A method for photoreactive synthesis of graphene

Abstract

This invention discloses a method for photoreactive synthesis of graphene, belonging to the field of graphene material technology. The method uses 1,2-bis(4-pyridyl)butadiyne as a reactant, which is ground and then subjected to solid-state polymerization under mercury lamp irradiation to obtain a brown solid. The resulting brown solid is then washed with dichloromethane until it becomes colorless, clear, and transparent. After ultrasonication and drying, graphene is obtained. Compared with traditional methods, this invention eliminates the need for high pressure to compress intermolecular distances, avoiding the problems of complex processes, high energy consumption due to high pressure, difficulty in obtaining equipment, and high production costs. This invention features a simple preparation method, a concise synthesis route, a reliable process, low energy consumption, readily available raw materials and equipment, and low production costs, making it suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of graphene material technology, specifically relating to a method for photo-reactive synthesis of graphene. Background Technology

[0002] Graphene is a polymeric carbon material with a single-layer two-dimensional structure formed by carbon atoms through sp2 hybridization, possessing excellent optical and electrical properties. With the development of synthesis methods and chemical modifications, methods for obtaining graphene are divided into two main types: top-down and bottom-up. These primarily include electron beam dicing of bulk graphene and ultra-high-speed shear homogenization to exfoliate graphene sheets. The disadvantages of the top-down approach are the difficulty in providing uniform supervessel widths and atomically precise edges, and the generation of inconsistent graphene mixtures. In contrast, the bottom-up strategy utilizes the precision control offered by synthetic chemistry to construct supervessels from small molecule precursors.

[0003] Currently, there are only two bottom-up methods for synthesizing graphene: (1) surface generation of aryl radicals and coupling to form oligomeric aromatic backbone polymers, followed by cyclodehydrogenation to generate graphene; and (2) formation of oligomeric aromatic backbone polymers in solution, followed by chemical aromatization to graphene. In the above methods, surface synthesis of aromatics allows for good control of the nanoribbon structure to obtain specific widths and edge functionalizations, but it typically only allows for small-scale production on very specific substrates and requires expensive equipment and conditions such as ultra-high vacuum scanning probe microscopy for characterization. In contrast, solid-phase synthesis of oligomeric aromatic backbone polymers can produce large quantities of graphene, but it usually requires the use of transition metal catalysts and solution oxidation using chemical oxidants.

[0004] Solid-state topological chemistry refers to a chemical reaction in which the structure of the product is related to the structure of the reactants. It allows the reaction to proceed while maintaining a certain crystal structure of the reactants, confining unsaturated molecules within a crystal lattice for minimal reaction motion, making it a feasible method for obtaining polymers. In this reaction, the structure of the product can be predicted and designed from the crystal structure of the reactants by following a crystal-to-crystal reaction route. However, reactions capable of solid-state topological polymerization are very limited; only specific unsaturated molecules can undergo topological polymerization. For example, the 1,4-diphenylbutyne described in the journal "High-Pressure Solid-Phase Topological Polymerization for the Synthesis of Nanocarbon Materials" undergoes a distance-selective dehydrogenation Diels-Alder reaction (DDA reaction) at pressures above 10 GPa using a Paris-Edinburgh press, with phenylacetylene as the diene and phenyl as the dienophile, producing crystalline graphene nanoribbons with sp3 carbons at the edges. High pressure can effectively control the packing pattern between molecules, compressing the intermolecular distance and, to some extent, overcoming the limitations of intermolecular packing, enabling the precise synthesis of graphene nanoribbons. However, this method has drawbacks, including the need to fix monomers for high-pressure graphene synthesis, which complicates the process; the use of high pressure also leads to high energy consumption and expensive, hard-to-obtain equipment, resulting in high production costs and unsuitability for large-scale production. Therefore, it is necessary to develop a simple, streamlined, and low-cost method for graphene synthesis. Summary of the Invention

[0005] To address the above problems, this invention provides a method for photoreactive synthesis of graphene, in which synthesized 1,2-bis(4-pyridyl)butadiyne is directly irradiated with light to obtain two-dimensional graphene. The preparation method is simple, the process route is concise, and the production cost is low.

[0006] This invention is achieved through the following technical solution:

[0007] A method for photoreactive synthesis of graphene involves using 1,2-bis(4-pyridyl)butadiyne as a reactant, grinding it, and then subjecting it to solid-state polymerization under mercury lamp illumination to obtain a brown solid. The obtained brown solid is then washed with dichloromethane until it becomes colorless, clear, and transparent. After ultrasonication and drying, graphene is obtained.

