WO2024026785A1 - Nanofeuille bidimensionnelle et son procédé de préparation - Google Patents

Nanofeuille bidimensionnelle et son procédé de préparation Download PDF

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WO2024026785A1
WO2024026785A1 PCT/CN2022/110357 CN2022110357W WO2024026785A1 WO 2024026785 A1 WO2024026785 A1 WO 2024026785A1 CN 2022110357 W CN2022110357 W CN 2022110357W WO 2024026785 A1 WO2024026785 A1 WO 2024026785A1
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dimensional
sno
van der
der waals
crystal
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PCT/CN2022/110357
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Chinese (zh)
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耿凤霞
嵇锦鹏
蒋坤
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苏州大学
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/054—Nanosized particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B19/00—Selenium; Tellurium; Compounds thereof
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G19/00—Compounds of tin
    • C01G19/02—Oxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G31/00—Compounds of vanadium
    • C01G31/02—Oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures

Definitions

  • the invention belongs to nanotechnology, and specifically relates to a two-dimensional nanosheet and a preparation method thereof.
  • auxiliary interposers e.g., Au, Al 2 O 3, etc.
  • this method requires the selection of different intermediary materials for different stripping objects.
  • complex methods need to be used to remove the intermediary materials after stripping, and the introduced impurities will greatly limit the intrinsic properties of the two-dimensional material.
  • layered materials such as hexagonal boron nitride (h-BN), transition metal dichalcogenide (TMD), metal organic framework (MOF), black phosphorus (BP), etc. also followed. was reported. It is worth noting that there are many functional materials with layered stacking crystal structures, but with significant electron density overlap between layers. For example, some metal oxides can be viewed as stacks of rigid layers, where each layer consists of metal-oxygen polyhedra connected by edges or corners and extending in two dimensions. There are usually metallic or electrostatic attractions between adjacent layers in these structures, called non-van der Waals structures (non-vdW), and their interlayer interactions are significantly higher than those in van der Waals layered structures.
  • non-vdW non-van der Waals structures
  • the method of the present invention includes a simple calendering pretreatment, followed by mechanical peeling using transparent tape to obtain thin layers; successfully peeling off a variety of materials, including metals (Bi, Sb), semiconductor metal oxides and chalcogenides (SnO, V 2 O 5 , Bi 2 O 2 Se) and superconducting compounds (KV 3 Sb 5 ). Electron density theoretical calculations have verified the existence of strong electronic coupling between the layers of these structures, and the exfoliation energy is usually several times higher than that of graphite, which naturally makes routine exfoliation of these materials difficult or even unfeasible.
  • the present invention adopts the following technical solution: a method for preparing two-dimensional nanosheets.
  • the crystal particles are rolled and then mechanically peeled off to obtain two-dimensional nanosheets.
  • the crystal particles are flattened and then rolled and then mechanically peeled off. , obtaining two-dimensional nanosheets.
  • the crystal particles are non-van der Waals layered structure crystal particles, such as metal particles, semiconductor metal oxide particles, chalcogenide particles, superconducting compound particles, etc.
  • the crystal particles are metal (Bi, Sb), semiconductor Metal oxides and chalcogen compounds (SnO, V 2 O 5 , Bi 2 O 2 Se) and superconducting compounds (KV 3 Sb 5 ) crystal particles; preferably, the particle size of the crystal particles is from micron to millimeter, such as 1 ⁇ m to 5 mm, preferably 1 to 500 ⁇ m, and further, 10 to 200 ⁇ m.
  • rollers or rods are used for rolling processing.
  • the rolling load is 0.5-10Kg and the speed is 10-300mm/min.
  • two-dimensional nanosheets can be obtained through conventional mechanical exfoliation.
  • crystal particles with a non-van der Waals structure with strong interlayer interactions two-dimensional nanosheets cannot be obtained through conventional mechanical exfoliation.
  • the present invention It is creatively proposed to perform conventional mechanical peeling after rolling to obtain two-dimensional nanosheets with a thickness of 0.1nm ⁇ 50nm, especially 0.1nm ⁇ 30nm, especially 0.3nm ⁇ 10nm, and more importantly, 0.5nm ⁇ 5nm.
