CN114436248A - Preparation method of laser-induced graphene, laser-induced graphene and application - Google Patents

Abstract

The invention discloses a preparation method of laser-induced graphene, the laser-induced graphene and application, and relates to the technical field of graphene. The preparation method of the laser-induced graphene takes chitosan hydrochloride which is highly water-soluble, biocompatible and biodegradable as a raw material, prepares the laser-induced graphene by a laser-induced method, does not need any chemical treatment in the preparation process, has simple and easy process, and is suitable for industrial application. The prepared laser-induced graphene can be further prepared into electronic devices such as a super capacitor and a sensor, and has wide application prospect in the field of manufacturing and packaging of advanced semiconductor devices.

Description

Preparation method of laser-induced graphene, laser-induced graphene and application

technical field

The invention relates to the technical field of graphene, in particular, to a preparation method of laser-induced graphene, laser-induced graphene and applications.

Background technique

Graphene is a carbon material with a two-dimensional layered structure. It is a single-layer graphite sheet obtained by a certain treatment of bulk graphite crystals. Its structure is composed of carbon atoms with sp ² hybridization. The regular hexagonal honeycomb two-dimensional plane, the carbon atoms in the structure are connected in the same way as carbon materials such as zero-dimensional fullerenes, one-dimensional carbon nanotubes and three-dimensional graphite. Due to its unique two-dimensional planar structure, graphene has excellent properties in electrical, thermal, optical and mechanical aspects, which also makes it suitable for electronic information, aerospace, energy conservation and environmental protection, biomedicine, energy storage equipment, energy and All aspects such as thermal management have very broad prospects, and are called "the king of new materials".

Strictly speaking, graphene is a single-layer structure, but in practical applications, few-layer graphene often exhibits excellent engineering properties. Therefore, the basic consensus in the industry is that structures with 10 layers or even thicker are collectively referred to as graphite. vinyl material. Among these materials, 3D porous graphene has high surface area while maintaining high electron mobility and mechanical stability, and is widely used in many fields such as supercapacitors, sensors, catalysis, environmental remediation, and gas adsorption.

The traditional three-dimensional porous graphene structure fabrication methods mainly include: (1) Assembling graphene oxide (GO) into foams, which requires the preparation of graphene oxide precursors through its oxidative acid synthesis route. (2) Three-dimensional porous graphene can also be produced by chemical vapor deposition (CVD) on porous substrates, but high temperature conditions and subsequent etching and drying processes may hinder its large-scale production. (3) Recently, a facile and scalable method was developed to laser engrave carbon-rich substrates to obtain 3D porous graphene, which is also known as laser-induced graphene (LIG).

Generally speaking, the preparation process of laser-induced graphene is as follows: under normal environmental conditions, carbon-containing precursor materials, such as polyimide (PI), are irradiated by a commercial CO ₂ infrared laser engraving machine at a certain laser power, After photochemical and thermochemical processes, the carbon-containing precursor is transformed into LIG, while other parts are emitted in the form of gas, and the generation of gas also promotes the formation of the three-dimensional porous structure of LIG. Since CO ₂ infrared lasers are a common tool in machine shops, this one-step method for laser-induced graphene (LIG) production offers significant advantages over conventional 3D graphene synthesis methods. This approach simplifies the process and reduces costs by avoiding the use of GO precursors compared to the laser-reduced graphene method (the laser reduces GO thin films to graphene). In particular, this method can be designed by a computer program to pattern the LIG obtained by the one-step method, which greatly promotes the application of 3D porous graphene in electronic devices such as supercapacitors and sensors.

At present, the precursors that can be used to prepare LIG are all carbon-rich materials, and there are two main categories, one is polymer plastics represented by PI, and the other is cellulose- or lignin-rich materials ( such as wood, paper, bread, and even potatoes). However, the former is expensive and easily pollutes the environment; the latter often requires flame retardant treatment before laser irradiation due to the low ignition point of the material. In addition, the solubility of cellulose and lignin is extremely low, and it is not easy to form a film, which limits the application of laser-induced graphene to a certain extent.

Therefore, exploring new LIG precursors is still an important topic. In view of this, the present invention is proposed.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a preparation method of laser-induced graphene, aiming to provide a highly water-soluble, biocompatible and biodegradable precursor material, which can be induced by laser without any chemical treatment. Preparation of graphene materials.

Another object of the present invention is to provide a laser-induced graphene with good biodegradability and short preparation process.

