阅读说明：本技术 一种3d打印制备三维石墨烯结构的方法 (Method for preparing three-dimensional graphene structure through 3D printing ) 是由 罗斯达 刘福 高燕 于 2021-08-27 设计创作，主要内容包括：本发明提供了一种3D打印制备三维石墨烯结构的方法。该方法利用激光选择碳化技术,以聚合物粉末为原材料,将聚合物粉末直接转化为石墨烯结构,再通过逐层累加,得到三维石墨烯结构。并且本发明通过设计、研究激光加工条件、铺粉厚度等参数对三维石墨烯结构的成型、性能的影响,通过采用后处理工艺,从而大大提升了材料的均质性、比表面积、孔隙率和导电率,从而使其应用于超级电容器电极材料时具有更高的比电容、能量密度和功率密度。本发明提出了一种高效、可靠的三维石墨烯的成型方法,在维持三维石墨烯外形形貌的同时,提高了三维石墨烯的综合性能。(The invention provides a method for preparing a three-dimensional graphene structure through 3D printing. The method utilizes a laser selective carbonization technology, takes polymer powder as a raw material, directly converts the polymer powder into a graphene structure, and then obtains the three-dimensional graphene structure through layer-by-layer accumulation. In addition, through designing and researching the influence of parameters such as laser processing conditions, powder laying thickness and the like on the forming and performance of the three-dimensional graphene structure and adopting a post-treatment process, the homogeneity, the specific surface area, the porosity and the conductivity of the material are greatly improved, so that the material has higher specific capacitance, energy density and power density when being applied to a super capacitor electrode material. The invention provides an efficient and reliable three-dimensional graphene forming method, which improves the comprehensive performance of three-dimensional graphene while maintaining the appearance and the shape of the three-dimensional graphene.)

1. A method for preparing a three-dimensional graphene structure through 3D printing comprises the following steps:

s1, processing a substrate, namely fixing Polyimide (PI) paper on a bottom plate, and performing laser induction on the PI paper to generate a laser-induced graphene (LIG) substrate;

s2, spreading powder, namely spreading polymer powder on the surface of the substrate LIG, wherein the thickness of the powder layer is 60% -80% of the growth height of graphene;

s3 laser Induction, using 10.6 μm CO₂Laser selective carbonization of the laid polymer powder to form the pre-designedA single layer graphene film;

s4, continuing to spread powder, spreading a layer of polymer powder on the surface of the formed graphene, wherein the thickness of the powder layer is 60% -80% of the growth height of the graphene;

s5 laser Induction, using 10.6 μm CO₂Carrying out laser selective carbonization on the paved polymer powder by laser to form a pre-designed single-layer graphene film;

s6, printing layer by layer, and repeating the steps S4 and S5 repeatedly until printing is finished to obtain a three-dimensional graphene structure;

s7 post-processing, namely soaking the three-dimensional graphene structure obtained in the S6 in an organic solvent, and then heating to obtain an optimized three-dimensional graphene structure;

the relation between the adopted laser processing power and the powder spreading thickness is as follows: l ═ a (93.5x-15.5), where a represents the correlation coefficient, in (60% to 80%), x represents the laser power in W, and L represents the laydown thickness in μm.

2. The method of claim 1, wherein the CO is selected from the group consisting of S3 and S5₂The laser focal length, the scanning speed and the printing resolution of the laser are respectively 33.1-43.1mm, 2.54-203.2mm/s and 10-1000ppi/inch, the laser power is 0.25-25W, and the laser selective carbonization can be carried out under the condition of room temperature and atmospheric environment.

3. The method of claim 1, wherein the substrate is a laser-induced PI paper-produced graphene film.

4. The method of claim 1, wherein the laser selective carbonization in S3 and S5 is performed with a single induction.

5. The method according to any one of claims 1 to 4, wherein the polymer powder has a particle size of 10 μm or less.

6. The method of any one of claims 1-4, wherein the polymer powder is a thermoplastic powder comprising Polyimide (PI), polyphenylene sulfide (PPS), Polyetherimide (PEI), or Polyetheretherketone (PEEK) powder.

7. The method according to any one of claims 1 to 4, wherein the organic solvent in S7 comprises one or more of N-methylpyrrolidone (NMP), N-Dimethylformamide (DMF), and N, N-Dimethylacetamide (DMAC).

8. The method according to any one of claims 1 to 4, wherein the heating treatment in S7 is: heating to 800 ℃ under the protective atmosphere, and keeping the temperature for 2 hours.

