Method for preparing large-area carbon nanotube arrays using origami

Abstract

The present invention discloses a method for preparing a large-area carbon nanotube array using an origami method, comprising the following steps: S1, preparing and cleaning a flexible substrate; S2, loading a catalytic metal on the growth region of the flexible substrate; S3, folding the flexible substrate using an origami method and placing it on a limiting device after folding; S4, placing the folded flexible substrate and the growth limiting device in S3 as a whole in a tube furnace, introducing a protective gas, a reducing gas, and a carbon source gas into the furnace to perform chemical vapor deposition to grow a carbon nanotube array on the catalyst-loaded surface of the flexible substrate; S5, after growth is completed, removing the entire substrate from the tube furnace, separating the flexible substrate and the limiting device; S6, unfolding the flexible substrate to obtain a large-area carbon nanotube array. Advantageously, the carbon nanotube array prepared by this method can exceed the area limitation of the growth substrate area due to the diameter of the tube furnace, which is a limitation imposed by the diameter of the tube furnace, in traditional horizontal or vertical growth methods.

Description

Technical Field

[0001] The invention relates to a method for preparing a large-area carbon nanotube array by utilizing an origami method. Background Art

[0002] Carbon nanotubes (CNTs) possess a unique geometric structure and excellent physical and chemical properties, including high elastic modulus and tensile strength, high aspect ratio, large specific surface area, and excellent electrical and thermal conductivity, thus possessing a wide range of applications. They are promising multifunctional materials for micro- and nano-electromechanical systems. CNT arrays are highly ordered structures composed of multiple individual CNT functional units in three dimensions. They embody both the specific functions of CNTs and the unique capabilities of the array structure, resulting in transformative and disruptive high-performance macroscopic materials with a wide range of applications.

[0003] Carbon nanotube arrays are primarily grown via chemical vapor deposition, which requires the use of catalytic metals. These metals are deposited on the growth substrate using two main methods: First, prior to growth, the catalyst metal is loaded onto the substrate via magnetron sputtering, atomic deposition, or solution spraying. Second, during the growth process, an organic metal compound is introduced along with a carbon source via a floating catalyst method to deposit the catalyst onto the substrate.

[0004] In addition, the growth substrate of the carbon nanotube array is usually a silicon substrate or a sapphire substrate containing a thermal oxide layer, etc., which serves as a hard growth substrate; some also use thin stainless steel substrates as flexible load substrates.

[0005] Currently, the production of large-area carbon nanotube arrays is limited by the diameter and length of tube furnaces. The growth substrate is primarily placed horizontally or vertically on a quartz boat. Requirement for larger-area carbon nanotube arrays generally requires a larger tube furnace, significantly increasing production costs. Alternatively, small carbon nanotube arrays must be prepared and then spliced ​​and transferred, often damaging the integrity of the arrays and preventing the production of high-quality, large-area carbon nanotube arrays. Summary of the Invention

[0006] The technical problem to be solved by the present invention is: in view of the fact that the area of ​​carbon nanotube arrays grown in a tubular furnace by the existing horizontal or vertical placement method is limited by the diameter of the tubular furnace, a method for growing large-area carbon nanotube arrays by preparing a flexible substrate using an origami method and cooperating with a limiting device is provided. The area of ​​the carbon nanotube arrays prepared by this method breaks through the limitation of the traditional horizontal growth method or vertical growth method on the area of ​​the growth substrate by the diameter of the tubular furnace. This method realizes the growth of large-area carbon nanotubes in a low-cost manner and with extremely high preparation efficiency; and in application, there is no need to use small-area carbon nanotubes to transfer and splice to obtain a large-area carbon nanotube array, reducing the damage to the carbon nanotube array structure caused by the transfer process; the large-area carbon nanotube array can also be transferred to the target surface at one time, thereby improving the transfer efficiency; the obtained large-area carbon nanotube array provides more applications in the fields of fuel cell membrane electrode, field emitter, electromagnetic shielding, etc.

