A ternary heterojunction photocatalyst, a preparation method and application thereof

Abstract

This invention discloses a ternary heterojunction photocatalyst, its preparation method, and its application. The catalyst comprises carbon nitride, graphylene, and Cu. x O is a composite, and GDY is mediated by C3N4 and Cu. x A ternary heterostructure is formed between O atoms. GDY utilizes its natural channels to polarize C-F bonds through C-F···π interactions, while simultaneously acting as an electron transport channel to promote the transfer of photogenerated electrons from C3N4 to Cu. x O migration enables a relay-style synergistic catalysis involving adsorption-polarization-electron injection-bond breaking. This catalyst is prepared using a one-pot in-situ growth method, simplifying the process. Under visible light irradiation, this catalyst efficiently catalyzes the defluorination and amination of aryl fluorides with amine sources, achieving yields of 87%-98%. It possesses advantages such as a broad substrate range, good functional group tolerance, easy catalyst recovery, absence of precious metals, and suitability for large-scale applications, belonging to the fields of photocatalytic materials and organic synthesis technology.

Description

Technical Field

[0001] This invention belongs to the field of photocatalytic materials and organic synthesis technology, specifically relating to a Cu x O / GDY / C3N4 ternary heterojunction photocatalyst, its one-pot preparation method, and its application in the catalytic defluorination and amination reaction of aryl fluorides. Background Technology

[0002] The carbon-fluorine (CF) bond is one of the strongest single bonds in nature (bond energies can reach 10⁵-130 kcal / mol), and its activation requires overcoming an extremely high thermodynamic energy barrier. This characteristic makes aryl fluorides significantly less reactive than aryl chlorides, bromines, and iodines, making the selective cleavage and transformation of fluorinated organic compounds extremely challenging. The defluorination functionalization of aryl fluorides is a key pathway for the synthesis of high-value-added aromatic amines, and it has significant implications in the fields of medicine, pesticides, and materials science.

[0003] Traditional nucleophilic aromatic substitution reactions (SNAr) are the classic route for achieving CF bond cleavage and C-C bond construction in aryl fluorides, but they have the following limitations: strong basic conditions: usually require high temperature (>100℃) and strong base (such as NaH), which limits the tolerance of functional groups; substrate limitations: mainly applicable to aryl fluorides activated by strong electron-withdrawing groups (such as p-nitrofluorobenzene), and has extremely low reactivity to electron-neutral or electron-rich substrates.

[0004] Although homogeneous photocatalytic methods developed in recent years have achieved defluorination under mild conditions, they still have fundamental drawbacks: (1) The catalyst is difficult to recover and reuse: the homogeneous photocatalyst is completely dissolved in the reaction system. After the reaction, it cannot be separated by simple filtration or centrifugation. It needs to be recovered by cumbersome column chromatography or solvent extraction. The recovery rate is low (usually <60%), and the catalytic activity decreases significantly after recovery. As a result, the catalyst is discarded after a single use, which increases the cost and environmental burden.

[0005] (2) Limited large-scale application: Homogeneous photocatalysis relies on light penetrating the inside of the reactor. Since the penetration depth of light in dense reaction media is limited (usually <1 cm), when the reaction volume is scaled up to more than 100 ml, the excitation efficiency of materials far from the light source drops sharply, resulting in uneven reaction and reduced conversion rate. Therefore, this technology is mainly limited to the milligram to gram scale in the laboratory and is difficult to meet the needs of industrial production.

[0006] (3) Dependence on precious metal photosensitizers: Most high-efficiency systems use Ir or Ru complexes, which are expensive (Ir complexes can cost thousands of yuan per gram) and pose a risk of heavy metal residues. In the fields of medicine, pesticides and electronic materials, additional purification steps are required to meet the residue limit standards, which further increases production costs.

