A surface-modified hybrid quantum dot cluster photocatalyst and a preparation method and application thereof

Abstract

The application discloses a surface-modified hybrid quantum dot cluster photocatalyst as well as a preparation method and application thereof, and belongs to the technical field of photocatalysis. The surface-modified hybrid quantum dot cluster photocatalyst is formed by surface coordination self-assembly of a metal chalcogen super-tetrahedral cluster and a ring tri-nuclear metal complex, a structural expression of cations in the metal chalcogen super-tetrahedral cluster is [MnIn 16 S 35 ] 14‑ , and a structural expression of the ring tri-nuclear metal complex is Cu3L3, L is a pyrazole ligand. The surface-modified hybrid quantum dot cluster photocatalyst has good catalytic performance and strong stability, can efficiently catalyze and activate a C-F bond under mild conditions, and improves activation degradation and defluorination functionalization efficiency of a fluorine-containing compound. The preparation method is simple, low in cost, and suitable for industrial application.

Description

Technical Field

[0001] This invention relates to a photocatalyst, specifically to a surface-modified hybrid quantum dot cluster photocatalyst, and also to its preparation method and application, belonging to the field of photocatalysis technology. Background Technology

[0002] Fluorinated organic compounds (FOCs) play an irreplaceable role in pharmaceuticals, pesticides, advanced materials, and electronic chemicals due to their unique metabolic stability, lipophilicity, and electronic effects, bringing immense convenience to modern life. However, it is precisely the C–F bond (with a bond dissociation energy of approximately 126 kcal / mol) that endows these compounds with their excellent properties that makes them highly persistent in the environment. Tens of thousands of fluorinated chemicals, represented by perfluorinated and polyfluoroalkyl substances (PFAS), are continuously accumulating in soil and water bodies, posing an increasingly serious threat of persistent organic pollution and causing significant potential harm to the ecological environment and human health. Photocatalysis technology can effectively address the problem of fluorinated pollutants.

[0003] However, conventional molecular photocatalysts are limited by single-photon energy, and their reduction potential is usually insufficient to directly break the highly inert aryl C–F bonds. Although Auger recombination in quantum dot clusters generates high-energy electrons far exceeding the single-photon limit, Auger recombination occurs in most systems in an uncontrollable, non-radiative dissipation manner. These high-energy electrons often undergo rapid thermalization within the bulk phase, making it difficult to effectively transfer them to surface catalytic sites.

[0004] Therefore, it is of great significance to develop a photocatalyst that can efficiently activate inert fluorides under mild conditions, promote the degradation efficiency of fluorine-containing pollutants, and improve the high-value utilization of fluorine resources. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a surface-modified hybrid quantum dot cluster photocatalyst. This photocatalyst exhibits high catalytic activity and strong stability.

[0006] A second objective of this invention is to provide a method for preparing surface-modified hybrid quantum dot cluster photocatalysts. This method is simple, low-cost, and suitable for industrial applications.

[0007] A third objective of this invention is to provide an application of a surface-modified hybrid quantum dot cluster photocatalyst. This photocatalyst exhibits high catalytic efficiency and good stability when photocatalyzing the defluorination of organofluorine compounds under mild conditions.

[0008] To achieve the above technical objectives, this invention provides a surface-modified hybrid quantum dot cluster photocatalyst, which is formed by surface coordination self-assembly of a metal chalcogenide supertetrahedral cluster and a cyclic trinuclear metal complex. The structural expression of the cation in the metal chalcogenide supertetrahedral cluster is [MnIn]. 16 S 35 ] 14- The structural formula of the cyclic trinuclear metal complex is Cu3L3, where L is a pyrazole ligand.

[0009] This invention utilizes cyclic trinuclear metal complexes to hybridize the surface of metal chalcogenide supertetrahedral quantum dot clusters, constructing an ordered interfacial coordination structure. This effectively regulates the generation and transport of Auger recombination hot carriers, enabling the efficient utilization of high-energy electrons by interfacial catalytic reactions. Specifically, the cyclic trinuclear cells, anchored to the T4-Mn surface through weak Cu···S coordination and π-electron coupling, form a directly optically accessible charge-transfer state. Simultaneously, the Auger recombination mechanism undergoes a fundamental transformation: from random collisional dissipation of three-molecule bound excitons to productive bimolecular energy concentration between interfacial CT excitons.

[0010] As a preferred embodiment, the pyrazole ligand is selected from one of 3,5-bis(trifluoromethyl)pyrazole, 3-methyl-5-trifluoromethylpyrazole, 3-(trifluoromethyl)pyrazole, 3,5-dimethyl-1H-pyrazole-4-amine, and 3,5-dimethylpyrazole.

[0011] The present invention also provides a method for preparing a surface-modified hybrid quantum dot cluster photocatalyst, which involves mixing and reacting a solution containing metal chalcogenide supertetrahedral clusters with a cyclic trinuclear metal complex to obtain the photocatalyst.

