A metal nanoarray structure controllably prepared in situ on graphene and a preparation method thereof

Abstract

The present invention belongs to the technical field of nanostructure manufacturing, and discloses a metal nanoarray structure that can be in-situ controllably prepared on graphene and a preparation method thereof. The present invention uses a silicon wafer as a substrate, and prepares a graphene layer on the silicon substrate by mechanical exfoliation method; then installs a silicon cantilever beam containing raw material molecules on an atomic force microscope to scan the prepared substrate to generate a high-resolution surface topography image. After selecting a flat and defect-free position according to the topography map, the tip of the silicon cantilever beam is brought into contact with the surface of graphene or the silicon substrate; subsequently, a positive voltage is applied to the tip, and the residence time and load are adjusted so that metal nanomaterials are deposited near the tip to form a metal nanoarray structure. Through this invention, in-situ controllable manufacturing of the size, morphology, composition, structure and position of metal particles on the graphene surface can be realized. It can be better promoted and applied in technical fields such as electronics, optics, catalysis, sensing, field emission, display devices, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanostructure manufacturing. Specifically, it relates to a metal nanoarray structure that can be in-situ controllably prepared on graphene and a preparation method thereof. Background Art

[0002] Graphene (GR) is a two-dimensional material with a honeycomb lattice structure formed by a single layer of carbon atoms in sp 2 hybrid orbitals. Since it was successfully prepared by Geim et al. in 2004, it has attracted much attention. Due to its excellent properties such as high electrical conductivity, high thermal conductivity, high strength and flexibility, and large specific surface area, graphene has become an ideal carrier for composites, and it shows great application prospects in the fields of electricity, catalysis, sensing, field emission and display devices, nano-optoelectronics, etc.

[0003] With the rapid development of nanotechnology and experimental equipment, the research on graphene itself in terms of optoelectronics and mechanics has gradually expanded to the research of its combination with various nanomaterials. Since metal nanostructures have high specific strength, high specific modulus, high corrosion resistance, excellent electrothermal properties, and excellent processing properties, combining graphene with metal nanomaterials can not only retain the original excellent properties of graphene, but also enable the composite material to exhibit properties beyond single components through the synergistic effect between the two, which makes graphene / metal nanocomposites a research hotspot. Among metal nanomaterials, the application of metal nanoparticles (NPs) is more extensive. Metal nanoparticles generally refer to metal crystals or clusters with a diameter less than 100 nanometers. These particles can be single elements such as gold (Au), silver (Ag), platinum (Pt), etc. or in the form of alloys.

[0004] Current research shows that metal nanoparticles (NPs) can be deposited on graphene by means such as photochemical-assisted self-assembly method, chemical reduction method, thermal evaporation method, plasma-assisted deposition, etc. For example, the Chinese patent with the publication number CN106000377B provides two titanium oxide / graphene nanocomposites. In the invention, the prepared one-dimensional titanium oxide nanotubes and two-dimensional titanium oxide nanosheets are combined with graphene nanosheets in a tiled or layer-by-layer self-assembly manner to form a nanocomposite material that can efficiently remove methylene blue. The composite material is green, environmentally friendly, simple and easy to prepare. However, the methods used in the prior art are difficult to achieve precise control over the size, morphology, composition, structure, and position of metal nanoparticles deposited on graphene, and the stability of metal nanoparticles deposited on graphene also needs to be improved. Summary of the Invention

[0005] Aiming at the above deficiencies existing in the prior art, the purpose of the present invention is to provide a metal nanoarray structure that can be in-situ controllably prepared on graphene and a preparation method thereof.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] A method for in-situ controllable preparation of metal nanoarray structures on graphene, comprising the following steps:

[0008] (1) Preparation of a silicon cantilever beam containing raw material molecules: Immerse the silicon cantilever beam in a solution containing raw material molecules, and dry it with filtered compressed gas to form a silicon cantilever beam containing raw material molecules;

[0009] (2) Preparation of a silicon substrate: Ultrasonically clean the silicon substrate with an oxide layer in turn with acetone, ethanol, and deionized water, and then immerse it in a strong acid solution to form a clean silicon substrate with H + as the terminal;

[0010] (3) Preparation of a graphene layer: Prepare a graphene layer on the silicon substrate described in step (2) by mechanical exfoliation method, and perform plasma controllable treatment on the graphene layer to make the graphene have a certain degree of defective structure;

[0011] (4) In-situ controllable preparation of metal nanoarray structures on graphene: Prepare by multi-mode nanotechnology. First, install the silicon cantilever beam containing raw material molecules prepared in step (1) on an atomic force microscope, scan the substrate prepared in step (3) to generate a high-resolution surface topography image, and select a flat and defect-free position according to the topography map; then make the tip of the silicon cantilever beam contact the surface of graphene or the silicon substrate; finally, apply a positive voltage at the tip, and adjust the residence time and load so that the metal nano material is deposited near the tip to form a metal nanoarray structure.