[0007] The specific technical solution adopted is a method for preparing a large-area carbon nanotube array using an origami method, comprising the following steps:

[0008] S1. Prepare a flexible substrate and clean it;

[0009] S2, loading the catalytic metal on the growth area of ​​the flexible substrate;

[0010] S3, folding the flexible substrate using origami, and placing it on a limiting device after folding;

[0011] S4, placing the folded flexible substrate and the growth limiting device in S3 in a tube furnace, introducing protective gas, reducing gas, and carbon source gas into the furnace, and performing chemical vapor deposition to grow a carbon nanotube array on the surface of the flexible substrate-supported catalyst;

[0012] S5. After the growth is completed, the entire tube furnace is removed and the flexible substrate and the limiting device are separated;

[0013] S6. Expand the substrate into a flexible substrate to obtain a large-area carbon nanotube array.

[0014] In a further preferred embodiment of the technical solution of the present invention, the flexible substrate folding method in S3 is to perform multiple forward and reverse folding along one side of the flexible substrate at a predetermined size to form a continuous stacked structure, and then place the stacked structure on a stop device to prevent the stacked structure from flattening. For rectangular flexible substrates larger than the diameter of the furnace opening, which cannot be directly placed in the furnace for growth, a forward and reverse folding method can be used for rectangular flexible substrates larger than the diameter of the furnace opening. This forward and reverse folding method ensures that the growth surface points in a single direction, facilitating subsequent stretching and growth without damaging the growth surface of the carbon nanotube array.

[0015] In a further preferred embodiment of the technical solution of the present invention, in S2, the limiting device includes a base plate and a plurality of support plates vertically disposed on the base plate. The base plate is placed horizontally, and the support plates are arranged at equal intervals on the base plate. The top ends of the support plates support a portion of the folding points within the stacking structure. The base plate surface is provided with a plurality of slots for engaging with another portion of the folding points within the stacking structure, as well as the outermost ends of the stacking structure. For rectangular flexible substrates larger than the diameter of the furnace mouth, the substrate will expand and deform due to heat in the growth environment. The provision of a limiting device can, to a certain extent, reduce the deformation of the substrate due to thermal expansion and prevent the random unfolding of the folded rectangular flexible substrate under no constraints.

[0016] In a further preferred embodiment of the technical solution of the present invention, in S6, the unfolding is horizontal unfolding, specifically: pulling the outermost ends of the stacked structure and stretching them outwards at the same time until they are flattened.

[0017] As a further optimization of the technical solution of the present invention, the flexible substrate folding method in S3 is to make n+2 auxiliary folding lines intersecting at the center point on the flexible substrate, where n is an even number; the auxiliary folding lines are evenly divided into outer crease lines and inner crease lines, and the outer crease lines and the inner crease lines are arranged alternately, and the flexible substrate folds the auxiliary folding lines inside and outside in the plane; after the folding is completed, the flexible substrate forms a bulge at each outer crease line to obtain a circular folding structure, and the circular folding structure is set on a limiting device to prevent the bulge from flattening. For circular / annular flexible substrates larger than the diameter of the furnace mouth, they cannot be placed directly in the furnace for growth. For circular / annular flexible substrates larger than the diameter of the furnace mouth, an inner and outer folding method can be adopted. The inner and outer folding method ensures that the growth surface points in a single direction, which is convenient for subsequent stretching and forming without damaging the growth surface of the carbon nanotube array.

[0018] In a further embodiment of the technical solution of the present invention, the limiting device in S3 includes an annular base and a plurality of support rods arranged inside the annular base. The support rods are arranged radially along the annular base, and all the support rods converge at the center of the annular base, leaving a storage space at the center of the annular base; a slot is provided on the inner wall of the annular base to engage the edge of the circular folding structure, and the free end of each support rod is used to support the intersection of the crease lines; and two corner blocks for placing the limiting device are provided on the outer wall of the annular base. For circular / annular flexible substrates larger than the diameter of the furnace mouth, the substrate will expand and deform due to heat in the growth environment. The provision of a limiting device can, to a certain extent, reduce the deformation of the substrate after thermal expansion and avoid the random expansion of the folded circular / annular flexible substrate under no constraints.

