A method and device for atomically fabricating two-dimensional metal oxide nanosheets based on controllable micro-explosion

Abstract

This invention relates to an atomic-level manufacturing method and apparatus for two-dimensional metal oxide nanosheets based on controllable micro-explosion, belonging to the field of functional nanomaterials and atomic-level precision manufacturing technology. This invention uses transition metal energetic complexes and energetic oxygen compounds as metal-oxygen integrated precursors. Under the constraint of an array-type nano-confined microcavity, controllable micro-explosions are synchronously triggered by nanosecond lasers to achieve nanosecond-level stoichiometric precision in the directional self-assembly of two-dimensional metal oxide nanosheets. The preparation cycle of this invention is reduced to less than 10 minutes, and the overall energy consumption is less than 1% of that of the traditional hydrothermal method. The product has excellent specific surface area, photocatalytic and cycling performance, and is 100% compatible with existing mass production lines. It is suitable for large-scale manufacturing in fields such as photocatalysis, energy storage, gas sensors, and environmental governance.

Description

[0001] This invention belongs to the fields of functional nanomaterial manufacturing, atomic-level precision manufacturing, and environmental protection and new energy materials technology. Specifically, it relates to an atomic-level preparation method of two-dimensional metal oxide nanosheets based on controllable micro-explosion of energetic precursors, as well as a supporting manufacturing device for realizing this method. It can be directly applied to the large-scale manufacturing of two-dimensional metal oxides in fields such as photocatalysis, energy storage, gas sensors, environmental governance, and flexible electronics.

[0002] Two-dimensional metal oxide nanosheets (typically such as...) (I) is a functional metal oxide material with an ultra-thin layered structure. It has an ultra-large specific surface area, abundant surface active sites, and excellent photocatalytic / electrochemical performance. It is a core basic material in the fields of environmental governance, new energy, and sensors, and has irreplaceable application value in the global environmental protection and new energy industries.

[0003] Currently, the mainstream manufacturing technologies for two-dimensional metal oxide nanosheets worldwide face insurmountable industry challenges, specifically as follows:

[0004] Hydrothermal / solvothermal method: The mainstream preparation process for industrial-grade two-dimensional metal oxides worldwide. Using metal salts as raw materials, a hydrothermal reaction is carried out in a high-pressure reactor at 100-200℃ for 12-48 hours to prepare two-dimensional nanosheets. This method has several key drawbacks: First, the preparation cycle is as long as tens of hours, resulting in extremely low production efficiency and making continuous mass production impossible; second, the products exhibit uneven size, uncontrollable layer count, low crystallinity, high defect density, and poor performance stability; third, the reaction process requires large amounts of organic solvents and surfactants, generating significant waste liquid and imposing enormous environmental pressure.

[0005] Mechanical exfoliation: It can only prepare a small number of metal oxide nanosheets with layered structures, has a very narrow range of applications, and can only be prepared manually at the laboratory level. Its production capacity is extremely low and it is completely unsuitable for industrial application.

[0006] Chemical vapor deposition (CVD) can only prepare small-sized, specific types of metal oxide thin films. The growth temperature is as high as 800-1200℃, which consumes a lot of energy and costs a lot, making it impossible to prepare powder materials on a large scale.

[0007] Existing technologies, such as the sol-gel method and the template method, all suffer from problems such as long preparation cycles, low product crystallinity, small specific surface area, the need for large amounts of template agents / surfactants, and high environmental pressure. They cannot simultaneously meet the industrial requirements of high efficiency, high quality, low cost, and green environmental protection.

[0008] In summary, existing technologies have consistently failed to simultaneously achieve the five core objectives of short cycle time and high efficiency, controllable atomic-level size and layer number, high crystallinity and low defects, green operation without environmental pressure, and low-cost scalability. This has become a major bottleneck restricting the high-quality development of the global two-dimensional metal oxide industry. Currently, there are no publicly available technological solutions worldwide that can address all of these pain points.

[0009] The purpose of this invention is to overcome the aforementioned defects of the prior art and provide an atomic-level manufacturing method and apparatus for two-dimensional metal oxide nanosheets based on controllable micro-explosion. This method breaks through the traditional technical logic of "high-temperature long-time reaction and large amount of solvent and auxiliary agent" preparation. It uses transition metal energetic complexes and energetic oxygen compounds as an integrated carrier of "metal source + oxygen source + energy source". Through the synergistic effect of nanoscale confinement, directional template anchoring and synchronous field-controlled orientation technology, it achieves the directional preparation of nanosecond-level high crystallinity two-dimensional metal oxide nanosheets. At the same time, it is 100% compatible with existing large-scale mass production lines, and completely solves the industry pain points of low efficiency, many defects, high environmental pressure and high cost of the existing technology.

