A noble metal-free photocatalyst and its preparation method and application

Abstract

The present invention discloses a noble metal-free photocatalyst and a preparation method and application thereof, wherein the noble metal-free photocatalyst comprises a metal organic framework material LIFM-28, a linear dicarboxylic acid ligand, a bipyridine-dicarboxylic acid organic ligand and a transition metal catalytic center, which are self-assembled by coordination. The preparation method of the noble metal-free catalyst of the present invention is to carry out fine ligand and metal modification and construction of the dynamic coordination space in the metal organic framework pores at the crystal structure scale, introduce ligand molecules that can provide a photoredox center and a ligand molecule that can accommodate a catalytic center, and then utilize the bipyridine site of the ligand molecule that can accommodate the catalytic center to accurately introduce the transition metal catalytic center site. The active site of the metal organic framework material introduced by this strategy can be stably present in the pores of the material, so that it has a very high application prospect in the field of organic small molecule catalysis and drug molecule development of functionalized nanomaterials.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, and in particular to a noble metal-free photocatalyst and a preparation method and application thereof. Background Art

[0002] In recent years, transition metal-catalyzed coupling reactions, such as Chan-Lam, Stadler-Ziegler, Buchwald-Hartwig, Ullmann-Goldberg, and Sonogashira, have become effective means of constructing carbon-heteroatom bonds. They are widely used in the synthesis of high-value chemicals such as natural products and drug molecules due to their efficient catalytic performance and good selectivity. For example, the Chan-Lam reaction achieves cross-coupling between thiophenol and arylboronic acid under the catalysis of nickel (Ni) complex; the Stadler-Ziegler reaction uses ruthenium (Ru) complex as a photocatalyst to promote the coupling of thiophenol and aromatic amine. In addition, palladium (Pd)-catalyzed CH bond activation reaction is also an effective method for constructing CS bonds. However, these homogeneous catalytic reactions face many challenges: complex separation and purification of catalysts, high metal residues, harsh reaction conditions, and poor substrate compatibility. At the same time, catalytic systems involving precious metals are often expensive and easy to deactivate, further limiting their widespread application in industry.

[0003] For the construction of CN bonds of nitrogen-containing compounds, the Ullmann-Goldberg reaction and the Buchwald-Hartwig reaction are two classic methods. The Ullmann-Goldberg reaction usually relies on a large amount of copper (Cu) salt catalysis, is carried out at high temperature, and has a low yield. In contrast, the Buchwald-Hartwig reaction requires a small amount of palladium catalyst and mild reaction conditions, so it is widely used in CN coupling. For example, Irena Škorić's team successfully achieved the Buchwald-Hartwig amination reaction of a rigid non-planar system by using Brett Phos ligands and Pd(OAc)2 catalysts; Huixiong Chen's research group used Pd2dba3 to catalyze the synthesis of a series of 2,5-disubstituted pyrimidine derivatives. Although these works show the potential of Pd catalysts in CN coupling, their high price, toxicity, and complexity of ligand design remain unresolved challenges. Therefore, although transition metal-catalyzed coupling reactions are widely used in the synthesis of carbon-heteroatom bonds, they also face problems such as harsh reaction conditions, high residual precious metals, low efficiency, and poor substrate compatibility. Therefore, it is particularly important to develop new efficient, economical and green synthetic methodologies to replace these traditional catalytic systems.

[0004] On the other hand, in recent years, the combination of photocatalysis and transition metal catalysis, namely metal photocatalysis, has gradually become an effective method for constructing functional compounds under mild conditions. Compared with traditional transition metal catalysis, metal photocatalysis has the advantages of low reaction energy barrier, high catalytic efficiency, good substrate compatibility, strong selectivity and green environmental protection, and has been widely used in the synthesis of carbon-heteroatom bonds. For example, MacMillan and F. Glorius's research group successfully realized a series of cross-coupling reactions of carbon-heteroatom bonds by combining cheap transition metals (such as Ni and Cu) with photoredox catalysts.