  • mechanical peeling is tape peeling.
  • the tape is used to stick the particles by folding, pressing and then tearing apart.
  • the thin layer of material will stick to the tape.
  • the specific operation of this method is conventional technology.
  • the existing technology uses this to peel off graphite to obtain graphene.
  • direct tape peeling cannot thin non-van der Waals layered crystals or obtain nanoscale flakes, let alone single-layer or few-layer two-dimensional nanosheets.
  • rolling is unidirectional rolling, which is a conventional understanding.
  • the roller presses the crystal particles in one direction and does not press the crystal particles back and forth.
  • the crystal particles are laid flat on the bottom plate of the electric calendering roller equipment, and then calendered in one direction and in one wheel to obtain the calendered particles; then a transparent tape is used to stick the calendered particles, and then peeled off to obtain a thin layer, that is, the two-dimensional product of the present invention
  • Nanosheets can prepare two-dimensional nanosheet assembly materials, such as superconducting materials, optical materials, electrode materials, thermally conductive materials, conductive materials, etc.
  • the present invention uses calendering pretreatment followed by transparent tape peeling to successfully obtain few-layer or even single-layer structures of several materials for the first time, and is able to observe exciting new phenomena in the peeled two-dimensional materials.
  • Metal antimony becomes a semiconductor with a band gap of 2.01 eV; the light absorption range of the semiconductor SnO can be adjusted from the infrared region (IR) to the ultraviolet region, and the band gap is adjusted from 0.60 eV in the bulk to 3.65 eV in the single layer.
  • IR infrared region
  • KV 3 Sb 5 flakes are a very promising two-dimensional superconducting material. Therefore, the new results of the present invention propose a general method for the mechanical cleavage of non-van der Waals layered materials and provide a variety of new 2D materials.
  • Figure 1(a) shows the exfoliation energy (meV ⁇ -2 ) for the non-van der Waals layered materials studied in this invention; the values for graphite are also listed for reference.
  • the exfoliation energy of non-van der Waals layered structures is typically 1.3-3.6 times that of graphite (which is in the vdW force range).
  • the exfoliation energy is calculated as the difference in ground state energy between the bulk material (each atomic layer) and the individual deviation layers.
  • (b) is a calculated contour diagram of the charge density difference of a representative structure of the material of the present invention, showing strong interlayer coupling; the red and blue isosurfaces represent electron accumulation and depletion respectively.
  • (c) is the corresponding AFM image, showing these materials as single or few layers.
  • Figure 2 shows the theoretical stability prediction of exfoliated monolayer SnO.
  • the minimum energy path for O dissociation on the SnO layer is calculated using the climbing elastic band (CI-NEB) method of density functional calculations.
  • CI-NEB climbing elastic band
  • Figure 3 shows the characterization of the crystal structure before and after rolling.
  • the rolled SnO crystal is represented as M-SnO.
  • SEM images of SnO crystals (c) before rolling treatment and (d) after rolling treatment.
  • the inset in each figure shows a schematic representation of the stacked plane.
  • Figure 4 shows the characteristics of SnO flakes with different thicknesses.
  • Figure 5 shows (a) Raman spectrum of SnO flakes; inset: optical image of nanosheets. (b) A 1g and (c) E g are Raman intensity mapping images collected on an area of 15 ⁇ 15 ⁇ m with a step size of 500 nm. The results show high thickness uniformity and good local bonding structure.
  • Figure 6 shows AFM images of SnO flakes on Si/SiO substrate before and after exposure to ambient air for 3 months and after additional heating in air at 200°C.
  • Figure 7 shows a comparison of the physical properties of single-layer SnO flakes and SnO bulk.
  • Figure 8 shows (a) optical transmittance and (b) absorbance of SnO nanosheets analyzed by ultraviolet-visible (UV-Vis) absorption. Spectra were collected using a UV-visible spectrometer on individual flakes deposited on a transparent quartz plate substrate with a laser spot radius of 2 ⁇ m; inset (a): optical photographs of individual flakes and bulk SnO crystals. Arrows indicate increased thickness. (c) Band gap as a function of thickness.