9. The method of any one of claims 1 to 4, wherein the S6-obtained three-dimensional graphene structure has an interlayer conductivity of 0.1-20.5S/m, an interfacial conductivity of 0.1-250.5S/m, and a density of 30-200mg/cm³The specific surface area is 10-500m²/g。

10. The method of any one of claims 1 to 4, wherein the S7-derived three-dimensional graphene structure has an interlayer conductivity of 0.1-50.5S/m, an interfacial conductivity of 0.1-500.5S/m, and a density of 10-50mg/cm³The specific surface area is 10-1050m²/g。

11. The method according to any one of claims 1 to 4, wherein the three-dimensional graphene structure obtained by S7 can be a cube, a cuboid, a cylinder, a cavity, a hollow structure, or a honeycomb structure.

12. Use of the three-dimensional graphene structure prepared according to any one of claims 1 to 11, wherein the three-dimensional graphene structure is useful as a sensor, a heater, an energy storage device, an electrical generating device, an adsorption interface, a flame retardant interface, a catalyst.

Technical Field

The invention belongs to the field of graphene material preparation, and particularly relates to a method for preparing a three-dimensional graphene structure through 3D printing.

Background

Graphene is a two-dimensional carbon nano material and is formed by sp²The hybridized carbon atoms are in a two-dimensional plane structure formed by network connection. The graphene has excellent properties such as large specific surface area, corrosion resistance, good electrical properties, extremely high mechanical properties and the like, so that the graphene has very large potential application in the material field, the flexible electronic field and the energy storage field. The three-dimensional graphene serving as a three-dimensional macroscopic material of graphene has the excellent characteristics of two-dimensional graphene, and also has an ultra-large specific surface area and a special conductive network. These properties make it widely applicable in the fields of energy storage, catalysts, environmental protection, sensors, biomedical, optics and thermal, etc.

The traditional preparation method of the three-dimensional graphene mainly comprises the following steps: template-assisted methods, self-assembly methods, and the like. However, the above methods all require the use of a large amount of chemical reagents and have severe requirements on the preparation environment. The existence of chemical reagents can affect the performance of the graphene material; in addition, the method has complex processing process and high cost, and the preparation cost and period are seriously influenced; in addition, the three-dimensional graphene material prepared by the method is simple in appearance structure, is mostly a regular cube, and is difficult to obtain a shell, a cavity and other complex structures.

In recent years, the application of 3D printing technology in the preparation of three-dimensional graphene materials is becoming popular. Researchers take graphene oxide, graphene-based mixed slurry and the like as precursors, and prepare three-dimensional graphene aerogel and three-dimensional graphene composite materials through 3D printing. However, the processing method still has a complex processing process, for example, in the technology of preparing three-dimensional graphene by 3D printing using graphene oxide as a raw material, the preparation process needs to perform dispersion and chemical reduction of graphene oxide; in the technology of preparing the three-dimensional graphene by 3D printing of the graphene mixed slurry, the dispersion of the graphene needs the assistance of an additional chemical reagent, and the consumed time is long; and the three-dimensional structures prepared by the two methods are both graphene composite materials, and are not three-dimensional graphene materials with complete significance.

Sha et al prepared three-dimensional graphene foam with complete structure by layer-by-layer assembly method by using 3D printing technology, and each layer of powder was treated with CO in experiments₂And (3) carbonizing by laser, and manually supplying nickel powder and cane sugar powder layer by layer to synthesize the independent three-dimensional graphene foam in situ. Compared with the prior 3D printing technology, the method for preparing the three-dimensional graphene material has simpler processing process, but still has a plurality of defects. Firstly, the technology needs nickel as a template, and the nickel is removed by adopting a chemical reaction method in the formed three-dimensional structure; secondly, in the process of mixing the nickel and the cane sugar, a plurality of steps of dispersing, mechanically stirring, heating and the like are required, and the consumed time is long; thirdly, in the laser carbonization process, the carbonization needs to be carried out under the hydrogen protective atmosphere; finally, the formed three-dimensional graphene structure is different from the originally designed structure, deformation and shrinkage exist, the appearance is simple, most of the three-dimensional graphene structure is solid structures such as blocks, and the forming of the complex three-dimensional structure is difficult to realize.