[0005] Metal photocatalytic systems are mainly composed of photoredox catalysts and transition metal catalysts. Under illumination, photocatalysts generate highly active free radicals through redox or energy transfer, which participate in the subsequent transition metal catalytic cycle; at the same time, photocatalysts promote the oxidative addition, transmetallation and reductive elimination steps of transition metals through single electron transfer or energy transfer to achieve efficient cross-coupling reactions. In this way, metal photocatalysis can complete the direct coupling reaction between non-traditional nucleophiles and free radicals that cannot be achieved by traditional transition metal catalysis. Although metal photocatalysis has shown great potential, some problems it faces still need to be solved. For example, most of the current metal photocatalytic systems are homogeneous catalysis, which makes catalyst recovery and recycling difficult; in addition, the low concentration of active intermediates in the homogeneous system leads to low electron transfer efficiency between the photoredox cycle and the metal catalytic cycle, which limits the application scope of this technology. In addition, the commonly used photosensitizers in metal photocatalysis are mainly divided into organic small molecule dyes and noble metal complexes based on iridium (Ir) or ruthenium (Ru). The former has low stability and catalytic efficiency, while the latter is limited to its wide application due to the scarcity and high cost of noble metals. Therefore, it is of great research significance to construct stable, efficient and inexpensive heterogeneous metal photocatalysts. Unlike homogeneous systems, heterogeneous catalysts are easy to recycle and reuse, and can avoid problems such as metal residues and separation difficulties. In addition, heterogeneous catalytic systems have higher electron transfer efficiency between photocatalysis and metal catalysis, which can significantly improve the reaction efficiency. Future research should further explore the design and development of new heterogeneous metal photocatalysts and optimize their performance to promote the widespread application of metal photocatalysis in green chemistry and industrial applications. Summary of the invention

[0006] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, the purpose of the present invention is to provide a noble metal-free photocatalyst and a preparation method and application thereof.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The first aspect of the present invention provides a noble metal-free photocatalyst, which includes a metal organic framework material LIFM-28, a linear dicarboxylic acid ligand, a bipyridine-dicarboxylic acid organic ligand and a transition metal catalytic center, which are self-assembled through coordination.

[0009] In the present invention, the linear dicarboxylic acid ligand has a photoredox property, and the dynamic coordination space in the metal organic framework pore is finely modified and constructed with ligands and metals, and a ligand molecule that can provide a photoredox center is introduced, and the transition metal catalytic center site is accurately introduced through the bipyridine-dicarboxylic acid organic ligand. The active site introduced into the metal organic framework material by this strategy can be stably present in the pores of the material. The photoredox center in the material can generate electrons under light excitation, and transfer electrons and energy through the ligands and metal clusters in the structure of the metal organic framework material, so that the valence state of the catalytic center metal changes, thereby realizing the activation of small organic molecules, generating intermediates, and further converting them into target products. After the fine light and catalytic active center modification, the material still maintains crystallinity and porosity, which is conducive to the movement of catalytic substrate molecules and product molecules in the pores.

[0010] In some embodiments of the present invention, the metal organic framework material LIFM-28 is coordinated with a linear dicarboxylic acid ligand.

[0011] In some embodiments of the present invention, the metal organic framework material LIFM-28 is coordinated with the transition metal catalytic center through the bipyridine-dicarboxylic acid organic ligand; and coordinated with the transition metal atom in the transition metal catalytic center through two nitrogen atoms on the bipyridine-dicarboxylic acid organic ligand.

[0012] In some embodiments of the present invention, the molar ratio of the metal organic framework material LIFM-28, the linear dicarboxylic acid ligand, the bipyridine-dicarboxylic acid organic ligand and the transition metal catalytic center is 1:3-4.5:0.5-3:0.1-2.

[0013] In some embodiments of the present invention, the bipyridine-dicarboxylic acid organic ligand includes at least one of 2,2'-bipyridine-5,5'-dicarboxylic acid and 3,3'-(2,2'-bipyridine)-5,5'-diyl-diacrylic acid.

[0014] In some embodiments of the present invention, the linear dicarboxylic acid ligand comprises at least one of 4,4'-(5,10-phenazinediyl)bis-benzoic acid and 4,4'-(1,2,4,5-tetrazine-3,6-diyl)dibenzoic acid.

[0015] In some embodiments of the present invention, the transition metal catalytic center is provided by a transition metal catalyst comprising one of nickel chloride, nickel bromide, nickel iodide, cobalt chloride, cobalt bromide, cobalt iodide, cupric chloride, cupric bromide, cupric iodide, cuprous iodide and the above metal salt hydrates.

[0016] In some embodiments of the present invention, the metal organic aggregate material LIFM-28 is {[Zr6(μ3-O)8-(H2O)8(L)4]·(free solvent molecules)} (L=2,2'-bis(trifluoromethyl)-[1,1'-biphenyl]-4,4'-dicarboxylate).