[0010] The core inventive concept of this invention is as follows: using a metal-oxygen-energy integrated energetic precursor system, a controllable micro-explosion is synchronously triggered within a wafer-level array-type nano-confined microcavity by nanosecond laser, simultaneously releasing the high-temperature and high-pressure thermodynamic environment and highly active transition metal and oxygen atom raw materials required for the growth of two-dimensional metal oxides; combined with a pre-positioned oxide growth template and a directional uniform electric field, the directional self-assembly of atoms and the formation of a two-dimensional nanosheet layered structure are completed within the nanosecond time window of the explosion, realizing the one-step completion of "ignition-nucleation-crystallization", completely subverting the long-term hydrothermal reaction logic of traditional two-dimensional metal oxide manufacturing.

[0011] Compared with the prior art, the present invention has the following disruptive and beneficial technical effects: 1. Achieving a breakthrough in production efficiency, completely overturning the industry's production cycle: Compared with the traditional hydrothermal method with a preparation cycle of 12-48 hours, the production efficiency of this invention is increased by more than 1,000 times, compressing the preparation cycle of two-dimensional metal oxide nanosheets to less than 10 minutes, enabling continuous and large-scale production, and completely solving the core pain point of extremely low production efficiency in existing technologies.

[0012] 2. Atomic-level precise control, high crystallinity and low defect rate: This invention, through nanoscale confinement and electric field-directed modulation, can precisely control the size (0.5-20 μm) and number of layers (1-5 layers) of nanosheets. The prepared nanosheets have high crystallinity, low defect density, and high specific surface area. It has a photocatalytic degradation efficiency of ≥95%, a cycle stability of ≥5000 times, and its overall performance far exceeds that of products prepared by traditional hydrothermal methods.

[0013] 3. Completely achieves green manufacturing with zero environmental pressure: This invention does not require the use of large amounts of organic solvents, surfactants, or template agents throughout the entire process, and there is no discharge of acid or alkaline waste liquid. The decomposition products of the energetic precursor are only the constituent atoms of the target material and harmless nitrogen gas, which fundamentally solves the environmental pressure problem of traditional processes and meets the dual carbon target and green manufacturing standards.

[0014] 4. Energy consumption and manufacturing costs drop dramatically: This invention does not require high temperature, high pressure and long-term reaction. The overall energy consumption is less than 1% of that of the traditional hydrothermal method. The raw material atom utilization rate is close to 100%, there is no waste of raw materials, and the overall manufacturing cost can be reduced by more than 80%, completely breaking the cost barrier of the two-dimensional metal oxide industry.

[0015] 5. Full material system compatibility, 100% compatible with existing mass production lines: This invention is compatible with... For most metal oxide systems, all core process modules adopt existing mature mass production technologies in the chemical and powder materials industries. There is no need to build new dedicated production lines. Modular upgrades can be carried out directly on existing production lines, and industrialization can be achieved within 1-2 years without any technological gaps.

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with preferred embodiments. All other embodiments obtained by those skilled in the art based on the core concept of this invention without creative effort are within the scope of protection of this invention.

[0017] Unless otherwise specified, the raw materials and equipment used in the specific embodiments of this invention are all commercially available conventional products; the process methods used are all conventional technical methods in the field unless otherwise specified.

[0018] The core equipment used in this invention includes: a 248nm / 193nm nanosecond pulsed excimer laser, a high-vacuum reaction chamber, an inductively coupled plasma (ICP) etching machine, a PECVD thin film deposition system, a high-precision micro-volume injection system, and a laser annealing module; the core detection methods include: X-ray diffraction (XRD) to test crystal structure, transmission electron microscopy (TEM) to observe layer structure, nitrogen adsorption method to test specific surface area, ultraviolet-visible spectrophotometer to test photocatalytic performance, and cyclic voltammetry to test electrochemical performance.

