A hybrid material based on photosensitive metal-organic coordination nanocages and covalent organic frameworks, a preparation method thereof, and applications thereof

Abstract

The present invention discloses a hybrid material based on photosensitive metal-organic coordination nanocages and covalent organic frameworks, as well as its preparation method and application. This hybrid material includes metal-organic coordination nanocages / rings and COFs. Also disclosed are a method for preparing this Z-scheme hybrid material based on photosensitive metal-organic coordination nanocages / rings and COFs, and the application of this hybrid material in photocatalysis. The fully organic hybrid material made of metal-organic coordination nanocages / rings and COFs of the present invention has a hierarchical porous structure, which can improve the free diffusion of gases, increase the adsorption amount and activation degree of reactants, and reduce the recombination probability of electron-hole pairs, effectively improving the photocatalytic efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalytic materials, and in particular to a hybrid material based on a photosensitive metal-organic coordination nanocage and a covalent organic framework, and a preparation method and application thereof. Background Art

[0002] With the progress and development of modern society, synthetic chemicals play a vital role in ensuring sustainable development. Traditional industrial processes are often accompanied by enormous energy consumption and environmental pollution, leading to an increasingly urgent demand for new, clean, and efficient energy sources. This method of converting solar energy into chemical energy can provide renewable fuels and chemicals, thereby reducing dependence on fossil fuels and alleviating energy shortages and environmental pollution. Therefore, research and development in this field is crucial for achieving sustainable development goals.

[0003] Metal-organic coordination cages, due to their discrete characteristics and structural features such as adjustable geometry, size, and confined cavities, and their relatively isolated porous molecular units that can be effectively dispersed in solutions or other doping systems, are unique in applications using such processes. Furthermore, the molecular cages can be stacked in a variety of ways, which allows them to be connected in a variety of supramolecular frameworks as solid-state materials and to be endowed with a variety of functions through post-modification, giving these supramolecular materials great potential for application in the field of photocatalysis. However, their application is restricted by the inherent disadvantages of homogeneous catalysts, such as poor stability and difficulty in recycling.

[0004] Covalent organic frameworks (COFs) photocatalysts are based on earth-abundant elements and have attracted widespread attention because COFs can easily achieve tuning of optical and electronic properties through molecular engineering. In general, COFs are a very promising photocatalytic platform that can provide efficient solutions for various photocatalytic applications. Although two-dimensional COFs are beneficial for some basic photocatalytic steps, such as light harvesting, charge separation, and charge carrier migration, most two-dimensional COFs exhibit poor photocatalytic activity, especially compared with inorganic semiconductors. This may be related to high exciton binding energy and rapid charge recombination. In addition, the lack of photocatalytic hydrogen production active sites on two-dimensional COFs further limits their application in hydrogen production reactions. Summary of the Invention

[0005] 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 hybrid material based on photosensitive metal-organic coordination nanocages and covalent organic frameworks, as well as its preparation method and application. Compared with traditional composite materials, hybrid materials are combined at a more microscopic nanometer or even molecular level, which can bring more new properties and performance. The present invention combines organic metal nanocages with specific functions and two-dimensional COFs materials at the nanometer or even molecular scale using appropriate methods to obtain metal-organic coordination nanocage / COFs hybrid materials with better performance.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The first aspect of the present invention provides a hybrid material based on photosensitive metal-organic coordination nanocages and covalent organic frameworks.

[0008] The second aspect of the present invention provides a method for preparing a hybrid material based on photosensitive metal-organic coordination nanocages and covalent organic frameworks.

[0009] A third aspect of the present invention provides a photocatalyst.

[0010] The fourth aspect of the present invention provides a method for producing hydrogen by photocatalysis.

[0011] According to the first aspect of the present invention, a hybrid material based on a photosensitive metal-organic coordination nanocage and a covalent organic framework is proposed, comprising a metal-organic coordination nanocage and a COFs material, wherein the general structural formula of the metal-organic coordination nanocage is at least one of formula (I), formula (II), and formula (III):

[0012] Formula (I) [M] 3 (Ln) 2 (X) 6;

[0013] Formula (II) [M]6(TPyP)3(X);

[0014] Formula (III) [M]6(Jn)4(X) 12 ;

[0015] Among them, Ln, TPyP, and Jn are all photosensitizing ligands; Ln is TPyP is Q is Zn 2+ , Cu 2+ , Fe 2+ ,Co 2+ , Ni 2+ At least one of;

[0016] Jn is The R substituents in Ln and Jn are independently selected from At least one of; the R substituents in TPyP are independently selected from One of or directly connected to pyridine;

[0017] M is a metal ion, which is independently selected from Pd in formula (I), (II) and (III). 2+ , Pt 2+ At least one of;

[0018] X is a counter anion, which is independently selected from BF4 in formula (I) and (II) - 、NO3 - or PF4 - At least one of .

[0019] In some embodiments of the present invention, the COFs material has a β-ketoamine structure.

[0020] In some preferred embodiments of the present invention, the general formula of the COFs material structural unit is: Among them, R amine It is an amino monomer.

[0021] In some preferred embodiments of the present invention, the R amine Select one of the following structures:

[0022]

[0023]

[0024] Wherein, the R groups are independently selected from at least one of H, -CN, -NO2, -CH3, and -OH.

[0025] In some preferred embodiments of the present invention, the structure of the metal-organic coordination nanocage is one of the following structures:

[0026] [M]3(Ln)2(X)6, where M=Pd 2+ , Ln= R= X=PF4 - or NO3 - ;

[0027] Or [M]6(TPyP)3(X), where M=Pd 2+ ,TPyP= Q is Zn 2+ or Cu 2+ , X=PF4 - or NO3 - ;

[0028] or [M]6(Jn)4(X) 12 , where M = Pd 2+ , Jn= R= X=BF4 - or NO3 - .

[0029] In some preferred embodiments of the present invention, the R amine Select one of the following structures:

[0030] Wherein, the R groups are independently selected from at least one of H, -CN, -NO2, -CH3, and -OH.

[0031] In some more preferred embodiments of the present invention, the R amine for

[0032] In some more preferred embodiments of the present invention, the metal-organic coordination nanocage in the hybrid material accounts for 1% to 7% of the mass of the COFs material, preferably 2% to 5%, and more preferably 3% to 4%.

