Method for preparing two-dimensional material with wrinkle structure with assistance of liquid metal and application

Abstract

The invention discloses a method for preparing a two-dimensional material with a wrinkle structure under the assistance of liquid metal and application, and belongs to the field of micro-nano machining of two-dimensional materials. The method comprises the following steps: S1, covering the upper surface of a two-dimensional material with liquid metal gallium, and solidifying the liquid metal gallium under a cooling condition to obtain a metal gallium ingot loaded with a two-dimensional material nanosheet; s2, heating the metal gallium ingot loaded with the molybdenum disulfide nanosheet until gallium is molten, cooling and solidifying, and obtaining a two-dimensional material with a wrinkle structure after solidification; the method disclosed by the invention can be used for efficiently preparing the large-area and high-density wrinkle type two-dimensional material, is suitable for manufacturing devices such as high-performance sensors and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano fabrication of two-dimensional materials, specifically relating to a method and application for preparing two-dimensional materials with wrinkled structures using liquid metal-assisted fabrication. Background Technology

[0002] In recent years, two-dimensional materials, including graphene, black phosphorus, and transition metal dichalcogenides (TMDCs), have been regarded as one of the key material systems for breaking through the physical limits of traditional silicon-based semiconductors. They possess unique properties such as atomically flat surfaces (no surface dangling bonds), ultra-large specific surface areas, excellent flexibility, and tunable electronic band structures (e.g., band gaps), showing significant application prospects in high-performance (opto)electronic devices, advanced energy technologies (catalysis and storage), and highly sensitive sensors.

[0003] Strain engineering can precisely control the lattice strain of two-dimensional materials, thereby manipulating their electronic structure and physicochemical properties. This provides a new degree of freedom for property control, greatly expanding its application potential in cutting-edge fields such as exciton engineering, molecular sensing, and spintronics. It has also made it a frontier research hotspot and a crucial breakthrough point for the interdisciplinary integration of condensed matter physics, materials science, and information technology. Wrinkling has become an important technical route for strain engineering in controlling the properties of two-dimensional materials. In graphene, wrinkle-induced lattice deformation can dynamically adjust the material's wettability and visible light transmittance. In transition metal chalcogenides (such as WS2 / WSe2), wrinkles accompanied by localized stress can modulate the band gap and enhance exciton radiation efficiency, potentially controlling exciton drift to enhance photoelectric properties. Strain engineering using wrinkle fabrication as a means can systematically control the optical, electrical, and electrochemical properties of two-dimensional materials, providing new ideas for developing high-sensitivity sensors, flexible electronic devices, and efficient catalysts. However, existing wrinkle fabrication technologies have significant shortcomings. For example, while chemical vapor deposition (CVD) can directly grow two-dimensional materials with wrinkled structures, it requires a large difference in the coefficients of thermal expansion between the substrate and the growth material, limiting the types of materials that can be selected. Polymer (such as polydimethylsiloxane, PDMS) substrate-assisted wrinkling strategies are limited by challenges such as interface adhesion uniformity and mechanical force control, making it difficult to meet the requirements for dense wrinkle fabrication of large-area two-dimensional materials. These limitations result in wrinkles fabricated by existing processes generally having a small distribution area (wrinkle area of ​​a single two-dimensional material < 1500 μm). 2 Low fold density (average fold density < 4μm) -1 However, it has shortcomings such as the inability to repeatedly prepare large-area, high-density wrinkled two-dimensional materials. Therefore, developing a method for the repeated preparation of large-area, high-density wrinkled two-dimensional materials is a core prerequisite for further advancing the strain engineering control of the properties of two-dimensional materials and for wrinkled two-dimensional materials to move from laboratory research to industrial applications such as flexible electronics manufacturing and advanced high-sensitivity sensors. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for preparing two-dimensional materials with wrinkled structures using liquid metal assistance. This method is simple to operate, highly repeatable, and can obtain large-area, high-density wrinkled two-dimensional materials.

[0005] The present invention also provides the application of the two-dimensional materials prepared by the method in the preparation of electronic devices, optical devices, optoelectronic devices, chemical and biological sensors and electrochemical catalytic devices.

