Method for regulating tension of a suspended graphene film and applications

Abstract

This invention belongs to the technical field of suspended graphene film materials, specifically relating to a method and application for controlling the tension of suspended graphene films. The method includes the following steps: S1, placing graphene with a growth substrate in an etching solution to etch away the growth substrate, obtaining a graphene film floating on the surface of the etching solution; S2, replacing the etching solution with water, and then replacing the water with solutions of different tensions; S3, draining the solutions of different tensions to allow the graphene film to adhere to the target substrate, obtaining graphene films with different tensions; S4, data processing to obtain a curve showing the relationship between the tension of the suspended graphene film and the solution tension; S5, based on the above relationship curve, controlling the tension of the suspended graphene film through steps S1 to S3. This invention's method can effectively control the tension of wet-transferred suspended graphene films using solutions of different tensions, filling a technological gap.

Description

Technical Field

[0001] This invention belongs to the field of suspended graphene film material technology, specifically relating to a method and application for controlling the tension of suspended graphene films. Background Technology

[0002] Graphene is a two-dimensional material with excellent electrical conductivity, high optical transparency, extremely high mechanical strength and flexibility, and good chemical stability. However, the cumbersome transfer operation from the growth substrate to the desired substrate is unavoidable. Existing transfer methods not only cause cracks, doping, wrinkles, and surface contamination in the graphene film, reducing its intrinsic properties, but more importantly, the tension of the film after transfer using current methods is almost uncontrollable. This severely limits applications that require high tension controllability, such as pressure sensors and pressure detectors.

[0003] Existing patent literature discloses a method for preparing high-integrity suspended graphene films through clean graphene transfer. This patent achieves high-integrity suspended graphene transfer by replacing water with a low-tension solution during the transfer process. However, it cannot achieve controllable regulation of the tension of the suspended graphene film. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects in the prior art, such as the inability to controllably regulate the tension of suspended graphene films, thereby providing a method and application for regulating the tension of suspended graphene films.

[0005] Therefore, the present invention provides the following technical solution:

[0006] This invention provides a method for controlling the tension of a suspended graphene film, comprising the following steps:

[0007] S1, the graphene with the growth substrate is placed in the etching solution and the growth substrate is etched away to obtain a graphene film floating on the surface of the etching solution.

[0008] S2, replace the etching solution with water, and replace the water with solutions of different tensions;

[0009] S3, drain the solutions with different tensions to allow the graphene film to adhere to the target substrate, thus obtaining suspended graphene films with different tensions;

[0010] S4, Data processing, to obtain the relationship curve between the tension of the suspended graphene film and the tension of the solution;

[0011] S5. Based on the above relationship curve, the tension of the suspended graphene film is controlled through steps S1 to S3.

[0012] The method of this invention can effectively control the tension of suspended graphene films transferred by wet method using solutions with different tensions.

[0013] Optionally, in step S2, the tension range of the solutions with different tensions is 20–90 mN / m. Solutions with different tensions are achieved by adjusting the reagent concentration or ratio. Water, organic compounds, inorganic salt aqueous solutions, or organic compound-water mixed solutions are mainly used. By controlling the reagent dosage and ratio, a series of solutions with tensions different from water are prepared, and these solutions are used to transfer suspended graphene films, thus achieving effective control of the tension of the suspended graphene films.

[0014] Optionally, in step S2, the solutions with different tensions include, but are not limited to, at least one of water, organic compounds, mixed solutions of organic compounds and water, or aqueous solutions of inorganic salts.

[0015] Optionally, the organic compound includes, but is not limited to, at least one of methanol, ethanol, isopropanol, glycerol, acetone, n-hexane, n-butanol, ethyl acetate, petroleum ether, acetic acid, and sucrose.

[0016] Optionally, the inorganic salt includes at least one of soluble alkali metal salts.

[0017] Optionally, the inorganic salt includes, but is not limited to, at least one of sodium chloride, potassium chloride, magnesium chloride, sodium sulfate, potassium sulfate, potassium carbonate, sodium carbonate, sodium nitrate, potassium nitrate, ammonium chloride, ammonium sulfate, barium chloride, and barium nitrate.

[0018] Optionally, in step S1, the etching solution includes at least one of ferric chloride solution, ammonium persulfate solution, and sodium persulfate solution.

[0019] Optionally, in step S1, the graphene with the growth substrate includes graphene prepared by chemical vapor deposition or reduced graphene oxide. The preparation method for reduced graphene oxide is conventional in the field and can be achieved using solution spin-coating or coating processes.

[0020] Optionally, in step S1, the growth substrate is a metal substrate, typically one of copper, nickel, platinum, or molybdenum.

[0021] Since the tension of suspended graphene films is also related to their size (such as thickness and diameter), the relationship curves obtained for suspended graphene films of different sizes are different.

