CN114735680B - A kind of graphene nanoribbon and preparation method thereof - Google Patents

Abstract

The invention relates to the technical field of carbon materials, specifically, a graphene nanobelt and a preparation method thereof. Dissolving small-molecule condensed-ring aromatic hydrocarbons and molten salt in a solvent and stirring in an inert atmosphere; adding a catalyst to carry out a constant temperature reaction; taking out a product after the reaction; carbonizing the carbonized product in an inert atmosphere, washing the carbonized product with water, and ultrasonically treating the graphene nanobelt to obtain the graphene nanobelt. The graphene nanobelt provided by the present invention has a clear molecular structure, and the molecular weight can be adjusted through the control of the synthesis process, and then the band gap value can be adjusted; the molten salt carbonization method used in the preparation process has rich sources of raw materials, low production cost, simple and controllable synthesis process, and easy realization of large-scale production.

Description

A kind of graphene nanoribbon and preparation method thereof

technical field

The invention relates to the technical field of carbon materials, in particular to a graphene nanobelt and a preparation method thereof.

Background technique

Graphene's unique electronic band structure and outstanding mechanical properties make it very potential in the research and development of field-effect transistors. However, since graphene itself is a semi-metallic material, its energy bands overlap at the Dirac point and there is no band gap. It cannot be controlled by changing the voltage like traditional transistors. In order to make graphene available for the preparation of field-effect transistors, an energy gap needs to be introduced into graphene. Studies have found that if two-dimensional graphene is cut into one-dimensional graphene nanoribbons, a semiconductor material with a certain energy gap can be obtained.

Graphene nanoribbons (GNRs) refer to ribbon-shaped graphene with a width less than 100 nm and a certain aspect ratio. The edge effects (such as edge configuration and edge disorder) brought about by the special structure of graphene nanoribbons enable this material to have different band gaps, and the band gap of the material can be adjusted by controlling the structure. The bandgap performance of GNRs directly depends on its structure, therefore, the precise synthesis of GNRs with specific width and edge structure is a major challenge for their practical application. At present, there are two completely different ways to prepare GNRs: top-down method and bottom-up method. There are two types of top-down methods. One is to cut or etch graphene or graphite precursors into graphene nanoribbons, and the other is to cut carbon nanotubes longitudinally to prepare corresponding graphene nanoribbons. The disadvantage is that the precise control of the GNRs structure can be achieved through the selection of precursor molecules and the control of the process, which is the preferred method for preparing functionalized graphene nanoribbons.

The organic synthesis method based on precursor molecules reported in the literature mainly uses fused-ring aromatic hydrocarbons as precursors and in situ synthesis on the metal surface in a high vacuum environment. However, the synthesis of the precursor molecules used in this method is complex and costly, and the synthesis of GNRs requires a harsh process, which is not conducive to industrialization.

Contents of the invention

The object of the present invention is to provide a graphene nanoribbon and a preparation method thereof, which can realize large-scale production of graphene nanoribbons with a controllable band gap width.

For realizing above object, technical scheme of the present invention is as follows:

A preparation method for graphene nanoribbons, comprising the steps of:

S1: Dissolve small molecule condensed aromatic hydrocarbons and molten salt in a solvent, and stir for 0.5 to 1 hour under an inert atmosphere;

The small-molecular fused-ring aromatics include one or more of the condensed-ring aromatics of naphthalene, methylnaphthalene, anthracene, phenanthrene, and pyrene. The small-molecule fused-ring aromatics are structural units of graphene nanobelts. Under the action of a catalyst, the small-molecule fused-ring aromatics undergo a polymerization reaction to generate large-molecular-weight fused-ring aromatics. Therefore, all small-molecular-weight fused-ring aromatics and their derivatives can be used as raw materials, but they have an impact on the structure and performance of the product;