[0007] (4) The scope of applicable substrates is still limited: Although homogeneous photocatalysis is milder than traditional nucleophilic aromatic substitution (SNAr) conditions, for neutral or electron-rich aryl fluorides that do not contain strong electron-withdrawing groups (such as -CN, -NO2, -CF3), the CF bond is more difficult to break due to the high electron cloud density. This still results in low conversion rates (often <30%) or the need to extend the irradiation time to more than 48 h, which limits the universality of this method.

[0008] (5) The reaction conditions are sensitive to water and oxygen: Most homogeneous photocatalytic systems require strict dehydration and deoxygenation, which is cumbersome and increases the complexity of process control and equipment requirements.

[0009] Therefore, there is an urgent need and great value in developing a non-precious metal-based, recyclable, easily scaled-up, and substrate-universal heterogeneous photocatalytic system to achieve the green and economical conversion of aryl fluorides. Summary of the Invention

[0010] To address the aforementioned issues, this invention aims to provide a novel, highly active, stable, and recyclable heterogeneous photocatalyst and its green preparation method, and to apply it to the defluorination and amination reaction of aryl fluorides, thereby solving the technical problems of difficult catalyst recovery, dependence on precious metals, difficulty in scaling up, and narrow substrate applicability in the prior art.

[0011] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a Cu x The preparation method of O / GDY / C3N4 ternary heterojunction photocatalyst includes the following steps: S1. Preparation of C3N4 nanosheets: Nitrogen-containing precursors (such as urea, melamine, etc.) are calcined in air for the first time, cooled and ground to obtain bulk C3N4; the bulk C3N4 is calcined in air for the second time, cooled naturally and ground to obtain light yellow C3N4 nanosheets.

[0012] S2. One-pot in-situ growth: The C3N4 nanosheets obtained in step S1, the graphyne (GDY) precursor (such as hexaethynylbenzene, HEB-TMS), and the copper salt (such as CuCl, CuBr, etc.) are dispersed in an organic solvent (such as N,N-dimethylformamide, DMF) and stirred at 50-80℃ for 12-48 hours.

[0013] S3. Post-processing: After the reaction is complete, the solid product is separated by centrifugation or filtration, and washed sequentially with DMF, tetrahydrofuran, and methanol to remove unreacted monomers and byproducts. After drying, the Cu is obtained. xO / GDY / C3N4 ternary heterojunction photocatalyst. Here, x takes values ​​of 1-2, indicating that Cu2O and / or CuO may be present in the catalyst.

[0014] Furthermore, the first heating and calcination process involves heating to 500-600℃ at a rate of 1-5℃ / min and holding at that temperature for 2-4 hours; the second heating and calcination process involves heating to 500-600℃ at a rate of 3-10℃ / min and holding at that temperature for 3-5 hours.

[0015] Secondly, the present invention provides Cu prepared by the above method. x O / GDY / C3N4 ternary heterojunction photocatalyst. This catalyst is a pale yellowish-gray powder, composed of carbon nitride, graphyne, and Cu. x Composed of O composites; Graphdiyne is grown in situ on the surface of carbon nitride and Cu is loaded in situ. x O nanoparticles form a tightly coupled ternary heterojunction structure.

[0016] Graphdiyne (GDY) with its unique sp / sp 2 The natural channels formed by the hybrid carbon structure play a dual role: firstly, they act as "electron highways," facilitating the transfer of electrons generated by photoexcitation of C3N4 to Cu. x The rapid migration of the O active center inhibits electron-hole recombination; secondly, through the non-covalent interaction of CF···π, the CF bond in the aryl fluoride is pre-adsorbed and polarized, which significantly reduces its breaking energy barrier.

[0017] The graphyne serves as an electron transport channel and a CF bond prepolarization layer, the carbon nitride serves as a visible light trapping host, and the Cu... x O is used as a catalytic active center.

[0018] Thirdly, the present invention provides the above-mentioned Cu x Application of O / GDY / C3N4 ternary heterojunction photocatalyst in the defluorination and amination reaction of aryl fluorides and amine compounds.

