Method for preparing molecular-level thickness-controllable two-dimensional water by extruding and stretching temperature control method

Abstract

According to the extruding and stretching temperature control method, the molecular-level controllable-thickness two-dimensional water is prepared from top to bottom through the six steps of extruding, heating, stretching, cooling, separating and repeating from top to bottom, the two-dimensional water is formed on the top substrate and the bottom substrate respectively, the separation distance of the substrates is large, the requirement for instrument precision is greatly lowered, but the precision of the prepared two-dimensional water film is not lowered. And the water molecule film is just frozen at the temperature of 150-260 K, so that repeated operation and observation detection are facilitated. According to the method, the existing mature technology is adopted, the principle is clear, the steps are simple, the material selection range is wide, the universality is high, and the large-scale application potential is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for preparing two-dimensional water, in particular, a method for preparing two-dimensional water with controllable thickness at molecular level by using extrusion stretching temperature control method. BACKGROUND

[0002] The preparation of two-dimensional water with controllable thickness at molecular level is a very cutting-edge research field, which combines two-dimensional materials, interface science, nanofluidics and precise mechanical control, aiming to realize the accurate manipulation and stable existence of water at the limit scale. Two-dimensional water refers to a layer of water molecules confined in a two-dimensional plane, with a thickness at the molecular level. Under such extreme constraints, the physical and chemical properties of water, such as hydrogen bond network, phase transition behavior, and proton transport, are fundamentally different from those of macroscopic bulk water, and may form new phases such as "square ice" that do not exist in nature. Verifying and discovering new phases of water at the two-dimensional limit can expand our understanding of water, the most basic substance, and study the formation of hydrogen bond network, proton transport, and thermal conductivity in confined spaces. Two-dimensional water can be used to construct highly energy-efficient ion circuits, proton transistors and molecular sieving membranes. Two-dimensional water channels can achieve nearly frictionless ion transport and extremely high selectivity. Two-dimensional water layers can be used as molecular-level lubricants, and understanding their behavior is crucial for designing ultra-smooth surfaces for micro-electro-mechanical systems and artificial joints. Two-dimensional water can help understand the initial adsorption of water molecules on metal surfaces and the formation process of oxide layers, providing atomic-level insights for corrosion prevention. Two-dimensional water can simulate the behavior of water films on the surface of interstellar dust ice caps or atmospheric cloud condensation nuclei. Two-dimensional water can simulate the working mechanism of water channel proteins on cell membranes, providing inspiration for designing biomimetic membranes. However, the preparation of two-dimensional water with large area, no defects, and single crystal domain at molecular level thickness is still extremely challenging. SUMMARY

[0003] The present application provides a method for preparing two-dimensional water with controllable thickness at molecular level by using extrusion stretching temperature control method. Extrusion stretching temperature control method is a top-down physical method that realizes "atomic-level carving" of water layer thickness in artificially constructed nanochambers through precise mechanical manipulation and temperature regulation. This technology not only opens the door to the science of two-dimensional water, but also provides a new platform and approach for the future innovation of nanotechnology in the fields of energy, information, biology and environment. The goal of two-dimensional water with controllable thickness at molecular level is to accurately prepare structures of strictly 1 layer, 2 layers, and 3 layers of water molecules and maintain their stability. This is the basis for studying the number of layers dependent properties.

[0004] The present application is based on the following basic principles: (1) Extrusion: First, the base-water-base sandwich structure is constructed by extrusion method. The base should be as flat as possible, and molybdenum disulfide, mica, silicon, sapphire, metal specific crystal exposure direction can be selected. For example, a layer of graphene is directly grown on the surface of copper by chemical vapor deposition method, or the graphene sheet is laid on the atomically flat substrate. Add water droplets to the surface of the substrate, place another substrate on the water droplets, and maintain the temperature in the range of liquid water. Slowly approach the two substrates by extrusion method, and the liquid water gradually flattens, thins, and the excess water overflows from the edge of the substrate. Stop extruding when the thickness of the water tends to be a few molecular layers. The purpose of this step is to leave a few microns or nanometers even thicker water molecules between the substrates by the fluidity of liquid water, and the substrate has a protective effect.