[0022] Optionally, when the thickness of the suspended graphene film is about 20 nm and the diameter is 10 mm, the relationship curve between the tension of the suspended graphene film and the tension of the solution is y = 10.323x + 6.6956; where x is the tension of the solution in mN / m and y is the tension of the suspended graphene film in mN / m.

[0023] Optionally, when the thickness of the suspended graphene film is about 20 nm and the diameter is 20 mm, the relationship curve between the tension of the suspended graphene film and the tension of the solution is y = 10.136x - 8.4191; where x is the tension of the solution in mN / m and y is the tension of the suspended graphene film in mN / m.

[0024] The present invention also provides an application of the suspended graphene film obtained by the above-mentioned method for regulating the tension of the suspended graphene film in the fields of photoelectric sensors, acoustic diaphragms, acoustic detectors, and micro-nano devices.

[0025] The technical solution of this invention has the following advantages:

[0026] The method for controlling the tension of suspended graphene films provided by this invention includes the following steps: S1, placing graphene with a growth substrate in an etching solution, etching away the growth substrate to obtain a graphene film floating on the surface of the etching solution; S2, replacing the etching solution with water, and then replacing the water with solutions of different tensions; S3, draining the solutions of different tensions to allow the graphene film to adhere to the target substrate, obtaining graphene films with different tensions; S4, data processing to obtain a relationship curve between the tension of the suspended graphene film and the solution tension; S5, based on the above relationship curve, controlling the tension of the suspended graphene film through steps S1 to S3. This invention's method can effectively control the tension of wet-transferred suspended graphene films using solutions of different tensions, filling a technological gap. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the solution replacement device used in the embodiments of the present invention;

[0029] Figure 2 This is a schematic diagram of the ball pressure testing device used in the embodiments of the present invention;

[0030] Figure 3 This is the force-displacement curve obtained in Embodiment 1 of the present invention;

[0031] Figure 4 This is the simulation verification result of the tension of the suspended graphene film in Embodiment 1 of the present invention;

[0032] Figure 5This is the relationship curve between the tension of the suspended graphene film and the solution tension obtained in Example 1 of the present invention;

[0033] Figure 6 This is the force-displacement curve obtained in Embodiment 2 of the present invention;

[0034] Figure 7 This is the simulation verification result of the tension of the suspended graphene film in Embodiment 2 of the present invention;

[0035] Figure 8 This is the relationship curve between the tension of the suspended graphene film and the solution tension obtained in Example 2 of the present invention;

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. Peristaltic pump; 2. First container; 3. Second container; 4. Support frame; 5. Suspended graphene film; 6. Indenter; 7. Force-displacement sensor; 8. Data processor. Detailed Implementation

[0038] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0039] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0040] Example 1

[0041] This embodiment provides a method for controlling the tension of a suspended graphene film using solutions with different tensions, specifically including the following steps:

[0042] (1) Graphene with a metal substrate (graphene prepared by chemical vapor deposition in this embodiment) is placed in ferric chloride or ammonium persulfate and sodium persulfate solution (the etching solution used in this embodiment is ferric chloride solution with a mass concentration of 1 mol / L) to etch away the metal substrate and obtain a graphene film floating on the surface of the etching solution.

[0043] (2) Replace the etching solution with water and clean the graphene film;

[0044] (3) Adopting such Figure 1The solution replacement device shown gradually replaces pure water with solutions of different (certain) tensions using a peristaltic pump 1. Here, water is stored in the first container 2, and solutions of different tensions are stored in the second container 3. Different tension solutions are achieved by adjusting the reagent concentration or ratio, and the adjustment range is generally: 20 < x < 90 mN / m. For example, the tension of an isopropyl alcohol solution (concentration 100%) at 20°C (in this invention, the tension of liquids is measured using a full-automatic surface and interfacial tension meter) is 21.7 mN / m. If pure water is used for transfer, the corresponding solution tension is 72.8 mN / m (the ratios and tensions of other different tension solutions are shown in Table 1 below).

[0045] (4) Slowly empty the above-mentioned solutions of different tensions until the graphene film adheres to the target substrate, then take it out and let it air dry naturally to obtain a suspended graphene film with a certain tension. In this embodiment, the size of the suspended graphene film is: thickness is about 20 nm, and diameter is 10 mm.