[0012] As a preferred embodiment, the mass ratio of the cyclic trinuclear metal complex to the metal chalcogenide supertetrahedral cluster is 2 to 3:1.

[0013] As a preferred embodiment, the mass concentration of the metal chalcogenide supertetrahedral cluster in the solution is 0.5~1.5 mg / mL.

[0014] As a preferred embodiment, the mass concentration of metal chalcogenide supertetrahedral clusters in the solution is 0.5~1.5 mg / mL.

[0015] As a preferred embodiment, the solution containing metal chalcogenide supertetrahedral clusters is prepared by mixing and stirring the metal chalcogenide supertetrahedral clusters with a solvent, centrifuging, and collecting the supernatant; wherein the mass ratio of metal chalcogenide supertetrahedral clusters to solvent is 1:100~1000. The solvent is an amine solvent, more preferably an amide solvent, and most preferably formamide. The stirring rate is 7000~9000 rpm, and the stirring time is 2~4 h. The centrifugation speed is 7000~9000 rpm, and the centrifugation time is 3~7 min.

[0016] As a preferred embodiment, the mixing reaction conditions are: temperature of 20~40℃, time of 5~15 minutes, and stirring speed of 1000~2000 rpm.

[0017] As a preferred embodiment, the method for preparing the metal chalcogenide supertetrahedral cluster is as follows: a metal salt, indium powder, sulfur powder, template agent and solvent are mixed and subjected to a solvothermal reaction to obtain the cluster.

[0018] As a preferred embodiment, the molar amount of the metal salt is 0.2 to 0.3 times the molar amount of the indium powder.

[0019] As a preferred embodiment, the molar amount of sulfur powder is 2 to 4 times the molar amount of indium powder.

[0020] As a preferred embodiment, the molar amount of the template agent is 6 to 7 times the molar amount of indium powder.

[0021] As a preferred embodiment, the template agent comprises at least one of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,5-diazabicyclo[4.3.0]-5-nonene (DBN).

[0022] As a preferred method, the solvents used in the preparation of metal chalcogenide supertetrahedral clusters include 2-(2-aminoethylamino)ethanol and hexamethyleneimine. The volume ratio of 2-(2-aminoethylamino)ethanol to hexamethyleneimine is 1~3:1~2.

[0023] As a preferred embodiment, the conditions for the solvothermal reaction are: a temperature of 120~180℃ and a time of 5~9 days.

[0024] As a preferred embodiment, the preparation method of the cyclic trinuclear metal complex is as follows: after mixing and reacting the metal source, pyrazole ligand and solvent, the solid and liquid are separated, the obtained filtrate is evaporated to remove the solvent to obtain a solid, and the solid is recrystallized to obtain the final product.

[0025] As a preferred embodiment, the molar ratio of the metal source to the pyrazole ligand is 1:1.5~2.

[0026] As a preferred option, the solvent used in the preparation of cyclotrinuclear metal complexes includes at least one of benzene-based solvents and tetrahydrofuran.

[0027] As a preferred embodiment, the conditions for the mixing reaction are: temperature of 50~70℃, time of 35~60h, and atmosphere of protective gas.

[0028] This invention also provides an application of a surface-modified hybrid quantum dot cluster photocatalyst for the photocatalytic defluorination of organofluorine compounds. The photocatalyst of this invention can drive the breaking of inert C–F bonds under mild conditions of room temperature, ambient pressure, and visible light irradiation, achieving high conversion rates (up to 75% or more), high selectivity in hydrodefluorination and cross-coupling. Furthermore, this catalytic system features a wide substrate applicability (covering electron-withdrawing and electron-donating substituted aryl fluorides and various perfluorinated compounds), strong functional group tolerance (compatible with cyano, carbonyl, nitro, etc.), and high catalyst conversion number.

[0029] As a preferred embodiment, the organofluorine compound includes at least one of aryl fluorides and perfluorinated compounds. Aryl fluorides include at least one of 4-fluorotoluene, 4-fluorobenzonitrile, 4-fluoroanisole, 4-fluoroethyl ether, 2-fluorotoluene, 3-fluorotoluene, fluorobenzene, or trifluorotoluene. Perfluorinated compounds include at least one of perfluorooctanoic acid (PFOA), tetradecylfluorohexane (PFHx), hexadecylfluorooctane, and polytetrafluoroethylene.

[0030] As a preferred embodiment, in the photocatalytic defluorination process of the organofluorine compound, the reducing agent used includes at least one of potassium formate, sodium formate, cesium formate, N,N-diisopropylethylamine, tris(2-aminoethyl)amine, or γ-terpinene; the ratio of surface-modified hybrid quantum dot cluster photocatalyst to organofluorine compound and reducing agent is (0.05~0.2mg):(0.1~0.3mmol):(0.5~0.7mmol); adamantane thiol is used as the hydrogen transfer reagent; the light source is 390~420nm LEDs with a power of 10~60W; the pH of the reaction system is 8~11; the reaction temperature is 20~40℃; and the reaction time is 24~48h.