Luong et al utilize a layered Object Manufacturing technique (layered Object Manufacturing) using a polyimide film as a raw material and CO as a carrier gas₂Carbonizing by laser, and preparing the three-dimensional graphene foam by a layer-by-layer assembly method; in order to realize the three-dimensional graphene foam with a certain shape and structure, the formed three-dimensional structure is cut by using fiber laser. This processing method is simpler than the prior 3D printing technology using sucrose as a carbon source, but still has many disadvantages. Firstly, the processing technology is to perform front and back (double-sided) graphene on a polyimide film, and then bond the formed graphene film layer by layer into a three-dimensional entity through a chemical reagent, wherein the process needs the assistance of a binder, and after the formation, the binder is removed under the high-temperature condition of 200 ℃, and then the residual polymer is removed under the high-temperature condition of 600 ℃; secondly, the process of preparing graphene by laser-induced polyimide film is caused by the property of thermal shrinkage of the filmThe generated graphene film can generate deformation such as folds and the like, which can seriously affect the precision of the formed three-dimensional graphene; finally, the structure with the complex appearance is difficult to be formed at one time, and an additional laser auxiliary processing technology is needed for realizing components such as a simple shell, a cavity and the like; however, the three-dimensional graphene structure with complex shapes such as variable cross-section and hollow-out is still difficult to realize.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a method for preparing a three-dimensional graphene structure by 3D printing. The method utilizes a laser selective carbonization technology, takes polymer powder as a raw material, directly converts the polymer powder into a graphene structure, and then obtains the three-dimensional graphene structure through layer-by-layer accumulation. The method specifically comprises the following steps:

s1, processing a substrate, namely fixing Polyimide (PI) paper on a bottom plate, and performing laser induction on the PI paper to generate a laser-induced graphene (LIG) substrate;

s2, spreading powder, namely spreading polymer powder on the surface of the substrate LIG, wherein the thickness of the powder layer is 60% -80% of the growth height of graphene;

s3 laser Induction, using 10.6 μm CO₂Carrying out laser selective carbonization on the paved polymer powder by laser to form a pre-designed single-layer graphene film;

s4, continuing to spread powder, spreading a layer of polymer powder on the surface of the formed graphene, wherein the thickness of the powder layer is 60% -80% of the growth height of the graphene;

s5 laser Induction, using 10.6 μm CO₂Carrying out laser selective carbonization on the paved polymer powder by laser to form a pre-designed single-layer graphene film;

s6, printing layer by layer, and repeating the steps S4 and S5 repeatedly until printing is finished to obtain a three-dimensional graphene structure;

s7 post-processing, namely soaking the three-dimensional graphene structure obtained in the S6 in an organic solvent, and then heating to obtain an optimized three-dimensional graphene structure;

the relation between the adopted laser processing power and the powder spreading thickness is as follows: l ═ a (93.5x-15.5), where a represents the correlation coefficient, in (60% to 80%), x represents the laser power in W, and L represents the laydown thickness in μm.

Further, CO in S3 and S5₂The laser focal length, the scanning speed and the printing resolution of the laser are respectively 33.1-43.1mm, 2.54-203.2mm/s and 10-1000ppi/inch, the laser power is 0.25-25W, and the laser selective carbonization can be carried out under the condition of room temperature and atmospheric environment.

Further, the substrate is a graphene film produced by laser-induced PI paper.

Further, the particle size of the polymer powder is 10 μm or less.

Further, the polymer powder is thermoplastic powder, and includes Polyimide (PI), polyphenylene sulfide (PPS), Polyetherimide (PEI) or Polyetheretherketone (PEEK) powder.

Further, the laser selective carbonization in S3 and S5 uses a single induction.

Further, the organic solvent in S7 includes one or more of N-methylpyrrolidone (NMP), N-Dimethylformamide (DMF), and N, N-Dimethylacetamide (DMAC).

Further, the heating treatment in S7 is: heating to 600-.

Furthermore, the conductivity between the three-dimensional graphene structures obtained by the S6 is 0.1-20.5(S/m), the interfacial conductivity is 0.1-250.5(S/m), and the density is 30-200 (mg/cm)³) The specific surface area is 10-500 (m)²/g)。

Furthermore, the interlayer conductivity of the three-dimensional graphene structure obtained by the S7 is 0.1-50.5(S/m), the interfacial conductivity is 0.1-550.5(S/m), and the density is 10-50 (mg/cm)³) The specific surface area is 10-1050 (m)²/g)。

Further, the three-dimensional graphene structure obtained in S7 may be a cube, a cuboid, a cylinder, a cavity, a hollow structure, or a honeycomb structure.

The three-dimensional graphene structure prepared by the method can be used as a sensor, a heater, an energy storage device, a power generation device, an adsorption interface, a flame-retardant interface and a catalyst.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the method for preparing the three-dimensional graphene structure through 3D printing, the polymer powder with the particle size of less than or equal to 10 microns is adopted, during processing, the powder volume change is small, the flowing speed is high, the generated deformation is small, and the precision of a molded sample is effectively improved.