Described molten salt comprises one or more in sodium chloride, ferric chloride, barium chloride, calcium chloride, cupric chloride and potassium chloride, and the effect of molten salt makes synthetic reaction carry out uniformly on the one hand, prevents the agglomeration of product in the synthesis process and carbonization process on the other hand, guarantees that product is graphene nanoribbon, and all inorganic salts that can exist stably in synthesis and carbonization process can be used as molten salt, but have influence on the structure and performance of product;

The molar ratio of the small molecule condensed ring aromatic hydrocarbon and the molten salt is 1:(0～3),

Preferably, the molar ratio of the small molecule condensed ring aromatic hydrocarbon and the molten salt is 1:(1～2),

More preferably, the molar ratio of the small molecule condensed ring aromatic hydrocarbon to the molten salt is 1:(1.5-2).

The solvent includes one or more of methylene chloride, chloroform, tetrachloromethane, ethylene dichloride and nitrotoluene. The effect of the solvent on the one hand enables the reaction raw materials to be in better uniform contact with each other; on the other hand, it inhibits the sublimation of small molecule condensed ring aromatics at the reaction temperature to ensure the smooth progress of the synthesis reaction;

The amount of inert gas used in this step is not critical, but its minimum amount should ensure that oxygen and water in the air do not enter the reaction system. Preferably, the inert atmosphere is nitrogen or argon, more preferably, the inert atmosphere is a mixture of nitrogen and argon.

S2: add a catalyst and carry out a constant temperature reaction at 0-80°C for 1-10 hours, and take out the product after the reaction;

The catalyst includes a Lewis acid. The Lewis acid can catalyze the polymerization of small molecule fused-ring aromatics, and can also catalyze the dehydrocyclization of the synthesized product to generate graphene nanobelts. All compounds that have a catalytic effect on the polymerization of small molecular weight fused-ring aromatics and their derivatives can be used as catalysts, but have an impact on the molecular weight and structure of the product;

Preferably, the catalyst includes one or more of aluminum chloride, ferric chloride, copper chloride, boron trifluoride and titanium tetrachloride;

The molar ratio of described small molecule condensed ring aromatic hydrocarbon and catalyst is 1:(0.5～4),

Preferably, the molar ratio of the small molecule condensed ring aromatic hydrocarbon to the catalyst is 1:(0.5～3),

More preferably, the molar ratio of the small molecule condensed ring aromatic hydrocarbon and the catalyst is 1:(1～2);

Preferably, the constant temperature reaction temperature is 10-60°C, and the time is 2-6h,

More preferably, the constant temperature reaction temperature is 20-40° C., and the time is 3-5 hours.

S3: carbonize the product described in S2 at 650-1000° C. for 1-3 h under an inert atmosphere, wash the carbonized product with water, and treat with ultrasonic to obtain the graphene nanobelt.

Preferably, the carbonization temperature is 650-800°C, and the time is 1-2h,

More preferably, the carbonization temperature is 650-750°C, and the time is 1-2h.

Another object of the present invention is to provide a kind of graphene nanoribbon, relative molecular mass is 500～2000, wide 1～2nm, length 3.0～15nm, bandgap width is 2.3～6eV, main molecular structure is

Compared with prior art, the present invention has following advantage:

1) In the preparation method provided by the present invention, the synthesis reaction mechanism is the simultaneous existence of cationic polymerization of fused-ring aromatic hydrocarbons and Friedel-Crafts alkylation reaction, which solves the problem in the prior art that Lewis acid-catalyzed polymerization of fused-ring aromatic hydrocarbons is difficult to generate multimers, and can synthesize expected full-fused-ring aromatic compounds of different molecular weights through the optimization and coordination of solvents and catalysts;

2) In the preparation method provided by the present invention, the synthesis reaction occurs in the molten salt medium, the raw material solution can be fully diffused in the system, and the solid or semi-solid large molecular weight condensed ring aromatics generated are attached to the molten salt compound, which is conducive to the homogeneity of the molecular weight of the product on the one hand; on the other hand, it can avoid the product from being agglomerated and bonded due to the large Π bond, and the excessive liquid molten salt in the carbonization process can promote the further dispersion of graphene nanoribbons, saving the stripping process after graphene is synthesized in the prior art;

3) The graphene nanoribbons provided by the present invention have a clear molecular structure, and can realize the regulation of molecular weight through the control of the synthesis process, and then achieve the regulation of the band gap value; the adopted molten salt carbonization method preparation process has rich sources of raw materials, low production cost, simple and controllable synthesis process, and is easy to realize large-scale production.