[0031] As a preferred embodiment, when performing photocatalytic defluorination and cross-coupling reactions of organofluorine compounds, the coupling agent includes at least one of bis(pinacol)diborone, N-methylpyrrole, and triethyl phosphite. Specifically, using bis(pinacol)diborone as the coupling agent allows for the construction of C–B couplings (C–B bonds), using N-methylpyrrole allows for the construction of C–C couplings (C–C bonds), and using triethyl phosphite as the coupling agent allows for the construction of C–P couplings (C–P bonds).

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) The surface-modified hybrid quantum dot cluster photocatalyst provided by the present invention can effectively regulate the generation and transport of Auger composite hot carriers, so that high-energy electrons can be efficiently utilized by interfacial catalytic reactions. It has high catalytic activity and strong stability. Under mild conditions, it can activate C-F bonds to achieve efficient defluorination of organic fluorides and improve the degradation rate of organic fluorine pollutants (which are difficult-to-degrade perfluorinated compounds). At the same time, it can also construct C-B bonds, C-C bonds and C-P bonds through cross-coupling to obtain high-value-added products. The catalyst has the characteristics of wide substrate applicability (covering electron-withdrawing and electron-donating substituted aryl fluorides and a variety of perfluorinated compounds), strong functional group tolerance (cyano, carbonyl, nitro, etc. are all compatible), high catalyst conversion number, and simple operation of catalytic application.

[0034] (2) The preparation method is simple and the cost is low, making it suitable for industrial application. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 The single-crystal structures of the T4-MnInS and T4-CdInS clusters obtained in Example 1 are shown in the analytical diagram.

[0037] Figure 2 TEM image of dispersed T4-MnInS clusters.

[0038] Figure 3 This is a schematic diagram of the formation of a surface-modified hybrid quantum dot cluster photocatalyst.

[0039] Figure 4 The UV-Vis absorption spectra of T4-MnInS, {[3,5-(CF3)2Pz]Cu}3 and T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 are shown.

[0040] Figure 5 XPS spectra of Mn, Cu, In, and S atoms in T4-MnInS and T4-MnInS•{[3,5-(CF3)2Pz]Cu}3.

[0041] Figure 6XAFS and EPR spectra of T4-MnInS and T4-MnInS•{[3,5-(CF3)2Pz]Cu}3.

[0042] Figure 7 The UV-Vis absorption spectra of the reaction solution and the separated T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 in Example 1 are shown.

[0043] Figure 8 The TA-fs spectra of T4-MnInS and T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 are shown.

[0044] Figure 9 This is a comparison chart showing the catalytic efficiency of photocatalytic reduction of 4-fluorotoluene hydrodefluorination using different catalysts.

[0045] Figure 10 The results represent the universality test results of photocatalytic defluorination and hydrogenation of aryl fluorides by T4-MnInS•{[3,5-(CF3)2Pz]Cu}3.

[0046] Figure 11 The results represent the universality test results of the cross-coupling reaction of T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 photocatalyzed aryl fluorides.

[0047] Figure 12 The results are for the photocatalytic degradation test of perfluorooctanoic acid (PFOA) by T4-MnInS•{[3,5-(CF3)2Pz]Cu}3. Detailed Implementation

[0048] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0049] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0050] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0051] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0052] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0053] In the specific embodiments of the present invention, room temperature and room temperature refer to 20-25℃; the solvothermal reaction time of 7 days specifically refers to 168 hours.

[0054] (1) Raw material metal chalcogenide supertetrahedral cluster T4-[Mn4In] 16 S 35 ] 14- The preparation steps for (abbreviated as T4-MnInS) are as follows:

[0055] Mn(Ac)₂·4H₂O (58.8 mg, 0.24 mmol), In powder (115 mg, 1 mmol), sulfur powder (96 mg, 3 mmol), 2-(2-aminoethylamino)ethanol (AEAE, 2 mL), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, 1 mL), and hexamethyleneimine (HMI, 1.5 mL) were mixed and added to a stainless steel autoclave lined with polytetrafluoroethylene. The mixture was stirred vigorously at 1000 rpm for 0.5 h, then sealed and placed in the autoclave. The autoclave was heated to 150 °C and kept at that temperature for 7 days. The mixture was then allowed to cool naturally to room temperature. The reaction product was washed several times with ethanol and dried under vacuum to obtain irregular yellow metallic chalcogenide supertetrahedral cluster-based microcrystals ([Mn₄In₂)). 16 S 35 ] 14- ·3[2H + -DBU]·7.2[H + -AEAE]·3.8[H +-HMI]), which is an aggregate of T4-MnInS cluster quantum dots, and the yield of T4-MnInS cluster quantum dots is calculated to be 55% based on metal salt.