[0006] According to a first aspect of the present invention, a method for preparing two-dimensional materials with a wrinkled structure using liquid metal assistance is provided, comprising the following steps:

[0007] S1. Liquid gallium metal is covered on the upper surface of a two-dimensional material, and the liquid gallium metal is solidified under cooling conditions to obtain a gallium ingot loaded with two-dimensional material nanosheets;

[0008] S2. A gallium ingot loaded with molybdenum disulfide nanosheets is heated until gallium melts and then cooled and solidified to obtain a two-dimensional material with a wrinkled structure.

[0009] The two-dimensional material includes at least one of molybdenum disulfide, tungsten disulfide, tungsten diselenide, and graphene.

[0010] Because chemical vapor deposition (CVD) can directly grow large-area wrinkled two-dimensional materials on substrates, and substrate-assisted wrinkling methods, such as those using polydimethylsiloxane (PDS) substrates, are simple to operate, CVD or substrate-assisted methods are commonly used to fabricate wrinkled structures in two-dimensional materials. However, this invention has found that CVD can only efficiently produce wrinkled two-dimensional materials when there is a significant difference in the coefficients of thermal expansion between the substrate and the grown two-dimensional material, limiting the method's versatility and imposing strict requirements on growth environment conditions. The basic process of substrate-assisted two-dimensional material wrinkling methods, represented by PDS tape pre-stretching, attaching two-dimensional material, and releasing the pre-stretching, suffers from transfer losses due to poor adhesion between the solid tape and the two-dimensional material, making it difficult to achieve wrinkle fabrication on large-area two-dimensional materials. This invention further discovers that gallium can transfer large-area flat two-dimensional materials grown on other substrates via CVD to its surface by enhancing adhesion from liquid to solid state. Furthermore, by heating and transferring the gallium loaded with the two-dimensional material, the surface-loaded two-dimensional material can be wrinkled. Therefore, gallium metal can achieve lossless transfer and efficient wrinkling of two-dimensional materials through two reverse phase transitions of liquid solidification and solid melting, thereby enabling the repeated fabrication of large-area, high-density wrinkled structures on a variety of two-dimensional materials.

[0011] This invention employs a phase transition assisted by the solidification and melting of liquid gallium to facilitate the transfer and wrinkling of two-dimensional materials. The tight adhesion between the liquid gallium and the solid substrate, along with the enhanced adhesion force of gallium solidification, ensures the lossless transfer of large-area samples, solving the problem of sample loss during traditional substrate-assisted transfer methods. The melting of gallium causes its own volume shrinkage, which in turn allows the two-dimensional material loaded on its surface to efficiently generate wrinkled structures under external force. Therefore, the prepared molybdenum disulfide nanosheets have a larger wrinkled area and a higher wrinkled density.

[0012] On the one hand, the solidification phase transition of gallium can assist in the non-destructive transfer of two-dimensional materials. The relative positional shift of the two-dimensional materials before and after transfer (in the horizontal x and y axes) is less than 95%, and the material retention rate (the ratio of the sample area after transfer to the sample area before transfer) is greater than 98%. Therefore, it ensures that a large area of ​​material can be transferred to the gallium surface and used for subsequent wrinkle fabrication. On the other hand, the melting of gallium causes a 3.1% volume shrinkage, similar to the release of tensile pre-strain in substrate-assisted methods, which leads to wrinkling of the surface-loaded two-dimensional material. The pit structure created on the surface of the two-dimensional material during the gallium transfer process is subjected to tensile stress, and the redistribution of stress around the pits after gallium melting further increases the wrinkle density. Traditional chemical vapor deposition-assisted wrinkle fabrication methods have limited universality, and traditional substrate-assisted wrinkle fabrication methods are difficult to manufacture two-dimensional material wrinkle structures with both large area and high density characteristics due to sample loss during the transfer process.

[0013] According to some embodiments of the present invention, the two-dimensional material is prepared by chemical vapor deposition.

[0014] According to some embodiments of the present invention, the purity of the gallium metal is ≥99.99%.

[0015] According to some embodiments of the present invention, in step S1, the temperature of the liquid gallium metal is 30 to 60°C.

[0016] This temperature range ensures that metallic gallium maintains ideal liquid fluidity, guaranteeing uniform gallium coverage.

[0017] According to some embodiments of the present invention, in step S1, the temperature of the cooling condition is -80 to 6°C.

[0018] The above cooling conditions ensured high-quality transfer and subsequent wrinkling of the two-dimensional material, and guaranteed the complete separation of the two-dimensional material from the substrate.

[0019] According to some embodiments of the present invention, in step S1, the cooling time is not less than 5 minutes.