[0019] In a further preferred embodiment of the technical solution of the present invention, in S6, the unfolding is performed in a circular manner, specifically: pulling the outermost edge of the circular folding structure and applying horizontal force to stretch it until it is flattened.

[0020] In a further preferred embodiment of the technical solution of the present invention, in S2, a buffer layer is prepared on the flexible substrate, and the catalytic metal is uniformly loaded on the buffer layer, which can improve the uniformity and growth quality of the carbon tube array.

[0021] In a further preferred embodiment of the technical solution of the present invention, in S5, the flexible substrate and the limiting device on which the carbon nanotube array is grown are taken out after being cooled in the furnace.

[0022] The beneficial effects of the present invention are:

[0023] 1. There is no need to use more expensive substrates such as single crystal silicon and sapphire with thermal oxide layer. Instead, a cheaper, high-temperature resistant flexible metal substrate can be used.

[0024] 2. There is no need to change the original preparation system. Just add a relatively cheap high-temperature resistant limiting device to achieve the growth of large-area carbon nanotube arrays.

[0025] 3. The origami method can be used to controllably adjust the required carbon nanotube array area, which is an efficient and low-cost method for growing large-area carbon nanotube arrays.

[0026] 4. This origami method for preparing large-area carbon nanotube arrays is also suitable for promoting other similar thin film preparation methods, such as graphene films and hexagonal boron nitride films. It can effectively improve the efficiency of the preparation process, reduce costs, adjust the area, and prepare large areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of a device for preparing a large-area carbon nanotube array using an origami method according to the present invention;

[0028] Figure 2 is a schematic diagram of a flexible substrate (a schematic diagram of a folding line of the flexible substrate is shown in the figure);

[0029] Figure 3 is a schematic diagram of a flexible substrate (the figure shows the growth area and reserved area of ​​the flexible substrate);

[0030] Figure 4 is a schematic diagram of a flexible substrate (the figure shows the surface of the flexible substrate opposite to the growth area);

[0031] Figure 5 is a schematic diagram of the limiting device in Example 1;

[0032] Figure 6 for Figure 5 Magnified view at point I in the middle;

[0033] Figure 7 Schematic diagram of the flattening process in Example 1;

[0034] Figure 8Schematic diagram of the flexible substrate in a semi-flattened state after folding and placed on the limiting device in Example 1;

[0035] Figure 9 This is a schematic diagram of the flexible substrate and the limiting device of Structure 1 in Example 1 being placed into a tube furnace;

[0036] Figure 10 for Figure 9 sectional view of ;

[0037] Figure 11 This is a schematic diagram of the flexible substrate and the limiting device of Structure 2 in Example 1 being placed into a tube furnace;

[0038] Figure 12 for Figure 11 sectional view of ;

[0039] Figure 13 Schematic diagram of the circular folding structure in Example 2 Figure 1 ;

[0040] Figure 14 To correspond Figure 13 Schematic diagram of the limiting device of the circular folding structure;

[0041] Figure 15 for Figure 13 The circular folded structure is placed in Figure 14 Schematic diagram of the limiting device;

[0042] Figure 16 Schematic diagram of the flexible substrate and the limiting device of Structure 1 in Example 2 being placed into a tube furnace;

[0043] Figure 17 for Figure 16 sectional view of ;

[0044] Figure 18 Schematic diagram of the flexible substrate and the limiting device of Structure 2 in Example 2 being placed into a tube furnace;

[0045] Figure 19 for Figure 18 sectional view of ;

[0046] Figure 20 Schematic diagram of the circular folding structure in Example 2 Figure 2 ;

[0047] Figure 21 To correspond Figure 20 Schematic diagram of the limiting device of the circular folding structure;

[0048] Figure 22 for Figure 20 The circular folded structure is placed in Figure 21 Schematic diagram of the limiting device;

[0049] Explanation of the numbers in the figure: 1 - tubular furnace, 2 - flexible substrate 21 - growth area 22 - reserved area 23 - folding line 24 - surface opposite to the growth area, 3 - limiting device, 31 - base plate, 32 - support plate, 33 - support rod, 34 - slot, 53 - corner block, 36 - ring-shaped base frame. DETAILED DESCRIPTION

[0050] The technical solution of the present invention is described in detail below, but the protection scope of the present invention is not limited to the embodiments.