[0005] (2) Heating: The periphery of the substrate is sealed, and it is necessary to completely isolate the external environment while ensuring the freedom of nanoscale movement. Heat the substrate to a temperature higher than 400 K, conduct heat to the water molecules between the layers, and the time should be sufficient to ensure that the water molecules are in a temperature range that can be converted to a gaseous state. The purpose of this step is to prepare for the spatial stretching in the later stage. The water molecules are heated to a high temperature in advance, and after stretching, they can quickly diffuse to the entire space.

[0006] (3) Stretching: Control the substrate to move away from the other substrate, with a distance of 10-1000 nm, and the water molecules between the layers expand to cause a decrease in density. The existing piezoelectric nanometer positioning table can reach sub-nanometer level in terms of accuracy, and can handle sample weights from a few kilograms to hundreds of kilograms in terms of load. The corresponding instrument parameters can be selected according to the accuracy and load. Since the substrate needs to be stretched to a higher distance, the present application can further reduce the requirement for instrument accuracy. The purpose of this step is to provide sufficient spatial distance for the separation of water molecules in the later stage.

[0007] (4) Cooling: Freeze the substrate, control the temperature to 150-260 K, and migrate the water molecules between the layers to the surface of the substrate to crystallize. The water loses its fluidity and the position is fixed. The purpose of this step is to disperse the water molecules to form a two-dimensional film on the two substrates.

[0008] (5) Separation: Remove the seal around the substrate and move one of the substrates to the outside, and remove the water at a temperature above room temperature. The other substrate remains in place and remains at a low temperature.

[0009] (6) Repeat: The substrate that has been cleared of water is again overlapped with the substrate that is in place, and the base-water-base sandwich structure is constructed by extrusion. At this time, the water molecules have been removed by half after the previous separation step, and the water is in a frozen state and will not be lost by extrusion. Seal the periphery of the substrate, and repeat the heating, stretching, cooling, and separation steps to reduce the water molecules by half each time, reducing the thickness of the water molecule layer by half.

[0010] The present invention adopts the following technical solution: The preparation of two-dimensional water with controllable thickness at the molecular level via extrusion stretching temperature control method includes the following steps: (1) Select a material with atomic-level flatness, chemical inertness and appropriate affinity for water molecules as a substrate. One substrate is used as the bottom substrate and the other is used as a movable top substrate. Add liquid water droplets to the surface of the bottom substrate and place the other substrate above the water droplets. Drive the top substrate slowly and accurately downwards through piezoelectric ceramics to reduce the spacing between the substrates and force excess water molecules to be discharged. The remaining water and the substrate form a substrate-water-substrate sandwich structure, and the substrate also has a protective function. (2) Use flexible corrugated pipes to seal the periphery of the substrate, control the temperature control components outside the substrate to heat the base, conduct heat to the water molecules between the layers, and the time should be sufficient to ensure that the temperature of the water molecules is in the range where they can change to gaseous state. (3) Controlling the top substrate away from the bottom substrate causes water molecules between the upper and lower substrate layers to expand, resulting in a decrease in density; (4) The temperature control components outside the substrate are controlled to cool the substrate, and the interlayer water molecules migrate to the substrate surface to crystallize and form a two-dimensional thin film. (5) Move the top substrate to the outside, remove moisture from the substrate surface, and leave the bottom substrate in place to keep it at a low temperature and retain water; (6) The top substrate, which has been dehydrated, is overlapped with the bottom substrate in place to reconstruct the substrate-water-substrate sandwich structure. The heating, stretching, cooling and separation steps are repeated to reduce the thickness of the water molecule layer to the target number of layers.

[0011] The substrates selected in step (1) include graphene, hexagonal boron nitride, molybdenum disulfide, mica, silicon, sapphire, and metals.

[0012] The thickness of the substrate-water-substrate water in step (1) can be at the angstrom level or the nanometer level.

[0013] The temperature reached in step (2) must be higher than 400 K, and the heating process can be carried out slowly.

[0014] The distance between the upper and lower base layers in step (3) is 10-1000 nm.

[0015] The cooling temperature in step (4) is controlled at 150-260 K, and the cooling process can be carried out slowly.