The third object of the present invention is to provide the application of the above-mentioned laser-induced graphene in the preparation of electronic devices.

The present invention is realized in this way:

In a first aspect, the present invention provides a method for preparing laser-induced graphene, comprising: laser-induced reduction of chitosan hydrochloride to prepare laser-induced graphene; the structural formula of the cationic part of chitosan hydrochloride is as follows :

where n is an integer greater than 1.

In an optional embodiment, the molecular weight of chitosan hydrochloride is 550-650, and the degree of deacetylation is greater than 80%.

In an optional embodiment, a laser is used to directly perform laser-induced reduction on the chitosan hydrochloride powder.

In an optional embodiment, the chitosan hydrochloride solution is obtained after dissolving the chitosan hydrochloride, and the chitosan hydrochloride solution is subjected to vacuum defoaming, and then coated on a mold for drying to form a film, Laser-induced reduction of film-like samples was carried out using a laser.

In an optional embodiment, a blending raw material is added during the preparation of the chitosan hydrochloride solution, and the blending raw material is selected from at least one of coke, charcoal, graphite, graphene oxide, cellulose and lignin kind.

In an optional embodiment, the process of drying to form a film includes first drying at 60-80°C, and then performing secondary drying at 20-30°C until drying is complete;

Preferably, the drying time of the primary drying is 25-40 h, and the drying time of the secondary drying is 15-30 h.

In an optional embodiment, the laser is an infrared laser;

Preferably, a carbon dioxide laser in an infrared laser is used, and in the process of laser-induced reduction, a laser reduction and a secondary laser reduction are performed in sequence, and the first laser reduction is controlled to have a stepping speed of 25-35 mm/s, and a stepping pixel of 1 -5, the laser power is 5.4-5.8% of the rated power of 40W; the secondary laser reduction is to control the stepping speed to be 25-35mm/s, the stepping pixel to be 1-5, and the laser power to be 4.8-5.2% of the rated power of 40W .

In an optional embodiment, the concentration of chitosan hydrochloride in the chitosan hydrochloride solution is 0.01-0.20 g/mL;

Preferably, vacuum defoaming is performed in a vacuum dryer for 8-15 minutes.

In a second aspect, the present invention provides a laser-induced graphene prepared by the preparation method of any one of the foregoing embodiments.

In a third aspect, the present invention provides the application of the laser-induced graphene in the foregoing embodiments in the preparation of electronic devices, and the preparation of electronic devices includes semiconductor device manufacturing and packaging.

The invention has the following beneficial effects: using highly water-soluble, biocompatible and biodegradable chitosan hydrochloride as a raw material, laser-induced graphene is prepared by a laser-induced method, without any chemical treatment in the preparation process, The process is simple and easy, and is suitable for industrial application. The prepared laser-induced graphene can further prepare electronic devices such as supercapacitors and sensors, and has broad application prospects.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation of the scope, and for those of ordinary skill in the art, other related drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the schematic diagram of the technical scheme of laser-induced chitosan hydrochloride to realize the preparation of various types of graphene materials;

Figure 2 is a physical flow chart of a specific implementation case;

Figure 3 is a text flow chart of a specific implementation case;

Fig. 4 is the Raman spectrum of chitosan hydrochloride laser-induced graphene material;

Figure 5 is a scanning electron microscope image of chitosan hydrochloride laser-induced graphene.

Detailed ways

In order to make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not indicated in the examples, it is carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used without the manufacturer's indication are conventional products that can be purchased from the market.

Through long-term and continuous exploration, the inventor has made continuous attempts for laser-induced precursor materials, and finally found that using chitosan hydrochloride as the precursor can overcome many defects in the prior art, and has the following advantages: (1 ) It is highly water-soluble and easy to form film, which lays the foundation for wide application; (2) It is biocompatible and biodegradable, and the prepared graphene material is an environmentally friendly product; (3) The preparation process does not require flame retardant and other chemical treatment, the process is simple and easy, suitable for industrial application.

Chitosan is a linear, semi-crystalline cationic polysaccharide produced by partial deacetylation of chitin and is the second most abundant natural biopolymer in nature. It has a wide range of sources and can be extracted at low cost, as well as biocompatibility and biodegradability. However, chitosan itself is not directly soluble in water, which limits its application. Benefiting from its structurally abundant substitution and cross-linking sites and the cleavable properties of polymer chains, a large number of functional water-soluble chitosan derivatives have been developed, such as chitosan hydrochloride.