[0019] A method for the defluorination and amination reaction of aryl fluorides, specifically the method described in the application, involves reacting the aryl fluoride, an amine compound, and the Cu under an inert atmosphere (such as nitrogen or argon). x The O / GDY / C3N4 ternary heterojunction photocatalyst was dispersed in a fluorinated alcohol solvent (preferably hexafluoroisopropanol, HFIP) and reacted with stirring at room temperature to 60°C for 4-24 hours under visible light irradiation (preferably wavelength 400-450 nm, such as 405 nm or 440 nm LED light source). After the reaction was completed, the catalyst was separated and recovered, the solvent was evaporated, and the product aromatic amine compounds were obtained by silica gel column chromatography.

[0020] Furthermore, the visible light is blue or violet light with a wavelength of 400-470 nm, and the illumination time is typically 12-48 hours. The reaction solvent is hexafluoroisopropanol (HFIP), the amine compound is pyrazole, aliphatic amine, or aromatic amine, and the aryl fluoride is a fluorobenzene derivative containing electron-withdrawing, electron-donating, or neutral substituents.

[0021] The relevant chemical formulas are as follows: ; The substituent R is independently selected from hydrogen, alkoxy, alkyl, halogen, cyano, nitro, ester, amide, or heterocyclic groups. The core of this reaction is the activation of the CF bond of the aryl fluorine by a catalyst, which couples with the NH bond of the pyrazole to form a CN bond, generating the N-arylpyrazole product.

[0022] In summary, this invention employs a one-step in-situ growth strategy to construct Cu x The O / GDY / C3N4 ternary heterojunction photocatalyst, when used in the defluorination and amination reaction of aryl fluorides, has the following core advantages: (1) Heterogeneous catalysis: recyclability and no metal residue Convenient separation and recycling: Cu x O / GDY / C3N4 is a heterogeneous solid catalyst that can be separated by simple centrifugation or filtration after reaction, enabling multiple recycling; product purity: avoiding the metal or organic molecule residues of homogeneous catalysts, meeting the stringent purity requirements of high-value-added fields such as drug synthesis; continuous flow compatibility: heterogeneous catalysts are easy to immobilize and adapt to continuous flow photoreactors, providing a feasible path for industrial scale-up.

[0023] (2) The unique electronic structure and CF bond activation ability of graphyne Graphdiyne (GDY) is a compound composed of sp and sp 2 Novel two-dimensional carbon allotropes composed of hybrid carbon possess the following key characteristics: a: Natural pore structure: The GDY conjugated structure and natural pores provide abundant CF bond anchoring points, which can effectively polarize CF bonds through CF···π interactions and reduce the activation energy barrier; b: Excellent electron transport performance: The highly conjugated structure of GDY endows it with excellent electron mobility, accelerating the transfer of photogenerated electrons from C3N4 to Cu. x Transport of O active sites.

[0024] (3) Synergistic catalytic mechanism of ternary heterojunction C3N4 is the visible light trapping host; GDY acts as an electron transport channel and pre-activates the CF bond to reduce interfacial charge transfer resistance; polarized aryl fluorides; Cu xO forms the catalytic active center, and GDY-mediated electron enrichment enhances the nucleophilicity of Cu sites.

[0025] Synergistic Achievement: Efficient Separation of Photogenerated Carriers: GDY acts as an electron "highway," suppressing electron-hole recombination in C3N4; Synergistic Activation of CF Bonds: Adsorption / Polarization of GDY and Cu x The catalytic activation of O forms a relay reaction; reaction pathway regulation: the spatial proximity effect of multiple active sites promotes rapid intermediate conversion and inhibits side reactions. This structure is not a simple physical mixture; the bridging effect of GDY achieves a dual improvement in charge separation efficiency and substrate pre-activation capability.