[0033] According to a second aspect of the present invention, a method for preparing the hybrid material described in the first aspect is provided, comprising the following steps: mixing the metal-organic coordination nanocage and the COFs material in an organic solvent to obtain the hybrid material.

[0034] In some embodiments of the present invention, the preparation method specifically comprises: mixing the metal-organic coordination nanocage and the COFs material, adding an organic solvent, ultrasonicating the mixture until it becomes dispersed and turbid, and separating and washing to obtain a hybrid material;

[0035] Alternatively, the metal-organic coordination nanocage and COFs material are mixed, an organic solvent is added, the mixture is ultrasonicated to a dispersed turbid state, and then continued to be stirred at room temperature, separated and washed to obtain a hybrid material.

[0036] In some embodiments of the present invention, the preparation method includes: mixing trialdehyde phloroglucinol (TP), an amino derivative monomer, a catalyst, a mixed organic solvent and a metal-organic coordination nanocage, heating the mixture to form a solid, and separating and washing to obtain a hybrid material.

[0037] In some embodiments of the present invention, the amino derivative monomer is selected from benzidine and p-phenylenediamine.

[0038] In some embodiments of the present invention, the organic solvent is at least one of THF, DMSO, and acetonitrile.

[0039] In some embodiments of the present invention, the concentration of the metal-organic coordination nanocage in the mixed solution is 1 mg / mL to 2 mg / mL.

[0040] In some embodiments of the present invention, the ultrasonication time is 10 min to 40 min.

[0041] In some embodiments of the present invention, the stirring time is 1.5 h to 3 h.

[0042] In some embodiments of the present invention, the catalyst is scandium trifluoromethanesulfonate, and the mixed solvent is 1,4-dioxane and 1,3,5-trimethylbenzene in a volume ratio of 4:1.

[0043] In some embodiments of the present invention, the heating temperature is 40° C. to 50° C., and the heating time is 5 h to 7 h.

[0044] In some embodiments of the present invention, the separation method is vacuum filtration.

[0045] In some embodiments of the present invention, the washing solvent is an organic solvent, such as DMF, HTF, acetonitrile, acetone, etc.

[0046] According to a third aspect of the present invention, a photocatalyst is provided, comprising the above-mentioned hybrid material based on the photosensitive metal-organic coordination nanocage and the covalent organic framework.

[0047] In some embodiments of the present invention, the photocatalyst may be a photocatalytic water splitting hydrogen production catalyst, a photocatalytic CO2 reduction catalyst, or a photocatalytic H2 / CO synthesis catalyst.

[0048] In some embodiments of the present invention, the photocatalyst is a photocatalytic water splitting hydrogen production catalyst.

[0049] In some embodiments of the present invention, the hybrid material based on the photosensitive metal-organic coordination nanocage and graphite-like carbon nitride is directly used as a catalyst for photocatalytic water splitting to produce hydrogen without loading other metal or metal oxide catalysts.

[0050] According to a fourth aspect of the present invention, a method for photocatalytic hydrogen production is provided, comprising using the above-mentioned photocatalyst to photocatalytically decompose water to produce hydrogen.

[0051] In some embodiments of the present invention, in the photocatalytic hydrogen production method, the amount of photocatalyst used is 0.03 g / L to 1 g / L based on the volume of water; more preferably, the amount of photocatalyst used is 0.05 g / L to 0.2 g / L.

[0052] In some embodiments of the present invention, the photocatalysis is performed under visible light.

[0053] The beneficial effects of the present invention are:

[0054] The hybrid material made of the metal-organic coordination nanocage and COFs of the present invention has a certain crystal form and high catalytic activity; the photosensitive cage has good light absorption performance, light excitation performance and efficient electron injection ability, and the cage structure is porous and can form a large number of channels, which is beneficial to increase the internal surface area of the material, provide more active sites and reaction sites, thereby increasing the reaction sites and active sites, which is beneficial to the progress of the photocatalytic reaction; the photosensitive cage itself carries co-catalyst metals, such as palladium and platinum metals, and does not require additional loading of metal nanoparticles for photocatalytic hydrogen production. After making a hybrid material, the photosensitive group, metal catalytic center and semiconductor are tightly combined into one, which is beneficial to the transfer of electrons between molecules, while improving the stability of the catalytic material, and catalytically decomposing water to produce hydrogen under visible light.

[0055] The hybrid material of the present invention has a hierarchical porous structure, which can improve the free diffusion of gases, increase the adsorption amount and activation degree of reactants, and reduce the recombination probability of electron-hole pairs, thereby effectively improving the photocatalytic efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 For L-2 1 H NMR (400 MHz, DMSO-d6) spectrum;

[0057] Figure 2 For MOC-Q3 1 H NMR (400 MHz, DMSO-d6) spectrum;

[0058] Figure 3 UV-visible absorption and fluorescence emission spectra of MOC-Q3 in DMSO solution;

[0059] Figure 4 Cyclic voltammetry test results of ferrocene (A) and MOC-Q3 (B) in CH3CN;

[0060] Figure 5 X-ray diffraction patterns of AA stacking structures from EA-COF experiments and computational simulations;

[0061] Figure 6 The scanning electron microscope and transmission electron micrographs of EA-COF;

[0062] Figure 7 The nitrogen adsorption isotherm and pore size distribution trend of EA-COF at 77K;

[0063] Figure 8 FTIR spectra of MOC-Q3, EA-COF, and EA-COF / 3wt%MOC-Q3;

[0064] Figure 9 Solid UV-visible absorption spectra (A) and Tauc plot curves (B) of MOC-Q3, EA-COF, and EA-COF / 3wt% MOC-Q3;

[0065] Figure 10 Mott-Schottky curve (A) and VB-XPS test results (B) of EA-COF;

[0066] Figure 11 is the average hydrogen evolution rate of the hybrid material MOC-Q3-EA-COF loaded with different contents of MOC-Q3;

[0067] Figure 12 This is the stability test diagram of EA-COF / 3wt%MOC-Q3;

[0068] Figure 13 Fluorescence emission spectra based on EA-COF, MOC-Q3, and EA-COF / 3wt%MOC-Q3 systems;