[0017] In some embodiments of the present invention, the morphology of the noble metal-free photocatalyst includes block, rod, plate or cone, and the particle size is 1 nm to 1 μm.

[0018] In some embodiments of the present invention, the molecular formula unit of the noble metal-free photocatalyst is C 102 H 46 Cl2F 24 N4NiO 32 Zr6; belongs to tetragonal phase, P 42 / mmc Space group.

[0019] In some embodiments of the present invention, the structural formula of the noble metal-free photocatalyst is [Zr6O4(OH)6(H2O)2L4(BPYDC) 1.42 (NiCl2) 1.21 (PBPDC) 0.21 ]·x Solvent ); PBPDC: 4,4'-(5,10-phenazinediyl)bis-benzoic acid.

[0020] In some embodiments of the present invention, the specific surface area of ​​the noble metal-free photocatalyst is 800-1400 cm 3 / g.

[0021] The second aspect of the present invention provides a method for preparing the precious metal-free photocatalyst, comprising the following steps: subjecting the metal organic framework material LIFM-28, linear dicarboxylic acid ligands, bipyridine-dicarboxylic acid organic ligands and transition metal catalytic centers to a solvent-assisted reaction to obtain the precious metal-free photocatalyst.

[0022] In some embodiments of the present invention, the temperature of the solvent-assisted reaction is 80-150°C, such as 85°C, 90°C, 100°C, 110°C, 120°C, 130°C, etc., and the reaction time is 1 to 3 days.

[0023] In some embodiments of the present invention, the method for preparing the precious metal-free photocatalyst comprises the following steps: subjecting the metal organic framework material LIFM-28 to a solvent-assisted reaction with a linear dicarboxylic acid ligand and a bipyridine-dicarboxylic acid organic ligand, and then subjecting the metal organic framework material LIFM-28 to a solvent-assisted reaction with a transition metal catalytic center to obtain the precious metal-free photocatalyst.

[0024] In some embodiments of the present invention, the solvent for the solvent-assisted reaction includes at least one of N,N-dimethylformamide, acetonitrile and methanol.

[0025] In some embodiments of the present invention, when performing the solvent-assisted reaction, fresh solvent is replaced 3 to 5 times a day.

[0026] In some embodiments of the present invention, the method for preparing the precious metal-free photocatalyst further comprises subjecting the reaction product to a reduced pressure drying and activation treatment; the reduced pressure drying and activation treatment comprises vacuum treatment at 18 to 35°C for 4 to 8 hours, and then vacuum treatment at 80 to 90°C for 10 to 14 hours.

[0027] The third aspect of the present invention provides the use of the noble metal-free photocatalyst in photocatalytic carbon-heteroatom bond cross-coupling and / or carbonylation reaction, photocatalytic degradation reaction, photocatalytic field hydrogen reaction, and photocatalytic conversion of carbon dioxide into carbon alcohol compounds and / or hydrocarbon compounds.

[0028] In some embodiments of the present invention, the carbon-heteroatom bond comprises CC, CO, CS, CN.

[0029] In some embodiments of the present invention, during the photocatalysis, the wavelength of the light source is 350-650nm, and the power is 1-100W.

[0030] The beneficial effects of the present invention are:

[0031] Based on the current situation that the prior art relies on precious metals and has difficulties in catalyst recovery, catalytic circulation, separation and purification, the present invention relies on the dynamic spatial ligand assembly synthesis and post-modification method of metal-organic framework materials, and provides a heterogeneous transition metal photocatalyst containing a photoredox center and a transition metal catalytic center, which can be used to catalyze the metal photocatalytic reaction of organic small molecules constructed by carbon-heteroatom bonds. This method can accurately anchor the photoredox center and the transition metal catalytic center to the metal-organic framework material with modifiable active sites, and the microstructure of the catalyst can be obtained by a single crystal diffractometer, which is helpful to analyze the catalytic mechanism of heterogeneous metal photocatalysis to construct carbon-heteroatom bonds. This method has great application potential in the fields of heterogeneous metal photocatalytic carbon-heteroatom bond construction of organic small molecules and photocatalytic carbon dioxide conversion.

[0032] The preparation method of the noble metal-free catalyst of the present invention is to carry out fine ligand and metal modification and construction of the dynamic coordination space in the metal organic framework pores at the crystal structure scale, firstly by introducing ligand molecules that can provide photoredox centers and ligand molecules that can accommodate catalytic centers, and then using the bipyridine sites of the ligand molecules that can accommodate catalytic centers to accurately introduce transition metal catalytic center sites. The active sites introduced into the metal organic framework material by this strategy can be stably present in the pores of the material.