Description of drawings

Fig. 1 is the mass spectrogram and the molecular structure of the graphene nanobelt prepared by embodiment 1;

Fig. 2 is the mass spectrogram and the molecular structure of the graphene nanobelt prepared by embodiment 2;

Fig. 3 is the mass spectrogram and the molecular structure of the graphene nanobelt prepared by embodiment 3;

Fig. 4 is the atomic force electron microscope photograph of the graphene nanobelt prepared by embodiment 1;

Fig. 5 is the atomic force electron micrograph of the graphene nanobelt prepared in embodiment 3.

Detailed ways

As used herein:

"Prepared from" is synonymous with "comprising". As used herein, the terms "comprises," "including," "has," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article or device comprising listed elements is not necessarily limited to those elements, but may include other elements not explicitly listed or inherent to such composition, step, method, article or device.

When an amount, concentration, or other value or parameter is expressed in terms of a range, preferred range, or range bounded by a series of upper preferred values and lower preferred values, this is to be understood as specifically disclosing all ranges formed by any pairing of any upper range limit or preferred value with any lower range limit or preferred value, whether or not the range is individually disclosed. For example, when the range "1-5" is disclosed, the described range should be construed to include the ranges "1-4", "1-3", "1-2", "1-2 and 4-5", "1-3 and 5", etc. When a numerical range is described herein, unless otherwise stated, that range is intended to include its endpoints and all integers and fractions within the range.

"And/or" is used to indicate that one or both of the stated situations may occur, for example, A and/or B includes (A and B) and (A or B).

The technical solutions of the present invention will be described in detail below in conjunction with specific examples, but those skilled in the art will understand that the following examples are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention.

Example 1

A preparation method for graphene nanoribbons, comprising the steps of:

S1: Use DF-101S oil bath as the reaction device, methyl silicone oil as the oil bath medium, add 6.4g of naphthalene and 5.8g of sodium chloride (molar ratio 1:2) into a 250mL three-necked flask, add 100mL of dichloromethane, blow nitrogen at room temperature 25°C, connect the outlet pipe to the silicone oil liquid seal, and stir for 0.5h;

S2: Add 13.3g of aluminum chloride (the molar ratio of naphthalene to aluminum chloride is 1:2), and react at a constant temperature for 6 hours under the condition of nitrogen protection and stirring, and take out the product after the reaction;

S3: The reaction product was put into a 100ml crucible and placed in a carbonization furnace. The temperature was raised to 800°C at a rate of 5°C/min in a nitrogen atmosphere for 1.5h for carbonization, and the temperature was lowered to room temperature in a nitrogen atmosphere. The carbonized product was taken out, washed with deionized water for 5 times, and ultrasonically treated with ethanol as a dispersion medium for 30 minutes. The black solid powder obtained after drying at 80°C was the product graphene nanobelt.

Example 2

A preparation method for graphene nanoribbons, comprising the steps of:

S1: Use DF-101S oil bath as the reaction device, methyl silicone oil as the oil bath medium, add 10.1 g of pyrene and 8.1 g of ferric chloride (molar ratio 1:1) into a 250 mL three-necked flask, add 100 mL of dichloroethane, and bubble argon gas at room temperature of 25 ° C, connect the gas outlet pipe to the silicone oil liquid seal, and stir for 1 h;

S2: Add 3.35 g of boron trifluoride (the molar ratio of pyrene to boron trifluoride is 1:1), heat up to 60° C. for constant temperature reaction for 3 hours under argon protection and stirring, and take out the product after the reaction;

S3: The reaction product was put into a 100ml crucible and placed in a carbonization furnace. Under an argon atmosphere, the temperature was raised to 1000°C at a rate of 5°C/min for 1 hour for carbonization, and the temperature was lowered to room temperature in an argon atmosphere. After the carbonized product was taken out and washed with deionized water for 5 times, it was ultrasonically treated with ethanol as a dispersion medium for 30 minutes, and the black solid powder obtained after drying at 80°C was the product graphene nanobelt.