[0056] The T4-MnInS cluster quantum dots exhibit a tetrahedral structure, such as Figure 1 As shown, the X-ray single-crystal diffraction structure indicates that the cluster has no surface ligands and is in an isolated state. Figure 2 It can be obtained that its average size in the monodisperse state is about 1.6 nm.

[0057] (2) Raw material metal chalcogenide supertetrahedral cluster T4-[Cd4In 16 S 35 ] 14- The preparation of (abbreviated as T4-CdInS) is the same as that of T4-MnInS, except that the metal salt is replaced with Cd(Ac)2·2H2O (64.1 mg, 0.24 mmol), resulting in the metal chalcogenide supertetrahedral cluster T4-[Cd4In 16 S 35 ] 14- (abbreviated as T4-CdInS), the yield of T4-CdInS cluster quantum dots is 40% based on metal salt calculations.

[0058] The T4-CdInS cluster quantum dots exhibit a tetrahedral structure, such as Figure 1 As shown, the X-ray single-crystal diffraction structure indicates that the cluster has no surface ligands and is in an isolated state. In the monodisperse state, its average size is about 1.6 nm.

[0059] (3) The preparation steps of the raw material tricyclic copper complex {[3,5-(CF3)2Pz]Cu}3 are as follows:

[0060] 3,5-bis(trifluoromethyl)pyrazole (abbreviated as [3,5-(CF3)2Pz]H, 500 mg, 2.45 mmol), Cu2O (190.0 mg, 1.43 mmol), and benzene (20.0 mL) were added to a 100 mL Schlenk flask. A few drops of acetonitrile were added, and the mixture was subjected to three freeze-evacuation-thawing cycles under a nitrogen atmosphere. The mixture was then heated to 60 °C and reacted for 48 h. After cooling, the mixture was filtered through a diatomaceous earth filter to remove insoluble impurities. The filtrate was collected and evaporated under reduced pressure at room temperature. The resulting white solid was dried under vacuum at room temperature for 12 h. Further purification by recrystallization from n-hexane at 5 °C yielded the cyclic trinuclear complex {[3,5-(CF3)2Pz]Cu}3, a white solid with a Cu-based yield of 70%.

[0061] The above-mentioned 3,5-bis(trifluoromethyl)pyrazole was replaced with 3-methyl-5-trifluoromethylpyrazole (abbreviated as [3-(CF3),5-CH3Pz]H) or 3-(trifluoromethyl)pyrazole (abbreviated as [3-(CF3),5-HPz]H) to prepare cyclic trinuclear copper complexes {[3-(CF3),5-CH3Pz]Cu}3 and {[3-(CF3),5-HPz]Cu}3, respectively.

[0062] (4) The preparation steps of the raw material tricyclic copper complex {[3,5-(CH3)2Pz]Cu}3 are as follows:

[0063] 3,5-Dimethylpyrazole [3,5-(CH3)2Pz]H (1.90 mmol), Cu(CH3CN)4PF6 (1.90 mmol), and tetrahydrofuran (5.0 mL) were stirred in a round-bottom flask until clear. Et3N (2.4 mmol) was added dropwise to the solution, and the mixture was stirred overnight at room temperature. After the reaction was complete, the tetrahydrofuran was removed under reduced pressure, and the residue was dried to give the crude product. The crude product was dissolved in dichloromethane (DCM, 15 mL) under an inert atmosphere, and this DCM solution was then added dropwise to anhydrous methanol at room temperature to induce precipitation. The precipitate was collected by filtration, washed repeatedly with anhydrous methanol, and dried under vacuum to give the purified target complex {[3,5-(CH3)2Pz]Cu}3, with a Cu-based yield of 85%.

[0064] (5) The preparation steps of the raw material tricyclic copper complex {3,5-(CH3)2,4-NH2PzCu}3 are as follows:

[0065] The ligand 3,5-dimethyl-1H-pyrazole-4-amine (50.0 mg, 0.45 mmol), Cu2O (21.5 mg, 0.15 mmol), ethanol (2 mL), and pyridine (0.2 mL) were added to an 8 mL Pyrex tube, sealed, and heated in an oven at 120 °C for 72 h. After cooling to room temperature, the mixture was filtered, and the resulting solid was washed several times with ethanol and dried to obtain the target cyclic trinuclear copper complex {3,5-(CH3)2, 4-NH2PzCu}3.

[0066] (6) The preparation method of the raw material tricyclic gold complex {[3,5-(CF3)2Pz]Au}3 is as follows:

[0067] The ligand 3,5-dimethylpyrazole [3,5-(CH3)2Pz]H (3.90 mmol) was dissolved in 20 mL of anhydrous tetrahydrofuran and treated with an excess of 60% sodium hydride (4.96 mmol) at room temperature. After stirring the mixture for 5 minutes, unreacted sodium hydride was removed by filtration. The filtrate was added to 3.0 mmol of Au2(THT)2Cl2 at room temperature and stirred for 2 hours. The resulting mixture was filtered, and the precipitate was washed with tetrahydrofuran. The combined filtrates were evaporated under reduced pressure to give the purified target compound {[3,5-(CF3)2Pz]Au}3 in 56% Au-based yield.