[0019] Example 1 Two-dimensional titanium dioxide ( Nanosheet preparation (for photocatalysis / environmental protection)

[0020] This embodiment is used to prepare two-dimensional anatase for wastewater treatment, air purification, and photocatalytic water splitting for hydrogen production. Nanosheets, the specific steps are as follows: 1. Substrate Pretreatment and Growth Template Preparation: A titanium foil substrate was selected. After polishing and cleaning, an array of nano-confined microcavities was fabricated on the substrate surface using photolithography and ICP dry etching. Each microcavity had a planar dimension of 10 μm × 10 μm and a depth of 5 μm. The fill factor of the microcavity array was 95%. The inner walls of the microcavities were modified with plasma oxides. A directional template for growth; 2. Preparation and Filling of Metal-Oxygen Integrated Energy Precursor: Using titanium-based titanium azide complex as the transition metal energetic complex (titanium source) and cuboethane peroxide as the energetic oxygen compound (oxygen source and detonation source), a homogeneous energetic precursor solution with a total solute mass concentration of 8% was prepared by precise mixing at a molar ratio of 1:2, using anhydrous ethanol as the solvent, and stirring for 20 min in an anhydrous and oxygen-free glove box; under a vacuum degree of Under high vacuum conditions, a micro-volume injection system was used to precisely fill all microcavities with the precursor solution, achieving a filling error of ≤0.1%. A 100nm thick layer was deposited using PECVD technology. A thin film is used to seal the opening of the microcavity; 3. Pre-field control and pre-temperature control: Place the filled substrate on the high-precision heating stage of the vacuum reaction chamber, and evacuate the vacuum reaction chamber to... The substrate was heated to 500°C and held at that temperature under extreme vacuum, while parallel plate electrodes were applied to the upper and lower sides of the substrate. A uniform electric field perpendicular to the substrate surface; 4. Controllable micro-explosion and directional growth of two-dimensional TiO2 nanosheets: A 248nm nanosecond pulsed excimer laser was used to expose the entire substrate surface, with a laser energy density of [missing information]. The pulse width is 20 ns, and the overall energy uniformity is ≤0.3%. The laser synchronously triggers nanosecond-level controllable micro-explosions in all precursors within the microcavities. The precursors decompose to generate highly reactive titanium atoms, oxygen atoms, and nitrogen protective gas, simultaneously releasing an instantaneous high temperature of 1200 K and an instantaneous high pressure of 8 GPa. Under the synergistic constraints of the oxide template, uniform electric field, and laser polarization, titanium and oxygen atoms complete in-situ directional self-assembly in a stoichiometric ratio of 1:2 within the microcavities, generating a few-layer two-dimensional anatase structure that matches the template. Nanosheets; 5. In-situ post-processing: After the micro-explosion reaction is completed, the substrate undergoes millisecond-level laser annealing with a peak annealing temperature of 900℃ and an annealing time of 5ms to repair the substrate. Lattice defects were identified; simultaneously, high-purity oxygen (99.9999%) was introduced to passivate the nanosheets at a low temperature of 180°C for 30 seconds; the gas generated in the reaction was extracted using a molecular pump system, and after cooling to room temperature, the substrate was removed. The titanium foil substrate was then removed by acid washing to obtain the target two-dimensional nanosheet. Nanosheets.

[0021] Performance test results: The product prepared in this embodiment The nanosheets have a 2-3 layer few-layer anatase structure, high crystallinity, no impurity phases, a sheet size of 5-10 μm, and a specific surface area of ​​[missing information]. Under visible light, the degradation efficiency of methyl orange wastewater reaches 98% within 2 hours, and the degradation efficiency remains ≥95% after 5000 cycles of recycling. Its photocatalytic performance far surpasses that of wastewater prepared by traditional hydrothermal methods. Nanomaterials; total preparation time < 8 minutes, and overall energy consumption is only 0.5% of that of traditional hydrothermal methods.

[0022] Example 2 Two-dimensional manganese dioxide ( Nanosheet fabrication (for supercapacitors)