[0008] Furthermore, the solid-phase polymerization reaction under the mercury lamp irradiation condition takes 48–50 hours.

[0009] Furthermore, the method for preparing the monomer 1,2-bis(4-pyridyl)butadiyne includes the following steps:

[0010] (1) Under an inert gas atmosphere, 4-iodopyridine, tetra(triphenylphosphine)palladium and cuprous iodide were dissolved in tetrahydrofuran, and trimethylsilylacetylene and triethylamine were added, wherein the mass ratio of trimethylsilylacetylene to 4-iodopyridine was 1 to 1.2:1. The solution was then stirred at room temperature to obtain a reaction mixture.

[0011] (2) Add potassium fluoride and methanol to the reaction mixture, continue stirring the solution in air, evaporate the product to dryness and dissolve it in dichloromethane, and after washing, drying, filtering and eluting, 1,2-bis(4-pyridyl)butyne is obtained.

[0012] Further, in step (1), the mass ratio of 4-iodopyridine, tetra(triphenylphosphine)palladium and cuprous iodide is 1:0.2-0.5:0.04-0.08.

[0013] Further, in step (1), the mass ratio of 4-iodopyridine to tetrahydrofuran is 1g:14-16mL.

[0014] Further, in step (2), the mass ratio of potassium fluoride to 4-iodopyridine is 0.7 to 1:1.

[0015] Further, in step (2), the ratio of methanol to 4-iodopyridine is 14-16 mL: 1 g.

[0016] Graphene obtained by a photoreactive synthesis method as described above.

[0017] Furthermore, the graphene has a layered structure or a sheet structure. The layered structure is formed by stacking graphene sheets layer by layer, and the sheet structure is a two-dimensional graphene nanosheet with nano-edges.

[0018] The principle of photoreactive synthesis of graphene in this invention:

[0019]

[0020] This invention uses monomer 1,2-bis(4-pyridyl)butadiyne as a reactant, grinds it, and then performs a solid-state polymerization reaction under mercury lamp irradiation to obtain graphene. The reaction process for synthesizing graphene is attributed to the adaptability of intermolecular reaction distances; the shortest distances between the C1 and C2 (D1 and D2) of two adjacent molecules of 1,2-bis(4-pyridyl)butadiyne are 3.801 and 1.801, respectively. Because the critical distance for similarity in acetylene reactions is Therefore, graphene can be synthesized through dehydrogenation cyclization reactions via D1 and D2 bonding routes. In the above reaction formula, after being irradiated with a mercury lamp, 1,2-bis(4-pyridyl)butadiyne undergoes solid-phase polymerization, and graphene is synthesized through dehydrogenation cyclization between C and C.

[0021] In the preparation of monomer 1,2-bis(4-pyridyl)butadiyne according to the present invention, reactants 4-iodopyridine and trimethylsilylacetylene are dissolved in tetrahydrofuran solvent. Under the catalysis of tetra(triphenylphosphine)palladium and cuprous iodide, a Sonogashira coupling reaction occurs, followed by the action of the acid-binding agent triethylamine to obtain a reaction mixture. Then, the reaction mixture is added to methanol solvent to undergo an oxidative Eglinton coupling reaction. After deprotection by potassium fluoride, monomer 1,2-bis(4-pyridyl)butadiyne is obtained.

[0022] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0023] 1. This invention uses 1,2-bis(4-pyridyl)butadiyne as a reactant. The monomer is ground to increase its surface area and ensure a more complete reaction. Then, the monomer is irradiated with a mercury lamp, undergoing solid-state polymerization under illumination to obtain graphene. Compared with traditional methods, this invention eliminates the need for high pressure to compress intermolecular distances, avoiding the problems of complex processes, high energy consumption due to high pressure, difficulty in obtaining equipment, and high production costs. This invention features a simple preparation method, a concise synthetic route, a reliable process, low energy consumption, readily available raw materials and equipment, and low production costs, making it suitable for large-scale production.

[0024] 2. The graphene synthesized in this invention has a layered or sheet-like structure. 1,2-bis(4-pyridyl)butadiyne is synthesized through molecular design. The pyridyl group is used to adjust the molecular width and N element composition, thereby adjusting the degree of conjugation, which is beneficial to improving the electrical properties of graphene, making it strong in storing and transmitting electrons, and suitable for application in fields such as sensor devices. Attached Figure Description

[0025] Figure 1 The image shows the 1H NMR spectrum of 1,2-bis(4-pyridyl)butadiyne from Example 1.