[0069] Figure 14 Energy level matching and photocatalytic mechanism diagram of EA-COF and MOC-Q3;

[0070] Figure 15 For Pd-MOC-H 1 H NMR (A) and Pd-MOC-Zn 1 H NMR (B);

[0071] Figure 16 Cyclic voltammetry curves of (A) MOC-Py-H, HTPyP, (B) MOC-Py-Cu, CuTPyP, (C) MOC-Py-Zn, ZnTPyP and (D) ferrocene in acetonitrile solution;

[0072] Figure 17 Infrared spectra of (A) EA-COF, Pd-MOC-H, MOC / EA-COF; (B) EA-COF, Pd-MOC-Cu, Pd-MOC-Cu / EA-COF; (C) EA-COF, Pd-MOC-Zn, Pd-MOC-Zn / EA-COF;

[0073] Figure 18(A) Liquid UV-visible absorption spectrum of Pd-MOC-M in ethanol; (B) Solid UV-visible absorption spectrum of EA-COF, Pd-MOC-h, and Pd-MOC-H / EA-COF; (C) Solid UV-visible absorption spectrum of EA-COF, Pd-MOC-Zn, and Pd-MOC-Zn / EA-COF; (D) Solid UV-visible absorption spectrum of EA-COF, Pd-MOC-Cu, and Pd-MOC-Cu / EA-COF;

[0074] Figure 19 The photocatalytic hydrogen production performance of the three hybrid materials;

[0075] Figure 20 For J-2 1 H NMR (DMSO-d6) spectrum;

[0076] Figure 21 For MOC-Q5 1 H NMR (DMSO-d6) spectrum;

[0077] Figure 22 UV-visible absorption spectrum and fluorescence emission spectrum of MOC-Q5 in DMSO solution;

[0078] Figure 23 Cyclic voltammetry test results of ferrocene (A) and MOC-Q5 (B) in acetonitrile;

[0079] Figure 24 is the XRD pattern of TPPA-COF;

[0080] Figure 25 FTIR spectra of MOC-Q5, TPPA@MOC-Q5-2, TPPA / MOC-Q5, TPPA@MOC-Q5, and TPPA;

[0081] Figure 26 (A) UV-visible absorption spectra of MOC-Q5, TPPA@MOC-Q5-2, TPPA / MOC-Q5, TPPA@MOC-Q5, and TPPA, as well as the AQY (%) of TPPA@MOC-Q5 and (B) the Tauc plot of TPPA;

[0082] Figure 27 (A) Photocatalytic hydrogen production curves of TPPA with different MOC-Q5 loading amounts and (B) Photocatalytic hydrogen production curves of TPPA with different MOC-Q5 loading methods;

[0083] Figure 28 TA-OH liquid PL spectra based on TPPA, MOC-Q5, and TPPA@MOC-Q5 (3 wt%) systems;

[0084] Figure 29 Diagram of the photocatalytic hydrogen production mechanism of TPPA@MOC-Q5 Z-scheme route. DETAILED DESCRIPTION

[0085] The present invention is further described in detail below using specific examples. Unless otherwise specified, the raw materials, reagents, and apparatus used in the examples and comparative examples are available from conventional commercial sources or by conventional methods. Unless otherwise specified, all experimental or testing methods are conventional in the art.

[0086] Example 1

[0087] In this embodiment, a hybrid material based on a photosensitive metal-organic coordination nanocage and a covalent organic framework is prepared. The structural formula of the metal-organic coordination nanocage MOC-Q3 in this embodiment is [M]3(Ln)2(X)6, where M=Pd 2+ , Ln=

[0088] X=PF6 - .

[0089] The specific process is as follows:

[0090] Synthesis of Metal-Organic Coordination Nanocage MOC-Q3:

[0091] (1) First synthesize ligand L-2:

[0092]

[0093] 2-Br (0.26 g, 0.36 mmol) and 3-pyridineboronic acid (0.27 g, 2.16 mmol) were weighed into a 100 mL round-bottom flask and dissolved in ethylene glycol dimethyl ether (DME) (21 mL). K2CO3 (0.72 g, 5.20 mmol) was weighed and dissolved in distilled water (3 mL). The resulting K2CO3 solution was added to form a mixed solution. Nitrogen was introduced into the mixed solution for deoxygenation for 15 minutes. Pd(PPh3)4 (0.84 g, 0.73 mmol) was then added to the reaction solution under a nitrogen atmosphere. The resulting reaction mixture was refluxed at 90°C for 24 hours under a nitrogen atmosphere, cooled, and dried using a rotary evaporator. The resulting residue was repeatedly extracted with dichloromethane and water. After filtration and concentration, the residue was separated on a silica gel column using a mixed solvent of ethyl acetate and petroleum ether in a volume ratio of 4:1 (v / v) as the eluent to obtain a yellow solid (0.13 g). The yield was 50%.

[0094] L-2 1 H NMR spectrum is shown in Figure 1 As shown:1 H NMR(400MHz,DMSO-d6)δ8.95(d,J=2.4Hz,1H),8.51(d,J=4.7Hz,1H),8.12-8.05(m,1H), 7.74-7.66(m,3H),7.59-7.52(m,1H),7.47(dd,J=8.1,4.8Hz,1H),7.17(d,J=8.3Hz,2H). 13 C NMR (101MHz, Chloroform-d) δ148.34,146.67,146.64,144.62,138.91,132.54,130.37,128.95,126.77,125.23,124.51,123.69,123.62.

[0095] (2) Synthesis of MOC-Q3 from ligand L-2

[0096]

[0097] Pd(tmeda)(NO3)2 (10 mg, 0.029 mmol) and L-2 (14 mg, 0.019 mmol) were weighed separately and dissolved in dimethyl sulfoxide (DMSO) (200 μL) solution. The mixture was stirred at room temperature overnight. After cooling, a large amount of ethyl acetate was added to precipitate the solid. The solid was centrifuged and dried in vacuo at 60°C to obtain a yellow solid MOC-Q3, 20 mg, with a yield of 83%.

