Graphene film-coated gas molecule storage and controllable release device

Abstract

The application relates to a graphene film coating type gas molecule storage and controllable release device, and belongs to the field of micro-nano element applications. The device comprises a gland, a graphene film and a flexible substrate; a plurality of grooves are formed in the flexible substrate; the graphene film is laid on the surface of the flexible substrate, and the graphene film is in a curved state through a pre-stretching flexible substrate production method; under the action of no external force, the film is kept in a closed tubular storage capsule form due to mechanical deformation; the two ends are closed by using the gland to prevent gas molecules from escaping. The graphene film is mechanically bent and deformed to realize the opening and closing of the storage space, the gas can be quickly collected, and the release rate of the internal gas molecules can be controlled by controlling the opening size of the storage space; compared with the existing adsorption type gas storage method, the device has higher storage speed and simple and controllable gas release function; the device is suitable for a wide range of gases and can be repeatedly used.

Description

TECHNICAL FIELD

[0001] The application relates to a graphene film coating type gas molecule storage and controllable release device and belongs to the field of micro-nano element applications. BACKGROUND

[0002] Hydrogen storage technology refers to a technology for safely and efficiently storing hydrogen in a suitable carrier so as to release the hydrogen for use when needed. Common hydrogen storage technologies include compressed hydrogen storage, liquefied hydrogen storage, adsorbed hydrogen storage, chemical hydrogen storage and physical hydrogen storage. In recent years, the method for adsorbing hydrogen molecules by using nanomaterials has become a popular research direction of hydrogen storage technology. Among them, graphene materials and carbon nanotubes have shown advantages in the application of adsorbed hydrogen storage due to their stable chemical properties and super-large specific surface area. The design principles of hydrogen storage by using graphene materials can be generally divided into physical adsorption, doping modification of graphene and catalytic hydrogen storage.

[0003] Physical adsorption hydrogen storage is to store and release hydrogen in the form of molecules by using the excellent specific surface area of graphene. The binding energy between hydrogen molecules and undoped original graphene materials is low, the stability of direct adsorption is poor, the hydrogen storage efficiency is low, hydrogen needs to be stored at low temperature, and the release of hydrogen after adsorption cannot be controlled.

[0004] Alkali metals, transition metals or metalloids can be used to dope and modify graphene materials to improve the hydrogen storage efficiency of graphene materials. Although the doping performance of graphene has been widely studied and shows certain advantages, most of the existing work only stays in the stage of theoretical analysis, and the number of doped atoms or functional groups that can actually improve the hydrogen storage function in experiments is very limited, and most of the materials cannot be mass-produced at present. Based on this, there are few reports on modified graphene materials that can be practically applied and effectively improve the hydrogen storage capacity.

[0005] Catalytic hydrogen storage is to use graphene or its derivatives as catalysts to produce hydrogen by water electrolysis, and store hydrogen in hydrogen storage materials or hydrogen storage electrodes. However, the current hydrogen storage design based on graphene generally has the disadvantages of low theoretical design conversion rate, low hydrogen storage density, unstable and uncontrollable release, repeated use, high cost and the like.

[0006] Similar to hydrogen storage technology, gas storage and controllable release technology has wide application requirements in many fields such as environmental detection, biological medicine and experimental research. SUMMARY

[0007] The application aims to solve the problems of low physical adsorption hydrogen storage capacity and uncontrollable release, and provides a graphene film coating type gas molecule storage and controllable release device.

[0008] The application is achieved by the following technical scheme:

[0009] The graphene film coating type gas molecule storage and controllable release device comprises a gland, a graphene film and a flexible substrate; a plurality of grooves are formed on the flexible substrate; the graphene film is laid on the surface of the flexible substrate, and the graphene film in the bent state is obtained by the production method of pre-stretching the flexible substrate, and the film remains in the closed tubular storage capsule form due to mechanical deformation under the action of no external force; the two ends are closed by using the gland to prevent gas molecules from escaping;

[0010] The flexible substrate material is polysilicone (PDMS).