[0026] Figure 2 The image shows the carbon NMR spectrum of 1,2-bis(4-pyridyl)butadiyne from Example 1.

[0027] Figure 3 This is the carbon NMR spectrum of the graphene in Example 1.

[0028] Figure 4 This is a SEM image of graphene from Example 1 at magnification of 10,000.

[0029] Figure 5 This is a SEM image of the graphene in Example 1 at magnification of 30,000. Detailed Implementation

[0030] The present invention will be further described in detail below through embodiments. These embodiments are only used to illustrate the present invention and do not limit the scope of protection of the present invention.

[0031] Example 1

[0032] A method for photoreactive synthesis of graphene includes the following steps:

[0033] (1) Under a nitrogen atmosphere, 1.0 g of 4-iodopyridine, 0.36 g of tetra(triphenylphosphine)palladium and 0.06 g of cuprous iodide were dissolved in 15 mL of degassed tetrahydrofuran solvent, and then placed in a 500 mL side-supported reaction flask. 1.11 g of trimethylsilylacetylene and 7.5 mL of triethylamine were added. After stirring the solution at room temperature for 6 h, the reaction mixture was obtained.

[0034] (2) Add 0.86 g potassium fluoride and 15 mL methanol to the reaction mixture. Stir the solution in air for 24 h. After the solution is evaporated to dryness, dissolve it in dichloromethane, wash with deionized water, and dry with anhydrous sodium sulfate. Filter, add silica gel powder and evaporate to dryness. Pass the silica gel powder through a column. The eluent is a mixture of petroleum ether and ethyl acetate (volume ratio 1:1), yielding a white solid product. The structure of the obtained white solid product is determined by 1H NMR spectroscopy. Its 1H NMR spectrum is shown below. Figure 1 As shown, the white solid obtained by analysis is 1,2-bis(4-pyridyl)butyne.

[0035] (3) 1,2-bis(4-pyridyl)butadiene was ground in a mortar and then placed in a mercury lamp illumination box for 48 hours to obtain a brown solid. After washing with dichloromethane until it was colorless, clear and transparent, graphene was obtained after sonication and drying.

[0036] Example 2

[0037] A method for photoreactive synthesis of graphene includes the following steps:

[0038] (1) Under a nitrogen atmosphere, 1.0 g of 4-iodopyridine, 0.45 g of tetra(triphenylphosphine)palladium and 0.08 g of cuprous iodide were dissolved in 16 mL of degassed tetrahydrofuran solvent, and then placed in a 500 mL side-supported reaction flask. 1.18 g of trimethylsilylacetylene and 8.0 mL of triethylamine were added. After stirring the solution at room temperature for 6 h, the reaction mixture was obtained.

[0039] (2) Add 0.95 g potassium fluoride and 16 mL methanol to the reaction mixture, stir the solution in air for 24 h, evaporate the solution to dryness, dissolve it in dichloromethane, wash with deionized water, add anhydrous sodium sulfate to dry, filter, add silica gel powder to evaporate to dryness, pass silica gel powder through a column, the eluent is a mixture of petroleum ether / ethyl acetate (petroleum ether: ethyl acetate = 1:1) to obtain a white solid product, which is 1,2-bis(4-pyridyl)butadiene.

[0040] (3) Take 1g of 1,2-bis(4-pyridyl)butadiene and grind it in a mortar. Then place it in a mercury lamp illumination box and irradiate it for 50h to obtain a brown solid. After washing with dichloromethane until it is colorless, clear and transparent, it is ultrasonicated and dried to obtain graphene.

[0041] Example 3

[0042] A method for photoreactive synthesis of graphene includes the following steps:

[0043] (1) Under a nitrogen atmosphere, 1.0 g of 4-iodopyridine, 0.22 g of tetra(triphenylphosphine)palladium and 0.04 g of cuprous iodide were dissolved in 16 mL of degassed tetrahydrofuran solvent, and then placed in a 500 mL side-supported reaction flask. 1.12 g of trimethylsilylacetylene and 6.0 mL of triethylamine were added. After stirring the solution at room temperature for 5 h, the reaction mixture was obtained.