Example 3

A preparation method for graphene nanoribbons, comprising the steps of:

S1: Use DF-101S oil bath as the reaction device, methyl silicone oil as the oil bath medium, add 8.9g of anthracene and 0.82g of a mixture of barium chloride and potassium chloride (molar ratio 1:0.1) into a 250mL three-necked flask, add 100mL of nitrotoluene, blow nitrogen and argon at room temperature of 25°C, connect the gas outlet pipe to the silicone oil liquid seal, and stir for 0.8h;

S2: Add 3.35g of copper chloride (the molar ratio of anthracene to copper chloride is 1:0.5), raise the temperature to 80°C for 1 hour under the protection and stirring of nitrogen and argon, and take out the product after the reaction;

S3: The reaction product was put into a 100ml crucible and placed in a carbonization furnace. Under nitrogen and argon atmosphere, the temperature was raised to 650°C at a constant temperature of 3 hours at a rate of 5°C/min for carbonization. The temperature was lowered to room temperature under nitrogen and argon atmosphere. After the carbonized product was taken out and washed with deionized water for 5 times, it was ultrasonically treated with ethanol as the dispersion medium for 30 minutes, and the black solid powder obtained after drying at 80°C was the product graphene nanobelt.

Example 4

A preparation method for graphene nanoribbons, comprising the steps of:

S1: Use DF-101S oil bath as the reaction device, methyl silicone oil as the oil bath medium, add 7.1g of methylnaphthalene and 16.5g of calcium chloride (molar ratio 1:3) into a 250mL three-necked flask, add 100mL of chloroform, blow nitrogen at room temperature of 25°C, connect the gas outlet pipe to the silicone oil liquid seal, and stir for 0.6h;

S2: Add 32.4g of ferric chloride (the molar ratio of methylnaphthalene to ferric chloride is 1:4), lower the temperature to 0°C for constant temperature reaction for 10 hours under nitrogen protection and stirring, and take out the product after the reaction;

S3: The reaction product was put into a 100ml crucible and placed in a carbonization furnace. Under a nitrogen atmosphere, the temperature was raised to 700°C at a constant temperature of 2 hours at a rate of 5°C/min for carbonization, and the temperature was lowered to room temperature in a nitrogen atmosphere. After the carbonized product was taken out and washed with deionized water for 5 times, it was ultrasonically treated with ethanol as a dispersion medium for 30 minutes, and the black solid powder obtained after drying at 80°C was the product graphene nanoribbons.

Example 5

A preparation method for graphene nanoribbons, comprising the steps of:

S1: Use DF-101S oil bath as the reaction device, methyl silicone oil as the oil bath medium, add 8.9g phenanthrene and 10g copper chloride (molar ratio 1:1.5) into a 250mL three-neck flask, add 100mL tetrachloromethane, blow nitrogen at room temperature 25°C, connect the gas outlet pipe to the silicone oil liquid seal, and stir for 0.7h;

S2: Add 28.5g of titanium tetrachloride (the molar ratio of phenanthrene to titanium tetrachloride is 1:3), raise the temperature to 40°C for constant temperature reaction for 5 hours under nitrogen protection and stirring, and take out the product after the reaction;

S3: The reaction product was put into a 100ml crucible and placed in a carbonization furnace. Under a nitrogen atmosphere, the temperature was raised to 900°C at a constant temperature of 2.5 hours at a rate of 5°C/min for carbonization, and the temperature was lowered to room temperature in a nitrogen atmosphere. After the carbonized product was taken out and washed with deionized water for 5 times, it was ultrasonically treated with ethanol as a dispersion medium for 30 minutes, and the black solid powder obtained after drying at 80°C was the product graphene nanoribbons.

test case 1

Use the L5S ultraviolet-visible light spectrometer to test the ultraviolet light absorption spectrum of the graphene nanoribbon prepared in embodiment 1-3 and calculate the bandgap width using Shanghai Jingke instrument electric upper division, the results are shown in Table 1.