  • UV-Vis ultraviolet-visible
  • Figure 9 shows the characteristics of Bi material.
  • Bismuth powder was purchased from Aladdin Industrial Co., Ltd. The lateral size of the crystallites is approximately 50 ⁇ m.
  • Figure 10 shows the characteristics of Sb material.
  • Sb powder was purchased from Aladdin Industrial Co., Ltd. The lateral size of the crystallites is approximately 60-80 ⁇ m.
  • Figure 11 shows the characteristics of V 2 O 5 material.
  • Vanadium pentoxide powder was purchased from Aladdin Industrial Co., Ltd. The lateral size of the crystallites is approximately 150 ⁇ m.
  • Figure 12 shows the characterization of Bi 2 O 2 Se material.
  • Bi 2 O 2 Se powder was purchased from Aladdin Industrial Co., Ltd. The lateral size of the crystallites is approximately 50 ⁇ m.
  • Figure 13 shows the characteristics of single crystal KV 3 Sb 5 material.
  • Figure 14 is (a) AFM image of Sb nanosheets on Si/SiO substrate ; from left to right: freshly peeled flakes, flakes after 3 months of exposure to air, and additional heating in air at 200°C for 10 Minutes later, and (b) the corresponding Raman spectrum. No obvious changes were observed in flake morphology, thickness or spectral characteristics, indicating good stability against O2 .
  • Figure 15 shows (a) AFM images of Bi nanosheets on Si/SiO substrate ; from left to right: freshly peeled flakes, flakes after exposure to air for 3 months, and air at 150°C and 200°C The flake after additional heating for 10 minutes, and (b) the corresponding Raman spectrum. No obvious changes in nanosheet morphology, thickness or spectral characteristics were observed at temperatures up to 150°C, indicating that Bi nanosheets have good stability against O2 .
  • Figure 16 shows (a) AFM images of Bi 2 O 2 Se flakes on Si/SiO 2 substrate; from left to right: freshly peeled flakes, flakes after exposure to air for 3 months, and in air at 200°C The flake after heating for 10 minutes, and (b) the corresponding Raman spectrum. No obvious changes in flake morphology, thickness or spectral characteristics were observed, indicating that the Bi nanosheets have good stability against O2 .
  • Figure 17 is a representative AFM image of KV 3 Sb 5 with a thickness less than 2 nm (one or two layers).
  • Figure 18 is a representative optical microscopy image (acquired in transmission mode) of directly tape-stripped SnO flakes on a glass slide substrate. It can be seen that these layered crystals are still thick and opaque.
  • the exfoliation energy of non-van der Waals layered structures is usually several times higher than that of graphite (Figure 1a), which naturally makes exfoliation of these materials difficult.
  • the method of the present invention involves a simple calendering pretreatment, followed by mechanical peeling using transparent tape to obtain thin layers, successfully peeling off a variety of materials, including metals (Bi, Sb), semiconducting metal oxides and chalcogenides (SnO, V 2 O 5 , Bi 2 O 2 Se) and superconducting compounds (KV 3 Sb 5 ), electron density calculations verified the existence of strong electronic coupling between these structural layers (Figure 1 bc).
  • the present invention uses calendering pretreatment followed by transparent tape peeling to successfully obtain few-layer or even single-layer structures of a variety of materials for the first time, and is able to observe exciting new phenomena in the peeled 2D materials.
  • Metal antimony becomes a semiconductor with a band gap of 2.01 eV; the light absorption range of the semiconductor SnO can be adjusted from the infrared region (IR) to the ultraviolet region, and the band gap is adjusted from 0.60 eV in the bulk to 3.65 eV in the single layer.
  • thin KV 3 Sb 5 is a potential two-dimensional superconductor. Therefore, the new results of the present invention propose a general method for the mechanical delamination of non-van der Waals layered materials and provide a variety of new 2D materials.