[0011]

Molecule collection

[0012]

Molecule storage and transportation

[0013]

Molecule release

[0014]

Device recycling and reuse

[0015] The method for preparing the above device comprises the following steps:

[0016] Step one, according to the required volume calculation design of the base groove configuration and add eaves square cavity configuration on the basis of the groove; cavity structure can be combined by a variety of materials (such as silicon, metal, etc.) with elastic matrix material PDMS, can play the role of auxiliary graphene film closed, also can increase the structure of the gas storage volume ratio;

[0017] Step two, according to the groove configuration and cavity configuration of step one, the corresponding structure is processed on the base material; the matrix material can be selected as PDMS, the tensile rate of which can reach 900%; PDMS forming technology has matured, micron level surface features can be prepared by etched hard template (such as silicon, quartz or metal template) casting - curing - demolding a series of standard processes; nanoscale surface features need to use ultraviolet imprinting or plasma etching method;

[0018] Step three, pre-stretching the base material according to the required stretching-closing size; pre-stretching should ensure that the graphene film can form a completely closed tubular storage bag after the external force is removed; the pre-stretching size should be slightly larger than the cross-sectional circumference of the graphene nanobelt in the ideal closed state, and the circumference value is determined by the groove geometry in step one. The stretching size is described in detail in the next section of structure size design;

[0019] Step four, graphene film is laid under low pressure conditions to ensure that the graphene film and the base form a closed low pressure condition;

[0020] Step five, clean the graphene film; keep the matrix stretched horizontally, place the device in a vacuum box under low temperature heating conditions to remove the molecules attached to the surface of the graphene film;

[0021] Step six, remove the external force, the elastic matrix shrinks, the graphene film is concave, and the two sides are closed using a gland;

[0022] The method for designing the groove configuration of the base according to the required volume in step one is as follows:

[0023] Under the condition of open groove without eaves structure, the end face geometry of the graphene film in the ideal closed state can be simplified as a symmetrical "J" shape connected by four congruent circular arcs, and the radian of each circular arc is 150°, and the two circular arcs at the bottom are in contact with the two circular arcs at the top to form an approximately circular closed space.

[0024] In order to accommodate the curved closed graphene film, the geometric size of the groove should ensure that:

[0025]

[0026] Where R is the radius of the ideal closed state circular arc;

[0027] The volume ratio between the gas storage space and the cavity at this time is 30.5%;

[0028] The circumference C of the graphene film accommodated in the groove under the end face observation condition is:

[0029] C = 10πR / 3 (4-2)

[0030] The tensile rate of the substrate under the fully expanded condition (graphene is expanded into a plane) is 523%, which is less than the ultimate elastic tensile rate 900% of the PDMS material;

[0031] The number of carbon atoms required by the graphene film per unit width is:

[0032]

[0033] Where d1 and d2 are the graphene lattice lengths;

[0034] The gas mass stored by the graphene film per unit width is:

[0035]

[0036] Where ρ is the density of the stored gas;

[0037] The storage volume of a single groove is:

[0038]

[0039] Where l is the length of the groove;

[0040] The storage mass of a single groove is:

[0041]

[0042] The ratio of the stored gas mass to the required graphene film mass is:

[0043] 2.764×10 5 ×R×ρ (4-7)

[0044] The unit of radius R in the calculation is meter, and the unit of gas density ρ is kg / m 3 ;

[0045] The method for designing the square cavity configuration of the substrate according to the required volume in step one is:

[0046] By adding a convex eave structure with an opening width smaller than the groove on the top of the groove, the open groove becomes a square cavity with an opening on the top, the storage ratio of the gas can be further improved, and the geometric shape of the graphene film in the ideal closed state can be simplified to a symmetric "J" shape formed by two congruent large arcs and two congruent small arcs, each arc has an arc greater than 150° and less than 180°, the two small arcs at the bottom are in contact, and the two large arcs at the top form an approximately circular closed space together;

[0047] The geometric size of the groove should ensure that:

[0048]

[0049] Where x is the length of the convex eave relative to the groove;

[0050] Increasing the length of the convex eave can increase the gas storage space ratio, which is greater than the pure groove structure without a convex eave, but its limit value does not exceed 78%;

[0051] The single-side length x of the convex eave relative to the groove should be less than 30% of the width of the groove:

[0052] x<30% width (4-9)

[0053] To ensure that the tensile rate of the flexible material of the substrate under the stretching condition is less than the elastic limit;

[0054] The circumference C of the graphene film contained in the square cavity under the end face observation condition is:

[0055] C=2θ×(2R-x)+2x (4-10)

[0056] Where θ is the central angle corresponding to the arc (in radians);

[0057] The storage volume of a single cavity is

[0058]

[0059] The mass ratio of the stored gas to the required graphene film is greater than that of the pure groove structure and less than

[0060] 4.381×10 5 ×R×ρ (4-12);

[0061] Advantages

[0062] 1. The graphene film coated gas molecule storage and controllable release device disclosed by the application can realize the opening and closing of the storage space through the mechanical bending deformation of the graphene film, can quickly collect gas, and can control the release rate of the internal gas molecules by controlling the opening size of the storage space; compared with the existing adsorption type gas storage method, the graphene film coated gas molecule storage and controllable release device has higher storage speed and simple and controllable gas release function.

[0063] 2. The graphene film coated gas molecule storage and controllable release device disclosed by the application has stable chemical properties, the single-layer structure and highly compact atomic arrangement of the graphene material used can prevent the penetration of gas and liquid, the specific surface area can reach 2630 m 2 / g, has no selectivity to the target gas molecules stored, can be widely used in the type range of molecules, and has potential application value in the application fields of dangerous gas separation, storage and corrosion prevention.

[0064] 3. The graphene film coated gas molecule storage and controllable release device disclosed by the application can be designed according to the use requirement of the device size, can realize the micron and nanometer scale gas sampling, collection, storage and controllable release, is convenient for realizing the small scale gas molecule regulation, can be applied to multiple directions such as environmental detection and biological medical experiment, and can also be used in cooperation with other micro-nano components.

[0065] 4. The graphene film coated gas molecule storage and controllable release device disclosed by the application can use an automatic control system to open and close the storage structure, and can also use a pure mechanical control without an electric circuit system, so that the graphene film coated gas molecule storage and controllable release device can be applied to occasions sensitive to electromagnetic signals or needing to completely avoid electromagnetic interference such as precision measurement, medical equipment and aircraft.

[0066] 5. The graphene film coated gas molecule storage and controllable release device disclosed by the application can be repeatedly used. The tensile rate of the elastic base material polysiloxane (PDMS) can reach 900%, which can meet the reciprocating tensile change of the structure designed by the application, the single-layer graphene has good mechanical properties and can withstand large-angle bending and reciprocating deformation of nanometer and micron scales; the storage space and the graphene film are cleaned through the preparation method step five, the device can realize the multiple collection, storage and controllable release of the same or different target molecules, and effectively reduces the use cost.

[0067] 6, The graphene film coated gas molecule storage and controllable release device has good low temperature performance, wherein the flexible substrate material PDMS can maintain its physical and chemical properties under low temperature conditions, that is, even at liquid nitrogen temperature (-196 DEG C), the PDMS can still maintain good flexibility and elasticity; the graphene material increases in strength and rigidity under low temperature conditions, and is not easy to be brittle or broken; therefore, the device can store gas contents under low temperature conditions, and can be applied to temperature sensitive gas molecule storage, such as collecting aerosol samples in biological experiments, or increasing the storage amount of contents by increasing the gas density through low temperature. BRIEF DESCRIPTION OF DRAWINGS

[0068] Figure 1 The principle schematic diagram of the graphene film coated gas molecule storage and controllable release device of the present application realizes the functions of molecule collection, storage and release through mechanical deformation of the graphene film; the dark part in the figure schematically shows the graphene film, the shaded part schematically shows the substrate material attached to the graphene film, and the circular part schematically shows the collected molecules.

[0069] Figure 2 The flexible substrate groove configuration of the present application; the left figure is the cross-sectional geometry of a single groove, and the right figure is a three-dimensional geometric appearance schematic diagram of the substrate.

[0070] Figure 3 The end face geometry of the graphene film under ideal closed state condition using the groove configuration of the present application; the left figure is the cross-sectional geometry of the graphene in a single groove, and the right figure is a three-dimensional geometric appearance schematic diagram of the flexible substrate surface covered with the graphene film.