2. According to the invention, the 3D printing process of graphene is a layer-by-layer accumulation process, and the forming of the first layer of graphene film influences the thickness of the subsequent powder laying layer, so that the subsequent forming is influenced; in particular, the growth height of the graphene film produced after laser induction of the polymer determines the powder thickness. If the powder is too thick, after the second induction, all the powder cannot be carbonized by laser, so that powder without carbonization exists between the first-time formed graphene and the second-time formed graphene to form layering, the first layer and the bottom layer and the layers are connected unstably, and finally three-dimensional graphene collapses, and the three-dimensional entity cannot be formed continuously. If the powder is spread to be too thin, after the second induction, excessive laser energy can excessively carbonize the graphene formed for the first time, and even can directly burn off, so that the three-dimensional graphene cannot be molded continuously. According to the method, through theoretical and experimental researches on the cross section of the graphene film generated by directly inducing the polymer powder by laser, the growth height of the graphene is determined, the relation between the laser power and the growth height of the graphene is established, the thickness of the powder laying layer is determined to be 60% -80% of the growth height of the graphene according to the growth height of the graphene, and finally the relation between the laser power and the corresponding powder laying thickness is established.

3. According to the method for preparing the three-dimensional graphene structure through 3D printing, Polyimide (PI) paper is fixed on a bottom plate, and the PI paper is subjected to laser induction to form a laser-induced graphene (LIG) substrate. After the PI paper is induced, the produced LIG film is very flat in surface, the polymer powder is paved on the LIG, and after the PI paper is induced, the produced LIG can be well combined with the LIG on the surface of the PI paper, so that a firm and reliable foundation is provided for subsequent layer-by-layer processing of 3D printing.

4. The method for preparing the three-dimensional graphene structure through 3D printing has the advantages that the forming efficiency and the performance of the formed three-dimensional graphene structure are both considered, the forming interval related to the laser power and the thickness of the powder laying layer is set, and the rapid preparation of the three-dimensional graphene can be realized.

5. The method for preparing the three-dimensional graphene structure by 3D printing can realize direct preparation of three-dimensional graphene structures with various shapes, can realize preparation of three-dimensional structures with complex shapes such as cavities, variable cross-section structures and hollow structures besides simple solid structures such as blocks and columns, and is beneficial to development and research of the three-dimensional graphene structures.

6. The invention provides a post-processing method of three-dimensional graphene, which can thoroughly remove residual polymer powder in a three-dimensional graphene structure while maintaining the appearance and the appearance of the three-dimensional graphene structure, further improves the performance of a formed three-dimensional graphene structure, and obtains the three-dimensional graphene structure with homogeneity, large specific surface area, high porosity and high conductivity; the three-dimensional graphene structure is applied to an electrode material of a super capacitor, and shows excellent energy storage characteristics.

Drawings

Fig. 1 is a schematic view of a 3D printing processing system and a manufacturing flow of a three-dimensional graphene structure.

Fig. 2 and 3 are diagrams of three-dimensional graphene structure samples prepared by 3D printing.

FIG. 4 is a graph of representative samples of five intervals corresponding to the production of laser-induced polymers; fig. 4(a) shows the polymer powder, fig. 4(b) shows the polymer film, fig. 4(c) shows the activated carbon film, fig. 4(d) shows the laser-induced graphene (LIG) film, and fig. 4(e) shows the carbon film having been excessively carbonized.

Fig. 5 is a Raman spectrum of the product of the laser-induced polymer in five bins.

Fig. 6 is a Raman spectrum of a graphene film formed at different laser powers.

Fig. 7 is a scanning electron microscope SEM photograph of the surface of the graphene film formed at different laser powers.

Fig. 8 is a scanning electron microscope SEM photograph of a cross section of a graphene film formed at different laser powers.

Fig. 9 is a graph of growth height data for cross-sections of graphene films formed at different laser powers.

Fig. 10 is a graph showing the relationship between the height of the molded three-dimensional graphene and the powder spreading frequency by setting the powder spreading thickness under different laser powers.

Fig. 11 is a Raman spectrum of three-dimensional graphene prepared from different raw materials.

Fig. 12 is a scanning electron microscope SEM picture of the molded three-dimensional graphene under different laser powers; fig. 12(a) represents a SEM picture of the surface of the three-dimensional graphene formed at a lower laser power; fig. 12(b) represents a SEM picture of the surface of the three-dimensional graphene formed when the laser power is high.