Chitosan hydrochloride is a strong cationic water-soluble chitosan derivative, usually obtained by protonation modification of chitosan. Compared with chitosan, the water solubility of chitosan hydrochloride is significantly increased, but other physiological and functional properties are basically preserved, which greatly expands the application of chitosan compounds.

An embodiment of the present invention provides a method for preparing laser-induced graphene, comprising: performing laser-induced reduction on chitosan hydrochloride to prepare laser-induced graphene; the structural formula of the cation part in chitosan hydrochloride is as follows:

where n is an integer greater than 1.

In some embodiments, the molecular weight of the chitosan hydrochloride is 550-650, and the degree of deacetylation is greater than 80%. It is appropriate to control the molecular weight of chitosan hydrochloride within the above range. If the molecular weight is too large and too viscous, it is not easy to remove air bubbles, and the uniformity of the obtained material is also poor.

Please refer to FIG. 1, the method for preparing graphene by using chitosan hydrochloride is roughly divided into three realization forms, including: (1) using a laser to directly carry out laser-induced reduction of chitosan hydrochloride powder, which can be prepared Obtain graphene or graphene quantum dots or graphene mesoporous material; (2) obtain chitosan hydrochloride solution after dissolving chitosan hydrochloride, carry out vacuum defoaming of chitosan hydrochloride solution, and then It is coated on the mold for drying to form a film, and the film-like sample is subjected to laser-induced reduction by a laser, as shown in Figure 2 and Figure 3, which can be used to prepare graphene or graphene mesoporous materials; (3) The Chitosan hydrochloride, blending raw materials and solvent are mixed and dissolved to obtain a chitosan hydrochloride solution. The chitosan hydrochloride solution is vacuum-defoamed, and then coated on a mold for drying to form a film. Laser-induced reduction of film-like samples can be used to prepare graphene or graphene composites.

Specifically, the blending raw material is selected from at least one of coke, charcoal, graphite, graphene oxide, cellulose and lignin, and the blending raw material can be one or more, which is not limited here. By adding blended raw materials, graphene materials can be endowed with more functions to meet different application requirements.

In some embodiments, the concentration of chitosan hydrochloride in the chitosan hydrochloride solution is 0.01-0.20g/mL, specifically 0.01g/mL, 0.02g/mL, 0.03g/mL, 0.04g /mL, 0.05g/mL, 0.06g/mL, 0.07g/mL, 0.08g/mL, 0.10g/mL, 0.11g/mL, 0.12g/mL, 0.13g/mL, 0.14g/mL, 0.15g /mL, 0.16g/mL, 0.17g/mL, 0.18g/mL, 0.19g/mL, 0.20g/mL, etc., can also be any value between the above adjacent concentration values.

Specifically, the solvent used to prepare the chitosan hydrochloride solution can be water or other organic solvents, which are not listed here.

In some embodiments, vacuum defoaming is performed in a vacuum dryer for 8-15 minutes. For chitosan hydrochloride with larger molecular weight, vacuum defoaming can be used to quickly achieve the purpose of defoaming. Can be any value between the above adjacent time values.

Specifically, the mold (or film-forming device) used for film formation can be a general boxed mold, and the bottom surface can be flat, and the chitosan hydrochloride solution is coated on the mold to obtain a film-like shape after drying. sample.

In some embodiments, the process of drying to form a film includes first drying at 60-80° C., and then performing secondary drying at 20-30° C. to complete drying; the drying time for the primary drying is 25- 40h, the drying time of the secondary drying is 15-30h. The inventor found that if it is completely dried under the condition of 60-80 ° C, the chitosan hydrochloride will curl, and a flat film cannot be formed; by adopting a two-step drying method, the curling phenomenon can be avoided, and the degree of tortuosity can be obtained. and chitosan hydrochloride film samples with less film stress. Specifically, the method of drying to form the film is not limited, and the method of baking at a high temperature in an oven or a vacuum dryer can be used for drying.

Specifically, the primary drying temperature can be 60°C, 65°C, 70°C, 75°C, 80°C, etc., or any value between the above adjacent temperature values; the primary drying time can be 25h, 28h, 30h , 32h, 35h, 38h, 40h, etc., can also be any value between the above adjacent time values. The temperature of secondary drying can be 25°C, 28°C, 30°C, 33°C, 35°C, 38°C, 40°C, etc., or any value between the above adjacent temperature values; the time of secondary drying can be 15h, 18h, 20h, 22h, 25h, 28h, 30h, etc., can also be any value between the above adjacent time values.