[0071] Figure 4 The schematic diagram of the storage device using gland closure at both ends of the present application.

[0072] Figure 5 The opening distance and tensile rate relationship diagram of the tubular storage capsule in Example 1 of the present application.

[0073] Figure 6 The schematic diagram of the cavity structure of the present application; by increasing the eave structure with an opening width smaller than the groove on the top of the groove, the open groove becomes a square cavity with an opening left on the top.

[0074] Figure 7 The end face geometry schematic diagram of the graphene film under ideal closed state condition using the cavity configuration of the present application; the graphene film is attached to the surface layer material, and the eave structure can assist the closing of the film.

[0075] Figure 8 The end face geometry size schematic diagram of the graphene film in Example 2 of the present application. DETAILED DESCRIPTION

[0076] To better illustrate the purposes and advantages of the present application, the summary of the application is further described below in conjunction with the accompanying drawings and examples.

[0077] Example 1

[0078]

Nanoscale ambient temperature and pressure hydrogen storage

[0079] According to the device preparation steps, the geometric size relationship of the groove should satisfy formula (4-1), and R=10 nm is taken:

[0080]

[0081] The width is 20 nm, the depth is 38 nm, and the length is 10 μm. The size of the flexible substrate is (10 μm x 30 μm x 200 nm), and there are 250 identical groove features in the width direction, with a distance of 20 nm between each two features, and the width direction sides are fixed to the external force applying device. PDMS is selected as the flexible substrate material, an electron beam etching nanostructure mold is used to copy the PDMS prepolymer and crosslinking agent, and a flexible substrate is obtained by using the prepared mold.

[0082] As shown in Figure 3 , the end face geometric shape of the ideal closed state graphene film can be simplified as a symmetrical "J" shape connected by four congruent circular arcs, each circular arc has an arc of 150°, and the two bottom circular arcs are in contact with the two upper circular arcs to form an approximately circular closed space. The circumference C of the graphene film contained in the groove under the end face observation condition is calculated by formula (4-2):

[0083]

[0084] The stretching rate of the substrate under the fully expanded condition (graphene is expanded into a plane) is 523%. During the curing process of PDMS, metal fasteners are added, and after complete curing, a tensile force is applied in the width direction of the groove. The pre-stretching ratio is slightly larger than the stretching rate under the fully expanded condition, which is taken as 530% here.

[0085] A single-layer graphene membrane with an area larger than (10 μm × 31.2 μm) was transferred to a PDMS substrate in a vacuum glove box. Unloading was performed to stretch the substrate to 400% of its initial length, and the vacuum level was reduced to standard atmospheric pressure. The membrane was then heated at 500°C for two hours under a hydrogen atmosphere to remove surface-attached molecules or functional groups. Unloading caused the flexible substrate to contract along the width of the groove, resulting in a nanoscale hydrogen storage micro-nano device.

[0086] When in use, stretch both ends of the substrate to 200% of the initial length, expose to hydrogen at room temperature and pressure, and unload to restore the substrate to its original length, thus achieving hydrogen collection. Figure 4 As shown, the device is sealed with pressure caps at both ends to ensure the device is sealed during storage.

[0087] Using formula (4-4), the volume of stored gas in this embodiment can be obtained as:

[0088]

[0089] In this embodiment, the hydrogen storage volume ratio is 30.5%, and the hydrogen density is about 0.081 kg / m 3 , the hydrogen storage mass is 6.688×10 -20 kg(3.345×10 -17 mol), the number of hydrogen storage molecules is about 2.01×10 7 The ratio of the stored gas mass to the required graphene film mass is 2.23×10 -4 .

[0090] If the ambient temperature is lowered and hydrogen is stored at 0°C, the density of hydrogen is about 0.089 kg / m 3 , the storage volume of hydrogen is 8.26×10 -19 m 3 , with a mass of 7.423×10 -20 kg(3.712×10 -17 mol), the number of hydrogen storage molecules is about 2.23×10 7 The ratio of the stored gas mass to the required graphene film mass is 2.48×10 -4 .