[0026] (4) Mild conditions and functional group compatibility a: Visible light driven: Utilizes sunlight or LED light sources to avoid the high temperature and high pressure conditions of traditional SNAr reaction; b: Functional group tolerance: Mild free radical pathway compatible with sensitive functional groups such as halogen, cyano, ester, and heterocyclic groups; c: Selective regulation: Heterogeneous confinement effect can suppress excessive defluorination and free radical dimerization side reactions; This method employs a visible light catalysis strategy, with mild reaction conditions and high selectivity. It can activate inert CF bonds and complete amination under visible light at room temperature. It has good functional group tolerance and is environmentally friendly, effectively avoiding the harsh reaction conditions such as high temperature and strong alkali required by traditional methods.

[0027] (5) Cost and environmental benefits Non-precious metals: Cu x O replaces precious metals such as Ir, Ru, and Pd, significantly reducing catalyst costs; carbon-neutral materials: C3N4 and GDY are both carbon-rich materials with abundant sources; scalability: the one-step in-situ growth process is simple and suitable for large-scale preparation.

[0028] This technical solution involves constructing Cu x The O / GDY / C3N4 ternary heterogeneous catalyst utilizes the natural porous structure of graphynyne to polarize CF bonds and act as electron transport channels, combined with Cu x The combination of the non-precious metal active center and the visible light-harvesting capability of C3N4 enables the efficient defluorination and amination of aryl fluorides under mild conditions, solving the core defects of existing homogeneous photocatalytic systems, such as the difficulty in catalyst recovery, dependence on precious metals, limited scalability, and insufficient substrate activity. Attached Figure Description

[0029] Figure 1 The 1H NMR spectrum of the product 1-(4-methoxyphenyl)-1H-pyrazole (3a) obtained in Example 1 ( 1 HNMR).

[0030] Figure 2 The carbon NMR spectrum of product 3a obtained in Example 1 ( 13 C NMR).

[0031] Figure 3 The product 1-(4-methoxy-2-methylphenyl)-1H-pyrazole (3b) obtained in Example 2 1 H NMR spectrum.

[0032] Figure 4 The product 3b obtained in Example 2 13 C10 NMR spectrum.

[0033] Figure 5 The product 1-(2-fluoro-4-methoxyphenyl)-1H-pyrazole (3c) obtained in Example 3 1 H NMR spectrum.

[0034] Figure 6 The product 3c obtained in Example 3 13 C10 NMR spectrum.

[0035] Figure 7 The nuclear magnetic resonance fluorine spectrum of product 3c obtained in Example 3 ( 19 F NMR).

[0036] Figure 8 The product 1-(2-chloro-4-methoxyphenyl)-1H-pyrazole (3d) obtained in Example 4 1 H NMR spectrum.

[0037] Figure 9 The product obtained in Example 4, 3d 13 C10 NMR spectrum.

[0038] Figure 10 The product 1-(2-bromo-4-methoxyphenyl)-1H-pyrazole (3e) obtained in Example 5 1 H NMR spectrum.

[0039] Figure 11 The product 3e obtained in Example 5 13 C10 NMR spectrum.

[0040] Figure 12 Cu obtained in Example 1 of this invention x Transmission electron microscopy (TEM) image of the O / GDY / C3N4 ternary heterojunction photocatalyst.

[0041] Figure 13 Cu obtained in Example 1 of this invention xTransmission electron microscopy (TEM) image of the O / GDY / C3N4 ternary heterojunction photocatalyst.

[0042] Figure 14 Cu obtained in Example 1 of this invention x High-resolution transmission electron microscopy (HRTEM) image of the O / GDY / C3N4 ternary heterojunction photocatalyst.

[0043] Figure 15 The image shows the Cu 2p X-ray photoelectron spectroscopy (XPS) spectrum of the catalyst in Example 1. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0045] Example 1: Cu x Preparation of O / GDY / C3N4 ternary heterojunction photocatalyst S1. Place 30g of urea in a covered crucible and calcine it in a muffle furnace under air atmosphere at a programmed heating rate of 2℃ / min to 550℃ for 3 hours. After natural cooling, grind to obtain a light yellow block of C3N4.