  • Thermal release tape (single-sided, heat release temperature 120°C) was purchased from Jiangsu Xianfeng Nano Materials Technology Co., Ltd.
  • Polydimethylsiloxane film (0.5 mm thick) was purchased from Luoyang Atmel Trading Co., Ltd.
  • Si/ SiO substrate SiO thickness: 300 nm was provided by Beijing Zhongjing Keyi Technology Co., Ltd.
  • the sample morphology was studied by scanning electron microscopy (SEM, Hitachi SU8010).
  • the surface chemical state of the sample was measured using an Al/K ⁇ target of an X-ray photoelectron spectrometer (XPS) on an Escalab 250Xi X-ray photoelectron spectrometer (Thermo Fisher Scientific Inc.) under ultra-high vacuum conditions, and the binding energy standard The deviation is 0.1 eV.
  • Atomic force microscopy was used to characterize the lateral dimensions and thickness of flakes on silicon substrates.
  • HR-TEM High-resolution transmission electron microscopy
  • STEM Themis aberration-corrected scanning transmission electron microscope
  • FIB focused ion beam
  • UV-visible near-infrared transmission spectra of exfoliated flakes on clear quartz slides were recorded on a 20/30 PV microspectrophotometer (Craic Technologies Inc.) at ambient temperature, from which band gap values were calculated using Tauc plots, and wavelengths were measured Range 350-2000 nm, using a confocal Raman spectrometer (WITec Alpha 300R) equipped with a UHTS 300 spectrometer (600 lines per mm grating) and a CCD detector (DU401A-BV-352), with laser excitation at 532 nm (power: Raman spectra were collected at 1 mW) with a spot radius of 2 ⁇ m.
  • WITec Alpha 300R confocal Raman spectrometer equipped with a UHTS 300 spectrometer (600 lines per mm grating) and a CCD detector (DU401A-BV-352)
  • laser excitation at 532 nm
  • Raman spectra were collected at 1 mW
  • Synthesis example Preparation of SnO crystal particles.
  • 0.02 mol (4.50 g) SnCl 2 •2H 2 O is dissolved in 70 mL of ultrapure water with stirring, and then NaOH is added until the pH of the mixture reaches 9.
  • the mixture was transferred to a 100 mL Teflon-lined autoclave, sealed, and heated at 150 °C for 15 h. Then let cool naturally to room temperature. The product was collected by centrifuging the mixture, washed three times with distilled water and absolute ethanol alternately, and then dried in vacuum overnight to obtain blue-black SnO crystals.
  • Single crystal KV 3 Sb 5 was prepared by flux method, and it was grown using KSb 2 alloy as flux. K, V, Sb elements and KSb precursors were sealed in a tantalum crucible at a molar ratio of 1:3:14:10, and then sealed in a high vacuum quartz ampoule. The ampoule was heated to 1273 K, held for 20 hours, and then cooled to 773 K. A single crystal with a lateral size of about 1000 ⁇ m and a silver luster is separated from the flux by centrifugal separation.
  • the present invention first calenders crystal particles, and then mechanically peels off the particles through transparent tape, and then transfers them to the target substrate using the existing all-dry technology.
  • the present invention tiles the crystal particles and then rolls them on the surface, that is, applying shear force on the crystals.
  • the rolling is only in one direction (not back and forth), resulting in continuous and unidirectional rolling.
  • the load of the roller or rod is 0.5 ⁇ 10kg, and the speed is 10 ⁇ 500mm/min.
  • the transfer step using heat release tape and/or polydimethylsiloxane membrane can be omitted.
  • the specific tiling method is a conventional technique and is not limited, and does not affect the realization of the technical effects of the present invention.
  • Example 1 Sandwich the crystal particles between two pieces of paper, and then roll a plastic rod on the surface by hand in one direction to obtain the calendered particles; then use the conventional classic tape peeling method, that is, stick the calendered particles with transparent tape, Fold in half and press, then tear to form peeling, and obtain a thin layer of material, that is, the two-dimensional nanosheet of the product of the present invention. Then bake it at 100°C for 5 seconds (to help the sheet maintain its lateral dimensions), then use thermal release tape to separate the thin layer from the transparent tape, and then release it at 150°C according to test needs, and transfer the sheet to different substrates.