[0023] This embodiment is used to prepare a two-dimensional supercapacitor for high-rate supercapacitors. Nanosheets, the specific steps are as follows: 1. Substrate pretreatment and growth template preparation: A stainless steel foil substrate was selected, and a three-dimensional mesh-like nano-confined microcavity was prepared on the substrate surface using MEMS technology. The microcavity pore size was 8 μm and the depth was 10 μm. The inner wall of the microcavity was modified with oxide. 2. Precursor Preparation and Filling: Using manganese diazo complex as the manganese source and cuboethane peroxide as the oxygen and detonation source, a homogeneous precursor solution with a total solute concentration of 10% was prepared by precise mixing at a molar ratio of 1:2 and using anhydrous ethanol as the solvent. Microcavity filling and... Membrane sealing; 3. Pretreatment: Heat the substrate to 450℃ and apply 1.5×10⁻⁶ ppm. 5 A uniform vertical electric field of V / m, with vacuum maintained at... ; 4. Synchronous Micro-Explosion and Nanosheet Forming: A 193nm nanosecond pulsed excimer laser was used to expose the entire substrate surface, with a laser energy density of [missing information]. With a pulse width of 15 ns, it synchronously triggers controllable micro-explosions in all precursors within the microcavities, completing two-dimensional [explosions] in one step. In-situ forming of nanosheets; 5. In-situ post-processing: Lattice defects were repaired using 800℃ millisecond-level laser annealing, followed by oxygen passivation at 150℃ for 30 seconds. After removing the reactive gases, the substrate was removed, and the stainless steel foil substrate was removed by acid washing to obtain a pure two-dimensional... Nanosheets.

[0024] Performance test results: The product prepared in this embodiment Nanosheets have a few-layer structure of 1-3 layers and a specific surface area of ​​up to Surface capacitance reaches It has a capacity retention rate of ≥93% after 5000 charge-discharge cycles, exhibits excellent rate performance, and can be directly used as electrode material for high-rate supercapacitors.

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly described below. These drawings constitute a part of this specification and are used to further understand the present invention. They are used together with the specific embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.

[0026] Figure 1 This is a schematic diagram of the overall structure of the atomic-level manufacturing device for two-dimensional metal oxide nanosheets described in this invention;

[0027] Figure 2 This is a process flow diagram of the atomic-level manufacturing method of two-dimensional metal oxide nanosheets according to the present invention;

[0028] Figure 3 This is a schematic diagram of the cross-sectional structure of the array-type nano-confined microcavity described in this invention;

[0029] Figure 4 This is a schematic diagram illustrating the principle of the controllable micro-explosion directional growth of two-dimensional metal oxide nanosheets described in this invention.

[0030] The component names marked in the attached diagram are as follows: 1-Vacuum reaction chamber system; 2-Upper electrode; 3-Lower electrode; 4-Substrate heating stage; 5-Conductive growth substrate; 6-Laser incident window; 7-Vacuum evacuation port; 8-Protective gas inlet; 9-Electrode terminal; 10-Array-type nano-confined microcavity; 11-Nanosecond-level controllable micro-explosion region; 12-Highly active metal atoms and oxygen atoms; 13-Oxide growth template; 14-Precursor filling and sealing system; 15-Wafer-level laser synchronous triggering system.

Claims

1. An atomic-level manufacturing method for two-dimensional metal oxide nanosheets based on controllable micro-explosion, characterized in that, Includes the following steps: S1 Substrate pretreatment and growth template preparation: A conductive substrate is selected as the growth substrate, and an array of nano-confined microcavities are prepared on the substrate surface. The inner wall of the nano-confined microcavities is modified with oxide to serve as a directional template for the growth of two-dimensional metal oxides. S2 Metal-Oxygen Integrated Precursor Preparation and Filling: Using transition metal energetic complexes as the metal source and energetic oxygen compounds as the oxygen source and initiation source, dopant elements are added as needed to prepare a homogeneous energetic precursor with precisely matched stoichiometry; under vacuum conditions... In a high vacuum environment, the energetic precursor is precisely filled into the nano-confined microcavity, and the opening of the microcavity is sealed. S3 Pre-field control and pre-temperature control: The filled substrate is placed in a vacuum reaction chamber and heated to a pre-temperature control range of 300-800℃. At the same time, a directional uniform electric field perpendicular to the substrate surface is applied to the upper and lower sides of the substrate. S4 Controllable Micro-Explosion and Directional Growth of Two-Dimensional Metal Oxides: A nanosecond pulsed excimer laser is used to expose the entire wafer surface of the substrate. The laser synchronously triggers nanosecond-level controllable micro-explosions in all energetic precursors within the nano-confined microcavities. The energetic precursors decompose to generate highly active transition metal atoms, oxygen atoms, and nitrogen protective gas, while simultaneously releasing instantaneous high temperatures of 800-1800K and instantaneous high pressures of 3-15GPa. Under the synergistic constraints of the oxide template, uniform electric field, and laser polarization, the transition metal atoms and oxygen atoms complete stoichiometric, precisely directed self-assembly in situ within the microcavities, generating single-layer / few-layer two-dimensional metal oxide nanosheets that match the template. S5 In-situ Post-processing: After the micro-explosion reaction is completed, the substrate is subjected to millisecond-level laser annealing to repair lattice defects. At the same time, high-purity oxygen / inert gas is introduced to perform low-temperature passivation treatment on the material surface. The protective gas generated by the reaction is removed through a vacuum system, and finally the target two-dimensional metal oxide nanosheet structure is obtained.