[0051] In order to make the purpose, technical solutions and advantages of the present invention more clear, the following Figure 1-22 It should be understood that the specific embodiments described herein are only used to illustrate the present invention and are not intended to limit the present invention. Example 1

[0052] A method for preparing a large-area carbon nanotube array using an origami method comprises the following steps:

[0053] S1, prepare a flexible substrate 2 and clean it; specifically: according to the size of the area of ​​the carbon nanotube array growth area, select a flexible substrate with an area slightly larger than the area of ​​the carbon nanotube array to be prepared; and ensure a certain reserved area to facilitate clamping and transfer. (such as Figure 2 、 3 As shown in FIG4 , a flexible substrate 2, a growth area 21, and a reserved area 22); after cleaning the flexible substrate 2, ensure that the desired growth surface is clean.

[0054] Cleaning the surface of the flexible substrate 2 is necessary. The key is that the flexible surface must be free of organic matter (such as grease left after touching with fingers). Residual organic matter will affect the stable growth of the carbon nanotube array in this area. The integrity of the carbon nanotube array grown over a large area must be ensured.

[0055] S2. Loading the catalytic metal on the growth region 21 of the flexible substrate 2. Specifically, the key technique is to uniformly load the catalytic metal on the surface of the flexible substrate. The uniformity of the catalytic metal on the flexible substrate surface affects the growth of the carbon nanotube array; in areas without catalyst, the carbon nanotube array growth quality is poor. Furthermore, a buffer layer can be prepared on the flexible substrate 2 before coating the catalytic metal to improve the uniformity and growth quality of the carbon nanotube array.

[0056] S3. Fold the flexible substrate using origami, and place it on a limiting device after folding to ensure that the flexible substrate does not shift during the growth process.

[0057] like Figure 2As shown, folding line 23. The flexible substrate folding method in this embodiment is to fold the flexible substrate multiple times along one side of the flexible substrate in a certain size to form a continuous stacking structure, and then set the stacking structure on the limiting device 3 to prevent the stacking structure from flattening. The stacking structure formed by the folding method of this embodiment is as shown in FIG. Figure 7 shown.

[0058] Origami is a key technology for producing large-area carbon nanotube arrays within a confined space. A flexible substrate 2 is folded along any edge, with the folding distance required to be less than the diameter of the tube furnace's opening. The number of folds and placement can be varied depending on the desired area and the furnace opening diameter. The folded flexible substrate is first partially unfolded to ensure adequate airflow contact with the folded surface during growth. The partially unfolded flexible substrate is then placed on a stopper 3.

[0059] like Figure 7 As shown, the semi-expansion of this embodiment involves simultaneously stretching the folded stacked structure outward along its outermost edges, placing the stacked structure in a semi-expanded state. This state ensures that airflow during growth can fully contact the folded surface. The outermost edges of the stacked structure referred to herein represent the reserved areas 22 on the flexible substrate 2.

[0060] like Figure 8 As shown, the stacked structure in the semi-expanded state of this embodiment is placed on the limiting device 3 to ensure that the flexible substrate does not shift during the growth process.

[0061] like Figure 5 and 6 As shown, the specific structure of the limiting device 3 in this embodiment is: the limiting device 3 includes a base plate 31 and a plurality of support plates 32 vertically arranged on the base plate, the base plate is placed horizontally, the support plates are arranged at equal intervals on the base plate, and the top of the support plate 32 supports a part of the folding points in the stacking structure; a plurality of card slots 34 for engaging another part of the folding points in the stacking structure and the outermost ends of the stacking structure are arranged on the plate surface of the base plate.