[0020] In some preferred embodiments of the present invention, in step S1, when the gallium cooling temperature is -80°C, the cooling time is 5 minutes.

[0021] In some preferred embodiments of the present invention, in step S1, during the two-dimensional material transfer process, when the gallium cooling temperature is 6°C, the cooling time is 30 minutes.

[0022] According to some embodiments of the present invention, in step S2, the heating temperature is 30 to 100°C. Specifically, it can be 30°C, 60°C, or 90°C.

[0023] According to some embodiments of the present invention, in step S2, when the two-dimensional material is molybdenum disulfide, the heating temperature is 60°C.

[0024] According to some embodiments of the present invention, the two-dimensional material is a single crystal or polycrystalline sample; the domain size of the two-dimensional material is 10 to 500 μm.

[0025] In some preferred embodiments of the present invention, when the transferred two-dimensional material is molybdenum disulfide, the side length of a single molybdenum disulfide crystal is greater than 100 μm.

[0026] According to some embodiments of the present invention, the density of the two-dimensional material folds in the folded structure is ≥5 μm / μm. 2 .

[0027] According to some embodiments of the present invention, the density of the two-dimensional material folds in the folded structure is ≥6.4 μm / μm. 2 .

[0028] In this invention, the area of ​​the folds in the two-dimensional material is the area of ​​the two-dimensional material.

[0029] According to some embodiments of the present invention, the area of ​​the two-dimensional material with the folded structure is ≥22000μm. 2 .

[0030] In this invention, the area of ​​the folds is positively correlated with the size of the transferred two-dimensional material.

[0031] According to some embodiments of the present invention, in step S1, the lower surface of the two-dimensional material is attached to a substrate; the substrate material includes at least one of silicon wafer, copper foil, sapphire and mica.

[0032] According to some embodiments of the present invention, the operation of covering the upper surface of the two-dimensional material with liquid gallium metal in step S1 is performed in an attachment and transfer device, the attachment and transfer device comprising:

[0033] The load-bearing base, limiting support, and flattening cover are stacked sequentially.

[0034] The supporting substrate is used to place a substrate with two-dimensional material attached and to provide a flat support surface;

[0035] The limiting support is provided along the relative edges of the bearing base, and is used to support the flattening cover and limit the gap between the flattening cover and the bearing base;

[0036] The flattening cover uses a downward pressing action to cover the upper surface of the two-dimensional material with liquid gallium metal.

[0037] In some embodiments of the present invention, step S1 includes the following steps:

[0038] After placing the substrate with the two-dimensional material attached at the geometric center of the support substrate, liquid gallium metal is drawn up with a dropper and dropped onto the center of the upper surface of the two-dimensional material to cover the upper surface of the two-dimensional material. The liquid gallium metal is then flattened by the cover material. After the liquid gallium metal is solidified under cooling conditions, a gallium ingot loaded with two-dimensional material nanosheets is obtained.

[0039] In this invention, the operation of flattening the liquid gallium surface with a flattening cover should satisfy the following conditions: the flattening cover first adheres to the liquid gallium and slowly falls while simultaneously squeezing the gallium surface to make it flow, deforming the spherical gallium droplets into flat cylindrical liquid gallium ingots, thus avoiding excessively fast falling speed of the glass sheet, which could cause the liquid gallium to splash or deform unevenly.

[0040] In some embodiments of the present invention, such a drop position setting is more conducive to the uniform circular spread of liquid gallium metal after the flattening cover is applied, while maximizing the contact area between liquid gallium metal and other substrates, and reducing the loss of two-dimensional material due to poor or no adhesion between the liquid metal and the edges of other substrates.

[0041] According to some embodiments of the present invention, the amount of liquid gallium metal added is a spherical droplet with a diameter of 0.5 to 2 cm.

[0042] In some preferred embodiments of the present invention, the amount of liquid gallium metal added is spherical droplets with a diameter of 0.8 to 1.2 cm.

[0043] According to some embodiments of the present invention, during the two-dimensional material transfer process, the liquid gallium metal is dropped onto the central position of the other substrate loaded with the two-dimensional material.

[0044] In some embodiments of the present invention, step S1 further includes separating the gallium ingot and the substrate from which the two-dimensional material nanosheets are loaded.

[0045] The separation process needs to be carried out rapidly in a low-temperature environment to avoid melting of solid gallium due to ambient temperature or heat generated during operation.