[0033] The photoredox center in the noble metal-free catalyst material of the present invention can generate electrons under light excitation, and transfer electrons and energy through ligands and metal clusters in the metal organic framework material structure, so that the valence state of the catalytic center metal changes, thereby activating small organic molecules, generating intermediates, and further converting them into target products. After fine light and catalytic active center modification, the material still maintains crystallinity and porosity, which is conducive to the movement of catalytic substrate molecules and product molecules in the pores. The noble metal-free photocatalyst of the present invention has extremely high application prospects in the field of organic small molecule catalysis and drug molecule development of functionalized nanomaterials. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a crystal structure diagram of the material in Example 1 of the present invention.

[0035] Figure 2 This is a 77K nitrogen adsorption curve of the material in Example 1 of the present invention.

[0036] Figure 3 This is the X-ray powder diffraction pattern of the material in Example 1 of the present invention.

[0037] Figure 4 This is a TEM image of the catalyst in Example 1 of the present invention.

[0038] Figure 5 This is the HADDF-STE diagram of the catalyst in Example 1 of the present invention.

[0039] Figure 6 This is the EDS image of the catalyst in Example 1 of the present invention.

[0040] Figure 7 This is a diagram of the CS cross-coupling photocatalytic cycle of the catalyst in Example 1 of the present invention.

[0041] Figure 8 This is a diagram of the CN cross-coupling photocatalytic cycle of the catalyst in Example 1 of the present invention.

[0042] Fig. 9 These are XPS graphs of the catalyst before photocatalysis (left) and after photocatalysis (right) in Example 1 of the present invention.

[0043] Fig.10 This is a TEM image of the catalyst after photocatalysis in Example 1 of the present invention.

[0044] Fig.11 This is the HADDF-STE diagram of the catalyst after photocatalysis in Example 1 of the present invention.

[0045] Fig.12 This is the EDS graph of the catalyst after photocatalysis in Example 1 of the present invention.

[0046] Fig.13 This is the adaptability result of the catalyst in Example 1 of the present invention to the CS photocatalytic substrate.

[0047] Fig.14 This is the adaptability result of the catalyst in Example 1 of the present invention to the CN photocatalytic substrate. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0049] Example 1

[0050] This example prepares a noble metal-free catalyst, and the specific process is as follows:

[0051] (1) Preparation of LIFM-28 containing dynamic coordination space metal organic framework material: Zirconium chloride (100 mg, 0.40 mmol), 2,5'-bis(trifluoromethyl)-4,4'-biphenyldicarboxylic acid (140 mg, 0.37 mmol), trifluoroacetic acid (1 mL, 13.46 mmol) and 20 mL of N,N-dimethylformamide were added to a 40 mL glass bottle and ultrasonicated until the system was clear. After heating at 120 °C for three days, colorless block crystals were obtained. Fresh N,N-dimethylformamide solvent was exchanged three to four times a day. After three days of exchange, it was stored in N,N-dimethylformamide solvent for future use.

[0052] Preparation of metal organic framework material LIFM-XYY-13 containing photoredox center and modifiable transition metal catalytic center ligand: LIFM-28 (100 mg, 0.04 mmol) and ligand 4,4'-(5,10-phenazine diyl) bis-benzoic acid (21 mg, 0.05 mmol), 2,2'-bipyridine-5,5'-dicarboxylic acid (12 mg, 0.05 mmol) and 10 mL of N,N-dimethylformamide were added to a glass bottle. Heated at 120 °C for two days to obtain yellow block crystals. Fresh N,N-dimethylformamide solvent was exchanged three to four times a day. After three days of exchange, it was stored in N,N-dimethylformamide solvent for use.

[0053] Preparation of heterogeneous transition metal catalyst LIFM-XYY-14 containing organic photoredox center and transition metal catalytic center: LIFM-XYY-13 (100 mg, 0.04 mmol), nickel chloride hexahydrate (23 mg, 0.1 mmol) and 10 mL of N,N-dimethylformamide were added to a glass bottle. After heating at 85 °C for two days, yellow block crystals were obtained. Fresh N,N-dimethylformamide solvent was exchanged three to four times a day. After three days of exchange, the solvent was exchanged again with acetone solvent three to four times a day for three days to obtain a brown-yellow sample acetone solution. The above sample was centrifuged, and the lower solid after centrifugation was transferred to a vacuum container, and then the decompression treatment was carried out at room temperature for 6 hours, and then the temperature was adjusted to 85 °C and the decompression treatment was continued for 12 hours to obtain a dry catalyst.