[0091] By controlling the stretching length of the matrix, the controlled release of hydrogen can be achieved. Figure 5 As shown, as the flexible substrate stretches, the opening distance of the tubular storage capsule gradually increases, and the substrate stretch ratio and opening distance are approximately linearly related. By controlling the substrate stretch ratio, the size of the storage capsule opening, and thus the gas release rate, can be controlled. A larger opening distance facilitates the release and diffusion of molecules. Complete gas release can be achieved by stretching the graphene membrane, with complete gas release achieved when the stretch ratio reaches 523%.

[0092] The device is placed again in a hydrogen environment to collect gas, which can be reused.

[0093] The device designed by the application can achieve nanoscale hydrogen storage and controllable release by a mechanical control method. The device can quickly complete gas collection and control the release rate of internal gas molecules by controlling the opening size of the storage space. Compared with the existing adsorption type gas storage method, the device has higher storage speed and simple and controllable gas release function. The same device can also be applied to the storage and controllable release of other gases.

[0094] Example 2

[0095]

Microscale room temperature and atmospheric pressure hydrogen storage

[0096] According to the device preparation steps, the geometric size relationship of the groove should satisfy formula (4-8), taking R = 1 μm, and the eave extension amount x = 600 nm:

[0097]

[0098] The end face geometric size of the cavity and the graphene film in the ideal closed state is shown in Figure 8 . The calculation shows that the width is 2 μm, the depth is 2.8 μm, and the length is 100 μm. The length, width and height dimensions of the flexible substrate are (100 μm x 300 μm x 6 μm), and there are 50 same groove features in the width direction, the distance between each two features is 2 μm, and the width direction two sides are fixed with the external force applying device. PDMS is selected as the flexible substrate material, an electron beam etching nanostructure mold is used to mix the PDMS prepolymer with the crosslinking agent, and the flexible substrate is obtained by copying with the prepared mold. Copper is selected as the metal fixing part and the eave layer. The metal fixing part and the eave layer with a rectangular aperture array of width 800 nm, length 100 μm and spacing 3.2 μm are added during the PDMS curing process. After complete curing, a tensile force is applied in the groove width direction.

[0099] The circumference C of the graphene film contained in the groove under the end face observation condition is calculated by using formula (4-10)

[0100] C = 2θ x (2R - x) + 2x = 9.185 μm (4-17)

[0101] The pre-stretching ratio is 459% of the initial length. A single-layer graphene film with an area of more than (100 μm x 560 μm) is attached to a PDMS substrate in a vacuum glove box, and the substrate is stretched to 350% of the initial length. The vacuum degree is reduced to standard atmospheric pressure. The substrate is heated to 500°C in a vacuum box under hydrogen protection for two hours to remove surface-attached molecules or functional groups. The flexible substrate is shrunk along the groove width direction after unloading, and a micron-scale hydrogen storage micro-nano device is obtained.

[0102] When used, the two ends of the substrate are stretched to 200% of the initial length, exposed to normal temperature and pressure hydrogen, and unloaded to restore the substrate to the original length, that is, to realize hydrogen collection.

[0103] The storage gas volume in this embodiment can be obtained by using formula (4-11):

[0104]

[0105] The hydrogen density is about 0.081 kg / m 3 , and the mass is 1.289 x 10 -15 kg (6.4 x 10 -13 mol). The ratio of the mass of the stored gas to the mass of the required graphene film is about 0.0246.

[0106] The opening size of the storage bag can be controlled by controlling the stretching ratio of the substrate, and the gas release speed is further controlled. A larger opening distance is conducive to the release and diffusion of molecules. The complete release of gas can be achieved by stretching the graphene film.

[0107] The device designed by the application can realize micron-scale hydrogen storage and controllable release by a mechanical control method. The same device can also be applied to the storage and controllable release of other gases.