[0044] (2) Add 0.73 g potassium fluoride and 14 mL methanol to the reaction mixture, stir the solution in air for 22 h, evaporate the solution to dryness, dissolve it in dichloromethane, wash with deionized water, add anhydrous sodium sulfate to dry, filter, add silica gel powder to evaporate to dryness, pass silica gel powder through column, the eluent is a mixture of petroleum ether / ethyl acetate (petroleum ether: ethyl acetate = 1:1) to obtain a white solid product, which is 1,2-bis(4-pyridyl)butadiene.

[0045] (3) 1,2-bis(4-pyridyl)butadiene was ground in a mortar and then placed in a mercury lamp illumination box for 48 hours to obtain a brown solid. After washing with dichloromethane until it was colorless, clear and transparent, it was ultrasonicated and dried to obtain graphene.

[0046] Material characterization analysis

[0047] (I) Carbon NMR Spectroscopy Analysis

[0048] The 1,2-bis(4-pyridyl)butadiyne and graphene in Example 1 were characterized and analyzed by carbon nuclear magnetic resonance spectroscopy, and the results are as follows: Figure 2 and Figure 3 As shown. By comparison Figure 2 and Figure 3Before illumination, the 75 and 77 ppm peaks of the ynyl carbon in 1,2-bis(4-pyridyl)butadiyne disappeared, and an asymmetric broad peak was observed at 120-150 ppm. After illumination, the carbon peaks in the graphene were classified, and the newly formed peaks at 45.1 and 70.5 ppm originated from newly formed sp... 3 The broad peaks at -C, 123.9, and 144.0 ppm are attributed to the sp-C centers in the graphene. 2 -C, the broad peak at 149.7 ppm is C with sp2 hybridization C=N.

[0049] (II) Scanning Electron Microscopy Analysis

[0050] The graphene in Example 1 was characterized and analyzed using scanning electron microscopy (SEM), and the results are as follows: Figure 4 and Figure 5 The images shown represent SEM images of graphene at magnifications of 10,000 and 30,000, respectively. Figure 4 and Figure 5 It is known that graphene has a layered structure or a sheet structure. The layered structure is formed by stacking graphene sheets layer by layer, while the sheet structure is a two-dimensional graphene nanosheet with nano-edges.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of photoreaction synthesis of graphene, characterized in that, The monomer 1,2-bis(4-pyridyl)butadiyne is used as a reactant, is ground, and then is subjected to a solid-phase polymerization reaction under mercury lamp light to obtain a brown solid, which is washed with dichloromethane until it is colorless and clear and transparent, and then is subjected to ultrasonic treatment and drying to obtain graphene.

2. The method of photoreaction synthesis of graphene according to claim 1, characterized in that, The solid-phase polymerization reaction under the mercury lamp light is performed for 48-50 h.

3. The method of photoreaction synthesis of graphene according to claim 1, wherein, The monomer 1,2-bis(4-pyridyl)butadiyne is prepared by the following steps: (1) 4-iodopyridine, tetrakis(triphenylphosphine)palladium and cuprous iodide are dissolved in tetrahydrofuran under an inert gas atmosphere, trimethylsilyl acetylene and triethylamine are added, the mass ratio of trimethylsilyl acetylene to 4-iodopyridine is 1-1.2:1, and then the solution is stirred at room temperature to obtain a reaction mixture; (2) potassium fluoride and methanol are added to the reaction mixture, the solution is continuously stirred in air, the obtained product is dissolved in dichloromethane after being spun dry, and then is subjected to washing, drying, filtration and elution to obtain 1,2-bis(4-pyridyl)butadiyne.

4. The method of photoreaction synthesis of graphene according to claim 3, wherein, In step (1), the mass ratio of 4-iodopyridine, tetrakis(triphenylphosphine)palladium and cuprous iodide is 1:0.2-0.5:0.04-0.

08.

5. The method of photoreaction synthesis of graphene according to claim 3, wherein, In step (1), the mass ratio of 4-iodopyridine to tetrahydrofuran is 1 g:14-16 mL.

6. The method of photoreaction synthesis of graphene according to claim 3, wherein, In step (2), the mass ratio of potassium fluoride to 4-iodopyridine is 0.7-1:

1.

7. The method of photoreaction synthesis of graphene according to claim 3, wherein, In step (2), the ratio of methanol to 4-iodopyridine is 14-16 mL:1 g.

8. Graphene obtained by the method of photo-reaction synthesis of graphene according to any one of claims 1-7.

9. The graphene of claim 8, wherein, The graphene has a layered structure or a sheet structure, the layered structure is formed by stacking graphene sheets, and the sheet structure is a two-dimensional nanosheet of graphene with nanometer edges.

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