffraction peaks of (110), (200), and (211), located at 2θ = 32.4°, 46.5°, and 57.8°, respectively, which is consistent with cubic SrTiO3 (CPDS#01-084-0443). It can be clearly seen that the characteristic peaks of MOF-801(N) and SrTiO3:Al are easily found in the XRD pattern of MS-20, indicating that the two substances coexist in the MS system.

[0151] Figure 2 The Fourier transform infrared (FTIR) spectra of MOF-801(N), SrTiO3:Al, and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al (MS-20), are shown. It can be seen that the FTIR spectrum of MS-20 is at 654 cm⁻¹. -1 A characteristic peak appeared at [value], corresponding to the Sr-Ti-O structure of SrTiO3:Al. Simultaneously, the characteristic peak of MOF-801(N) was also reflected in MS-20, indicating that the chemical structures of MOF-801(N) and SrTiO3:Al were well preserved in MS-20.

[0152] Figure 3 The images show the Raman spectra of MOF-801(N), SrTiO3:Al, and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al (MS-20). It can be seen that the Raman spectrum of MS-20 not only contains the characteristic bands of SrTiO3:Al, but also has bands located at 372, 421, 631, 699, and 761 cm⁻¹. -1 These correspond to the typical SrTiO3 LO2, LO3, TO4 and LO4 modes, respectively, and also have the characteristic peaks of MOF-801(N).

[0153] Figure 4 Image a is a scanning electron microscope (SEM) image of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of this invention. It can be seen that the diameter of SrTiO3:Al is 400-500 nm, and it has a cubic structure surrounded by MOF-801(N).

[0154] Figure 4 b, Figure 4 c, Figure 4 Image d shows a transmission electron microscope (TEM) image of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al (MS-20) obtained in Example 3 of this invention. This image further confirms the presence of MOF-801(N) and SrTiO3:Al.

[0155] Figure 4 e, Figure 4 f, Figure 4 g, Figure 4 h, Figure 4 i, Figure 4 j, Figure 4 k, Figure 4 l, Figure 4 m, Figure 4n is the linear distribution diagram of each element in the metal-organic framework composite material MOF-801(N)@SrTiO3:Al(MS-20) obtained in Example 3 of the present invention; Figure 4 fn is the elemental distribution pattern of MOF-801(N)@SrTiO3:Al (MS-20). As can be seen from the figure, Zr and N, originating from MOF-801(N), are uniformly detected on MS-20, further revealing the uniform distribution of MOF-801(N) crystals on the MS system. Furthermore, the distribution of Ti and Sr confirms that SrTiO3:Al is uniformly distributed throughout the system.

[0156] Figure 5 The N2 adsorption-desorption curves for MOF-801(N), SrTiO3:Al, and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al (MS-20), show that MOF-801(N) is a microporous material with a typical type I isotherm, while SrTiO3:Al is a non-porous material with a surface area of ​​2.96 m². 2 g -1 This is a typical type II isotherm. This is because MOF-801(N) has a high specific surface area (650.39 m²). 2 g -1 The presence of SrTiO3 and its porous structure provides numerous adsorption sites for water molecules. However, after the introduction of SrTiO3:Al, the BET surface area (ST) of MS-20 decreases. BET It dropped to 299.98m 2 g -1 .

[0157] Figure 6 Thermogravimetric analysis (TGA) of MOF-801(N), SrTiO3:Al and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al(MS-20), shows that MOF-801(N)@SrTiO3:Al(MS-20) has excellent thermal stability.

[0158] Figure 7The UV-Vis absorption spectra of MOF-801(N), SrTiO3:Al, and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al (MS-20), are shown. It can be seen that both SrTiO3:Al and MOF-801(N) exhibit good light absorption performance in the ultraviolet region, with absorption edges at 410 and 309 nm, respectively. Furthermore, two distinct absorption edges can be clearly observed in the optical absorption of MS-20, which is due to the coexistence of SrTiO3:Al and MOF-801(N).