Fig. 13 is a transmission electron microscope TEM picture of the shaped three-dimensional graphene.

Fig. 14 is a test chart and a test result of the molded three-dimensional graphene for the electrode material of the supercapacitor; fig. 14(a) is a diagram of a three-electrode method testing system of a capacitor, and fig. 14(b) is a graph of cyclic voltammetry characteristic and constant current charging and discharging curves of a super capacitor.

Fig. 15 shows the sensing performance of the formed three-dimensional graphene for a sensor: fig. 15(a) shows real-time relative resistance change data when the tensile strain is 0.1%, and fig. 15(b) shows real-time relative resistance change data when the compressive strain is 0.5%.

Detailed Description

Exemplary embodiments of the present invention will be described in more detail below. While exemplary embodiments, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It is to be noted that, unless otherwise specified, technical or scientific terms used herein shall have the ordinary meaning as understood by those skilled in the art to which the present invention belongs.

A method for preparing a three-dimensional graphene structure through 3D printing comprises the following steps:

s1, processing a substrate, namely fixing Polyimide (PI) paper on a bottom plate, and performing laser induction on the PI paper to generate a laser-induced graphene (LIG) substrate;

s2, spreading powder, namely spreading polymer powder on the surface of the substrate LIG, wherein the thickness of the powder layer is 60% -80% of the growth height of graphene;

s3 laser Induction, using 10.6 μm CO₂Carrying out laser selective carbonization on the paved polymer powder by laser to form a pre-designed single-layer graphene film;

s4, continuing to spread powder, spreading a layer of polymer powder on the surface of the formed graphene, wherein the thickness of the powder layer is 60% -80% of the growth height of the graphene;

s5 laser Induction, using 10.6 μm CO₂Carrying out laser selective carbonization on the paved polymer powder by laser to form a pre-designed single-layer graphene film;

s6, printing layer by layer, and repeating the steps S4 and S5 repeatedly until printing is finished to obtain a three-dimensional graphene structure;

and S7 post-treatment, namely soaking the three-dimensional graphene structure obtained in the S6 in an organic solvent, and then heating to obtain an optimized three-dimensional graphene structure.

The preparation method can realize the direct preparation of three-dimensional graphene structures with various shapes, and can realize the preparation of three-dimensional structures with complex shapes such as a cavity 3(c), a variable cross-section structure 3(d) and a hollow structure 3(e) besides simple solid structures such as a block 3(a) and a cylinder 3 (b); the diversity of the macrostructure is more beneficial to developing and researching the wide application of the three-dimensional graphene structure.

According to the invention, by fixing the laser focal length, the scanning speed and the printing resolution and selecting the mode of inducing the powder by lasers with different powers, the polymer powder is found to be divided into 5 stages according to the gradual increase of the laser processing power in the laser induction process: powder particles, PI film, activated carbon film, graphene film, over-carbonized carbon film, i.e., representative samples of corresponding 5 intervals in fig. 4, the powder gradually changed from the initial powder particles 4(a) to the sintered polymer film 4(b), the unstable activated carbon film 4(c), the graphene film 4(d) having excellent performance, and the over-carbon film having severe damageAnd a carbon film 4 (e). The Raman spectroscopy was used to characterize the structure of the product in 5 intervals, as shown in fig. 5, curve a and curve b are polymer powder and polymer film, curve c is activated carbon film, curve d is Laser Induced Graphene (LIG) film, and curve e is over-carbonized carbon film. During the polymer transition, the polymer powder and the polymer film in the corresponding product did not exhibit any peaks; carbon chain and sp in carbon ring are expressed in the corresponding products of activated carbon film and over-carbonized carbon film²D peak of atomic respiratory vibration (1350 cm)^-1) And sp in carbon chain and carbocycle²G peak (1580 cm) of atomic pair stretching vibration^-1) (ii) a The corresponding products are graphene films, and a D peak, a G peak and a 2D characteristic peak generated by the two-phonon resonance are all shown, wherein the 2D peak (2700 cm)^-1) Is a characteristic peak of graphene, and the 2D peak intensity is very high as can be seen from the figure, indicating that a graphene structure is formed. In the graphene processing interval, lasers with different powers are selected for induction to obtain graphene with different tissue morphologies, and Raman spectrum Raman characterization is performed on graphene films generated under different powers, and the result is shown in FIG. 6. As can be seen from fig. 6, the product corresponding to each power shows a D peak, a G peak, and a 2D peak in the graphene structure, again demonstrating the formation of a graphene film in this interval. Through scanning electron microscope SEM observation of graphene films generated under different powers, the surface micro-morphology is shown in figure 7, and the cross-sectional micro-morphology is shown in figure 8. As can be seen from fig. 7, with the gradual increase of the laser power, the graphene film surface undergoes the evolution of a sheet-like structure, a porous structure, a long-strip-like fiber structure, and a shorter fiber-like structure; as can be seen from fig. 8, as the laser power is gradually increased, the growth height of the graphene film is correspondingly increased; according to the analysis of the cross section SEM of the graphene film, a growth height data graph of the cross section of the graphene film formed under different laser powers is established, as shown in FIG. 9, the relation between the laser power and the growth height of the graphene film is obtained by further calculating and fitting, wherein x represents the laser power (unit is W) and h represents the growth height (unit is mum) of the graphene film, and then the optimal powder laying is determined according to the growth height of the graphene and experimental researchThe thickness of the layer is 60% -80% of the growth height of the graphene, and further the relation between the laser processing power and the corresponding thickness of the powder laying layer is established, wherein L is a (93.5 x-15.5%), wherein a is (60% -80%), x represents the laser power (unit is W), h represents the growth height (unit is mum) of the graphene film, and L represents the thickness (unit is mum) of the powder laying layer. Based on the above studies, the relationship between the height of the three-dimensional graphene and the number of times of powder spreading was investigated under the condition that the laser power and the thickness of the powder spreading layer were constant, and the result is shown in fig. 10. As can be seen from fig. 10, as the number of times of powder spreading increases, the height of the three-dimensional graphene gradually increases, and a linear change relationship is shown, as shown in table 1.