  • the conventional classic tape peeling method that is, stick the calendered particles with transparent tape, Fold in half and press
  • tear to form peeling and obtain a thin layer of material, that is, the two-dimensional nanosheet of the product of the present invention.
  • bake it at 100°C for 5 seconds to help the sheet maintain its lateral dimensions
  • thermal release tape to separate the thin layer from the transparent tape, and then release
  • the crystal particles are metal Bi, metal Sb, semiconductor metal oxide SnO, V 2 O 5 , Bi 2 O 2 Se, and superconducting compound KV 3 Sb 5 .
  • the crystal structure of SnO belongs to the P4/nmm space group and has a tetragonal unit cell structure.
  • Sn and O atoms are alternately arranged in the order of Sn 1/2 ⁇ O ⁇ Sn 1/2 along the [001] crystal direction to form a layered sequence ( Figure 2a) .
  • Each O atom is coordinated with four surface metal Sn atoms to form a Sn 4 O tetrahedron. Therefore, the lone pair electrons composed of Sn 5s orbitals are directed towards the interlayer spacing, so there is a strong dipole-dipole interaction between adjacent SnO layers.
  • the differential charge density map of this structure shows high electron density between layers, indicating the presence of strong interlayer interactions (Figure 2b).
  • the invention peels off a single-layer SnO flake from SnO crystal particles.
  • the nanoflake has an unusual metal covering structure, in which two Sn atomic layers sandwich an O atomic layer.
  • the crystallographic thickness of the SnO monolayer is 0.38 nm.
  • the present invention prepares SnO crystal particles through the hydrothermal reaction of stannous chloride dihydrate and sodium hydroxide (see synthesis examples for details).
  • X-ray photoelectron spectroscopy (XPS) confirmed the presence of Sn and O elements, and the Sn/O ratio was close to 1.
  • the high-resolution Sn 3d spectrum shows two significant peaks at 486.1 and 494.5 eV, corresponding to the Sn 3d 5/2 and Sn 3d 3/2 core energy levels of Sn 2+ , respectively.
  • the valence state is also consistent with the blue-black color of the crystal (see Figure 3a for an illustration).
  • the Raman spectrum of the original crystal shows E g at 112 cm ⁇ 1 and A 1g peak at 210 cm ⁇ 1 , which are characteristic of the SnO structure (Fig. 3b).
  • Scanning electron microscopy (SEM) shows that the lateral size of SnO crystals is 100 ⁇ m and the thickness is about 10 ⁇ m ( Figure 3c).
  • the sheet-like shape may be related to the intrinsic anisotropic layered structure, and its thickness is related to the stacking of sheets.
  • a simple rolling process on these crystals can change the SnO crystal structure, which is called M-SnO.
  • Morphological characterization by SEM showed slipping of the planes (Fig. 3d), and a new diffraction peak was observed in the low-angle region of the XRD pattern, indicating a slight increase in the layer spacing from 4.844 ⁇ to 4.949 ⁇ (Fig. 3a).
  • Figure 3e shows in situ AFM.
  • Figure 3f Scanning transmission electron microscopy (STEM) shows repulsion between adjacent layers and increases the repeating distance along the stacking direction. No vacancies were observed at the Sn site.
  • the in-plane Sn-Sn distance slightly changes from 2.684 ⁇ to 2.715 ⁇ , which is consistent with the XRD results.
  • the intensity of the in-plane Raman vibration mode E g is significantly reduced (Fig. 3b).
  • the crystal can be exfoliated and stratified into individual SnO flakes using a conventional transparent tape method; the optical microscope image of the exfoliated SnO flakes transferred to a transparent glass substrate shows high transparency ( Figure 4a) .
  • the number of layers is verified by AFM, as shown in Figure 4b-f.