Table 1 Band gap width of graphene nanoribbons

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Furthermore, those skilled in the art will understand that although some embodiments herein include some features included in other embodiments but not others, combinations of features from different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the following claims, any one of the claimed embodiments may be used in any combination. The information disclosed in this background section is only intended to enhance the understanding of the general background of the present invention, and should not be considered as an acknowledgment or any form of suggestion that the information constitutes the prior art that is already known to those skilled in the art.

Claims (13)

1. The preparation method of the graphene nanoribbon is characterized by comprising the following steps of:

s1: dissolving small-molecule polycyclic aromatic hydrocarbon and molten salt in a solvent, and stirring under inert atmosphere; the small-molecule polycyclic aromatic hydrocarbon comprises one or more of naphthalene, methylnaphthalene, anthracene, phenanthrene and pyrene; the molten salt comprises one or more of sodium chloride, ferric chloride, barium chloride, calcium chloride, copper chloride and potassium chloride; the molar ratio of the small-molecule polycyclic aromatic hydrocarbon to the molten salt is 1 (0-3), wherein the dosage of the molten salt is not 0;

s2: adding a catalyst to perform a constant temperature reaction, and taking out a product after the reaction is finished; the catalyst comprises one or more of aluminum chloride, ferric trichloride, copper chloride, boron trifluoride and titanium tetrachloride; the molar ratio of the small molecular polycyclic aromatic hydrocarbon to the catalyst is 1 (0.5-4);

s3: and (3) carbonizing the product of the step (S2) in an inert atmosphere, and washing and ultrasonically treating the carbonized product to obtain the graphene nanoribbon.

2. The method according to claim 1, wherein in step S1, the solvent comprises one or more of dichloromethane, chloroform, tetrachloromethane, dichloroethane, and nitrotoluene.

3. The method of claim 1, wherein step S1 further satisfies one or more of the following conditions:

a. the inert atmosphere comprises nitrogen and/or argon;

b. the stirring time is 0.5-1 h.

4. The preparation method of claim 1, wherein the molar ratio of the small-molecule polycyclic aromatic hydrocarbon to the molten salt is 1 (1-2).

5. The method according to claim 4, wherein the molar ratio of the small-molecule polycyclic aromatic hydrocarbon to the molten salt is 1 (1.5-2).

6. The preparation method of claim 1, wherein the molar ratio of the small-molecule polycyclic aromatic hydrocarbon to the catalyst is 1 (0.5-3).

7. The preparation method of claim 6, wherein the molar ratio of the small-molecule polycyclic aromatic hydrocarbon to the catalyst is 1 (1-2).

8. The preparation method according to claim 1, wherein the constant temperature reaction temperature in step S2 is 0-80 ℃ and the time is 1-10 h.

9. The preparation method according to claim 8, wherein the constant temperature reaction temperature in step S2 is 10-60 ℃ for 2-6 hours.

10. The preparation method according to claim 9, wherein the constant temperature reaction temperature in step S2 is 20-40 ℃ for 3-5 hours.

11. The method according to claim 1, wherein the carbonization temperature in step S3 is 650-1000 ℃ for 1-3 hours.

12. The method according to claim 11, wherein the carbonization temperature in step S3 is 650-800 ℃ for 1-2 hours.

13. The method according to claim 12, wherein the carbonization temperature in step S3 is 650-750 ℃ for 1-2 hours.