[0062] In this embodiment, the limiting device 3 includes a support plate 32 detachably connected to the base plate 31 . The spacing between two adjacent support plates 32 is adjusted based on the folded dimensions of the flexible base. The height of the support plates is also determined based on the folded dimensions of the flexible base.

[0063] In this embodiment, the stacked structure in the semi-expanded state is placed on the limiting device 3 and fixed by the top of the support plate 32 and the slot on the surface of the substrate to ensure that the flexible substrate does not shift during the growth process. Figure 8 shown.

[0064] S4. Place the folded flexible substrate and the growth limiting device in S3 in a tubular furnace, introduce protective gas, reducing gas, and carbon source gas into the furnace, and perform chemical vapor deposition to grow a carbon nanotube array on the surface of the flexible substrate-loaded catalyst.

[0065] like Figure 9 、 10 As shown in Figures 11 and 12, the stacked structure, folded using the folding method of this embodiment and then partially unfolded, is placed on the limiting device 3. The semi-expanded stacked structure, together with the limiting device, is then placed in the tubular furnace 1 and placed in the heating area. The tubular furnace 1 mentioned in this step is well known in the art and is known to those skilled in the art.

[0066] S5. After growth is complete, the entire tube furnace is removed, and the flexible substrate and the retaining device are separated. Specifically, the flexible substrate and the retaining device, after cooling the carbon nanotube array within the furnace, are removed. This step is known in the art and is understood by those skilled in the art.

[0067] S6. Expand the flexible substrate to obtain a large-area carbon nanotube array. Stretching is performed along the crease direction to obtain a planar, large-area carbon nanotube array. Expanding is performed horizontally by simultaneously pulling the outermost edges of the stacked structure outward until it is flattened. Example 2

[0068] The difference between this embodiment and embodiment 1 lies in that the flexible substrate folding method used in S3 is different, the limiting device is different, and the unfolding method in S6 is different.

[0069] In this embodiment, the flexible substrate folding method is as follows: n+2 auxiliary folding lines intersecting at the center point are made on the flexible substrate 2, where n is an even number; the auxiliary folding lines are evenly divided into outer folding lines and inner folding lines, and the outer folding lines and the inner folding lines are arranged alternately. The flexible substrate folds the auxiliary folding lines inside and outside in the plane; after the folding is completed, the flexible substrate forms a bulge at each outer folding line, obtaining a circular folding structure, such as Figure 13 The circular folding structure is set on a limiting device to prevent the bulge from flattening.

[0070] like Figure 14 As shown, in this embodiment, corresponding to the circular folding structure, the specific structure of the limiting device provided is:

[0071] The limiting device includes an annular base 36 and multiple support rods 33 arranged inside the annular base. The support rods 33 are arranged radially along the annular base, and all the support rods converge at the center of the annular base 36, leaving an accommodating space at the center of the annular base; a card groove 34 for engaging the edge of the circular folding structure is provided on the inner wall of the annular base 36, and the free end of each support rod is used to support the intersection of the crease line; two corner blocks 35 for placing this limit are provided on the outer wall of the annular base.

[0072] In this embodiment, the number of the limiting device 3 and the supporting rods 33 can be determined according to the number of auxiliary folding lines of the flexible substrate, that is, Figure 20 、 21 As shown in 22, Figure 13 The circular folding structure shown is formed by folding into eight equal parts. Figure 14 The limiting device shown in the figure needs to be provided with four support rods 33, and four slots 34 are provided on the inner wall of the annular base frame on the limiting device. Figure 20 The circular folding structure shown is formed by folding into eight equal parts. Figure 21 The limiting device shown is provided with eight support rods 33 , and eight slots 34 are provided on the inner wall of the annular base frame on the limiting device.

[0073] In this embodiment, the height of the support rod 33 is also determined based on the folded size of the flexible substrate.