[0016] In step (5), the method of removing moisture should keep the substrate from being contaminated. The wet substrate can be placed in a clean environment at room temperature to allow it to evaporate naturally.

[0017] When the top base in step (6) coincides with the bottom base in its original position again, it is not required that they coincide completely without gaps.

[0018] This invention has the following advantages: (1) The method described in this invention can prepare two-dimensional water with controllable thickness at the molecular level.

[0019] (2) The method described in this invention uses existing mature technology. During the stretching process, water molecules will concentrate on the substrate surface within a specified temperature range, forming two-dimensional water on the top and bottom substrates respectively. If the temperature is too low, a network structure will form between the layers; if the temperature is too high, the kinetic energy of the water molecules will be too great, causing them to diffuse and distribute between the layers. The substrate needs to be separated over a larger distance, thus greatly reducing the requirements for instrument precision, but not reducing the precision of preparing the two-dimensional water film. The temperature of 150-260 K is just right to freeze the water molecule film, which is beneficial for repeated operation and observation.

[0020] (3) The method described in this invention uses physical methods throughout and does not involve chemical reactions, making it green and environmentally friendly.

[0021] (4) The method described in this invention has strong scalability. The shape and composition of the substrate are not the decisive factors in the formation of two-dimensional thin films. It can be diversified to form two-dimensional thin films of various shapes.

[0022] (5) The method described in this invention uses an extrusion method to construct a substrate-water-substrate sandwich structure, which can control the amount of water remaining between the layers, greatly reduce the number of repetitions of the operation, and can also directly construct a two-dimensional water film protected by the substrate.

[0023] (6) The method described in this invention has a clear principle, simple steps, a wide range of material selection, strong versatility, and potential for large-scale application. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the temperature dependence principle of the method for preparing two-dimensional thin films according to the present invention. The Ni interlayer spacing is 56.384 Å, and the water molecule density is 0.3 g / cm³. 3 1 is a water molecule, 2 is a nickel substrate. Figure 1 All parts together present the variation of the same system under different temperature parameters.

[0025] Figure 2 This is a schematic diagram illustrating the process of preparing two-dimensional encapsulated water using the extrusion method based on the fluidity of liquid water, as described in this invention. 3 represents the lower graphene substrate, 4 the copper support, 5 the water droplet, and 6 the upper graphene substrate.

[0026] Figure 3 This is a schematic diagram of the process for preparing molecularly controllable thickness two-dimensional water using the extrusion stretching temperature control method in this invention. 7 represents the upper substrate temperature control stage, and 8 represents the lower substrate temperature control stage.

[0027] Figure 4This is a schematic diagram of the graphene-two-dimensional water-graphene structure prepared by the method of this invention. In the diagram, the graphene-two-dimensional water-graphene structure is abbreviated as G-H2O-G. 9 represents graphene.

[0028] Figure 5 This is a schematic diagram of the graphene-two-dimensional water structure prepared by the method of this invention. The graphene-two-dimensional water structure is abbreviated as G-H2O in the diagram.

[0029] Figure 6 This is a schematic diagram of the two-dimensional water structure prepared by the method of this invention. In the diagram, the two-dimensional water structure is abbreviated as H2O.

[0030] Figure 7 This is a schematic diagram of the graphene substrate structure used in the method of this invention. The graphene structure in the diagram is abbreviated as G.

[0031] Figure 8 The electron density map and charge distribution map of the two-dimensional water structure prepared by the method of the present invention are shown.

[0032] Figure 9 This is a cross-sectional view of the differential charge density of the two-dimensional water structure prepared by the method of the present invention.

[0033] Figure 10 for Figures 4 to 7 A comparison chart of the electrical properties of the four structures. Figure 10 a represents the density of states curves for G, H₂O, G-H₂O, and G-H₂O-G. Figure 10 b is the band structure diagram of G. Figure 10 c is the band structure diagram of H2O. Figure 10 d is the band structure diagram of G-H2O. Figure 10 e represents the band structure of G-H2O-G. Comparing the four band structures together clearly demonstrates the electrical properties of the four systems.