[0046] In step S2, the process of heating the gallium ingot to the point of gallium melting should be controlled in a windless and dry environment to avoid airflow disturbance causing displacement or adhesion of the two-dimensional material, and to avoid the possibility that a humid environment may cause damage to the two-dimensional material.

[0047] According to some embodiments of the present invention, the gap between the flattening cover and the supporting substrate is 0.1 to 0.6 cm. Specifically, it can be 0.1 cm, 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, or 0.6 cm.

[0048] According to a second aspect of the present invention, the method is provided for use in the preparation of electronic devices, optical devices, optoelectronic devices, chemical and biological sensors, and electrochemical catalytic devices.

[0049] Since the two-dimensional material with a wrinkled structure provided by the present invention has the above-mentioned parameters, it has stress distribution, electronic structure and optical properties based on the wrinkled morphology, and has broad application prospects in the fields of sensors, electrochemical catalysis and the like.

[0050] Unless otherwise specified, the term "about" in this invention actually means that the error is allowed to be within ±2%, for example, about 100 is actually 100 ± 2% × 100.

[0051] Unless otherwise specified, "between" in this invention includes the number itself, for example, "between 2 and 3" includes the endpoint values ​​2 and 3.

[0052] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0053] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0054] Figure 1 This is a schematic flowchart of the manufacturing method of the two-dimensional material with a folded structure according to the present invention.

[0055] Figure 2 This is a physical image of the attachment and transfer device in Example 1.

[0056] Figure 3 This is a schematic diagram of the gallium-assisted two-dimensional material transfer process in Example 1.

[0057] Figure 4 This is a schematic diagram of the gallium-assisted wrinkling process of two-dimensional materials in Example 1.

[0058] Figure 5 This is an optical microscope image of the two-dimensional material in Example 1 before transfer.

[0059] Figure 6 This is an electron microscope image of the two-dimensional material from Example 1 after transfer.

[0060] Figure 7 This is an electron microscope image of the two-dimensional material of Example 1 after wrinkling.

[0061] Figure 8 This is an optical microscope image of the two-dimensional material in Example 2 before transfer.

[0062] Figure 9 This is an electron microscope image of the two-dimensional material of Example 2 after transfer.

[0063] Figure 10 This is an electron microscope image of the two-dimensional material in Example 2 after wrinkling.

[0064] Figure 11 This is an optical microscope image of the two-dimensional material in Example 3 before transfer.

[0065] Figure 12 This is an electron microscope image of the two-dimensional material of Example 3 after transfer.

[0066] Figure 13 This is an electron microscope image of the two-dimensional material of Example 3 after wrinkling.

[0067] Figure 14 This is an optical microscope image of the two-dimensional material in Example 4 before transfer.

[0068] Figure 15 This is an electron microscope image of the two-dimensional material in Example 4 after transfer.

[0069] Figure 16 This is an electron microscope image of the two-dimensional material in Example 4 after wrinkling.

[0070] Figure 17 This is an electron microscope image of the two-dimensional material in Example 5 after wrinkling.

[0071] Figure 18 This is an electron microscope image of the two-dimensional material of Example 6 after wrinkling.

[0072] Figure 19 The image shows optical microscope images of the two-dimensional material in Comparative Example 1 before and after the transfer.

[0073] Figure 20 This is an atomic force microscope image of the two-dimensional material in Comparative Example 2 after wrinkling.

[0074] Figure 21This is a scanning electron microscope observation result of the two-dimensional material with a wrinkled structure in Example 1, and a schematic diagram of the wrinkle distribution area calculation.

[0075] Figure 22 This is an atomic force microscopy observation result and a statistical diagram of the wrinkle density of the two-dimensional material with a wrinkled structure in Example 1.

[0076] Figure 23 The two-dimensional material with a pleated structure of Example 1 was measured at 1650 cm. -1 Surface scan Raman spectroscopy image at (Rhodamine 6G molecule Raman characteristic peak).

[0077] Figure 24 The Raman spectrum of the two-dimensional material with a wrinkled structure used in Example 1 as a surface-enhanced Raman substrate for detecting low concentrations of Rhodamine 6G was used to calibrate the detection limit.

[0078] Figure 25 The Raman spectrum of the two-dimensional material with a wrinkled structure used in Example 1 as a surface-enhanced Raman substrate for evaluating the stability of Rhodamine 6G is shown.