[0108] Example 3

[0109] In the experiment of testing harmful gas sensors, ppm, ppb, and even ppt order of gas concentration is required. The device of the application can realize the concentration regulation of gas molecules. Taking the controllable release of micron-scale nitrogen dioxide (NO2) molecules as an example, under the micron-scale storage condition, the flexible substrate adopts the square cavity configuration with additional eaves as shown in Figure 6 , and as shown in Figure 7The graphene film is attached on the surface of the eaves material. According to the device preparation steps, the groove width is 2 μm, the depth is 2.8 μm, the length is 100 μm, and the eaves elongation is x = 600 nm. The flexible substrate has a size of (100 μm x 300 μm x 6 μm), and 50 identical groove features are designed in the width direction, with a distance of 2 μm between each two features, and the two sides in the width direction are fixed with the external force applying device. PDMS is selected as the flexible substrate material, and an electron beam lithography is used to make a nanostructure mold. The PDMS prepolymer is mixed with a crosslinking agent, and the flexible substrate is obtained by copying the prepared mold. Copper is selected as the metal fixing part and the eaves layer. The metal fixing part and the eaves layer with a rectangular aperture array of a width of 800 nm, a length of 100 μm, and a spacing of 3.2 μm are added during the PDMS curing process. After complete curing, a tensile force is applied in the groove width direction. The calculation shows that the circumference of the graphene film in the cavity is 9.185 μm, and the pre-stretching ratio is 459% of the initial length. The single-layer graphene film with an area of (100 μm x 560 μm) is removed in the vacuum glove box and attached to the PDMS substrate. The substrate is stretched to 350% of the initial length, and the vacuum degree is reduced to standard atmospheric pressure. The substrate is heated to 500°C for two hours in the vacuum box under hydrogen protection to remove the surface-attached molecules or functional groups. The flexible substrate is unloaded and shrunk along the groove width direction to obtain a micrometer-scale hydrogen storage micro-nano device. The end face geometry of the cavity and the graphene film in the ideal closed state is shown in Figure 8 .

[0110] When in use, the substrate is stretched to 200% of the initial length, exposed to NO2 gas, and unloaded to restore the substrate to the original length, that is, to realize the collection of NO2 molecules. Under the conditions of normal temperature and pressure, the density of NO2 is about 2.62 kg / m 3 , the storage volume is 1.592 x 10 -14 m 3 , and the mass is 4.17 x 10 -14 kg (6.4 x 10 -13 mol). The mass ratio of the stored gas to the required graphene film is about 0.846.

[0111] The storage device is transferred to a nitrogen gas mixing bin, the substrate is stretched to 400% of the initial length to realize complete release of the gas, and is completely mixed with the nitrogen gas in the experimental bin. Every 15.92 L of nitrogen gas mixture can obtain 1 ppt concentration of test gas. Assuming that the volume of the mixing bin is 1 L, 15.92 ppt concentration of NO2 test gas is obtained.

[0112] The application can realize micron and nanometer scale gas sampling, collection, storage and controllable release, facilitate small scale gas molecule regulation, can be applied to environmental detection, biological medical experiment and multiple directions, and can be used in cooperation with other micro-nano components.

[0113] The above description of the specific description further details the purpose, technical scheme and beneficial effects of the application. It should be understood that the above description is only a specific embodiment of the application and is not used to limit the protection scope of the application. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A graphene film-based encapsulation device for gas molecule storage and controllable release, characterized in that: It comprises a cover, a graphene film and a flexible substrate; a plurality of grooves are formed on the flexible substrate; the graphene film is laid on the surface of the flexible substrate and is obtained by a pre-stretching method of the flexible substrate to form a curved graphene film; under no external force, the film is kept in a closed tubular storage capsule form due to mechanical deformation; The two ends are closed by the cover to prevent gas molecules from escaping; The flexible substrate material is polysiloxane; Stretching the substrate material reduces the bending degree of the graphene and opens the closed storage structure; External molecules enter the storage capsule; after the external force is removed, the substrate elastically shrinks to the original state, the storage capsule returns to the closed state, and the graphene material plays a role in storing the internal molecules; Stretching the substrate material opens the closed storage structure, and the graphene material releases the stored molecules into the required environment; By changing the stretching degree of the substrate, the opening degree of the storage structure can be adjusted, and the release rate can be adjusted. 2.The graphene film based encapsulation device for gas molecule storage and controllable release according to claim 1, wherein: It also comprises a convex eave; by increasing the convex eave structure with an opening width smaller than the groove on the top of the groove configuration, the open groove configuration is changed into a square cavity with an opening on the top, and the gas storage ratio is further improved; the convex eave is fixed on the upper end of the flexible substrate.