[0034] Figure 11 for Figures 4 to 7 Optical properties diagram of the four structures. Figure 11 a is the absorption coefficient in the (100) direction. Figure 11 b is the absorption coefficient in the (001) direction. Figure 11 c is the absorption coefficient of two-dimensional water in the (100) and (001) directions. Figure 11 d is the reflectivity in the (100) direction. Figure 11 e is the reflectivity in the (001) direction. Figure 11 f is the reflectivity of two-dimensional water in the (100) and (001) directions. Figure 11 g is the real part of the dielectric function in the (100) direction. Figure 11 h is the real part of the dielectric function in the (001) direction. Figure 11i is the real part of the dielectric function of two-dimensional water in the (100) and (001) directions. Figure 11 j is the imaginary part of the dielectric function in the (100) direction. Figure 11 k is the imaginary part of the dielectric function in the (001) direction. Figure 11 l is the imaginary part of the dielectric function of two-dimensional water in the (100) and (001) directions. Figure 11 m is the real part of the photoconductivity in the (100) direction. Figure 11 n is the real part of the photoconductivity in the (001) direction. Figure 11 o is the real part of the photoconductivity of two-dimensional water in the (100) and (001) directions. Figure 11 p is the energy loss function in the (100) direction. Figure 11 q is the energy loss function in the (001) direction. ​ r is the energy loss function of two-dimensional water in the (100) and (001) directions. Comparing the above figures together clearly demonstrates the optical performance of the four systems. Detailed Implementation

[0035] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention. Example 1

[0036] (1) Graphene was selected as the substrate. One substrate was fixed as the bottom substrate and the other was a movable top substrate. Liquid water droplets were added to the surface of the bottom substrate. The top substrate was moved slowly and precisely downward by piezoelectric ceramics to reduce the spacing between the substrates to 40 nm, which forced the excess water molecules to be discharged. The remaining water and the substrate formed a substrate-water-substrate sandwich structure, and the substrate also had a protective function.

[0037] (2) A flexible corrugated pipe is used to seal the periphery of the substrate, and the temperature control component outside the substrate is controlled to heat the substrate to 500 K for 10 min, so that the heat is conducted to the water molecules between the layers, ensuring that the water molecules are in the range where they can change to gas.

[0038] (3) By controlling the top substrate to be far away from the bottom substrate through piezoelectric ceramics, the distance between the upper and lower substrate layers is 100 nm, and the water molecules expand, resulting in a decrease in density.

[0039] (4) The temperature control component outside the substrate is controlled to cool the substrate to 200 K for 10 min. Water molecules in the interlayer migrate to the surface of the upper and lower substrates and crystallize to form a two-dimensional film. (5) Move the top substrate to the outside and place it in a dry and clean room temperature environment. The moisture on the substrate surface will evaporate naturally, while the bottom substrate will remain in place to maintain a low temperature, thus preserving the two-dimensional water film. (6) The top substrate, which has been dehydrated, is overlapped with the bottom substrate in place to reconstruct the substrate-water-substrate sandwich structure. The heating, stretching, cooling and separation steps are repeated 6 times to reduce the thickness of the water molecule layer to 3 layers. Example 2

[0040] (1) Molybdenum disulfide was selected as the substrate. One substrate was fixed as the bottom substrate and the other was a movable top substrate. Liquid water droplets were added to the surface of the bottom substrate. The top substrate was moved slowly and precisely downward by piezoelectric ceramics to reduce the spacing between the substrates to 40 nm, which forced the excess water molecules to be discharged. The remaining water and the substrate formed a substrate-water-substrate sandwich structure, and the substrate also had a protective function.

[0041] (2) A flexible corrugated pipe is used to seal the periphery of the substrate, and the temperature control component outside the substrate is controlled to heat the substrate to 500 K for 10 min, so that the heat is conducted to the water molecules between the layers, ensuring that the water molecules are in the range where they can change to gas.

[0042] (3) By controlling the top substrate to be far away from the bottom substrate through piezoelectric ceramics, the distance between the upper and lower substrate layers is 100 nm, and the water molecules expand, resulting in a decrease in density.