[0079] Figure 26 The Raman spectra of the two-dimensional material with a wrinkled structure used in Example 1 as a surface-enhanced Raman substrate for detecting different types of dye molecules demonstrate its advantages over flat two-dimensional materials. Detailed Implementation

[0080] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0081] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0082] Example 1

[0083] This embodiment prepares a two-dimensional material with a wrinkled structure, the process is as follows: Figure 1 As shown.

[0084] The specific preparation process is as follows:

[0085] D1. Transfer preparations, including:

[0086] The first step is to construct the attachment and transfer device: The attachment and transfer device includes a support substrate, a limiting support, and a flattening cover, which are stacked sequentially. The support substrate is a glass sheet with a size of 7.5cm × 7.5cm, used to place the substrate with the two-dimensional material attached and to provide a flat support surface. The limiting support consists of two rectangular glass sheets, each with a size of 7.5cm × 2.5cm, placed parallel to each other on the opposite edges of the support substrate and fixed with tape to form a groove structure that defines the substrate placement area. This groove structure supports the flattening cover and defines the gap between the flattening cover and the support substrate. The flattening cover is a glass sheet with a size of 7.5cm × 7.5cm, which covers the limiting support during use and, through downward pressure, makes the liquid gallium metal uniformly cover the upper surface of the two-dimensional material.

[0087] Actual picture of the attachment transfer device is shown below. Figure 2 As shown.

[0088] D2. Heat the reagent bottle containing solid gallium in a 60°C water bath for 5 minutes to melt the gallium into liquid gallium, which will be used for subsequent two-dimensional material transfer.

[0089] S1. Place a 1×1cm silicon wafer loaded with molybdenum disulfide (the lower surface of molybdenum disulfide is attached to the silicon wafer) at the center of the substrate. Use a 1ml dropper to draw molten liquid gallium metal and add a drop of liquid gallium metal with a diameter of about 0.8cm to the center of the silicon wafer, so that it is close to covering the surface of the silicon wafer (the liquid gallium metal covers the upper surface of molybdenum disulfide). Gently press down the flattened cover (7.5cm×7.5cm glass plate) to make the glass plate contact and flatten the liquid surface of the liquid gallium metal, forming a uniform liquid layer covering the silicon wafer. Then place it in a 6℃ refrigerator to cool for 5 minutes. Then take it out and peel off the glass top plate (flattened cover). At this time, the silicon wafer and the solidified gallium metal ingot are tightly attached together. Separate the two along the bonding surface of the silicon wafer and the gallium metal ingot to obtain a gallium metal ingot loaded with molybdenum disulfide nanosheets.

[0090] The process diagram for this step is shown below. Figure 3 As shown;

[0091] S2. Place the gallium ingot loaded with molybdenum disulfide nanosheets (a clean glass plate can be placed at the bottom to prevent it from sticking to the hot stage) on a 60°C hot stage and heat it until the gallium is completely melted. Then turn off the hot stage and let the gallium ingot cool and solidify naturally. The molybdenum disulfide nanosheets on the top of the solidified gallium ingot are wrinkled nanosheets.

[0092] The process diagram for this step is shown below. Figure 4 As shown.

[0093] The resulting two-dimensional material with a wrinkled structure was retained on a gallium substrate. The microstructure and domain size of the two-dimensional material before transfer were measured using optical microscopy; the microstructure and domain size of the two-dimensional material after transfer and wrinkling were measured using scanning electron microscopy. The results show:

[0094] Figure 5 This is a microscopic observation of the two-dimensional material with a wrinkled structure before transfer.

[0095] Figure 6 This is a microscopic observation of the two-dimensional material with a wrinkled structure after transfer in this embodiment.

[0096] Depend on Figure 5 , 6 It can be seen that the molybdenum disulfide nanosheets had a triangular morphology before transfer, and no observable structural damage was observed after transfer.

[0097] Figure 7 This is a microscopic observation of the two-dimensional material with a wrinkled structure in this embodiment after wrinkling.

[0098] Depend on Figure 7 It can be seen that the surface of molybdenum disulfide has a wrinkled structure, including edge wrinkles and internal wrinkles of nanosheets.

[0099] Example 2

[0100] This embodiment prepares a two-dimensional material with a wrinkled structure. The specific process differs from that in Example 1 in that:

[0101] In steps S1 and S2, the selected two-dimensional material is tungsten disulfide, not molybdenum disulfide.