[0098] MOC-Q3 1 H NMR spectrum Figure 2 As shown: 1 H NMR(400MHz,DMSO-d6)δ9.79(s,1H),8.98(d,J=5.6Hz,1H),8.49(d,J=8.5Hz,1H),7.85-7.7 5(m,3H),7.70(d,J=7.0Hz,1H),7.63(d,J=3.8Hz,1H),3.05(s,2H),2.66(d,J=10.6Hz,6H).

[0099] MOC-Q3 (anion is PF6 - ) was subjected to ESI-MS determination, and its ESI-MS: {[Me4(en)Pd]3(L-2)2(PF6)4} 2+ , measured: 1346.6456, simulated: 1346.6458; {[Me4(en)Pd]3(L-2)2(PF6)3} 3+, measured: 849.1097, simulated: 849.4423; {[Me4(en)Pd]3(L-2)2(PF6)3} 4+ , measured: 600.8412, simulated: 600.8405.

[0100] In order to clarify the thermodynamic process of electron transfer in the hybrid material, the UV-visible absorption and fluorescence emission of MOC-Q3 were first measured. Figure 3 As shown, the E of MOC-Q3 is obtained 0-0 The value is 2.69eV. The cyclic voltammetry test of MOC-Q3 is as follows Figure 4 The first oxidation peak of MOC-Q3 appears at 0.86 V vs NHE. 0-0 The value is 2.69 eV, so the LUMO value of MOC-Q3 is -1.83 V vs NHE.

[0101] Synthesis of EA-COF materials:

[0102]

[0103] Trialdehyde phloroglucinol (16.8 mg, 0.08 mmol), benzidine (22.1 mg, 0.12 mmol), o-dichlorobenzene (0.75 mL), and n-butanol (0.25 mL) were ultrasonically dispersed in a 10 mL Parker tube. Then, 0.1 mL of pyrrolidine catalyst was added and the mixture was ultrasonically dispersed for 5 minutes. The mixture was then flash-frozen in liquid nitrogen at 77 K. After three freeze-vacuum-thaw cycles, the Parker tube was evacuated to a pressure below 13 Pa and sealed with heat. The reaction was continued at 393 K for 72 hours. After cooling to room temperature, the solid was filtered to obtain a dark yellow solid precipitate. The solid was washed multiple times with tetrahydrofuran and anhydrous ethanol and dried in a vacuum oven at 80°C to afford the benzidine-covalent organic framework (EA-COF) product (34 mg) as a yellow powder in 88% yield. Figure 5 X-ray diffraction of EA-COF and the simulated AA stacking structure, Figure 6 Transmission electron microscope and scanning electron microscope images of EA-COF. Figure 7 The nitrogen adsorption isotherm of EA-COF at 77K and its pore size distribution trend. From the above three figures, it can be analyzed that the EA-COF material has been successfully prepared, and it has a two-dimensional sheet-like crystalline porous material. Preparation of hybrid material MOC-Q3-EA-COF

[0104] A small amount of MOC-Q3 cages was placed in a small reagent vial and DMSO was added to prepare a 1 mg / mL solution. Three 5 mg samples of EA-COF were placed in 20 mL reagent vials and 5 mL of DMSO was added to each. 75 μL of the MOC-Q3 cage solution was added to the vial containing EA-COF. The mixture was sonicated for 15 minutes and filtered to obtain a MOC-Q3-EA-COF hybrid material. The theoretical cage loading on the EA-COF was 3%.

[0105] Example 2

[0106] In this embodiment, a hybrid material based on a photosensitive metal-organic coordination nanocage and a covalent organic framework is prepared. The structural formula of the metal-organic coordination nanocage in this embodiment is [M]6(TPyP)3(X), where M=Pd 2+ ,TPyP=

[0107] Q is Zn 2+ or Cu 2+ , X=PF4 - or NO3 - .

[0108] The specific process is:

[0109] Synthesis of Pd-MOC-Q (Q = H / Zn / Cu) cages:

[0110]

[0111] (1) Synthesis of Pd-MOC-H cages:

[0112] 5,10,15,20-Tetrakis(3-pyridyl)-21H,23H-porphine (12 mg, 0.020 mmol) and Pd(tmeda)(NO3)2 (14 mg, 0.040 mmol) were weighed into a 5 mL vial. 1.5 mL of acetonitrile and 1.5 mL of purified water were added, and the mixture was stirred in a sealed container at 80°C for 8 h. After completion of the reaction, the mixture was cooled to room temperature and transferred to a 100 mL round-bottom flask. 1 mL of acetone and 10 mL of ether were added. After stirring, a large amount of black flocculent solid precipitated. After washing with ether several times, the mixture was rotary evaporated at 50°C. The solid was removed, washed with 2 mL of acetone, and centrifuged at 6000 rpm for 2 min. The lower layer of solid was removed and dried to obtain the Pd-MOC product as a black powder (16.2 mg, 0.0040 mmol) with a yield of 62.31%.

[0113] Pd-MOC-H 1 H NMR spectrum is shown in Figure 15 A: 1H NMR (400MHz, CD3CN / D2O (1 / 1)): δ = 10.25 (d, J = 5.7Hz, 1H), 10.21–10.16 (m, 1H), 9.3 3(s,1H),9.11(s,1H),9.00(s,1H),8.72(t,J=6.8Hz,1H),3.88(s,2H),3.59(s,6H).

[0114] In order to further determine the structure of the synthesized MOC-Py-H, ESI-MS was performed on it. However, before that, an anion replacement experiment was performed on it to replace the counter anion nitrate (NO3 - ) is replaced with hexafluorophosphate and (PF6 - The specific process is as follows: MOC-Py-H is dissolved in methanol, and then a saturated methanol solution of NH4PF6 is added, and stirred at room temperature for 6 hours. A large amount of purple-red solid is precipitated, which is filtered and washed with methanol several times, and then dried in vacuum at room temperature to obtain hexafluorophosphate and (PF6 - )-substituted MOC-Py-H[MOC-Py-Cu-(PF6 - ) 11 (NO3 - )]. Its ESI-MS: [MOC-Py-H-(PF6 - )9] 3+ , experimental value: 1499.5246, theoretical value: 1499.5264; [MOC-Py-H-(PF6 - )8] 4+ , experimental value: 1087.9026, theoretical value: 1087.9035; [MOC-Py-H-(PF6 - )7] 5+ , experimental value: 841.7298, theoretical value: 841.7299.