[0043] (4) The temperature control component outside the substrate is controlled to cool the substrate to 200 K for 10 min. Water molecules in the interlayer migrate to the surface of the upper and lower substrates and crystallize to form a two-dimensional film. (5) Move the top substrate to the outside and place it in a dry and clean room temperature environment. The moisture on the substrate surface will evaporate naturally, while the bottom substrate will remain in place to maintain a low temperature, thus preserving the two-dimensional water film. (6) The top substrate, which has been dehydrated, is overlapped with the bottom substrate in place to reconstruct the substrate-water-substrate sandwich structure. The heating, stretching, cooling and separation steps are repeated 6 times to reduce the thickness of the water molecule layer to 3 layers. Example 3

[0044] (1) Molybdenum disulfide was selected as the substrate. One substrate was fixed as the bottom substrate and the other was a movable top substrate. Liquid water droplets were added to the surface of the bottom substrate. The top substrate was moved slowly and precisely downward by piezoelectric ceramics to reduce the spacing between the substrates to 40 nm, which forced the excess water molecules to be discharged. The remaining water and the substrate formed a substrate-water-substrate sandwich structure, and the substrate also had a protective function.

[0045] (2) A flexible corrugated pipe is used to seal the periphery of the substrate, and the temperature control component outside the substrate is controlled to heat the substrate to 600 K for 10 min, so that the heat is conducted to the water molecules between the layers, ensuring that the water molecules are in the range where they can change to gas.

[0046] (3) By controlling the top substrate to be far away from the bottom substrate through piezoelectric ceramics, the distance between the upper and lower substrate layers is 100 nm, and the water molecules expand, resulting in a decrease in density.

[0047] (4) The temperature control component outside the substrate is controlled to cool the substrate to 200 K for 10 min. Water molecules in the interlayer migrate to the surface of the upper and lower substrates and crystallize to form a two-dimensional film. (5) Move the top substrate to the outside and place it in a dry and clean room temperature environment. The moisture on the substrate surface will evaporate naturally, while the bottom substrate will remain in place to maintain a low temperature, thus preserving the two-dimensional water film. (6) The top substrate, which has been dehydrated, is overlapped with the bottom substrate in place to reconstruct the substrate-water-substrate sandwich structure. The heating, stretching, cooling and separation steps are repeated 6 times to reduce the thickness of the water molecule layer to 3 layers. Example 4

[0048] (1) Molybdenum disulfide was selected as the substrate. One substrate was fixed as the bottom substrate and the other was a movable top substrate. Liquid water droplets were added to the surface of the bottom substrate. The top substrate was moved slowly and precisely downward by piezoelectric ceramics to reduce the spacing between the substrates to 40 nm, which forced the excess water molecules to be discharged. The remaining water and the substrate formed a substrate-water-substrate sandwich structure, and the substrate also had a protective function.

[0049] (2) A flexible corrugated pipe is used to seal the periphery of the substrate, and the temperature control component outside the substrate is controlled to heat the substrate to 600 K for 10 min, so that the heat is conducted to the water molecules between the layers, ensuring that the water molecules are in the range where they can change to gas.

[0050] (3) By controlling the top substrate to be far away from the bottom substrate through piezoelectric ceramics, the distance between the upper and lower substrate layers is 100 nm, and the water molecules expand, resulting in a decrease in density.

[0051] (4) The temperature control component outside the substrate is controlled to cool the substrate to 200 K for 10 min. Water molecules in the interlayer migrate to the surface of the upper and lower substrates and crystallize to form a two-dimensional film. (5) Move the top substrate to the outside and place it in a dry and clean room temperature environment. The moisture on the substrate surface will evaporate naturally, while the bottom substrate will remain in place to maintain a low temperature, thus preserving the two-dimensional water film. (6) The top substrate, which has been dehydrated, is overlapped with the bottom substrate in its original position to reconstruct the substrate-water-substrate sandwich structure. The heating, stretching, cooling and separation steps are repeated 6 times to reduce the thickness of the water molecule layer to 2 layers. Example 5

[0052] (1) Graphene was selected as the substrate. One substrate was fixed as the bottom substrate and the other was a movable top substrate. Liquid water droplets were added to the surface of the bottom substrate. The top substrate was moved slowly and precisely downward by piezoelectric ceramics to reduce the spacing between the substrates to 40 nm, which forced the excess water molecules to be discharged. The remaining water and the substrate formed a substrate-water-substrate sandwich structure, and the substrate also had a protective function.