[0159] Figure 8 The images show the photoluminescence (PL) spectra of MOF-801(N), SrTiO3:Al, and the metal-organic framework composite material obtained in Example 3 of this invention, namely MOF-801(N)@SrTiO3:Al (MS-20). It can be seen that compared to MOF-801(N), the PL intensity of SrTiO3:Al under 365 nm photoexcitation is significantly reduced. This is due to its inherent properties, implying effective carrier separation. Furthermore, the introduction of SrTiO3:Al reduces the PL signal of the MS series to varying degrees, with its emission peak located at the same wavelength of ~450 nm. Interestingly, a new emission peak appears in the PL spectrum of MS-20, which may be due to partial chemical bonding caused by electron transfer between MOF-801(N) and SrTiO3:Al.

[0160] Figure 9 The water absorption curve of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al (MS-20) obtained in Example 3 of this invention is shown at 60 min (25℃, RH=30%). This indicates that the moisture absorption capacity of MS-20 at 30% RH is approximately 1.06 g. H2O g absorbent -1 And it only takes about 15 minutes to reach 90% adsorption equilibrium.

[0161] Figure 10 The metal-organic framework composite material MOF-801(N)@SrTiO3:Al (MS-20) obtained in Example 3 of this invention exhibits photocatalytic decomposition of atmospheric water to produce hydrogen and oxygen under ultraviolet-visible light irradiation (λ>300nm). This demonstrates that MS-20 shows excellent photocatalytic activity after absorbing moisture in a dry environment (30% RH, 25℃), with yields of H2 and O2 of 1033 and 494.34 μmol g, respectively. -1 h -1 .

[0162] Figure 11The UV-Vis absorption spectrum and apparent quantum efficiency (AQY) of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al (MS-20) obtained in Example 3 of this invention are shown. It can be seen that after moisture saturation in a dry environment (30% RH, 25℃), the AQY values ​​of MS-20 at 350, 365, and 380 nm are 0.17%, 0.14%, and 0.06%, respectively. Interestingly, the AQY trend of MS-20 is closely related to the absorbance of SrTiO3:Al, indicating that the photocatalytic activity of MS-20 in splitting atmospheric water depends on the intrinsic photocatalytic activity of SrTiO3:Al, while MOF-801(N) provides atmospheric water for conversion into hydrogen energy.

[0163] Figure 12 The X-ray diffraction (XRD) patterns of the metal-organic framework composite material MOF-801(N)@SrTiO3:Al (MS-20) obtained in Example 3 of this invention before and after water absorption-desorption-hydrogen production in air are shown. It can be seen that the XRD pattern of MS-20 before and after water absorption-dehydration-hydrogen production in a dry environment is almost unchanged, which means that the crystallinity is very good before and after the reaction.

[0164] Figure 13 The water absorption curve of the metal-organic framework composite material MOF-801(N) obtained in Comparative Example 1 of this invention is shown at 60 min (25℃, RH = 30%). This indicates that the moisture absorption capacity of MOF-801(N) at 30% RH is approximately 1.5 g. H2O g absorbent -1 And it only takes about 15 minutes to reach 90% adsorption equilibrium.

[0165] Figure 14 The metal-organic framework composite material MOF-801(N) obtained in Comparative Example 1 of this invention exhibits photocatalytic decomposition of atmospheric water to produce hydrogen under ultraviolet-visible light irradiation (λ>300nm). It can be seen that MOF-801(N) does not produce hydrogen.

[0166] Figure 15 The image shows the water absorption curve of the photocatalytic material SrTiO3:Al obtained in Comparative Example 2 of this invention at 60 min (25℃, RH = 30%). This indicates that the moisture absorption capacity of SrTiO3:Al at 30% RH is approximately 0.25 g. H2O g absorbent -1 Its performance is poor.

[0167] Figure 16The photocatalytic material obtained in Comparative Example 2 of this invention, namely SrTiO3:Al, demonstrates its photocatalytic hydrogen production performance by decomposing atmospheric water under ultraviolet-visible light irradiation (λ>300nm). It can be seen that SrTiO3:Al exhibits certain photocatalytic activity after absorbing moisture in a dry environment (30% RH, 25℃), with an H2 yield of 25.76 μmol g. -1 h -1 .