[0115] (2) Synthesis of Pd-MOC-Zn and Pd-MOC-Cu cages

[0116] Pd-MOC-H (5 mg, 0.0012 mmol) was weighed into two small reagent bottles respectively, and anhydrous zinc acetate (1.5 mg, 0.005 mmol) and anhydrous copper chloride (1.5 mg, 0.005 mmol) were added to two different reagent bottles respectively. 0.3 mL of acetonitrile and 0.2 mL of purified water were added to each to dissolve the mixture. The mixture was stirred at room temperature for 3 h, and 5 mL of ether was added to precipitate the solid. The solid was removed by centrifugation, washed with ether several times, and dried to obtain a green powdery Pd-MOC-Zn product (2.3 mg, 0.0006 mmol) with a yield of 46.0% and a red powdery Pd-MOC-Cu product (3.2 mg, 0.0009 mmol) with a yield of 64.0%.

[0117] Pd-MOC-Zn 1 H NMR spectrum is shown in Figure 15 B: 1 H NMR (400MHz, CD3CN / D2O (1 / 1)): δ = 10.14 (d, J = 5.6Hz, 1H), 10.05 (d, J = 1.9Hz, 1H), 9.04 (dd, J = 7.8, 1. 7Hz,1H),8.96(s,1H),8.80(s,1H),8.61(dd,J=7.9,5.6Hz,1H),3.83(s,2H),3.54(d,J=16.0Hz,6H).

[0118] The counter anion was replaced by the same method, and the counter anion nitrate (NO3 - ) is replaced with hexafluorophosphate and (PF6 - ). Its ESI-MS: [MOC-Py-Zn-(PF6 - )9] 3+ , experimental value: 1562.7697, theoretical value: 1562.7713; [MOC-Py-Zn-(PF6 - )8] 4+ , experimental value: 1135.8361, theoretical value: 1135.8373; [MOC-Py-Zn-(PF6 - )7] 5+ , experimental value: 879.6767, theoretical value: 879.6769.

[0119] On this basis, MOC-Py-Cu was synthesized by replacing different metal ions. MOC-Py-H (20 mg, 0.005 mmol) was dissolved in 1.5 mL of acetonitrile and 1.0 mL of deionized water, and then copper acetate (3.55 mg, 0.0177 mmol) was added. The mixture was stirred at room temperature for 3 h, and then a mixed solvent of ether: acetone (9:1, v / v) was added. The mixture was stirred at room temperature for 1 h, and a large amount of red solid was precipitated. The solution was filtered and washed with ether several times. It was dried in vacuo at room temperature to obtain 19 mg of red solid, which was MOC-Py-Cu, with a yield of 92%. According to the same method, the counter anion was replaced by the counter anion nitrate (NO3 - ) is replaced with hexafluorophosphate and (PF6 - ). Its ESI-MS: [MOC-Py-Cu-(PF6 - )9] 3+ , experimental value: 1560.7748, theoretical value: 1560.7730; [MOC-Py-Cu-(PF6 - )8] 4+ , experimental value: 1134.3404, theoretical value: 1134.3386; [MOC-Py-Cu-(PF6 - )7] 5+ , experimental value: 878.4800, theoretical value: 848.4779.

[0120] In order to further demonstrate the thermodynamic feasibility of photocatalytic water splitting by metal-organic cages in hybrid materials, the redox potentials of various metal-organic cages were tested by cyclic voltammetry. Figure 16 .like Figure 16 As shown in D, the redox potential of ferrocene was first tested, and this was used as a benchmark to calibrate the potential of the metal organic cage. HOMO =-(E ox (vs. Fc + / Fc)+4.8)=-(E ox (vs.NHE) + 4.5) The obtained redox potential is converted to the electrode potential relative to the standard hydrogen electrode (NHE). Figure 16As shown in Figure A, the cyclic voltammogram (CV) curve of MOC-Py-H corresponding to the porphyrin HTPyP was measured. From the figure, the reduction and oxidation potentials of HTPyP can be calculated to be -0.96 V and 0.97 V vs. NHE, respectively. Similarly, the reduction and oxidation potentials of MOC-Py-H can be calculated to be -0.79 V, -0.98 V (corresponding to the lowest occupied molecular orbital (LUMO) of MOC-Py-H), and 1.02 V (corresponding to the highest occupied molecular orbital (HOMO) of MOC-Py-H) vs. NHE, respectively. The first reduction potential is the reduction potential of Pd connected to pyridine in MOC-Py-H. According to the same method, the redox potential of MOC-Py-Cu was measured to be -0.80V, -1.02V (corresponding to the lowest occupied orbital LUMO of MOC-Py-Cu) and 1.00V (corresponding to the highest occupied orbital HOMO of MOC-Py-Cu) vs. NHE, where the first reduction potential is the reduction potential of Pd connected to pyridine in MOC-Py-Cu. The redox potential of MOC-Py-Zn was -0.82, -1.04V (corresponding to the lowest occupied orbital LUMO of MOC-Py-Zn), 0.88V corresponding to the highest occupied orbital HOMO of MOC-Py-Zn) vs. NHE, where the first reduction potential is the reduction potential of Pd connected to pyridine in MOC-Py-Zn ( Figure 16 B, C).

[0121] Preparation of Pd-MOC-Q (Q = H / Zn / Cu) / EA-COF hybrid materials:

[0122] Take a small amount of Pd-MOC-Q (Q = H / Zn / Cu) cages in a small reagent bottle and add acetonitrile to make a 1 mg / mL solution. Take three EA-COF samples, 5 mg each in a 20 mL reagent bottle, and add 5 mL of acetonitrile. Take 0.2 mL of Pd-MOC-Q (Q = H / Zn / Cu) cage solution and add it to the reagent bottle containing EA-COF. After ultrasonic dispersion, stir at room temperature for 2 hours, centrifuge and remove the lower layer of solid to dry. Three reddish-brown powdered hybrid materials were prepared, each with 5 mg, of which the theoretical loading rate of the cage on EA-COF was 4%. After the hybrid material was synthesized, it was tested to confirm its structure. Figure 17 The infrared spectra of the cage, COF and its corresponding hybrid material. The MOC-Q3-EA-COF hybrid material was tested by ultraviolet spectrum. Figure 18 UV spectra of cages, COFs and their corresponding hybrid materials.