[0054] The structures of samples LIFM-XYY-13~14 and catalysts were characterized by X-ray single crystal diffractometer. The relevant crystallographic parameters of the samples are shown in Table 1:

[0055] Table 1

[0056]

[0057] In addition, Figure 1 As shown, the sample structure is clear, which is helpful for the subsequent catalytic mechanism analysis. The N2 isotherm adsorption curve of the sample was tested at 77K to detect the specific surface area (BET) of the sample. The results are shown in Figure 2 As shown in Figure 2, the specific surface areas of LIFM-XYY-13 and 14 are 1252 cm 3 / g and 1145 cm 3 / g, the material maintains high porosity.

[0058] LIFM-28, LIFM-XYY-13 and LIFM-XYY-14 were subjected to X-ray powder diffraction (PXRD) analysis, such as Figure 3As shown, the catalyst is able to maintain the crystallinity of the metal-organic framework material.

[0059] The catalyst was characterized by high-resolution transmission electron microscopy, and the results were as follows: Figure 4 As shown, the material is a bulk crystalline material, and under high-angle annular bright field or dark field mode (see Figure 5 ), the nickel transition metal in the material exists in the material in the form of single atoms. Through the energy spectrum test results (see Figure 6 ) shows that the elements in the material are evenly distributed.

[0060] The above results indicate that the present invention can prepare a noble metal-free photocatalyst with metal single atom dispersion. Through precise dynamic coordination space ligands and transition metal modification, the obtained catalyst containing a photoredox center and a catalytic center has high porosity and high dispersion of the catalytic center, providing more catalytic reaction sites, which is beneficial to the contact between the catalyst and the reactants, and has extremely high application prospects in the field of organic small molecule catalysis and drug molecule development of functionalized nanomaterials.

[0061] Example 2

[0062] In this example, the noble metal-free catalyst prepared in Example 1 was subjected to photocatalytic CS cross-coupling cycle catalysis, and the specific process was as follows:

[0063] In the glove box, weigh 20 mg of catalyst LIFM-XYY-14 and put it into a 10 mL glass bottle, then add 4-iodotrifluorotoluene (37 uL, 0.25 mmol), 4-methoxythiophenol (46 uL, 0.375 mmol), pyridine (41 uL, 0.5mmol), add a magnetic particle and tighten the bottle cap, take out the sample bottle from the glove box, and use a 30 W LED lamp with a wavelength of 456nm for 24 hours. After the reaction is completed, filter the reaction solution, spin dry the filtrate, add 0.5 mL of deuterated chloroform, and perform nuclear magnetic hydrogen spectrum and Fluorospectroscopy tests. Then follow the above steps, recover the catalyzed catalyst by centrifugation and vacuum dry it, and repeat the above catalytic steps. After repeating the operation for six rounds, the results are as follows: Figure 7 shown.

[0064] Example 3

[0065] In this example, the noble metal-free catalyst prepared in Example 1 was subjected to photocatalytic CN cross-coupling cyclic catalysis, and the specific process was as follows:

[0066] In the glove box, weigh 20 mg of catalyst LIFM-XYY-14 and put it into a 10 mL glass bottle, then add 4-bromotrifluorotoluene (69 uL, 0.5 mmol), tetrahydropyrrole (82 uL, 1.2 mmol), triethylenediamine (78 mg, 0.7 mmol), add a magnetic particle and tighten the bottle cap, take out the sample bottle from the glove box, use a 30 W LED lamp with a wavelength of 456 nm to illuminate for 48 hours, after the reaction is completed, filter the reaction solution, spin dry the filtrate, add 0.5 mL of deuterated chloroform, and perform nuclear magnetic resonance spectroscopy. 1 and F 19 Then, according to the above steps, the catalyst was recovered by centrifugation and vacuum dried, and then the above catalytic steps were repeated. After six rounds of repeated operation, the results are as follows: Figure 8 shown.

[0067] The catalyst after catalytic reaction was subjected to PXRD ( Figure 3 )、XPS( Fig. 9 )、TEM( Fig.10 )、HADDF-STE( Fig.11 ) and EDS spectrum test ( Fig.12 ), proving that the material can maintain structural stability before and after photocatalysis.