[0046] S2. The above-mentioned bulk C3N4 was placed in a muffle furnace and calcined at 550°C at a rate of 5°C / min for 4 hours under air atmosphere. After natural cooling, it was ground to obtain light yellow C3N4 nanosheets.

[0047] S3. Weigh 100 mg of C3N4 nanosheets, 2 mg of hexa-[(trimethylsilyl)ethynyl]benzene (HEB-TMS), and 10 mg of CuCl, and add them to 20 mL of DMF. Stir the mixture in an oil bath at 60 °C for 24 hours.

[0048] S4. After the reaction was complete, the solid product was obtained by centrifugation and washed three times each with DMF, THF, and methanol. It was then dried in a vacuum oven at 60°C for 12 hours to obtain a pale yellowish-gray Cu. x O / GDY / C3N4 ternary heterojunction photocatalyst powder.

[0049] Examples 2-6: Defluorination and amination of aryl fluorides (general procedure)

[0050] Add 1 mg of Cu prepared in Example 1 to a 10 mL lightfastness reaction tube.x O / GDY / C3N4 catalyst and 4 mL hexafluoroisopropanol (HFIP) were stirred to form a suspension. Then, 0.2 mmol of aryl fluoride and 0.6 mmol of pyrazole were added sequentially. The reaction tube was sealed and bubbled with nitrogen for 5 minutes to displace the air. Under a nitrogen atmosphere, the reaction was carried out at room temperature with stirring for 12 hours.

[0051] After the reaction was completed, the reaction solution was centrifuged to recover the catalyst. The supernatant was concentrated by rotary evaporation, and the residue was purified by silica gel column chromatography to obtain the target product. The specific substrates, products, and yields for each example are shown in the table below:

[0052] Product 3a was characterized by NMR, and the results are as follows: Figure 1 ( 1 H NMR) and Figure 2 ( 13 As shown in the C NMR (C6NMR) data. Figure 1 This proves that the target product was successfully synthesized; Figure 2 Further confirmation of the product structure.

[0053] The product 3b was characterized by NMR, and the results are as follows: Figure 3 ( 1 H NMR) and Figure 4 ( 13 As shown in the C NMR (C6NMR) data.

[0054] The product 3c was characterized by NMR, and the results are as follows: Figure 5 ( 1 H NMR) Figure 6 ( 13 (C NMR) and Figure 7 ( 19 As shown in F NMR.

[0055] The product was characterized by NMR on day 3, and the results are as follows: Figure 8 ( 1 H NMR) and Figure 9 ( 13 As shown in the C NMR (C6NMR) data.

[0056] The NMR characterization results of product 3e are as follows: Figure 10 ( 1 H NMR) and Figure 11 ( 13 As shown in the C NMR (C6NMR) data.

[0057] Figure 12 and Figure 13 All of them are Cu obtained in Example 1 of this invention. xTransmission electron microscopy (TEM) images of the O / GDY / C3N4 ternary heterojunction photocatalyst. Figure 12 It can be clearly observed that a tight heterojunction is formed between graphyne and carbon nitride: the black rod-shaped morphology is carbon nitride, and the light-colored area is graphyne. Figure 13 The image was taken at a higher magnification, which further revealed the tight heterojunction structure between graphdiene and carbon nitride, with C3N4 inside the red circle and GDY inside the blue circle. Figure 14 Cu obtained in Example 1 of this invention x High-resolution transmission electron microscopy (HRTEM) image of the O / GDY / C3N4 ternary heterojunction photocatalyst, with the red circle indicating Cu. x O particles, proving Cu x O was successfully loaded onto the surface of graphyne (GDY), forming a ternary heterojunction structure, which confirms the successful realization of the "bridging" structure.

[0058] Figure 15 The high-resolution X-ray photoelectron spectroscopy (XPS) spectrum of the Cu 2p catalyst in Example 1 shows that copper is expressed as Cu 2p. + and Cu 2+ The presence of mixed valence states (corresponding to CuO and Cu2O) indicates that active copper species were successfully loaded and that the species is a mixture of CuO and Cu2O.