[0123] Example 3

[0124] In this embodiment, a hybrid material based on a photosensitive metal-organic coordination nanocage and a covalent organic framework is prepared. The structural formula of the metal-organic coordination nanocage in this embodiment is [M]6(Jn)4(X) 12 , where M = Pd 2+ , Jn=

[0125] X=NO3 - .

[0126] The specific process is:

[0127] Synthesis of photosensitive metal-organic coordination nanocage MOC-Q5:

[0128] (1) First synthesize ligand J-2:

[0129]

[0130] Weigh 2-Br (0.20 g, 0.28 mmol) and 4-pyridineboronic acid pinacol ester (0.34 g, 1.65 mmol) in a 100 mL round-bottom flask and add DME (21 mL) to dissolve. Weigh anhydrous potassium carbonate (0.72 g, 5.20 mmol) and dissolve it in distilled water (3 mL). Add the resulting potassium carbonate solution to form a mixed solution. After nitrogen is passed through the mixed solution to deoxygenate for 15 minutes, Pd(PPh3)4 (0.84 g, 0.73 mmol) is added to the above reaction solution under a nitrogen atmosphere. The resulting reaction mixture is condensed and refluxed at 90°C for 24 hours under a nitrogen atmosphere, cooled, and dried using a rotary evaporator. The resulting residue is repeatedly extracted with dichloromethane and water. After filtration and concentration, the residue was separated on a silica gel column using ethyl acetate and dichloromethane in a volume ratio of 4:1 (v / v) as the eluent and a small amount of triethylamine to obtain an orange-red solid J-2 (0.08 g, 40% yield).

[0131] J-2 1 H NMR spectrum is shown in Figure 20 : 1 H NMR (400MHz, DMSO-d6) δ8.67-8.52(m,1H),7.86(d,J=3.9Hz,1H),7.80-7.64(m,2H),7.30-7.08(m,1H).

[0132] (2) MOC-Q5 is synthesized from ligand J-2:

[0133]

[0134] Pd(tmeda)(NO3)2 (10 mg, 0.029 mmol) and J-2 (14 mg, 0.019 mmol) were weighed separately and dissolved in DMSO (250 μL) solution. The mixture was stirred at 90°C overnight. After cooling, a large amount of ethyl acetate was added to precipitate the solid. The solid was centrifuged and dried in vacuo at 60°C to obtain an orange-red solid MOC-Q5, 15 mg, with a yield of 63%.

[0135] MOC-Q5 1 H NMR Figure 21 : 1 H NMR (400MHz, DMSO-d6) δ9.10 (s, 2H), 7.96 (d, J = 6.0Hz, 3H), 7.69 (d, J = 8.6Hz, 3H), 7.18 (d, J = 9.1Hz, 2H), 2.60 (s, 6H), 2.55 (d, J = 1.8Hz, 2H). ESI-MS: {[Pd(tmeda)]6(J-2)4(NO3)9} 3+ , measured 1595.2512, simulated: 1594.9202; {[Pd(tmeda)]6(J-2)4(NO3) 10} 2+ , measured 2423.3641, simulated 2423.3745.

[0136] In order to clarify the energy band gap of MOC-Q5 material, the UV-visible absorption and fluorescence emission of MOC-Q5 in liquid phase were first measured. The results are as follows: Figure 22 As shown, the E of MOC-Q5 is obtained 0-0 The value is 2.55eV.

[0137] In order to further study the energy band gap of the hybrid material, cyclic voltammetry (CV) test was performed on MOC-Q5 to obtain its HOMO and LUMO ( Figure 23 B) The redox potential of the measured ferrocene should be tested under the same conditions. + / Ferrocene (Fe + / Fe) redox potential correction ( Figure 23 A), and then converted to the electrode potential relative to the standard hydrogen electrode (Normal Hydrogen Electrode, NHE). The conversion formula is E HOMO =-(E OX (vs.Fe + / Fe)+4.8)=-(E OX (vs.NHE)+4.5), i.e. the initial oxidation potential E of MOC-Q5 OX is 1.13V vs NHE, that is, EHOMO =1.13Vvs.NHE; while MOC-Q5's E 0-0 is 2.55eV; finally, we can calculate E LUMO =E HOMO -E 0-0 =-1.42V vs. NHE.

[0138] Synthesis of TPPA-COF:

[0139]

[0140] Weigh trialdehyde phloroglucinol (21.0 mg, 0.100 mmol) and p-phenylenediamine (16.2 mg, 0.15 mmol) into a 20 mL reaction flask. Also prepare 5.0 mL of solvent A (1,4-dioxane (Diox) to 1,3,5-trimethylbenzene (Mes) in a 4:1 volume ratio. Add 3.50 mL of this solvent to the reaction flask and sonicate in an ultrasonicator to fully dissolve the two reactants. Weigh 6.0 mg of scandium trifluoromethanesulfonate and dissolve it in 1.00 mL of solvent A. Then, pipette 0.5 mL of the catalyst solution and add it to the reaction flask. Ultrasonicate the reaction flask to thoroughly mix the catalyst and reactants. Finally, place the reaction flask in an incubator at 45°C for 6 hours. Filter and vacuum dry to obtain the product. Figure 24 This is the powder X-ray diffraction pattern of TPPA-COF, which shows that TPPA-COF was successfully synthesized.

[0141] Preparation of MOC-Q5-TPPA-COF hybrid materials

[0142] Method 1: Use an electronic balance to weigh trialdehyde phloroglucinol (21.0 mg, 0.100 mmol) and p-phenylenediamine (16.2 mg, 0.150 mmol) into a 20 mL reaction vial. Then, using a pipette, add 111 μL of a 1.0 mg / 100 μL DMSO solution of MOC-Q5. Prepare 5.00 mL of solvent A, add 3.50 mL of this solvent to the reaction vial, and sonicate the reaction vial to fully dissolve the reactants and evenly disperse the MOC-Q5 in the solution. Weigh 6.0 mg of scandium trifluoromethanesulfonate and dissolve it in 1.00 mL of solvent A. Then, using a pipette, add 0.500 mL of the catalyst solution to the reaction vial. The reaction vial is sonicated to thoroughly mix the catalyst and reactants. Finally, the reaction flask was placed in an incubator at 45°C for 2 hours. The product was filtered and vacuum-dried to obtain TPPA@MOC-Q5 with a MOC-Q5 loading of 3 wt%. The volume of DMSO solution containing MOC-Q5 was varied to 37 μL, 74 μL, 186 μL, and 260 μL. A control group without MOC-Q5 was also prepared. The above steps were repeated to obtain the corresponding products. The photocatalytic hydrogen production performance of these five products was then tested to determine the optimal MOC-Q5 loading.