[0168] Figure 17 The water absorption curve of the metal-organic framework composite material obtained in Comparative Example 3 of this invention is shown in the figure for 60 min (25°C, RH = 30%). This indicates that the moisture absorption capacity of this composite material at 30% RH is approximately 1 g. H2O g absorbent -1 .

[0169] Figure 18 The metal-organic framework composite material obtained in Comparative Example 3 of this invention exhibits photocatalytic hydrolysis of atmospheric water to produce hydrogen under ultraviolet-visible light irradiation (λ>300nm). It is evident that this composite material displays excellent photocatalytic activity after absorbing moisture in a dry environment (30% RH, 25℃), with an H2 yield of 523.07 μmol g. -1 h -1 .

[0170] It should be understood that the specific embodiments described above are merely illustrative or explanatory of the principles of the invention and do not constitute a limitation thereof. Therefore, any modifications, equivalent substitutions, improvements, etc., made without departing from the spirit and scope of the invention should be included within the protection scope of the invention. Furthermore, the appended claims are intended to cover all variations and modifications falling within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A method for preparing a metal-organic framework composite material, characterized in that, The heated activated metal-organic framework material was impregnated in a methanol suspension of SrTiO3:Al photocatalyst and then dried to obtain a metal-organic framework composite material. The preparation method of the metal-organic framework material is as follows: a metal source and an organic ligand source containing hydrazine hydrate are added to a solvent, stirred evenly, and then reacted at 120-140℃ for 5-7 h. After separation, the metal-organic framework material is obtained. The metal source is zirconium chloride octahydrate, and the organic ligand source containing hydrazine hydrate is fumaric acid and hydrazine hydrate. The conditions for heat activation are: under vacuum, keep at 50-80℃ for 10-14 h, and then keep at 130-170℃ for 22-26 h; The drying conditions are: stirring in an oil bath and drying at 50-70℃ for 10-12 hours.

2. The preparation method according to claim 1, characterized in that, The ratio of fumaric acid to hydrazine hydrate was 12.5 mmol: 0.1-0.5 mL, and the molar ratio of fumaric acid to the metal source was 1:

1.

3. The preparation method according to claim 1, characterized in that, The solvent is a mixture of N,N'-dimethylformamide and formic acid; the volume ratio of N,N'-dimethylformamide to formic acid is 50:10-25.

4. The preparation method according to claim 1, characterized in that, The mass ratio of metal-organic framework material to SrTiO3:Al photocatalyst is 100-60:0-40, where the amount of SrTiO3:Al photocatalyst does not include 0.

5. The preparation method according to claim 4, characterized in that, The preparation method of SrTiO3:Al photocatalyst includes the following steps: 1) A mixture of SrTiO3, SrCl2∙6H2O and Al2O3 was ground and mixed evenly, and then calcined in air at 1273-1473 K for 4-8 hours to obtain the SrTiO3:Al precursor; the molar ratio of SrTiO3, SrCl2∙6H2O and Al2O3 was 1-2:9-11:0.01-0.04; 2) Add the SrTiO3:Al precursor to a mixed solution of H2O and methanol, then add the Rh source and disperse it evenly with ultrasound. 3) Subsequently, the mixed solution obtained in step 2) was transferred to the reactor, the air was first purged, and then the Cr source was added. The mixture was irradiated with an Xe lamp for 1-3 hours. After the reaction was completed, the reaction solution was centrifuged, washed, and dried to obtain the SrTiO3:Al photocatalyst. Among them, the Rh source is Na3RhCl6, and the mass of Rh contained in the Rh source accounts for 0.6wt-0.8wt% of the mass of SrTiO3:Al precursor; the Cr source is K2CrO4, and the mass of Cr contained in the Cr source accounts for 0.5-1wt% of the mass of SrTiO3:Al precursor.

6. A metal-organic framework composite material, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

7. The application of the metal-organic framework composite material according to claim 6 in in-situ air hydrogen production.

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