  • the minimum thickness of the 2D SnO flakes measured by AFM is 0.8 nm. Based on its crystal structure, the thickness of the SnO monolayer is 0.38 nm, taking into account the 0.1-0.6 nm interface "invalid layer" that usually exists between the exfoliated sheet and the substrate.
  • the measured height of 0.8nm cannot correspond to two or more layers, but should correspond to a single layer of SnO.
  • Layers of different thicknesses were measured, specifically 1.3, 1.8, 2.4 and 2.9 nm, with the thickness increasing in steps of approximately 0.5 nm, as shown in the inset of Figure 4c, with the ideal step size being the crystallographic repeating distance of adjacent layers (0.48 nm ), exactly matches the experimentally measured step size values, therefore, these lamellae correspond to layer numbers 2, 3, 4 and 5.
  • the size of the peeling sheet of the present invention is in the micron level, the size of the single-layer sheet is 2-6 ⁇ m, and the size of the five-layer sheet is increased to about 15 ⁇ m (Fig.
  • Example 3 Physical properties of other material sheets obtained by the present invention.
  • the present invention can be applied to a variety of materials, including metals (Bi, Sb), semiconductor metal oxides and chalcogen compounds (SnO, V 2 O 5 , Bi 2 O 2 Se) and superconducting compounds (KV 3 Sb 5 );
  • metals Bi, Sb
  • semiconductor metal oxides and chalcogen compounds SnO, V 2 O 5 , Bi 2 O 2 Se
  • superconducting compounds KV 3 Sb 5
  • the interlayer interactions and corresponding AFM images are shown in Figure 1b and c.
  • metallic antimony (Sb) is a three-dimensional pseudo-layered crystal that belongs to the R 3-mh space group and has triangular and hexagonal lattice. The crystal can be viewed as an ABCABC stack of antimony atoms arranged in a curved honeycomb arrangement.
  • the minimum interlayer spacing is only 0.23 nm, which means that the interlayer interactions are mainly chemical interactions (structure and density map in Figure 1b), which makes direct mechanical exfoliation difficult to achieve.
  • a 1.2 nm thick Sb monolayer can be obtained. Characterization details for antimony and other example materials are given in Figures 9-13. Nanosheets exfoliated from these materials, including Bi, Sb, and Bi 2 O 2 Se, exhibit long-term stability against oxidation even with additional heating in air ( Figure 14-16). Importantly, metallic antimony transforms into a wide bandgap semiconductor (2.01 eV) when thinned to a 1.2 nm thick monolayer (Fig. 7c,d).
  • the broad modulation of thickness-dependent physical properties achieved by the present invention may be related to the strong electronic coupling in the interlayer region.
  • strong interlayer interactions lead to subtle changes in the lattice structure as the number of layers decreases, which, in addition to size effects, affects the physical properties of the exfoliated flakes, uniquely observed in these materials.
  • the thickness-property relationship further highlights the importance of extending 2D flakes to non-van der Waals materials.
  • KV 3 Sb 5 is a member of the recently discovered quasi-two-dimensional Kagome metal family, and its general formula is AV 3 Sb 5 (a:K, Rb, Cs).
  • the material belongs to the P6/mmm space group, and the layers are connected by chemical bonds between A and V.
  • Kagome lattices of transition metal atoms are viewed as an exciting platform to study a range of electronically correlated phenomena, including charge density waves, the anomalous Hall effect and superconductivity, with surprising results.
  • 2D structures have several advantages over bulk materials: the two-dimensional geometry will enhance quantum fluctuations and correlations, and can also facilitate charge modulation through carrier doping, all of which may alter superconductivity and charge Density waves.
  • the superconducting transition temperature Tc increases from about 2.5 K in bulk to 4.28 K for flakes with a thickness of 60 nm, however the opposite behavior is observed when the sample is further thinned to 4.8 nm, i.e. Tc decreases to 0.76 K.
  • the charge density wave transition temperature has an opposite trend with thickness. Taking advantage of the reactivity of the surface A-layer, a recent work reported hole doping through natural oxidation of the Cs layer by simply exposing it to air for several minutes. For lamellae less than 82 nm thick, T jumps significantly to about 4.7 K.