[0143] It was found that the product obtained with a MOC-Q5 loading of 3 wt% had the best hydrogen production performance, so the MOC-Q5 loading in the following experiments was 3 wt%.

[0144] Method 2: Using an electronic balance, weigh trialdehyde phloroglucinol (21.0 mg, 0.100 mmol) and p-phenylenediamine (16.2 mg, 0.150 mmol) into a 20 mL reaction flask. Add 5.00 mL of solvent A, add 3.50 mL of this solvent, and sonicate the flask to fully dissolve the reactants. Then, use a pipette to dropwise add 111 μL of a 1.0 mg / 100 μL DMSO solution of MOC-Q5. Sonicate to evenly disperse the MOC-Q5 in the solution. Weigh 6.0 mg of scandium trifluoromethanesulfonate and dissolve it thoroughly in 1.00 mL of solvent A. Then, use a pipette to add 0.500 mL of the catalyst solution to the flask, and sonicate the flask to thoroughly mix the catalyst and reactants. Finally, the reaction bottle was placed in a thermostat and reacted at 45°C for 2 hours. The product was filtered and dried in a vacuum oven to obtain the TPPA@MOC-Q5-2 product with a MOC-Q5 loading of 3 wt%.

[0145] Method 3: Use an electronic balance to weigh trialdehyde phloroglucinol (21.0 mg, 0.100 mmol) and p-phenylenediamine (16.2 mg, 0.150 mmol) in a 20 mL reaction bottle. At the same time, prepare 5.00 mL of solvent A. Then add 3.50 mL of the solvent to the reaction bottle and place the reaction bottle in an ultrasonic machine for ultrasonication to fully dissolve the two reactants. Weigh 6.0 mg of scandium trifluoromethanesulfonate and fully dissolve it with 1.00 mL of solvent A. Then use a pipette to take 0.500 mL of the catalyst-containing solution and add it to the reaction bottle. Place the reaction bottle in an ultrasonic machine for ultrasonication to fully mix the catalyst and reactants. Finally, place the reaction bottle in a constant temperature box and react at 45 ° C for 2 hours. Filter and vacuum dry to obtain TPPA. Take 5.0 mg of TPPA, add 75 μL of DMSO solution with a concentration of MOC-Q5 at 2.0 mg / mL using a pipette, then add 5.00 mL of DMSO solution, ultrasonicate for 5 minutes to mix TPPA and MOC-Q5 evenly, then stir and react for 2 hours to obtain a TPPA / MOC-Q5 product with a MOC-Q5 loading of 3 wt%.

[0146] This experiment shows that the hybrid material product prepared by method 1 has the best hydrogen production performance. The products prepared by the three methods are all red solid powders, but the color of the product prepared by method 1 is lighter, tending to orange-red, while the colors of the products prepared by the other two methods are darker, tending to black-red. After the hybrid material was synthesized, it was tested to confirm its structure. Figure 25 The infrared spectra of COF, cage and hybrid materials are shown in Figure 2. The MOC-Q3-EA-COF hybrid material was tested by UV spectrum. Figure 26 A is the UV spectra of EA-COF, MOC-Q3 and their hybrid materials, and AQY (%) of TPPA@MOC-Q5; Figure 26 B is the Tauc plot curve of TPPA-COF.

[0147] In TPPA@MOC-Q5, TPPA is a better electron donor and MOC-Q5 is an electron acceptor. Considering that the redox potential of the sacrificial agent ascorbic acid (AA) is more negative than the VB energy level of TPPA (1.23V vs. NHE), electrons are more easily transferred from AA to the VB energy level of TPPA, resulting in quenching of the photogenerated holes generated by TPPA and the electrons of AA. Therefore, it is reasonable that the electron transfer between TPPA and MOC-Q5 follows the Z-scheme route ( Figure 28 and Figure 29), where the CB and VB energy levels of TPPA are -0.82V and 1.23V vs. NHE, and the LUMO and HOMO energy levels of MOC-Q5 are -1.42V and 1.13V vs. NHE. Under visible light, MOC-Q5 and TPPA are excited to generate photogenerated electrons (e - ) and holes (h + ), the electrons in TPPA tend to transfer from its CB level to the HOMO level of MOC-Q5, while h + The electrons remaining on the VB level of TPPA are quenched by the electrons transferred from AA. Therefore, the Z-scheme heterojunction has a high efficiency of spatial separation of photogenerated carriers. In TPPA@MOC-Q5, MOC-Q5 acts as an electron acceptor and the actual photocatalyst. - Finally, it flows to the active site of Pd, making H + is reduced to generate H2, and the h on VB of TPPA + It is consumed by AA. In this process, TPPA and MOC-Q5 are activated, which inhibits the recombination of photogenerated carriers and promotes charge separation.

[0148] Test example

[0149] Photolysis of water to produce hydrogen and determine the amount of hydrogen produced: 2 mg of the hybrid material prepared in Examples 1 to 3 was added to a quartz reactor for testing. Add 60 ml of an aqueous solution of ascorbic acid with a concentration of 0.1 M to the reactor, cover the reactor lid, ensure sealing and connect the reactor to the photocatalytic system, while ensuring good airtightness at the connection between the reactor and the system, then carefully open the valve, stir the reaction liquid while gradually evacuating the vacuum. Control the vacuum degree: Pay attention to control the vacuum degree to avoid violent boiling of the solvent. When equilibrium is reached, close the evacuation valve, irradiate the reaction liquid with a xenon lamp (with filter, cut-off type, >420 nm), take samples every hour, and use a gas chromatograph (GC) to determine the amount of hydrogen produced.