3. The method for preparing the graphene film-based encapsulation type gas molecule storage and controlled release device according to claim 1, characterized in that: It comprises the following steps: Step one: according to the required volume, the groove configuration of the substrate is designed; Step two: according to the configuration of step one, the corresponding structure is processed on the substrate material; Step three: the substrate material is pre-stretched according to the required stretching-closing size; the pre-stretching should ensure that the laid graphene film can form a completely closed tubular storage capsule after the external force is removed; The pre-stretching size is slightly larger than the cross-sectional circumference of the graphene nanobelt under the ideal closed state condition; Step four: the graphene film is laid under low pressure conditions to ensure that the graphene film and the substrate form a closed low pressure condition; Step five: the graphene film is cleaned; the substrate is kept stretched transversely, the device is placed in a vacuum box for low-temperature heating under the condition that the graphene film is stretched, so as to remove the molecules attached to the surface of the graphene film; Step six: the external force is removed, the elastic substrate shrinks, the graphene film is concave, the two sides are closed by the cover, and the device is completed.

4. The method of claim 3, wherein: The method for designing the groove configuration of the substrate according to the required volume in step one is as follows: Under the condition of the open groove configuration without the convex eave structure, the end face geometry of the graphene film under the ideal closed state is simplified as a symmetrical "U" shape connected by four congruent circular arcs, and the radian of each circular arc is 150°; the two circular arcs at the bottom are in contact, and together with the two circular arcs at the top, they form an approximately circular closed space; In order to accommodate the curved and closed graphene film, the geometric size of the groove should ensure that: Where R is the radius of the circular arc under the ideal closed state; At this time, the volume ratio between the gas storage space and the cavity is 30.5%; The circumference C of the graphene film contained in the groove under the end face observation condition is: C=10πR / 3 (3-2) Under the condition of complete unfolding, that is, the graphene is unfolded into a plane, the stretching rate of the substrate is 523%, which is less than the ultimate elastic stretching rate of 900% of the PDMS material; The number of carbon atoms required for the graphene film per unit width is: Where d1 and d2 are the graphene lattice lengths; The gas mass stored by the unit width of the graphene film is: wherein p is the density of the stored gas; The storage volume of a single groove is: wherein l is the groove length; The storage mass of a single groove is: The ratio of the stored gas mass to the mass of the required graphene film is: 2.764 x 10 5 x R x p (3-7) The units of the radius R in the calculation are meters, and the units of the gas density p are kg / m3 3 .

5. The method of claim 3, wherein: Step one also includes calculating the corresponding size of the square cavity configuration of the designed substrate according to the required volume, and the specific method is: By adding a convex eave structure with an opening width smaller than the groove on top of the groove configuration, the open groove configuration is changed into a square cavity configuration with an opening on top, and the gas storage ratio can be further improved; the geometric shape of the graphene film in the ideal closed state is simplified to a symmetric "U" shape formed by two congruent large circular arcs and two congruent small circular arcs, each circular arc has an arc greater than 150° and less than 180°, and the two small circular arcs at the bottom are in contact with the two large circular arcs at the top to form an approximately circular closed space; The geometric size of the groove should ensure that: wherein x is the protruding length of the convex eave relative to the groove; Increasing the length of the convex eave can increase the gas storage space ratio, which is greater than that of the pure groove structure without the convex eave, but the limit value is not more than 78%; The single-side protruding length x of the convex eave relative to the groove should be less than 30% of the width of the groove: x < 30% width (3-9) To ensure that the tensile rate of the flexible material of the substrate under the relaxed condition is less than the elastic limit; The circumference C of the graphene film contained in the square cavity under the end face observation condition is: C = 2θ × (2R - x) + 2x (3-10) wherein θ is the central angle corresponding to the circular arc, in radian units; The storage volume of a single cavity is The ratio of the stored gas mass to the mass of the required graphene film is greater than that of the pure groove structure and less than 4.381 x 10 5 x R x p (3-12).

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