[0068] (7) The preparation method of the raw material tricyclic silver complex {[3,5-(CF3)2Pz]Ag}3 is the same as that of the tricyclic copper complex {[3,5-(CF3)2Pz]Cu}3, except that Cu2O is replaced with an equimolar amount of Ag2O.

[0069] Example 1

[0070] The preparation steps of the surface-modified hybrid cluster quantum dot photocatalyst T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 are as follows:

[0071] (1) Add 2 mg of the above T4-MnInS cluster to 2 mL of formamide, stir at 1500 rpm for 1 h, then centrifuge at 8000 rpm for 5 min, and transfer the supernatant to obtain a solution containing metal chalcogenide supertetrahedral clusters (mass concentration of 1 mg / mL).

[0072] (2) Take 100 μL of the above solution containing metal chalcogenide supertetrahedral clusters (0.1 mg of metal chalcogenide supertetrahedral clusters), add 0.0003 mmol of the above tricyclic copper complex {[3,5-(CF3)2Pz]Cu}3, stir at room temperature for 5 min (stirring speed 6000 rpm) to obtain a solution containing surface-modified hybrid quantum dot cluster photocatalyst. Separate the solid from the solution by precipitation with tetrahydrofuran, which is the surface-modified hybrid quantum dot cluster photocatalyst. Figure 3 A schematic diagram of the formation of T4-MnInS•{[3,5-(CF3)2Pz]Cu}3.

[0073] Figure 4The UV-Vis absorption spectra of T4-MnInS, {[3,5-(CF3)2Pz]Cu}3, and T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 are shown. As can be seen from the figure, T4-MnInS(a) and {[3,5-(CF3)2Pz]Cu}3(b) have almost no absorption in the visible light region, while T4-MnInS•{[3,5-(CF3)2Pz]Cu}3(c) has obvious absorption in the visible light region (400~600nm). This indicates that the cyclic trinuclear copper complex is anchored to the T4-Mn surface through weak Cu-S coordination and π-electron coupling, forming a charge-transfer state that can be directly accessed by light.

[0074] Figure 5 The XPS spectra of Mn, Cu, In, and S atoms in T4-MnInS and T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 are shown. It can be seen from the figure that Mn has a +2 valence, Cu has a +1 valence, In has a +3 valence, and S has a -2 valence.

[0075] Figure 6 The XAFS and EPR spectra of T4-MnInS and T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 are shown. It can be seen from the figure that there is a weak Cu-S interaction in T4-MnInS•{[3,5-(CF3)2Pz]Cu}3, and T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 still has the Mn-Mn coupling effect unique to T4-Mn.

[0076] Figure 7 The image shows a comparison of the UV-Vis absorption spectra of the solution obtained from the direct reaction in Example 1 and the isolated T4-MnInS•{[3,5-(CF3)2Pz]Cu}3. The isolated T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 was dissolved in 100 μL of formamide and 900 μL of DMSO before testing. As can be seen from the image, the absorption intensity of the reaction solution and the isolated T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 only changed slightly (a), and the normalized absorption peak shape remained unchanged (b). Therefore, in this invention, the reaction solution obtained in Example 1 (a solution containing surface-modified hybrid quantum dot cluster photocatalyst) was directly used for catalytic experiments.

[0077] Figure 8 The figure shows the TA-fs spectra of T4-MnInS and T4-MnInS•{[3,5-(CF3)2Pz]Cu}3. It can be seen from the figure that the T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 complex has obvious hot electron Auger recombination signal.

[0078] Example 2

[0079] Surface-modified hybrid cluster quantum dot photocatalysts were prepared using the method described in Example 1, with the only difference being that the tricyclic copper complex was replaced with {[3-(CF3),5-CH3Pz]Cu}3, {[3-(CF3),5-HPz]Cu}3, {[3,5-(CH3)2Pz]Cu}3, or {3,5-(CH3)2, 4-NH2PzCu}3, respectively. Solutions of the corresponding quantum dot cluster photocatalysts T4-MnInS•{[3-(CF3),5-CH3Pz]Cu}3, T4-MnInS•{[3-(CF3),5-HPz]Cu}3, T4-MnInS•{[3,5-(CH3)2Pz]Cu}3, or T4-MnInS•{3,5-(CH3)2, 4-NH2PzCu}3 containing the same surface-modified hybrid clusters were then prepared.