[0150] Results of photocatalytic hydrogen production using hybrid material MOC-Q3-EA-COF

[0151] The hydrogen production performance of the hybrid material EA-COF / 3wt%MOC-Q3 / was tested without loading Pt particles. The results showed that under visible light (λ>420nm), 2mg of the hybrid material in 60mL 0.1M ascorbic acid aqueous solution had a hydrogen production efficiency of about 25.8mmol / g / h (see Figure 11 The hybrid material of the present invention can decompose water to produce hydrogen under visible light catalysis without the need to load Pt catalytic particles, and exhibits excellent performance and outstanding stability (see Figure 12This is mainly because a Z-scheme heterojunction is formed between MOC-Q3 and EA-COF, which has a high efficiency of spatial separation of photogenerated carriers. In EA-COF / MOC-Q1, MOC-Q3 acts as an electron acceptor and actual catalyst. - Finally, it flows to the active site of Pd, making H + is reduced to generate H2, and the h on the VB of EA-COF + Consumed by ascorbic acid, during this process, EA-COF and MOC-3 are activated, inhibiting charge recombination and promoting charge separation. (See Figure 13 and Figure 14 )

[0152] Photocatalytic hydrogen production results of Pd-MOC-Q (Q = H / Zn / Cu) / EA-COF hybrid materials

[0153] 2 mg of each of the three hybrid materials (loading rate of 4%) was added to the hydrogen production system, 20 mL of pure water was used as a dispersant and raw material, and 0.1 M ascorbic acid was used as a sacrificial agent. The hydrogen production rate of the three hybrid materials was tested, and the hydrogen production in 5 hours was measured as follows: Figure 19 As shown, all three hybrid materials exhibit high hydrogen production rates, which increase over time with a generally linear response. Loading metal Zn and Cu significantly increases the photocatalytic hydrogen production rate. Compared to Pd-MOC-Cu, Pd-MOC-Zn exhibits a greater increase in hydrogen production rate within 1 to 4 hours. The hydrogen production rates of the three hybrid materials are as follows: Pd-MOC-Zn / COF (16.8 mmol / g / h) > Pd-MOC-Cu / COF (15.8 mmol / g / h) > Pd-MOC-H / COF (13.7 mmol / g / h). This is due to the different wavelengths of light absorption by the three MOC cages. The MOC cage supported on COF exhibits a higher hydrogen production rate than the cage alone. In the hybrid material, the n-type semiconductor EA-COF acts as an electron donor, while the metal organic cage acts as an electron acceptor to receive electrons for photocatalytic water splitting and hydrogen production on the Pd surface. This is because COF and MOC form a Z-scheme heterojunction structure, which is conducive to the separation of photogenerated electrons and holes, thus greatly promoting the generation of hydrogen.

[0154] Photocatalytic hydrogen production results of MOC-Q5-TPPA-COF hybrid materials

[0155] TPPA with different MOC-Q5 loading amounts and TPPA loaded with Pt (3 wt%) were tested for photocatalytic hydrogen production within 5 h. Figure 27 As shown in A. Figure 27As shown in Figure 1, the hydrogen production rates of the three TPPA groups with MOC-Q5 loadings of 3wt%, 5wt%, and 7wt% were relatively similar. This is presumably because the loading is near saturation at around 3wt%. In this case, a 3wt% MOC-Q5 loading offers the best economic benefits and is the optimal loading concentration.

[0156] In addition, three different MOC-Q5 loaded TPPA and Pt (3 wt%) loaded TPPA were tested for photocatalytic hydrogen production within 5 h, as shown in Figure 2. Figure 27 As shown in B. Figure 27 B shows that the TPPA obtained by loading MOC-Q5 using method 1 has very excellent hydrogen production performance, and its hydrogen production rate is much greater than the hydrogen production rate of other methods and Pt as a co-catalyst.

[0157] 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 considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A hybrid material based on a photosensitive metal-organic coordination nanocage and a covalent organic framework, characterized in that: It includes a metal-organic coordination nanocage and a COFs material, wherein the general structural formula of the metal-organic coordination nanocage is at least one of formula (I), formula (II), and formula (III): Formula (I) [M]3(Ln)2(X)6; Formula (II) [M]6(TPyP)3(X); Formula (III) [M]6(Jn)4(X) 12 ; Among them, Ln, TPyP, and Jn are all photosensitizing ligands; Ln is TPyP is or , Q is Zn 2+ , Cu 2+ , Fe 2+ ,Co 2+ , Ni 2+ At least one of; Jn is ; The R substituents in Ln and Jn are independently selected from 、 、 、 、 、 At least one of; the R substituents in TPyP are independently selected from 、 、 、 、 、 One of or R is a single bond; M is a metal ion, which is independently selected from Pd in formula (I), (II) and (III). 2+ , Pt 2+ At least one of; X is a counter anion, which is independently selected from BF4 in formula (I) and (II). - 、NO3 - or PF4 - At least one of; The general formula of the COFs material structural unit is: ; Among them, R amine It is an amino monomer; The R amine Select one of the following structures: 、 、 、 、 、 、 、 、 、 、 、 、 ， Wherein, the R groups are independently selected from at least one of H, -CN, -NO2, -CH3, and -OH.

2. The hybrid material according to claim 1, wherein The metal-organic coordination nanocage in the hybrid material is 1% to 7% of the mass of the COFs material.

3. The method for preparing the hybrid material according to any one of claims 1 to 2, comprising the steps of: mixing the metal-organic coordination nanocage and the COFs material in an organic solvent to obtain the hybrid material.

4. The method for preparing the hybrid material according to claim 3, characterized in that: The organic solvent is selected from at least one of THF, DMSO and acetonitrile.

5. A photocatalyst, characterized in that The hybrid material comprises the photosensitive metal-organic coordination nanocage and covalent organic framework according to any one of claims 1 to 2.

6. The photocatalyst according to claim 5, characterized in that The photocatalyst is at least one of a photocatalytic water splitting hydrogen production catalyst, a photocatalytic CO2 reduction catalyst or a photocatalytic H2 / CO synthesis catalyst.

7. A method for photocatalytic hydrogen production, characterized in that: The photocatalyst according to claim 5 is used to photocatalytically decompose water to produce hydrogen.

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