[0046] (5) Use a ball pressure device (the schematic diagram of the ball pressure test device is as shown in Figure 2 ) to test the force-displacement curve of the suspended graphene film, and establish a model for simulation fitting to obtain the tension value of the suspended graphene film. The specific results are shown in Table 2. The specific test method is as follows: (1), Place the suspended graphene film 5 on the support frame 4 (sample stage), and the indenter 6 is directly below the center position of the film; (2), Operate the device to make the indenter approach the film gradually in steps of 1 μm until the indenter touches the film and continues to press down. Monitor the force and displacement through the force-displacement sensor 7, and use the data processor 8 to process the obtained data to obtain the force-displacement curve, as shown in Figure 3 (in the figure, "ethanol 10 - water" represents the curve corresponding to "10wt% ethanol aqueous solution" in Table 1, the same below). (3), Use the simulation software ABAQUS and the fitted material parameters, and use the data processor 8 to simulate and verify the film tension, as shown in Figure 4 . It can be seen from Figure 4 that the tension value of the self-supporting film with a diameter of 10 mm and a thickness of 20 nm obtained by software simulation (the transfer solution used is 10wt% K2SO4 aqueous solution, and the solution tension value is 76.5 mN / m) is 790 mN / m, and its force-displacement curve coincides with the experimental curve. Therefore, the film tension measured experimentally should be 790 mN / m.

[0047] (6) Data processing: Plot the tension of the suspended graphene film on the vertical axis and the solution tension on the horizontal axis to obtain the relationship curve between the tension of the suspended graphene film and the solution tension: y = 10.323x + 6.6956, as shown in Figure 5 . Here, x is the solution tension, with the unit of mN / m, and y is the tension of the suspended graphene film, with the unit of mN / m.

[0048] (7)Subsequently, according to the above relationship curve, the precise regulation of the tension of the suspended graphene film can be achieved through steps (1) to (4).

[0049] For example, if you want to obtain a suspended graphene film with a tension value of 480 mN / m, you only need to transfer the film according to steps (1) to (4). In step (3), replace the clear water with a solution with a tension of 46 mN / m (10 wt% ethanol aqueous solution). Test the tension value of the suspended graphene film obtained in step (4). The test result is 479 mN / m, which is relatively close to the target tension value of 480 mN / m of the suspended graphene film, proving that the method provided by the present invention can achieve the precise regulation of the tension of the suspended graphene film.

[0050] Table 1

[0051] Solution and proportion Solution tension (mN / m) Thin film tension (mN / m) water 72.8 760 25wt% KCl aqueous solution 85.2 910 25wt% NaCl aqueous solution 83 850 <![CDATA[10 wt% aqueous K2SO4 solution]]> 76.5 790 <![CDATA[10 wt% aqueous Na2SO4 solution]]> 74 755 5wt% sucrose aqueous solution 51.5 535 ethanol 22.3 240 10wt% ethanol aqueous solution 46 480 10wt% acetic acid aqueous solution 54.6 585 Isopropanol 21.7 230 10wt% isopropanol aqueous solution 33.3 350 10wt% methanol aqueous solution 41 430 glycerin 63 670

[0052] Example 2

[0053] This example provides a method for regulating the tension of a suspended graphene film using solutions with different tensions, specifically including the following operating steps:

[0054] (1) Place the chemical vapor deposition graphene with a metal substrate in a ferric chloride or ammonium persulfate and sodium persulfate solution (the etching solution used in this example is a ferric chloride solution with a mass concentration of 1 mol / L), etch away the metal substrate, and obtain a graphene film floating on the surface of the etching solution;

[0055] (2) Replace the etching solution with water and wash the graphene film;

[0056] (3) Use the solution replacement device as shown in Figure 1 to gradually replace pure water with a solution of different (certain) tensions using a peristaltic pump 1. Among them, water is stored in the first container 2, and solutions of different tensions are stored in the second container 3. Solutions of different tensions are achieved by regulating the reagent concentration or ratio, and the regulation range is generally: 20 < x < 90 mN / m. For example: the tension of an isopropanol solution (concentration 100%) at 20 °C is 21.7 mN / m, and if pure water is used for transfer, the corresponding solution tension is 72.8 mN / m (the ratios and tensions of other solutions with different tensions are shown in Table 2 below).

[0057] (4) Slowly drain the above solution with different tensions until the graphene film adheres to the target substrate, take it out, and air dry it naturally to obtain a suspended graphene film with a certain tension. In this example, the size of the suspended graphene film is: thickness about 20 nm, diameter 20 mm.

[0058] (5) Use a ball pressure device (the schematic diagram of the ball pressure test device is as shown in Figure 2The force-displacement curve of the suspended graphene film was obtained by testing (as shown in Table 2). The tension value of the suspended graphene film was obtained by model simulation fitting. The specific results are shown in Table 2. The specific test method is as follows: (1) The suspended graphene film 5 is placed on the support frame 4 (sample stage), and the center position of the film is directly below the pressure head 6; (2) The equipment is operated to make the pressure head gradually approach the film in 1μm steps until the pressure head contacts the film and continues to press down. The force and displacement are monitored by the force-displacement sensor 7, and the obtained data is processed by the data processor 8 to obtain the force-displacement curve, as shown in Table 2. Figure 6 As shown. (3) Using the simulation software ABAQUS and the fitted material parameters, the film tension was simulated and verified using the data processor 8, as shown. Figure 7 As shown, from Figure 7 As can be seen from the simulation, the tension value of the self-supporting film with a diameter of 20 mm and a thickness of 20 nm (the transfer solution used is a 10 wt% K2SO4 aqueous solution with a solution tension value of 76.5 mN / m) is 760 mN / m. Its force-displacement curve coincides with the experimental curve, so the experimentally tested film tension should be 760 mN / m.