[0080] Example 3 (Application of photocatalytic defluorination of 4-fluorotoluene)

[0081] DMSO solvent was added to a 100 μL solution of the surface-modified hybrid quantum dot cluster photocatalyst (T4-MnInS•{[3,5-(CF3)2Pz]Cu}3) prepared in Example 1 until the volume of the mixture reached 3 mL. Then, 0.2 mmol of 4-fluorotoluene, 0.6 mmol of potassium formate, 0.2 mmol of cesium carbonate, 0.2 mmol of potassium carbonate, and 0.02 mmol of adamantane thiol were added. The mixture was bubbled with high-purity argon for 20 min to remove dissolved oxygen and maintain an inert atmosphere. The reaction vessel was sealed and irradiated with a 420 nm, 40 W LED light source, and stirred at room temperature for 36 h. After the reaction, gas chromatography-mass spectrometry analysis showed that the conversion rate of 4-fluorotoluene was 75%, and the selectivity of the defluorination hydrogenation product toluene was >99%. The hydrogen source for the hydrodefluorination reaction came from the CH bond of the reducing agent or trace amounts of water in the reaction system.

[0082] The photocatalytic defluorination experiments of 4-fluorotoluene were conducted using the catalyst solution from Example 2 according to the above method. The catalytic effects are shown in the figure. Figure 9 .

[0083] Comparative Example 1

[0084] The catalyst was prepared using the method of Example 1, with the only difference being that the T4-MnInS clusters were replaced with T4-CdInS clusters, resulting in a solution containing T4-CdInS•{[3,5-(CF3)2Pz]Cu}3. Using this catalyst solution prepared in the comparative example, a photocatalytic defluorination experiment of 4-fluorotoluene was conducted according to the method of Example 3. The catalytic effect is shown in […]. Figure 9 .

[0085] Comparative Example 2

[0086] The catalyst was prepared using the method of Example 1, with the only difference being that the tricyclic copper complex {[3,5-(CF3)2Pz]Cu}3 was replaced with the tricyclic gold complex {[3,5-(CF3)2Pz]Au}3, resulting in a solution containing T4-MnInS•{[3,5-(CF3)2Pz]Au}3. Using the catalyst solution prepared in this comparative example, a photocatalytic defluorination experiment of 4-fluorotoluene was conducted according to the method of Example 3, and the catalytic effect is shown in […]. Figure 9 .

[0087] Comparative Example 3

[0088] The catalyst was prepared using the method of Example 1, with the only difference being that the tricyclic copper complex {[3,5-(CF3)2Pz]Cu}3 was replaced with the tricyclic silver complex {[3,5-(CF3)2Pz]Ag}3, resulting in a solution containing T4-MnInS•{[3,5-(CF3)2Pz]Ag}3. Using the catalyst solution prepared in this comparative example, a photocatalytic defluorination experiment of 4-fluorotoluene was conducted according to the method of Example 3, and the catalytic effect is shown in […]. Figure 9 .

[0089] Comparative Example 4

[0090] 2 mg of the above T4-MnInS cluster was added to 2 mL of formamide and stirred at 1500 rpm for 1 h. The mixture was then centrifuged at 8000 rpm for 5 min, and the supernatant was collected to obtain a solution of metal chalcogenide supertetrahedral clusters (mass concentration 1 mg / mL). 100 μL of the above metal chalcogenide supertetrahedral cluster solution was added to DMSO solvent until the volume of the mixture reached 3 mL. Then, 0.2 mmol of 4-fluorotoluene, 0.6 mmol of potassium formate, 0.2 mmol of cesium carbonate, 0.2 mmol of potassium carbonate, and 0.02 mmol of adamantane thiol were added. The mixture was bubbled with high-purity argon for 20 min to remove dissolved oxygen and maintain an inert atmosphere. The reaction vessel was sealed and irradiated with a 420 nm, 40 W LED light source. The reaction was stirred at room temperature for 36 h. The catalytic effect is shown in the figure. Figure 9 .

[0091] Comparative Example 5

[0092] 0.0003 mmol of the above-mentioned tricyclic copper complex {[3,5-(CF3)2Pz]Cu}3 was added to 2 mL of DMSO to obtain a solution of the tricyclic copper complex. 100 μL of this solution was added to DMSO until the volume of the mixture reached 3 mL. Then, 0.2 mmol of 4-fluorotoluene, 0.6 mmol of potassium formate, 0.2 mmol of cesium carbonate, 0.2 mmol of potassium carbonate, and 0.02 mmol of adamantane thiol were added. The mixture was bubbled with high-purity argon for 20 min to remove dissolved oxygen and maintain an inert atmosphere. The reaction vessel was sealed and irradiated with a 420 nm, 40 W LED light source. The reaction was stirred at room temperature for 36 h. The catalytic effect is shown in the figure. Figure 9 .