[0074] The semi-expansion of this embodiment is to pull the outermost edge of the folded circular stacked structure and apply horizontal force to stretch it, so that the stacked structure is in a semi-expanded state. This state is to ensure that the airflow during the growth process can fully contact the folded surface. The outermost edges of the circular stacked structure mentioned here are the reserved areas 22 on the flexible substrate 2. Figure 15 As shown, the semi-expanded circular stacking structure is placed on a limiting device to ensure that the flexible substrate does not shift during the growth process.

[0075] like Figure 16 、 17 As shown in Figures 18 and 19, the circular stacked structure, folded and partially unfolded using the folding method of this embodiment, is placed on the limiting device 3. The semi-expanded stacked structure, together with the limiting device, is placed in the tubular furnace 1 and placed in the heating area. The tubular furnace 1 mentioned in this step is well known in the art and is known to those skilled in the art. Specific embodiments

[0076] Taking the growth of large-area carbon nanotube arrays on flexible stainless steel sheets as an example, further detailed description is given:

[0077] Step 1: Based on the desired size of the carbon nanotube array, a 0.02 mm thick flexible stainless steel sheet with an area slightly larger than the area of ​​the carbon nanotube array is selected.

[0078] Step 2: Place a 0.02 mm thick flexible stainless steel sheet on a flat surface and soak it in propanol for 20 minutes. Remove it from the acetone solution and rinse the surface with deionized water. Finally, blow dry with nitrogen and store in a dust-free environment.

[0079] Step 3: Place and fix a 0.02 mm thick flexible stainless steel sheet on the magnetron sputtering system platform. Use physical vapor deposition to coat a 10-20 nm thick aluminum oxide film on the surface of the stainless steel sheet, and then coat a 1-2 nm thick iron film as a flexible growth substrate for the carbon nanotube array.

[0080] Step 4: Fold the catalytic metal-loaded flexible stainless steel substrate as needed, with each fold width smaller than the diameter of the tube furnace opening. Once folded, partially unfold the flexible stainless steel substrate and position it along the folds within the support bracket and slots of the horizontal restraint mechanism. Place the flexible stainless steel substrate and restraint mechanism together in the heating zone of the tube furnace.

[0081] Step 5: Place the folded flexible substrate and the growth limiter in the heating zone of a tube furnace. The ambient pressure in the tube furnace is set to 10 Torr. Argon shielding gas is introduced before heating. In an argon atmosphere, the temperature is rapidly raised to approximately 750°C at a heating rate of 1.5°C / min. When the temperature stabilizes at 750°C, a reducing gas, hydrogen, is introduced for a 1-minute pretreatment. After pretreatment, a carbon source gas is introduced to chemically vapor-deposit carbon nanotube arrays on the stainless steel substrate. After the carbon nanotube arrays are grown, the carbon source gas is stopped, and argon shielding gas is continued, followed by a slow cooling process in an argon atmosphere.

[0082] Step 6: After the carbon nanotube array is cooled in the furnace, the limiting device and the flexible substrate are removed from the tube furnace, and the flexible stainless steel substrate is separated from the limiting device using a clamp.

[0083] Step 7: Clamp the reserved area of ​​the flexible stainless steel substrate in the folded state after the carbon nanotube array is grown, and slowly stretch and unfold it to flatten the flexible stainless steel substrate from the folded state to obtain a large-area flat carbon nanotube array.