[0102] Figure 8 This is a microscopic observation of the two-dimensional material before transfer in this embodiment.

[0103] Figure 9 This is a microscopic observation result of the two-dimensional material after transfer in this embodiment.

[0104] Depend on Figure 8 , 9 It can be seen that the tungsten disulfide nanosheets had a triangular morphology before transfer, and no observable structural damage was observed after transfer.

[0105] Figure 10 This is a microscopic observation of the two-dimensional material after wrinkling in this embodiment.

[0106] Depend on Figure 10It can be seen that the surface of tungsten disulfide has a wrinkled structure, including edge wrinkles and internal wrinkles of triangular nanosheets.

[0107] Example 3

[0108] This embodiment prepares a two-dimensional material with a wrinkled structure. The specific process differs from that in Example 1 in that:

[0109] In steps S1 and S2, the selected two-dimensional material is tungsten diselenide, rather than molybdenum disulfide.

[0110] Figure 11 This is a microscopic observation of the two-dimensional material before transfer in this embodiment.

[0111] Figure 12 This is a microscopic observation result of the two-dimensional material after transfer in this embodiment.

[0112] Depend on Figure 11 , 12 It can be seen that the morphology of tungsten diselenide nanosheets was an irregular polygon before transfer, and no structural damage was observed after transfer.

[0113] Figure 13 This is a microscopic observation of the two-dimensional material after wrinkling in this embodiment.

[0114] Depend on Figure 13 It can be seen that the surface of tungsten diselenide has a wrinkled structure, including edge wrinkles and internal wrinkles of nanosheets.

[0115] Example 4

[0116] This embodiment prepares a two-dimensional material with a wrinkled structure. The specific process differs from that in Example 1 in that:

[0117] In steps S1 and S2, the selected two-dimensional material is graphene, rather than molybdenum disulfide.

[0118] Figure 14 This is a microscopic observation of the two-dimensional material before transfer in this embodiment.

[0119] Figure 15 This is a microscopic observation result of the two-dimensional material after transfer in this embodiment.

[0120] Depend on Figure 14 , 15 It can be seen that the graphene nanosheets had a uniform morphology before the transfer, and there was no observable structural damage after the transfer.

[0121] Figure 16 This is a microscopic observation of the two-dimensional material after wrinkling in this embodiment.

[0122] Depend on Figure 16It can be seen that the graphene surface has a wrinkled structure.

[0123] Example 5

[0124] This embodiment prepares a two-dimensional material with a wrinkled structure. The specific process differs from that in Example 1 in that:

[0125] In step S2, the temperature of the heating platform is 100°C, not 60°C.

[0126] Figure 17 This is a microscopic observation of the two-dimensional material after wrinkling in this embodiment.

[0127] Depend on Figure 17 It can be seen that the surface of molybdenum disulfide has a wrinkled structure, including edge wrinkles and internal wrinkles of nanosheets.

[0128] Example 6

[0129] This embodiment prepares a two-dimensional material with a wrinkled structure. The specific process differs from that in Example 1 in that:

[0130] In step S2, after the gallium is heated to complete melting, the gallium ingot is transferred to a -80°C freezer to condense, instead of being allowed to cool and solidify naturally.

[0131] Figure 18 This is a microscopic observation of the two-dimensional material after wrinkling in this embodiment.

[0132] Depend on Figure 18 It can be seen that the surface of molybdenum disulfide has a wrinkled structure, including edge wrinkles and internal wrinkles of nanosheets.

[0133] Comparative Example 1

[0134] This comparative example presents a method for manufacturing a two-dimensional material with a wrinkled structure, which differs from Example 1 in that:

[0135] Steps S1 and S2 are excluded;

[0136] Place a drop of liquid gallium metal in the center of a 7.5×7.5cm glass slide using a 1ml dropper. Gently touch the top of the liquid gallium metal droplet (material side down) with a silicon wafer loaded with molybdenum disulfide in the center of the glass slide. After a brief contact, remove the silicon wafer, allowing some of the molybdenum disulfide to transfer onto the gallium droplet.

[0137] The gallium-loaded glass plate was placed in a 6°C refrigerator and cooled for 5 minutes, and then removed to obtain a gallium ingot loaded with molybdenum disulfide nanosheets.

[0138] Figure 19 The images show the microscopic observation results of the two-dimensional material before and after transfer in this comparative example.