2. The manufacturing method according to claim 1, characterized in that, The transition metal energetic complex is one or more of the azide complexes and carbonyl complexes of titanium, zinc, manganese, tungsten, and iron; the energetic oxygen compound is one or more of the cuboethane peroxide and oxocyclic energetic compounds; the two-dimensional metal oxide is... One of them.

3. The manufacturing method according to claim 2, characterized in that, The homogeneous energetic precursor is an anhydrous and oxygen-free solution, and the solvent is anhydrous ethanol or anhydrous tetrahydrofuran. The molar ratio of the transition metal to oxygen element is precisely matched to the stoichiometric ratio of the target oxide, and the total solute mass concentration is 2%-15%.

4. The manufacturing method according to claim 1, characterized in that, The conductive substrate is one of titanium foil, stainless steel foil, silicon wafer, or FTO conductive glass. The depth of the nano-confined microcavity is 5nm-50μm, and the planar size of a single microcavity is 20nm-80μm. It is prepared by MEMS photolithography and dry etching processes.

5. The manufacturing method according to claim 4, characterized in that, In step S2, a 50-150 nm thick SiO2 film is deposited using PECVD process to seal the microcavity opening, and the precursor filling error in a single microcavity is ≤0.1%.

6. The manufacturing method according to claim 1, characterized in that, In step S3, the field strength of the directional uniform electric field is Vacuum degree of the vacuum reaction chamber .

7. The manufacturing method according to claim 1, characterized in that, In step S4, the wavelength of the nanosecond pulsed excimer laser is 193nm or 248nm, and the laser energy density is... The pulse width is 10-100ns, and the energy uniformity of the entire wafer in surface exposure is ≤0.5%.

8. The manufacturing method according to claim 1, characterized in that, In step S4, the instantaneous high temperature of the controllable micro-explosion is maintained for 10-80 ns, and the generated two-dimensional metal oxide nanosheets are 1-5 layer few-layer structures or single-layer structures with a sheet size of 0.5-20 μm.

9. The manufacturing method according to claim 1, characterized in that, In step S5, the peak temperature of laser annealing is 600-1200℃, the passivation temperature is 100-220℃, the passivation time is 10-60s, and the gas used is high-purity oxygen or argon with a purity ≥99.9999%.

10. The manufacturing method according to any one of claims 1-9, characterized in that, The specific surface area of ​​the prepared two-dimensional metal oxide nanosheets Photocatalytic degradation efficiency ≥95%, cycle stability ≥5000 times.

11. An atomic-level manufacturing apparatus for two-dimensional metal oxide nanosheets implementing the manufacturing method of any one of claims 1-10, characterized in that, include: The high-vacuum reaction chamber system is equipped with a high-precision substrate heating stage, a molecular pump pumping unit, and multiple gas pathways, achieving an ultimate vacuum level. ; The precursor filling and sealing system includes a high-vacuum micro-injection unit and a nano-scale thin-film sealing unit, which are used to complete the precise filling and micro-cavity sealing of energetic precursors in a high-vacuum environment. The electric field control system, including parallel plate electrodes and a high-precision high-voltage power supply, can output electric field strength. Adjustable vertical uniform electric field; The wafer-level laser synchronous triggering system includes a nanosecond pulsed excimer laser with wavelengths of 193nm / 248nm and pulse widths of 10-100ns, as well as a surface exposure homogenizing optical path, which can achieve uniform exposure of the entire 8 / 12-inch wafer with energy uniformity ≤0.5%. The in-situ post-processing system, including a millisecond-level laser annealing module and an atmosphere control unit, is used for lattice repair and surface passivation of two-dimensional metal oxides. The closed-loop measurement and control system is electrically connected to the above systems and is used for real-time monitoring and closed-loop control of vacuum degree, temperature, electric field intensity, laser parameters and reaction process.

Images