[0093] Comparative Example 6

[0094] Add 2 mg of the above T4-MnInS cluster to 2 mL of formamide, stir at 1500 rpm for 1 h, then centrifuge at 8000 rpm for 5 min, and transfer the supernatant to obtain a solution of metal chalcogenide hypertetrahedral clusters (mass concentration of 1 mg / mL). DMSO was added to a 100 μL solution of the metal chalcogenide supertetrahedral cluster until the volume of the mixture reached 3 mL. Then, 0.2 mmol of 4-fluorotoluene, 0.6 mmol of potassium formate, 0.2 mmol of cesium carbonate, 0.2 mmol of potassium carbonate, 0.02 mmol of adamantane thiol, and 0.0003 mmol of the aforementioned tricyclic copper complex {[3,5-(CF3)2Pz]Cu}3 were added. The mixture was bubbled with high-purity argon for 20 min to remove dissolved oxygen and maintain an inert atmosphere. The reaction vessel was sealed, and the mixture was irradiated with a 420 nm, 40 W LED light source and stirred at room temperature for 36 h. The catalytic effect of the T4-MnInS+{[3,5-(CF3)2Pz]Cu}3 mixture is shown in [reference needed]. Figure 9 .

[0095] from Figure 9 It can be seen that the surface-modified hybrid quantum dot cluster photocatalysts prepared in this invention can effectively catalyze the reduction of 4-fluorotoluene hydrodefluorination reaction, with conversion rates all exceeding 65%, while the conversion rate of Comparative Example 1 is only 18%, and the 4-fluorotoluene in Comparative Examples 2-6 did not undergo conversion. Therefore, only the surface-modified hybrid quantum dot cluster photocatalysts of this invention exhibit excellent catalytic effects for 4-fluorotoluene.

[0096] Example 4 (Application of photocatalytic defluorination of aryl fluorides)

[0097] Photocatalytic experiments were conducted according to the method in Example 3, using T4-MnInS•{[3,5-(CF3)2Pz]Cu}3 as the photocatalyst. The substrate 4-fluorotoluene was replaced with 2-fluorotoluene, p-fluorotoluene, 2-fluoroanisole, 3-fluoroanisole, p-fluoroanisole, fluorobenzene, p-fluorobenzonitrile, 2-fluorobenzonitrile, methyl 4-fluorobenzoate, 4-fluorodiphenylmethane, 3,4-dimethylfluorobenzene, 1,4-dimethoxy-2-fluorobenzene, pinacol 4-fluorophenylboronic acid, 4-fluorobiphenyl, 1-(4-fluorophenyl)pyrrole, and p-trifluoromethylbenzonitrile. The corresponding catalytic effects are shown in [the table below]. Figure 10 .

[0098] from Figure 10 As can be seen from the above, the photocatalyst of the present invention has good catalytic activity for different aryl fluorides and a high catalytic conversion rate. That is, the quantum dot photocatalyst can convert a variety of aryl fluorides into defluorinated hydrogenated compounds, and the reaction can tolerate a variety of functional groups. This fully demonstrates that the surface-modified hybrid quantum dot cluster photocatalyst of the present invention has good universality for the defluorination hydrogenation of aryl fluorides.

[0099] Example 5 (Photocatalytic defluorination of 4-fluorotoluene and cross-coupling to construct C–C coupling products)

[0100] Using a solution of the surface-modified hybrid quantum dot cluster photocatalyst (T4-MnInS•{[3-(CF3),5-CH3Pz]Cu}3) from Example 2, DMSO solvent was directly added to this solution (100 μL) until the mixed volume was 3 mL. Then, 0.2 mmol of 4-fluorotoluene, 2.0 mmol of N-methylpyrrole, and 0.4 mmol of sodium formate were added. The mixture was bubbled with nitrogen for 20 min to remove dissolved oxygen and maintain an inert atmosphere. The reaction vessel was sealed, and the reaction was carried out at room temperature with stirring for 32 h under 420 nm, 12 W LED light source irradiation. After the reaction, the corresponding C–C coupling product was obtained by column chromatography.

[0101] By replacing the coupling reagent with triethyl phosphite or bis(pinacol)diboron, respectively, with triethyl phosphite being used and irradiation at 390 nm, 40 W LED light source for 60 h, and bis(pinacol)diboron being used with 0.6 mmol of bis(pinacol)diboron and 0.6 mmol of cesium carbonate being added, and irradiation at 390 nm, 40 W LED light source for 36 h, C–P coupling products and C–B coupling products can be obtained, respectively. Specific catalytic effects are detailed in [the table below]. Figure 11 .

[0102] from Figure 11As can be seen from the present invention, the photocatalyst can efficiently convert a variety of aryl fluorides into corresponding cross-coupling products. The substrate range covers aryl fluorides with different substitution types, and the reaction has good tolerance to a variety of functional groups. This fully demonstrates that the surface-modified hybrid quantum dot cluster photocatalyst of the present invention has good universality in the cross-coupling reaction of aryl fluorides.