[0139] Depend on Figure 19 It can be seen that the molybdenum disulfide nanosheets had a uniform morphology before transfer, while the molybdenum disulfide nanosheets showed obvious damage after transfer.

[0140] Comparative Example 2

[0141] This comparative example presents a method for manufacturing a two-dimensional material with a wrinkled structure, which differs from Example 1 in that:

[0142] Step S2 does not include placing a 1×1cm silicon wafer loaded with molybdenum disulfide at the center of the transfer device base plate, and directly dripping gallium onto the center of the transfer device base plate instead of dripping it onto the silicon wafer, thus finally obtaining a solidified gallium ingot.

[0143] The molybdenum disulfide on the silicon wafer was transferred to the top of the solidified gallium ingot using a polymethyl methacrylate (PMMA) spin coating-hydrofluoric acid etching method. Then, the PMMA was cleaned with acetone and dried to obtain a gallium ingot loaded with molybdenum disulfide nanosheets, which was used for wrinkle fabrication in step S2.

[0144] Figure 20 This is an atomic force microscope image showing the results of the molybdenum disulfide wrinkled structure obtained in this comparative example.

[0145] Depend on Figure 20 It can be seen that the wrinkled structure distributed on the surface of the molybdenum disulfide nanosheets is wavy and has a low density.

[0146] Figure 21 This is a scanning electron microscope observation result of the two-dimensional material with a wrinkled structure obtained in Embodiment 1 of the present invention, and a schematic diagram of the calculation of the wrinkle distribution area.

[0147] The results show that the surface of the molybdenum disulfide nanosheets is covered with a wrinkled structure. The triangular nanosheets have a base length of about 230 μm, a height of about 197 μm, and a calculated area greater than 22000 μm. 2 This is the largest area reported so far for molybdenum disulfide nanosheet wrinkled structures, indicating that this method is suitable for fabricating large-area two-dimensional material wrinkled structures.

[0148] Test case

[0149] In this test case, an atomic force microscope was used to characterize a two-dimensional material with a wrinkled structure. The wrinkle density was statistically analyzed and the average value was calculated. The wrinkle density is defined as the total wrinkle length per unit area of ​​the two-dimensional material.

[0150] Figure 22 This is a schematic diagram showing the atomic force microscopy observation results and wrinkle density statistics of the molybdenum disulfide nanosheets with wrinkled structures obtained in Example 1 of the present invention.

[0151] The results show that the average wrinkle density of molybdenum disulfide with a wrinkled structure obtained by this method is calculated to be 6.4 μm / μm. 2 This is the highest reported wrinkle density among all molybdenum disulfide nanosheets to date, indicating that this method is suitable for fabricating high-density two-dimensional material wrinkled structures.

[0152] In Examples 2, 3, and 4, this method was used to transfer and wrinkle other two-dimensional materials (tungsten disulfide, tungsten diselenide, and graphene). The results show that this method is universally applicable to the fabrication of wrinkled structures in a variety of two-dimensional materials.

[0153] In Examples 5 and 6, molybdenum disulfide wrinkled structures were fabricated by changing the wrinkling operation parameters (heating and cooling rates) using this method. The results showed that the morphology of the obtained molybdenum disulfide nanosheet wrinkled structures was the same as that in Example 1, indicating that the method has stability and reproducibility.

[0154] In Comparative Example 1, molybdenum disulfide nanosheets on a silicon wafer were transferred using liquid gallium without a solidification process. After the transfer, the solidified gallium surface showed a damaged molybdenum disulfide nanosheets. The results show that the gallium solidification process before transfer is a necessary condition to ensure the non-destructive transfer of molybdenum disulfide, providing a large area of ​​molybdenum disulfide for wrinkle manufacturing.

[0155] In Comparative Example 2, molybdenum disulfide on a silicon wafer was directly transferred to a solidified gallium ingot using a polymethyl methacrylate (PMMA) homogenization-hydrofluoric acid etching method. The results showed that the surface of the molybdenum disulfide nanosheets had a low-density wrinkled structure, indicating that gallium solidification and transfer of molybdenum disulfide is a necessary condition to ensure the fabrication of high-density wrinkles.