[0059] (6) Data processing: Plotting the tension of the suspended graphene film as the ordinate and the solution tension as the abscissa, the relationship curve between the tension of the suspended graphene film and the solution tension is obtained: y = 10.136x - 8.4191, as shown below. Figure 8 As shown; where x is the solution tension in mN / m and y is the tension of the suspended graphene film in mN / m.

[0060] (7) Subsequently, based on the above relationship curve, the tension of the suspended graphene film can be precisely controlled through steps (1) to (4).

[0061] For example, to obtain a suspended graphene film with a tension value of 465 mN / m, it is only necessary to transfer the film according to steps (1) to (4), and in step (3), replace the water with a solution (10 wt% ethanol aqueous solution) with a tension value of 46 mN / m. The suspended graphene film obtained in step (4) is then tested for tension value according to step (5), and the test result is 463 mN / m, which is close to the target graphene film tension value of 465 mN / m, proving that the method provided by the present invention can achieve precise control of the tension of the suspended graphene film.

[0062] Table 2

[0063] Solution and proportion Solution tension (mN / m) Thin film tension (mN / m) 25wt% KCl aqueous solution 85.2 860 25wt% NaCl aqueous solution 83 835 <![CDATA[10 wt% aqueous K2SO4 solution]]> 76.5 760 <![CDATA[10 wt% aqueous Na2SO4 solution]]> 74 735 ethanol 22.3 220 10wt% ethanol aqueous solution 46 465 10wt% acetic acid aqueous solution 54.6 540 Isopropanol 21.7 210 10wt% isopropanol aqueous solution 33.3 330 10wt% methanol aqueous solution 41 400 glycerin 63 640

[0064] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for controlling the tension of a suspended graphene film, characterized in that, Includes the following steps: S1, the graphene with the growth substrate is placed in the etching solution and the growth substrate is etched away to obtain a graphene film floating on the surface of the etching solution. S2, replace the etching solution with water, and replace the water with solutions of different tensions; S3, drain the solutions with different tensions to allow the graphene film to adhere to the target substrate, thus obtaining suspended graphene films with different tensions; S4, Data processing, to obtain the relationship curve between the tension of the suspended graphene film and the tension of the solution; S5. Based on the above relationship curve, the tension of the suspended graphene film is controlled through steps S1 to S3.

2. The method for regulating the tension of a suspended graphene film according to claim 1, characterized in that, In step S2, the tension range of the solutions with different tensions is 20–90 mN / m.

3. The method for regulating the tension of a suspended graphene film according to claim 2, characterized in that, In step S2, the solutions with different tensions include at least one of water, a mixed solution of an organic compound and water, or an aqueous solution of an inorganic salt.

4. The method for regulating the tension of a suspended graphene film according to claim 3, characterized in that, The organic compound includes at least one of methanol, ethanol, isopropanol, glycerol, acetone, n-hexane, n-butanol, ethyl acetate, petroleum ether, acetic acid, and sucrose.

5. The method for regulating the tension of a suspended graphene film according to claim 3, characterized in that, The inorganic salt includes at least one of soluble alkali metal salts.

6. The method for regulating the tension of a suspended graphene film according to claim 5, characterized in that, The inorganic salt includes at least one of sodium chloride, potassium chloride, sodium sulfate, potassium carbonate, potassium sulfate, sodium carbonate, sodium nitrate, and potassium nitrate.

7. The method for regulating the tension of a suspended graphene film according to claim 3, characterized in that, The inorganic salt includes at least one of magnesium chloride, ammonium chloride, barium chloride, barium nitrate, and ammonium sulfate.

8. The method for regulating the tension of a suspended graphene film according to any one of claims 1-7, characterized in that, In step S1, the etching solution includes at least one of ferric chloride solution, ammonium persulfate solution, and sodium persulfate solution.

9. The method for regulating the tension of a suspended graphene film according to any one of claims 1-7, characterized in that, In step S1, the graphene with the growth substrate includes graphene prepared by chemical vapor deposition or reduced graphene oxide.

10. The method for regulating the tension of a suspended graphene film according to any one of claims 1-7, characterized in that, In step S1, the growth substrate is a metal substrate.

11. The application of a suspended graphene film obtained by the method for regulating the tension of a suspended graphene film according to any one of claims 1-10 in the fields of photoelectric sensors, acoustic diaphragms, acoustic detectors, and micro / nano devices.

Images