  • the KV 3 Sb 5 bulk has a lower Tc of 0.93 K, and since valence electrons on Cs are easily lost, K-related materials may be a better platform to tune the carrier concentration more efficiently.
  • the anomalous Hall conductivity of thin KV 3 Sb 5 crystals is as high as 15507 ohm -1 cm -1 .
  • CsV 3 Sb 5 crystals cannot be thinned to the nanometer scale (below 100 nm) using the regular, traditional Scotch tape method, which is attributed to the chemical interaction between the Sb and Cs layers.
  • KV 3 Sb 5 flakes with a thickness of 2 to 5 nm were obtained, corresponding to layers 2 to 5 (Figs. 1c and 17).
  • the 5.4 nm flakes have a fairly smooth surface even when exposed to air for at least 10 minutes under ambient conditions.
  • Successful exfoliation of KV 3 Sb 5 into single or few layers will provide valuable insights into the study of unconventional superconductivity and its interaction with two-dimensional Kagome crystals. The interaction of charge density waves in the lattice provides new opportunities.
  • Application Example Lay the crystal particles flat on the bottom plate of the electric rolling roller (HZ-2403), and roll it in one direction and one wheel at 200 mm/min to obtain the rolled particles; then use transparent tape to stick the rolled particles, fold it in half, press it, and then tear it off It is peeled off to obtain a thin layer of material, that is, the two-dimensional nanosheet of the product of the present invention.
  • the crystal particles are metal Bi, metal Sb, semiconductor metal oxide SnO, V 2 O 5 , Bi 2 O 2 Se, and superconducting compound KV 3 Sb 5 respectively.
  • the obtained two-dimensional nanosheet is similar to Example 1, including a single layer Or few-layer exfoliated flakes, the lateral size can also reach 15 ⁇ m. It shows that the method of the present invention not only has universal applicability to a variety of crystal particles, but can also be prepared using industrial equipment, providing a basis for industrialization.
  • the present invention presents a general scheme for the mechanical exfoliation of various crystal structures with non-van der Waals type interlayer forces, including metals (Bi, Sb), semiconducting metal oxides and chalcogenides (SnO, V O 5 , Bi 2 O 2 Se) and superconducting compounds (KV 3 Sb 5 ).
  • Metals Bi, Sb
  • KV 3 Sb 5 superconducting compounds
  • New 2D sheets from non-van der Waals structures show significantly better physical properties that are different from those of crystalline bulk; the bandgap can be tuned from 0.60 Ev (IR) of bulk SnO to 3.65 eV (UV) of a single layer; bulk A metal-semiconductor (2.01 eV band gap) transition occurs when Sb transitions to a monolayer.
  • the single- and few-layer KV 3 Sb 5 obtained in this work are exciting products for 2D superconductors.
  • the present invention proposes for the first time a method to mechanically exfoliate non-van der Waals layered structures into high-quality 2D analogs and opens the door to the easy preparation of a new family of materials with potential applications.
  • Comparative Example The conventional tape peeling method is used: use transparent tape to directly stick SnO crystal particles (not calendered), fold it in half and press it, then tear it to form peeling, and obtain the peeling product.
  • Figure 18 is an example of an optical microscopy image of tape-stripped SnO flakes on a glass slide substrate collected in transmission mode. It can be seen that these layered crystals are still very thick and opaque, with thicknesses in the micron range, indicating that conventional tape peeling cannot obtain two-dimensional Sheets, let alone nanometer-thick sheets, cannot be obtained.
  • Two-dimensional (2D) materials under a single layer thickness have many new properties and thickness dependencies.
  • Mechanical exfoliation of layered structures is the most effective method to obtain ultrathin sheets, but this method is limited to materials where interlayer interactions are controlled by weak van der Waals forces and is not applicable to materials with non-van der Waals structures.
  • the present invention discloses for the first time a general method for mechanically stripping non-van der Waals structures to obtain a variety of new two-dimensional materials, including metals (Bi, Sb), semiconductor metal oxides and chalcogenide compounds (SnO, V 2 O 5 , Bi 2 O 2 Se) and superconducting compounds (KV 3 Sb 5 ).