[0156] Finally, this test case examined the performance of the two-dimensional wrinkled molybdenum disulfide nanosheets obtained in Example 1 as a surface-enhanced Raman spectroscopy (SERS) substrate for detecting low-concentration organic dyes. A Raman laser with a wavelength of 532 nm, a power of ≤5 mW, and an excitation time of 10⁻²⁵ s was selected. The results showed that the detection signal was more visualized in high-density wrinkled regions than in low-density wrinkled regions on the surface of the molybdenum disulfide nanosheets. The detection limit of the wrinkled molybdenum disulfide for Rhodamine 6G molecules was as low as 10⁻²⁰. -15 mol L -1 This value represents the best reported performance of molybdenum disulfide materials for surface-enhanced Raman spectroscopy (SERS) substrates to date. The wrinkled samples exhibit good stability, remaining usable for detection even after three weeks of storage at room temperature and atmospheric pressure. Furthermore, wrinkled molybdenum disulfide is suitable for detecting a variety of dye molecules, including rhodamine, crystal violet, and methylene blue. Specific results are as follows: Figure 23-26 As shown. The performance test results of the remaining embodiments are similar to those of Embodiment 1.

[0157] In summary, this invention utilizes the solid-liquid and liquid-solid phase transitions of liquid gallium to fabricate large-area, high-density wrinkled structures in two-dimensional materials, with the resulting two-dimensional material wrinkled areas exceeding 22000 μm. 2 (For a single molybdenum disulfide crystal), the average wrinkle density is approximately 6.4 μm / μm. 2 Two-dimensional materials with wrinkled structures exhibit improved detection capabilities as surface-enhanced Raman spectroscopy substrates, showing broad application prospects in fields such as sensors and electrochemical catalysis.

[0158] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing two-dimensional materials with a wrinkled structure using liquid metal-assisted synthesis, characterized in that, Includes the following steps: S1. Liquid gallium metal is covered on the upper surface of a two-dimensional material, and the liquid gallium metal is solidified under cooling conditions to obtain a gallium ingot loaded with two-dimensional material nanosheets; S2. A gallium ingot loaded with molybdenum disulfide nanosheets is heated until gallium melts and then cooled and solidified to obtain a two-dimensional material with a wrinkled structure. The two-dimensional material includes at least one of molybdenum disulfide, tungsten disulfide, tungsten diselenide, and graphene.

2. The method for preparing two-dimensional materials with wrinkled structures using liquid metal assisted preparation according to claim 1, characterized in that, In step S1, the temperature of the liquid gallium metal is 30–60°C.

3. The method for preparing two-dimensional materials with a wrinkled structure using liquid metal assisted preparation according to claim 1, characterized in that, In step S1, the temperature of the cooling condition is -80 to 6°C.

4. The method for preparing two-dimensional materials with wrinkled structures using liquid metal assisted preparation according to claim 1, characterized in that, In step S2, the heating temperature is 30–100°C.

5. The method for preparing two-dimensional materials with a wrinkled structure using liquid metal assisted preparation according to claim 1, characterized in that, The two-dimensional material is a single-crystal or polycrystalline sample prepared by chemical vapor deposition; the domain size of the two-dimensional material is 10–500 μm.

6. The method for preparing two-dimensional materials with a wrinkled structure using liquid metal assisted preparation according to claim 1, characterized in that, The density of the two-dimensional material folds in the folded structure is ≥5μm / μm. 2 .

7. The method for preparing two-dimensional materials with a wrinkled structure using liquid metal assisted preparation according to claim 1, characterized in that, In step S1, the lower surface of the two-dimensional material is attached to a substrate; the substrate material includes at least one of silicon wafer, copper foil, sapphire, and mica.

8. The method for preparing two-dimensional materials with wrinkled structures using liquid metal assistance according to claim 1, characterized in that, The operation of covering the upper surface of the two-dimensional material with liquid gallium metal in step S1 is performed in an attachment and transfer device, which includes: The load-bearing base, limiting support, and flattening cover are stacked sequentially. The supporting substrate is used to place a substrate with two-dimensional material attached and to provide a flat support surface; The limiting support is provided along the relative edges of the bearing base, and is used to support the flattening cover and limit the gap between the flattening cover and the bearing base; The flattening cover uses a downward pressing action to cover the upper surface of the two-dimensional material with liquid gallium metal.

9. The method for preparing two-dimensional materials with a wrinkled structure using liquid metal assistance according to claim 8, characterized in that, The gap between the flattening cover and the supporting substrate is 0.1 to 0.6 cm.

10. The application of the method according to any one of claims 1 to 9 in the preparation of electronic devices, optical devices, optoelectronic devices, chemical and biological sensors, and electrochemical catalytic devices.

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