According to the relationship shown in table 1, one skilled in the art can achieve selective printing of three-dimensional graphene processing rates by selecting different powers.

TABLE 1 relationship between height H (μm) of three-dimensional graphene and the number of powder spreading n

Laser power (W)	Powder layer thickness (mum)	Relation between three-dimensional graphene height H (mum) and powder paving times n (not less than 5)
			0.75	30	H＝52.6*n-30
1	50	H＝83.9*n-118
			1.5	100	H＝115.9*n+127
2	150	H＝201.9*n-35
			2.5	200	H＝267.7*n-95

Three-dimensional graphene structures were prepared using Polyimide (PI), polyphenylene sulfide (PPS), Polyetherimide (PEI), and Polyetheretherketone (PEEK) powders as raw materials, respectively, and analyzed by raman spectroscopy, and as a result, as shown in fig. 11, the three-dimensional structures all exhibited a D peak (1350 cm) of graphene^-1) G peak (1580 cm)^-1) And 2D peak (2700 cm)^-1) The graphene structure obtained by the preparation method is proved. Different processing powers are selected to prepare the three-dimensional graphene, wherein the laser power and the thickness of the corresponding powder laying layer are shown in table 1, and the surface appearance of the prepared three-dimensional graphene is shown in fig. 12. The surface appearance of the three-dimensional graphene formed by the polymer induced by the laser is consistent with that of a single-layer graphene film, and the surface of the three-dimensional graphene gradually changes from a lamellar structure to a fluffy fibrous structure along with the change of power. Fig. 12(a) represents a SEM picture of a typical surface of a three-dimensional graphene formed at a lower laser power, in which a porous network structure of the graphene can be clearly observed; fig. 12(b) represents a typical surface SEM picture of the three-dimensional graphene formed at a higher laser power, in which a fibrous graphene structure can be clearly observed.

Example 1

A method for preparing a three-dimensional graphene structure through 3D printing comprises the following steps:

s1, processing a substrate, namely fixing Polyimide (PI) paper on an aluminum plate, and performing laser induction on the PI paper to generate a laser-induced graphene (LIG) substrate;

s2 spreading the polyimide powder uniformly on the LIG surface of S1 in air atmosphere, and performing selective graphitization on the polyimide powder by a laser at a power of 1W, a scanning speed of 50.8mm/S and a printing resolution of 500;

s3, continuously spreading powder, and spreading the powder for the second time on the surface of the formed graphene, wherein the spreading thickness is 50 microns;

s4 laser induction, performing selective graphene oxidation on polyimide powder by a laser at the power of 1W, the scanning speed of 50.8mm/S and the printing resolution of 500 to form a pre-designed single-layer graphene film;

s5, printing layer by layer, repeating the steps S4 and S5 repeatedly, and finishing the printing of the three-dimensional structure after the powder spreading times are accumulated to 280 times;

and S6 post-treatment, namely soaking the three-dimensional graphene structure obtained in the S6 in an organic solvent, and then preserving heat at 800 ℃ for 2h to obtain an optimized three-dimensional graphene structure. As shown in fig. 2.