  • the method of the invention involves calendering the raw material and then mechanically peeling off the slid structure using a typical Scotch tape method, resulting in a stable single layer or several layers of material with exciting new physical properties.
  • the band gaps of metals and semiconductors are modulated over a wide range depending on the number of layers (0 to 2.01 eV for Sb, 0.60 eV (IR) to 3.65 eV (UV) for SnO).
  • IR 0.60 eV
  • UV 3.65 eV
  • Several layers of KV 3 Sb 5 were also obtained, an exciting material for studying unconventional superconductivity.
  • the present invention's new direct mechanical exfoliation method of non-van der Waals layered materials greatly broadens the availability of 2D materials to explore their unique physical properties and practical applications.

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  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Nanotechnology (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Abstract

La présente invention concerne un procédé de préparation d'une nanofeuille bidimensionnelle. Le procédé comprend : la réalisation d'un traitement de calandrage sur des particules cristallines stratifiées de Van der Waals, puis la réalisation d'une exfoliation mécanique, de façon à obtenir une nanofeuille bidimensionnelle. L'exfoliation mécanique est couramment appelée procédé de ruban adhésif, et l'exfoliation mécanique peut uniquement être effectuée au moyen d'un ruban adhésif (parfois, l'assistance d'un interposeur est requise) lorsque l'interaction intercouche d'un matériau en vrac est dominée par une force de van der Waals faible ; cependant, il existe une densité d'électrons significative se chevauchant entre des couches de nombreux matériaux fonctionnels avec des structures cristallines empilées en couches, et le chevauchement de densité d'électrons forme une structure non-Van der Waals, qui ne peut pas être directement exfoliée au moyen du ruban adhésif. Dans le présent procédé, des structures de quelques couches ou même monocouches de différents matériaux cristallins stratifiés non-Van der Waals sont obtenues avec succès pour la première fois au moyen d'un prétraitement de calandrage combiné à une exfoliation mécanique ; en outre, un nouveau phénomène physique peut être observé dans un cristal bidimensionnel exfolié.
PCT/CN2022/110357 2022-08-04 2022-08-04 Nanofeuille bidimensionnelle et son procédé de préparation WO2024026785A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101857195A (zh) * 2010-05-21 2010-10-13 哈尔滨工业大学 高效率机械剥离层状化合物的方法
CN104609413A (zh) * 2015-02-11 2015-05-13 合肥微晶材料科技有限公司 一种吨级生产石墨烯的类机械剥离装置及其生产方法
WO2017158334A1 (fr) * 2016-03-15 2017-09-21 The University Of Manchester Exfoliation mécanique de matériaux bidimensionnels
CN107324320A (zh) * 2017-07-10 2017-11-07 安徽理工大学 一种机械剪切制备二维纳米材料的方法
CN107381643A (zh) * 2016-12-12 2017-11-24 广东纳路纳米科技有限公司 一种机械剥离范德华层状材料制备二维材料的通用方法
CN113200523A (zh) * 2021-03-25 2021-08-03 华南师范大学 一种大面积层状二维材料的剥离及其转移方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101857195A (zh) * 2010-05-21 2010-10-13 哈尔滨工业大学 高效率机械剥离层状化合物的方法
CN104609413A (zh) * 2015-02-11 2015-05-13 合肥微晶材料科技有限公司 一种吨级生产石墨烯的类机械剥离装置及其生产方法
WO2017158334A1 (fr) * 2016-03-15 2017-09-21 The University Of Manchester Exfoliation mécanique de matériaux bidimensionnels
CN107381643A (zh) * 2016-12-12 2017-11-24 广东纳路纳米科技有限公司 一种机械剥离范德华层状材料制备二维材料的通用方法
CN107324320A (zh) * 2017-07-10 2017-11-07 安徽理工大学 一种机械剪切制备二维纳米材料的方法
CN113200523A (zh) * 2021-03-25 2021-08-03 华南师范大学 一种大面积层状二维材料的剥离及其转移方法

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