[0084] The above embodiments are only for illustrating the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a large-area carbon nanotube array using an origami method, characterized in that: The steps include: S1. Prepare a flexible substrate and clean it; S2, loading the catalytic metal on the growth area of ​​the flexible substrate; S3. Folding the flexible substrate using origami techniques and placing it on a limiting device after folding; the flexible substrate folding method comprises folding the flexible substrate multiple times along one side of the flexible substrate in a certain size, forming a continuous stacking structure; the folded flexible substrate is first partially unfolded, and then the stacking structure is placed on the limiting device to prevent the stacking structure from flattening; the limiting device includes a base plate and a plurality of support plates vertically arranged on the base plate, the base plate being placed horizontally, and the support plates being arranged at equal intervals on the base plate, with the top ends of the support plates supporting a portion of the folding points within the stacking structure; A plurality of slots are provided on the surface of the base plate for engaging with another part of the folding points in the stacking structure and the outermost ends of the stacking structure; S4, placing the folded flexible substrate and the growth limiting device in S3 in a tube furnace, introducing protective gas, reducing gas, and carbon source gas into the furnace, and performing chemical vapor deposition to grow a carbon nanotube array on the surface of the flexible substrate-supported catalyst; S5. After the growth is completed, the entire tube furnace is removed and the flexible substrate and the limiting device are separated; S6. Horizontally unfold the substrate into a flexible substrate to obtain a large-area carbon nanotube array.

2. The method for preparing a large-area carbon nanotube array using origami technology according to claim 1, wherein: The unfolding is horizontal unfolding, specifically, pulling the outermost ends of the stacked structure outward at the same time until it is flattened.

3. The method for preparing a large-area carbon nanotube array using origami technology according to claim 1, wherein: In S2, a buffer layer is prepared on a flexible substrate, and the catalytic metal is uniformly loaded on the buffer layer.

4. The method for preparing a large-area carbon nanotube array using origami technology according to claim 1, wherein: In S5, the flexible substrate and the limiting device on which the carbon nanotube array is grown are taken out after being cooled in the furnace.

5. A method for preparing a large-area carbon nanotube array using an origami method, characterized in that: The steps include: S1. Prepare a flexible substrate and clean it; S2, loading the catalytic metal on the growth area of ​​the flexible substrate; S3. Folding the flexible substrate using an origami technique and placing it on a limiting device after folding; the flexible substrate folding method comprises making n+2 auxiliary folding lines intersecting at a center point on the flexible substrate, where n is an even number; the auxiliary folding lines are evenly divided into outer folding lines and inner folding lines, the outer folding lines and the inner folding lines being arranged alternately, and the flexible substrate folding the auxiliary folding lines inside and outside in a plane; After the folding is completed, a bulge is formed on the flexible substrate at each outer crease line to obtain a circular folding structure. The folded circular stacking structure is pulled by the outermost edge of the circular folding structure and horizontal force is applied to stretch the stacking structure so that the stacking structure is in a semi-expanded state. The circular folding structure is set on a limiting device to prevent the bulge from flattening. The limiting device includes an annular base and a plurality of support rods arranged inside the annular base, the support rods are arranged radially along the annular base, and all the support rods converge at the center of the annular base, leaving an accommodating space at the center of the annular base; a slot for engaging the edge of the circular folding structure is provided on the inner wall of the annular base, and the free end of each support rod is used to support the intersection of the crease lines; Two corner blocks for placing the limit are provided on the outer wall of the annular base; S4, placing the folded flexible substrate and the growth limiting device in S3 in a tube furnace, introducing protective gas, reducing gas, and carbon source gas into the furnace, and performing chemical vapor deposition to grow a carbon nanotube array on the surface of the flexible substrate-supported catalyst; S5. After the growth is completed, the entire tube furnace is removed and the flexible substrate and the limiting device are separated; S6. Expand the substrate into a flexible substrate to obtain a large-area carbon nanotube array.

6. The method for preparing a large-area carbon nanotube array using origami technology according to claim 5, characterized in that: In S6, the unfolding is annular unfolding, specifically: pulling the outermost edge of the circular folding structure and applying horizontal force to stretch it until it is flattened.

7. The method for preparing a large-area carbon nanotube array using origami technology according to claim 5, characterized in that: In S2, a buffer layer is prepared on a flexible substrate, and the catalytic metal is uniformly loaded on the buffer layer.

8. The method for preparing a large-area carbon nanotube array using origami technology according to claim 5, wherein: In S5, the flexible substrate and the limiting device on which the carbon nanotube array is grown are taken out after being cooled in the furnace.

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