[0103] Example 6 (Photocatalytic degradation of perfluorinated compounds)

[0104] DMSO solvent was added to a 100 μL solution of the surface-modified hybrid quantum dot cluster photocatalyst prepared in Example 1 until the volume of the mixture was 3 mL. Then, 0.2 mmol of perfluorooctanoic acid, 0.6 mmol of potassium formate, 0.2 mmol of cesium carbonate, and 0.6 mmol of potassium carbonate were added. The mixture was bubbled with high-purity argon for 20 min to remove dissolved oxygen and maintain an inert atmosphere. The reaction vessel was sealed and irradiated with a 420 nm, 40 W LED light source. The reaction was stirred at room temperature for 36 h. After the reaction was completed, an appropriate amount of the reaction solution was taken, and a DMSO-d6 solution containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, 0.2 mmol) was used as an internal standard. 19 Quantitative analysis of the degradation rate and defluorination rate of perfluorinated compounds using 1F NMR.

[0105] When the perfluorinated compound is tetradecylhexane, hexadecylfluorooctane, or polytetrafluoroethylene, the potassium carbonate in the above catalytic reaction process is replaced with 2 mmol of potassium hydroxide, and the illumination time is controlled to 48 h to obtain excellent catalytic effect.

[0106] Figure 12 To illustrate the degradation effect of the {[3,5-(CF3)2Pz]Cu}3 photocatalyst of this invention on perfluorooctanoic acid (PFOA), from... Figure 11 As can be seen, the degradation rate of perfluorooctanoic acid (PFOA) is 94% (a), and the overall defluorination rate is 87.5% (b).

[0107] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A surface-modified hybrid quantum dot cluster photocatalyst, characterized in that: It is formed by surface coordination self-assembly of metal chalcogenide supertetrahedral quantum dot clusters and cyclic trinuclear metal complexes. The structural expression of the anion in the metal chalcogenide supertetrahedral quantum dot cluster is [Mn4In]. 16 S 35 ] 14- The structural formula of the cyclic trinuclear metal complex is Cu3L3, where L is a pyrazole ligand selected from one of 3,5-bis(trifluoromethyl)pyrazole, 3-methyl-5-trifluoromethylpyrazole, 3-(trifluoromethyl)pyrazole, 3,5-dimethyl-1H-pyrazole-4-amine, and 3,5-dimethylpyrazole.

2. The method for preparing a surface-modified hybrid quantum dot cluster photocatalyst according to claim 1, characterized in that: The solution containing metal chalcogenide supertetrahedral quantum dot clusters is reacted with a cyclic trinuclear metal complex to obtain the product.

3. The method for preparing a surface-modified hybrid quantum dot cluster photocatalyst according to claim 2, characterized in that: The mass ratio of the cyclic trinuclear metal complex to the metal chalcogenide supertetrahedral quantum dot cluster is 2~3:

1.

4. The method for preparing a surface-modified hybrid quantum dot cluster photocatalyst according to claim 2 or 3, characterized in that: The mass concentration of the metal chalcogenide supertetrahedral quantum dot clusters in the solution is 0.5~1.5 mg / mL.

5. The method for preparing a surface-modified hybrid quantum dot cluster photocatalyst according to claim 2, characterized in that: The conditions for the mixing reaction are: temperature 20~40℃, time 5~15 minutes.

6. The method for preparing a surface-modified hybrid quantum dot cluster photocatalyst according to claim 2, characterized in that: The method for preparing the metal chalcogenide supertetrahedral quantum dot clusters is as follows: manganese salt, indium powder, sulfur powder, template agent and solvent are mixed and subjected to a solvothermal reaction to obtain the product. The molar amount of the manganese salt is 0.2 to 0.3 times the molar amount of the indium powder, the molar amount of the sulfur powder is 2 to 4 times the molar amount of the indium powder, and the molar amount of the template agent is 6 to 7 times the molar amount of the indium powder. The conditions for the solvothermal reaction are: temperature of 120~180℃ and time of 5~9 days.

7. The method for preparing a surface-modified hybrid quantum dot cluster photocatalyst according to claim 2, characterized in that: The preparation method of the cyclic trinuclear metal complex is as follows: copper source, pyrazole ligand and solvent are mixed and reacted, followed by solid-liquid separation. The obtained filtrate is evaporated to remove the solvent to obtain a solid. The solid is then recrystallized to obtain the final product. The molar ratio of the copper source to the pyrazole ligand is 1:1.5~2; The conditions for the mixing reaction are: temperature 50~70℃, time 35~60h.

8. The application of the surface-modified hybrid quantum dot cluster photocatalyst according to claim 1, characterized in that: Used for photocatalytic defluorination of organofluorine compounds.

9. The application of the surface-modified hybrid quantum dot cluster photocatalyst according to claim 8, characterized in that: The organofluorine compounds include at least one of aryl fluorides and perfluorinated compounds.

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