[0059] As can be seen, characterization by TEM, HRTEM, and X-ray photoelectron spectroscopy confirmed that Cu x O / GDY / C3N4 heterojunction was successfully prepared.

[0060] Examples 7-10:

[0061] To further expand the reaction substrates of aryl fluorides, the reaction steps are the same as in Example 2. The specific substrates, products, and yields for each example are shown in the table below:

[0062] The reaction formulas and reaction product structural formulas of each embodiment are shown below:

[0063] Comparative example: To demonstrate the necessity and synergy of the various elements in the technical solution of this invention, the following comparative experiments were conducted, and the results are summarized below: Comparative Example 1 (without catalyst): No catalyst was added, and other conditions were the same as in Example 2 (standard conditions). The product yield was only 17%, indicating that the reaction is highly catalyst-dependent.

[0064] Comparative Example 2 (Binary Catalyst): Using C3N4 / GDY (Cu-free) xReplacing the three-way catalyst with O reduces the yield to 33%. This demonstrates that Cu... x O is the key catalytic active center, and the ternary structure exhibits a synergistic effect.

[0065] Comparative Example 3 (different light sources): When the light source was changed from 405 nm to 440 nm, the yield decreased to 66%. This shows that 405 nm is a better light source condition for this system.

[0066] Comparative Example 4 (Aerobic Conditions): The reaction was carried out in an air atmosphere instead of nitrogen, and the yield decreased to 50%. This indicates that an inert atmosphere is conducive to the reaction.

[0067] Comparative Example 5 (different solvents): Using trifluoroethanol (TFE) instead of HFIP, the yield was only 21%; using a TFE / HFIP mixed solvent, the yield was 80%. This demonstrates that HFIP is the optimal solvent for this reaction.

[0068] Comparative Example 6 (Dark Conditions): The reaction was carried out in darkness, and no product formation was detected. This demonstrates that the reaction is light-driven.

[0069] The above comparative examples show that: none of the ternary components can be omitted, and the synergistic effect is significant; the reaction is a light-driven process; and the specific wavelength (405 nm) and solvent (HFIP) are crucial to the efficiency.

[0070] In summary, the Cu provided by this invention x The O / GDY / C3N4 ternary heterojunction photocatalyst successfully solved the problem of difficult activation of the CF bond in aryl fluorides through a synergistic mechanism of "physical adsorption + electronic relay". This method does not require precious metals, the catalyst can be recycled and reused, the reaction conditions are mild, and it has excellent tolerance to various functional groups such as halogens and methyl groups, making it of great industrial application value.

[0071] The core technical points of this invention are as follows: 1. Core Structure: Ternary heterogeneous heterojunction catalyst system Specific structural composition: composed of Cu x A ternary heterojunction catalyst composed of O, GDY (graphyne), and C3N4 (carbon nitride). Among them: C3N4 serves as the visible light trapping host; GDY serves as an electron transport channel and a CF bond prepolarization layer; Cu x O serves as the catalytic active center.

[0072] Technical highlights: The ternary combination itself, especially GDY with C3N4 and Cu xO's specific spatial coupling mode (e.g., GDY mediates the formation of a "sandwich" or "bridge" structure between the two) distinguishes it from traditional binary heterojunctions or single-component photocatalysts.

[0073] 2. Core Structure: Natural Channels and Interface Electron Transport Pathways of GDY Specific structural features: GDY's natural pore structure: utilizing the sp / sp structure in GDY 2 The inherent pores formed by hybrid carbon atoms serve as anchoring sites for CF bonds, and aryl fluorides are physically adsorbed and polarized through CF···π interactions.

[0074] Electron transport channel construction: The highly conjugated network of GDY in C3N4 and Cu x The spaces between O form an "electron highway," directionally accelerating photogenerated electrons from C3N4 to Cu. x Migration of O active sites.

[0075] Key technical points: The pre-polarization function of GDY channels on CF bonds, and the intercalation of GDY as an independent electron transport layer between C3N4 and Cu. x The interface structure between O (rather than a random mixture of the three) solves the dual problems of fast charge recombination and difficult activation of CF bonds.