Further, the laser-induced reduction of the film-like sample by a laser is to use the high temperature irradiated by the laser to the surface of the film sample to rapidly carbonize chitosan hydrochloride to form porous graphene. The laser is an infrared laser, which can rapidly carbonize chitosan hydrochloride.

In some embodiments, using a carbon dioxide laser in an infrared laser, in the process of laser-induced reduction, a laser reduction and a secondary laser reduction are sequentially performed, and the step speed of the first laser reduction is controlled to be 25-35mm/s, and the step The pixel is 1-5, and the laser power is 5.4-5.8% of the 40W rated power (such as 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, etc.); the secondary laser reduction is to control the stepping speed to 25-35mm/ s, the stepping pixels are 1-5, and the laser power is 4.8-5.2% of the rated power of 40W (such as 4.8%, 4.9%, 5.0%, 5.1%, 5.2%, etc.).

It should be noted that the inventors found that if only one laser reduction is performed, the quality of the graphene material obtained is relatively poor, the intensity of the 2D characteristic peak obtained from the Raman characterization is low, the wave peak is wide, and the number of graphene layers is thick. .

Specifically, the step speed of the two laser reductions can be 25mm/s, 26mm/s, 27mm/s, 28mm/s, 29mm/s, 30mm/s, 31mm/s, 32mm/s, 33mm/s, 34mm /s, 35mm/s, etc., can also be any value between the above adjacent stepping speeds; stepping pixels can be 1, 2, 3, etc.

The embodiment of the present invention also provides a kind of laser-induced graphene, which is prepared by the preparation method in the foregoing embodiment, the preparation process is simple and easy, no chemical treatment is required, and the product can be in various forms, such as graphene quantum dots, graphite Graphene mesoporous materials and graphene composite materials, etc., can be further prepared to form environmentally friendly and human-friendly electronic devices, such as supercapacitors and sensors.

In addition, due to its excellent electrical and thermal conductivity, laser-induced graphene can also have potential application value in the manufacture and packaging of advanced semiconductor devices, such as three-dimensional chip integration, advanced packaging material preparation, and 5G RF chip packaging.

The features and performances of the present invention will be further described in detail below in conjunction with the embodiments.

Example 1

The present embodiment provides a method for preparing laser-induced graphene, including:

(1) Weigh 10 grams of chitosan hydrochloride powder (molecular weight 610.866) into a beaker, add 150 mL of deionized water, and slowly dissolve under the stirring of a magnetic stirrer to obtain a chitosan hydrochloride solution.

(2) Transfer the beaker containing the chitosan hydrochloride solution to a vacuum dryer, and carry out vacuum treatment under low vacuum for 10 minutes to obtain a bubble-free and uniform chitosan hydrochloride solution.

(3) 20 mL of chitosan hydrochloride solution was drawn with a pipette and transferred to a plastic circular sample box with a diameter of 66 mm and a height of 12 mm.

(4) Transfer the circular plastic box and the chitosan hydrochloride liquid contained in it to a vacuum dryer, and after drying at 70°C for 36 hours, transfer the incompletely dried samples to room temperature (25°C) It was further slowly dried for 24 hours, and a chitosan hydrochloride film sample with less tortuosity and less film stress was obtained by two-step drying.

(5) The chitosan hydrochloride film sample was induced to be reduced by a commercial CO ₂ laser in an ambient atmosphere, and the high temperature of the laser irradiated on the surface of the film sample caused the chitosan hydrochloride to be rapidly carbonized to form porous Graphene. Two-step laser irradiation was used, the first laser condition was that the laser spot was focused on the sample surface, the stepping speed was 30 mm/s, the stepping pixel was 2, and the laser power was 5.6% of the rated laser power (40 W). The second laser condition is that the laser spot is focused on the sample surface, the stepping speed is 30 mm/s, the stepping pixel is 2, and the laser power is 5.0% of the rated laser power (40 W).

Example 2

This embodiment provides a method for preparing laser-induced graphene, including: adding 3 g of cellulose when preparing a chitosan hydrochloride solution.

The inventor found that adding cellulose can have the following advantages: (1) chitosan hydrochloride can be flame retardant for cellulose, so that it can be converted into LIG without flame retardant under normal temperature and normal pressure air atmosphere, (2) obtained The quality of the products is better, which is embodied in: the number of graphene layers is less and the conductivity is stronger.