Example 2

S1, processing a substrate, namely fixing Polyimide (PI) paper on an aluminum plate, and performing laser induction on the PI paper to generate a laser-induced graphene (LIG) substrate;

s2 spreading the polyimide powder uniformly on the LIG surface of S1 in air atmosphere, and performing selective graphitization on the polyimide powder by a laser at a power of 1.5W, a scanning speed of 50.8mm/S and a printing resolution of 500;

s3, continuously spreading powder, and spreading the powder for the second time on the surface of the formed graphene, wherein the spreading thickness is 100 mu m;

s4 laser induction, performing selective graphene treatment on polyimide powder by a laser at the power of 1.5W, the scanning speed of 50.8mm/S and the printing resolution of 500 to form a pre-designed single-layer graphene film;

s5, printing layer by layer, repeating the steps S4 and S5 repeatedly, and finishing the printing of the three-dimensional structure after the powder spreading times are accumulated to 70 times; as shown in fig. 3 (c).

As a result of observing the surface of the three-dimensional graphene obtained in example 1 by using a scanning electron microscope SEM, as shown in fig. 12(a), it can be seen that the three-dimensional graphene prepared at a laser power of 1W has a lamellar and porous structure. As a result of observing the surface of the three-dimensional graphene obtained in example 2 by using a scanning electron microscope SEM, as shown in fig. 12(b), it can be seen that the three-dimensional graphene prepared at a laser power of 1.5W has a fiber network structure. The three-dimensional graphene structure obtained in the example is observed by a Transmission Electron Microscope (TEM), and the result is shown in FIG. 13, and it can be seen from the figure that the prepared structure is a lamellar stack structure, and the interlayer distance is 0.34nm, which indicates that the generated structure is a few-layer graphene structure. The prepared three-dimensional graphene structure is applied to a supercapacitor electrode material, the performance result of a capacitor tested is shown in fig. 14(b), and the three-dimensional graphene structure shows excellent energy storage performance and stability as can be seen from a cyclic voltammetry characteristic o curve and a constant current charging and discharging curve in the figure.

Example 3

S1, processing a substrate, namely fixing Polyimide (PI) paper on an aluminum plate, and performing laser induction on the PI paper to generate a laser-induced graphene (LIG) substrate;

s2 spreading the polyimide powder uniformly on the LIG surface of S1 in air atmosphere, and performing selective graphitization on the polyimide powder by a laser at a power of 1.5W, a scanning speed of 50.8mm/S and a printing resolution of 500;

s3, continuously spreading powder, and spreading the powder for the second time on the surface of the formed graphene, wherein the spreading thickness is 100 mu m;

s4 laser induction, performing selective graphene oxidation on polyimide powder by a laser at the power of 1W, the scanning speed of 50.8mm/S and the printing resolution of 500 to form a pre-designed single-layer graphene film;

s5, printing layer by layer, repeating the steps S4 and S5 repeatedly, and finishing the printing of the three-dimensional structure after the powder spreading times are accumulated to 20 times;

and S6 post-treatment, namely soaking the three-dimensional graphene structure obtained in the S6 in an organic solvent, and then preserving heat at 800 ℃ for 2h to obtain an optimized three-dimensional graphene structure for the electrode material of the super capacitor. As shown in fig. 3 (a). The prepared supercapacitor was subjected to a three-electrode method test, as shown in fig. 14 (a); the obtained voltammogram curve and galvanostatic charge-discharge curve are shown in fig. 14 (b).

The prepared three-dimensional graphene structure is subjected to performance test, the interlayer conductivity of the graphene structure obtained in the step S5 is 5.0S/m, the interfacial conductivity can reach 42.2S/m, and the density is 100mg/cm³Specific surface area of 87m²(ii)/g, tensile strength 10 kPa; after the post-treatment of the step S6, the interlayer conductivity of the three-dimensional graphene is 10.6S/m, the interfacial conductivity is 70.5S/m, and the density is 30mg/cm³Specific surface area of 870m²(ii) in terms of/g. The three-dimensional graphene structure processed by S6 is used as an electrode material of a super capacitor, and the maximum obtainable surface capacitance is 4.69F/cm²Bulk capacitance of 34.6F/cm³The mass capacitance was 210.5F/g.