[0068] Example 4

[0069] In this example, the noble metal-free catalyst prepared in Example 1 was used to explore the substrate adaptability of photocatalysis CS and CN. The specific process is as follows:

[0070] In the glove box, weigh 10 mg of catalyst LIFM-XYY-14 and place it in a 10 mL glass bottle containing 0.25 mmol of aryl iodides with different substituents, 0.375 mmol of thiophenols with different substituents, pyridine (41 μL, 0.5 mmol) and 5 mL of acetonitrile. Add a magnetic particle and tighten the bottle cap. Outside the glove box, irradiate with a 30 W LED lamp with a wavelength of 456 nm for 24 hours. After the reaction is completed, filter the reaction solution, spin dry the filtrate, add 0.5 mL of deuterated chloroform, and perform nuclear magnetic resonance hydrogen and fluorine spectrum tests. The results are as follows: Fig.13 shown.

[0071] In the glove box, weigh 10 mg of catalyst LIFM-XYY-14 and place it in a 10 mL glass bottle containing 0.5 mmol of aromatic bromides with different substituents, 1 mmol of thiophenols with different substituents, 1 mmol of triethylenediamine and 5 mL of N,N-dimethylacetamide. Add a magnet and tighten the bottle cap. Outside the glove box, irradiate with a 30 W LED lamp with a wavelength of 456 nm for 48 hours. After the reaction is completed, filter the reaction solution, spin dry the filtrate, add 0.5 ml of deuterated chloroform, and perform nuclear magnetic resonance hydrogen and fluorine spectrum tests. The results are as follows: Fig.14 As shown (the yield marked in red requires the addition of 55°C photocatalytic reaction conditions).

[0072] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. Application of a noble metal-free photocatalyst in photocatalytic carbon-heteroatom bond cross coupling, characterized in that: The noble metal-free photocatalyst comprises a metal organic framework material LIFM-28, a linear dicarboxylic acid ligand, a bipyridine-dicarboxylic acid organic ligand and a transition metal catalytic center, which are self-assembled through coordination; The metal organic framework material LIFM-28 is coordinated with a linear dicarboxylic acid ligand; The metal organic framework material LIFM-28 is coordinated with the transition metal catalytic center through the bipyridine-dicarboxylic acid organic ligand; The linear dicarboxylic acid ligand includes at least one of 4,4'-(5,10-phenazinediyl)bis-benzoic acid and 4,4'-(1,2,4,5-tetrazine-3,6-diyl)dibenzoic acid.

2. The use according to claim 1, characterized in that: The metal organic framework material LIFM-28 is coordinated with the transition metal atom in the transition metal catalytic center through two nitrogen atoms on the bipyridine-dicarboxylic acid organic ligand.

3. The use according to claim 1, characterized in that: The molar ratio of the metal organic framework material LIFM-28, the linear dicarboxylic acid ligand, the bipyridine-dicarboxylic acid organic ligand and the transition metal catalytic center is 1:3-4.5:0.5-3:0.1-2.

4. The use according to claim 1, characterized in that: The bipyridine-dicarboxylic acid organic ligand includes at least one of 2,2'-bipyridine-5,5'-dicarboxylic acid and 3,3'-(2,2'-bipyridine)-5,5'-diyl-diacrylic acid.

5. The use according to claim 1, characterized in that: The transition metal catalytic center is provided by a transition metal catalyst including nickel chloride, nickel bromide, nickel iodide, cobalt chloride, cobalt bromide, cobalt iodide, cupric chloride, cupric bromide, cupric iodide, cuprous iodide or one of the above metal salt hydrates.

6. The use according to claim 1, characterized in that: The noble metal-free photocatalyst satisfies at least one of the following conditions: (I) The morphology of the noble metal-free photocatalyst includes block, rod, plate or cone; (II) The particle size of the noble metal-free photocatalyst is 1 nm to 1 μm.

7. The use according to claim 1, characterized in that: The molecular formula unit of the noble metal-free photocatalyst is C 102 H 46 Cl2F 24 N4NiO 32 Zr6; belongs to tetragonal phase, P 42 / mmc Space group.

8. The use according to any one of claims 1 to 7, characterized in that: The method for preparing the noble metal-free photocatalyst comprises the following steps: subjecting the metal organic framework material LIFM-28, linear dicarboxylic acid ligands, bipyridine-dicarboxylic acid organic ligands and transition metal catalytic centers to a solvent-assisted reaction to obtain the noble metal-free photocatalyst.

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