Comparative Example 1

This comparative example provides a preparation method of laser-induced graphene, the only difference from Example 1 is that the chitosan hydrochloride is replaced with an equivalent amount of chitosan (deacetylation degree ≥ 95%), and an equivalent amount of chitosan is used. The volume fraction of 5% acetic acid solution was dissolved, and the chitosan film obtained after the same operation was treated with a laser under the same conditions.

The results showed that the target product LIG could not be obtained after trying various laser conditions.

Test Example 1

The Raman spectrum of the product obtained in Test Example 1 is shown in Figure 4 .

As can be seen from Figure 4, the characteristic peaks such as G peak, D peak and 2D peak in the Raman spectrum indicate that the obtained product is LIG, that is, laser-induced graphene, and a higher D peak indicates that the obtained LIG has more defect state, which is consistent with the reported properties of LIG. Furthermore, the sharp 2D peaks indicate the characteristic of the resulting LIG few layers. Raman spectroscopy qualitatively describes the properties of the resulting LIGs.

Test Example 2

The electron microscope image of the graphene material was obtained in Test Example 1, and the result is shown in FIG. 5 . In FIG. 5 , (a)-(b) are 100 μm and 10 μm, respectively.

It can be seen from Fig. 5 that the prepared graphene exhibits sheet-like characteristics and has a porous structure, and the size of the pores ranges from several microns to tens of microns, which is consistent with the three-dimensional porous graphene reported in the literature. Features are the same.

To sum up, the present invention provides a preparation method of laser-induced graphene, laser-induced graphene and application thereof, using highly water-soluble, biocompatible and biodegradable chitosan hydrochloride as a raw material, through laser Laser-induced graphene is prepared by an induced method. The raw material chitosan hydrochloride powder required by the method of the invention is green and environmentally friendly, and can also be made into a film or mixed with other substances to make pulp, the preparation process is simple, efficient, and the production cost is low, and is suitable for mass production of functionalized graphite vinyl material.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A preparation method of laser-induced graphene is characterized by comprising the following steps: performing laser-induced reduction on chitosan hydrochloride to prepare the laser-induced graphene; the structural formula of the cation part in the chitosan hydrochloride is as follows:

wherein n is an integer greater than 1.

2. The method as claimed in claim 1, wherein the molecular weight of the chitosan hydrochloride is 550-650 and the degree of deacetylation is greater than 80%.

3. The preparation method according to claim 2, wherein the chitosan hydrochloride powder is directly subjected to laser-induced reduction by using a laser.

4. The preparation method according to claim 2, characterized in that the chitosan hydrochloride solution is obtained after dissolving the chitosan hydrochloride, the chitosan hydrochloride solution is vacuumed, and then coated on a mold for drying and film forming, and the film-shaped sample is subjected to laser-induced reduction by a laser.

5. The method according to claim 4, wherein a blending raw material selected from at least one of coke, charcoal, graphite, graphene oxide, cellulose, and lignin is added during the preparation of the chitosan hydrochloride solution.

6. The preparation method according to claim 4, wherein the drying to form the film comprises performing primary drying at 60-80 ℃, and then performing secondary drying at 20-30 ℃ until the drying is complete;

preferably, the drying time of the primary drying is 25-40h, and the drying time of the secondary drying is 15-30 h.

7. The method of manufacturing according to claim 4, wherein the laser is an infrared laser;

preferably, the laser adopts a carbon dioxide laser in an infrared laser, and primary laser reduction and secondary laser reduction are sequentially carried out in the laser-induced reduction process, wherein the primary laser reduction is carried out by controlling the stepping speed to be 25-35mm/s, the stepping pixel to be 1-5 and the laser power to be 5.4-5.8% of the rated power of 40W; the secondary laser reduction is to control the stepping speed to be 25-35mm/s, the stepping pixel to be 1-5 and the laser power to be 4.8-5.2% of the rated power of 40W.

8. The production method according to claim 4, wherein the concentration of the chitosan hydrochloride in the chitosan hydrochloride solution is 0.01 to 0.20 g/mL;

preferably, the vacuum defoaming is carried out in a vacuum drier for 8-15min by vacuumizing.

9. Laser-induced graphene prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the laser-induced graphene according to claim 9 for the preparation of an electronic device;

preferably, preparing the electronic device includes semiconductor device fabrication and packaging.

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