Example 4

S1, processing a substrate, namely fixing Polyimide (PI) paper on an aluminum plate, and performing laser induction on the PI paper to generate a laser-induced graphene (LIG) substrate;

s2 spreading the polyimide powder uniformly on the LIG surface of S1 in air atmosphere, and performing selective graphitization on the polyimide powder by a laser at a power of 1.5W, a scanning speed of 50.8mm/S and a printing resolution of 500;

s3, continuously spreading powder, and spreading the powder for the second time on the surface of the formed graphene, wherein the spreading thickness is 100 mu m;

s4 laser induction, performing selective graphene oxidation on polyimide powder by a laser at the power of 1W, the scanning speed of 50.8mm/S and the printing resolution of 500 to form a pre-designed single-layer graphene film;

s5, printing layer by layer, repeating the steps S4 and S5 repeatedly, and finishing the printing of the three-dimensional structure after the powder spreading times are accumulated to 20 times;

and S6 post-treatment, namely soaking the three-dimensional graphene structure obtained in the step S6 in an organic solvent, and dissolving the three-dimensional graphene structure into polymer powder of the material to obtain an optimized three-dimensional graphene structure which can be used for adsorbing materials. The adsorption test of the prepared adsorption material shows that the adsorption capacity of the adsorption material to pump oil can reach 60 times of the self-mass, the adsorption capacity of the adsorption material to acetone can reach 45 times of the self-mass, and the adsorption capacity of the adsorption material to ethyl acetate can reach 50 times of the self-mass.

Example 5

S1, processing a substrate, namely fixing Polyimide (PI) paper on an aluminum plate, and performing laser induction on the PI paper to generate a laser-induced graphene (LIG) substrate;

s2 spreading the polyimide powder uniformly on the LIG surface of S1 in air atmosphere, and performing selective graphitization on the polyimide powder by a laser at a power of 1W, a scanning speed of 50.8mm/S and a printing resolution of 500;

s3, continuously spreading powder, and spreading the powder for the second time on the surface of the formed graphene, wherein the spreading thickness is 50 microns;

s4 laser induction, performing selective graphene oxidation on polyimide powder by a laser at the power of 1W, the scanning speed of 50.8mm/S and the printing resolution of 500 to form a pre-designed single-layer graphene film;

s5, printing layer by layer, repeating the steps S4 and S5 repeatedly, and finishing the printing of the three-dimensional structure after accumulating the powder paving times for 40 times; the prepared three-dimensional graphene structure is used as a heating device, when the input power of the heating device is 2W, the temperature can reach 240 ℃, and the heating efficiency can reach 120 ℃ cm 2/W.

Example 6

S1, processing a substrate, namely fixing Polyimide (PI) paper on an aluminum plate, and performing laser induction on the PI paper to generate a laser-induced graphene (LIG) substrate;

s2 spreading the polyimide powder uniformly on the LIG surface of S1 in air atmosphere, and performing selective graphitization on the polyimide powder by a laser at a power of 1W, a scanning speed of 50.8mm/S and a printing resolution of 500;

s3, continuously spreading powder, and spreading the powder for the second time on the surface of the formed graphene, wherein the spreading thickness is 50 microns;

s4 laser induction, performing selective graphene oxidation on polyimide powder by a laser at the power of 1W, the scanning speed of 50.8mm/S and the printing resolution of 500 to form a pre-designed single-layer graphene film;

s5, printing layer by layer, repeating the steps S4 and S5 repeatedly, and finishing the printing of the three-dimensional structure after accumulating the powder paving times for 25 times; the prepared three-dimensional graphene structure is used as a sensor, and the test result is shown in fig. 15. When the tensile strain of the sensor is 0.1%, the sensing coefficient can reach 10, as shown in fig. 15 (a); at a compressive strain of 0.5%, the sensing coefficient may reach 120, as shown in fig. 15 (b).

It is to be understood that the foregoing is merely illustrative of some embodiments and that changes, modifications, additions and/or variations may be made without departing from the scope and spirit of the disclosed embodiments, which are intended to be illustrative and not limiting. Furthermore, the described embodiments are directed to embodiments presently contemplated to be the most practical and preferred, it being understood that the embodiments should not be limited to the disclosed embodiments, but on the contrary, are intended to cover various modifications and equivalent arrangements included within the spirit and scope of the embodiments. Moreover, the various embodiments described above can be used in conjunction with other embodiments, e.g., aspects of one embodiment can be combined with aspects of another embodiment to realize yet another embodiment. In addition, each individual feature or element of any given assembly may constitute additional embodiments.

The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.