[0076] 3. Core Steps / Functions: Relay-style CF Bond Co-activation Mechanism Specific steps or functional flow: Step 1 (physical polarization): GDY channels adsorb and elongate CF bonds through non-covalent CF···π interactions, thereby lowering the activation energy barrier; Step 2 (Electron Injection): Electrons generated by photoexcitation of C3N4 are rapidly transported to Cu via GDY. x O makes Cu sites electron-rich and enhances nucleophilicity; Step 3 (Catalytic Breakdown): Electron-Rich Cu x The O active site performs nucleophilic attack on the polarized CF bond, achieving mild conditional breakage.

[0077] Key technical points: The relay-style synergistic mechanism of "adsorption-polarization-electron injection-bond breaking" is used, especially GDY, which simultaneously undertakes the dual functions of "physical polarization" and "electron conduction". This is fundamentally different from the path of direct electron reduction of CF bonds by the catalyst in traditional photocatalysis.

[0078] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. The application of a ternary heterojunction photocatalyst in the defluorination and amination reaction of aryl fluorides and amine compounds, wherein the preparation method of the ternary heterojunction photocatalyst includes the following steps: S1. The nitrogen-containing precursor is calcined for the first time in air atmosphere to obtain bulk C3N4; the bulk C3N4 is calcined for the second time in air atmosphere to obtain C3N4 nanosheets. S2. Disperse the C3N4 nanosheets, graphyne precursor and copper salt in an organic solvent and react at 50-80℃ for 12-48 hours; S3. Separate, wash, and dry the solid product after step S2 to obtain Cu. x O / GDY / C3N4 ternary heterojunction photocatalyst; where x takes the value of 1-2.

2. The application according to claim 1, characterized in that, The nitrogen-containing precursor is urea; the first calcination process is to heat to 500-600℃ at a rate of 1-5℃ / min and hold for 2-4 hours; the second calcination process is to heat to 500-600℃ at a rate of 3-10℃ / min and hold for 3-5 hours.

3. The application according to claim 1, characterized in that, The graphyne precursor is hexa-[(trimethylsilyl)ethynyl]benzene, the copper salt is CuCl, and the organic solvent is DMF.

4. The application according to claim 1, characterized in that, The catalyst consists of carbon nitride, graphylene, and Cu. x It is composed of O composites; wherein, the graphyne is grown in situ on the surface of carbon nitride and Cu is loaded in situ. x O nanoparticles form a tightly coupled ternary heterojunction structure.

5. The application according to claim 4, characterized in that, The graphyne has a large conjugated structure and natural pores, which can adsorb and polarize the CF bonds in aryl fluorides through CF···π interactions.

6. The application according to claim 4, characterized in that, The graphyne serves as an electron transport channel and a CF bond prepolarization layer, the carbon nitride serves as a visible light trapping host, and the Cu... x O is used as a catalytic active center.

7. A method for the defluorination and amination reaction of aryl fluorides, characterized in that, The process includes the following steps: under an inert atmosphere and visible light irradiation, aryl fluorides, amine compounds, and the ternary heterojunction photocatalyst used in any one of claims 1-6 are mixed in a solvent and reacted to catalyze the defluorination coupling reaction between the aryl fluoride and the amine source. After the reaction is completed, the solvent is evaporated and the product aromatic amine compounds are obtained by silica gel column chromatography.

8. The method for defluorination and amination of aryl fluorides according to claim 7, characterized in that, The visible light is blue or violet light with a wavelength of 400-470 nm and an illumination time of 12-48 h.

9. The method for defluorination and amination of aryl fluorides according to claim 8, characterized in that, The solvent is hexafluoroisopropanol, the amine compound is pyrazole, aliphatic amine or aromatic amine, and the aryl fluoride is a fluorobenzene derivative containing an electron-withdrawing group, an electron-donating group or a neutral substituent.

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