[0053] (2) A flexible corrugated pipe is used to seal the periphery of the substrate, and the temperature control component outside the substrate is controlled to heat the substrate to 500 K for 10 min, so that the heat is conducted to the water molecules between the layers, ensuring that the water molecules are in the range where they can change to gas.

[0054] (3) By controlling the top substrate to be far away from the bottom substrate through piezoelectric ceramics, the distance between the upper and lower substrate layers is 100 nm, and the water molecules expand, resulting in a decrease in density.

[0055] (4) The temperature control component outside the substrate is controlled to cool the substrate to 200 K for 10 min. Water molecules in the interlayer migrate to the surface of the upper and lower substrates and crystallize to form a two-dimensional film. (5) Move the top substrate to the outside and place it in a dry and clean room temperature environment. The moisture on the substrate surface will evaporate naturally, while the bottom substrate will remain in place to maintain a low temperature, thus preserving the two-dimensional water film. (6) The top substrate, which has been dehydrated, is overlapped with the bottom substrate in place to reconstruct the substrate-water-substrate sandwich structure. The heating, stretching, cooling and separation steps are repeated 7 times to reduce the thickness of the water molecule layer to 1 layer.

[0056] The applicant declares that the detailed process equipment and process flow of this invention are illustrated through the above embodiments, but this invention is not limited to the above detailed process equipment and process flow, that is, it does not mean that this invention must rely on the above detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the products of this invention, additions of auxiliary components, and selection of specific methods, all fall within the protection scope and disclosure scope of this invention.

Claims

1. Preparation of two-dimensional water with controllable thickness at the molecular level by extrusion stretching temperature control method, including the following steps: (1) Select a material with atomic-level flatness, chemical inertness and appropriate affinity for water molecules as a substrate. One substrate is used as the bottom substrate and the other is used as a movable top substrate. Add liquid water droplets to the surface of the bottom substrate and place the other substrate above the water droplets. Drive the top substrate slowly and accurately downwards through piezoelectric ceramics to reduce the spacing between the substrates and force excess water molecules to be discharged. The remaining water and the substrate form a substrate-water-substrate sandwich structure, and the substrate also has a protective function. (2) Use flexible corrugated pipes to seal the periphery of the substrate, control the temperature control components outside the substrate to heat the base, conduct heat to the water molecules between the layers, and the time should be sufficient to ensure that the temperature of the water molecules is in the range where they can change to gaseous state. (3) Controlling the top substrate away from the bottom substrate causes water molecules between the upper and lower substrate layers to expand, resulting in a decrease in density; (4) The temperature control components outside the substrate are controlled to cool the substrate, and the interlayer water molecules migrate to the substrate surface to crystallize and form a two-dimensional thin film. (5) Move the top substrate to the outside, remove moisture from the substrate surface, and leave the bottom substrate in place to keep it at a low temperature and retain water; (6) The top substrate, which has been dehydrated, is overlapped with the bottom substrate in place to reconstruct the substrate-water-substrate sandwich structure. The heating, stretching, cooling and separation steps are repeated to reduce the thickness of the water molecule layer to the target number of layers.

2. The preparation method according to claim 1, characterized in that, The substrate selection in step (1) includes graphene, hexagonal boron nitride, molybdenum disulfide, mica, silicon, sapphire, and metal.

3. The preparation method according to claim 1, characterized in that, The thickness of the substrate-water-substrate water in step (1) can be at the angstrom level or the nanometer level.

4. The preparation method according to claim 1, characterized in that, The temperature reached in step (2) must be higher than 400 K, and the heating process can be carried out slowly.

5. The preparation method according to claim 1, characterized in that, The distance in step (3) is 10-1000 nm.

6. The preparation method according to claim 1, characterized in that, The cooling temperature in step (4) is controlled at 150-260K, and the cooling process can be carried out slowly.

7. The preparation method according to claim 1, characterized in that, In step (5), the method of removing moisture should keep the substrate from being contaminated. The wet substrate can be placed in a clean environment at room temperature to allow it to evaporate naturally.

8. The preparation method according to claim 1, characterized in that, When the top base in step (6) coincides with the bottom base in its original position again, it is not required that they coincide completely without gaps.

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