[0012] In the present invention, the metal nano material is deposited on graphene and the two are combined. Not only can the excellent properties of graphene such as high specific surface area, high conductivity, and good thermal stability be retained, but also the composite material can exhibit performance beyond that of a single component through the synergistic effect between the two. When the metal nano material is embedded between the graphene layers, it can weaken the interaction force between the graphene layers, thereby effectively preventing the stacking and aggregation between the graphene layers and the metal nano materials, and at the same time enhancing the activity of the metal nano materials. Among them, the substrate provides a stable physical support platform for the deposition of graphene and metal nano materials, ensuring that it will not be easily damaged or fall off during subsequent preparation and application.

[0013] Preferably, in step (1), the raw material molecule is hexachloroplatinic acid; a 25-nm-thick platinum-iridium alloy is coated on the tip of the silicon cantilever beam, its spring constant is 2.8 N / m, and the resonance frequency is 75 kHz.

[0014] Hexachloroplatinic acid (H 2 PtCl 6) as raw material molecules, nanoparticles can be generated in situ through chemical reactions. 2 PtCl 6 , which can ensure that in the subsequent use process, the tip can effectively act as an electrode to promote the reduction reaction of metal ions. Moreover, the operation is simple and easy, and deposition can be carried out by simply applying voltage without additional solution processing steps. Among them, the specific reaction formula of the reduction reaction is as follows:

[0015]

[0016] Silicon cantilever is a key component in atomic force microscope (AFM). It is a thin and long silicon chip with one end fixed and the other end free. There is a sharp probe on the cantilever for contacting the sample surface and detecting the morphology and properties of the sample surface through interaction. In the present invention, the silicon cantilever is also used as an electrode for energizing and depositing metal nanomaterials. The platinum-iridium (PtIr) alloy coated on the tip of the silicon cantilever is a coating with good electrochemical activity, high corrosiveness and conductivity, which effectively promotes the reduction reaction of nanometal materials, thereby depositing metal nanomaterials on the graphene layer. Its spring constant refers to the stiffness of the silicon cantilever, which indicates the displacement of the silicon cantilever under the action of unit force. 2.8N / m is a lower value, which means that the silicon cantilever is softer and more sensitive to changes in force; the resonant frequency refers to the frequency at which the silicon cantilever vibrates naturally without external interference; the resonant frequency determines the performance of the silicon cantilever in different operating modes. In mode 1, the silicon cantilever vibrates near the resonant frequency to reduce wear on the sample surface. A higher resonance frequency of 75kHz usually means a faster response speed, which helps to improve the resolution and speed of imaging.

[0017] Preferably, in step (1), the compressed gas is an inert gas, specifically argon; the drying time is 10 to 40 minutes; and the mass percentage of the hexachloroplatinic acid solution is 1 to 10 wt%.

[0018] Preferably, in step (2), the silicon substrate is selected from a p-type silicon wafer, and the thickness of the oxide layer of the silicon substrate is 100 to 400 nm.

[0019] A silicon substrate with a certain thickness of the oxide layer has higher mechanical strength and a very flat surface, providing a support platform for the stable attachment of graphene and the subsequently deposited metal nanomaterials. The thickness of the oxide layer affects the transfer quality, electrical properties, and subsequent applications of graphene. If the oxide layer is too thick, it will affect the visibility of graphene; if it is too thin, when the graphene-metal nanomaterials are applied in electronic devices, it will result in a higher leakage current and a lower breakdown voltage. Therefore, a thickness of 100 - 400 nm is preferred. The silicon substrate with a thickness within this range can not only provide good optical contrast, making graphene easy to observe under a microscope, but also, due to the good thermal conductivity of the silicon substrate itself, help dissipate heat effectively, promoting the conduction of heat from graphene and metal nanomaterials to the silicon substrate, thereby improving the thermal stability of the entire composite material.

[0020] Preferably, in the step (2), the ultrasonic cleaning time is 5 - 10 min each time, the strong acid solution is a hydrofluoric acid solution, the volume fraction of the hydrofluoric acid solution is 5% - 50%, and the immersion time is 10 s - 5 min.

[0021] Acetone, ethanol, and deionized water are used to remove organic pollutants on the surface of the silicon substrate, and a hydrofluoric acid (HF) solution is used to remove the natural oxide layer on the surface of the silicon substrate. During the subsequent electrochemical deposition, an oxidation reaction occurs on this substrate to form a silicon-based bottom layer with H as the terminal, which helps improve the hydrophilicity of the silicon substrate surface. The involved electrochemical reaction is as follows: + which helps improve the hydrophilicity of the silicon substrate surface. The involved electrochemical reaction is as follows:

[0022] SiO 2 + 4HF → SiF 4 + 2H 2 O

[0023] 2H 2 O - 4e - → O 2 + 4H +

[0024] Preferably, in the step (3), the parameters of the plasma controllable treatment are: the oxygen treatment time is 30 s - 5 min, and the power is 20 - 100 W.

[0025] Through the controllable plasma treatment of graphene, the graphene surface has a certain defect structure, which increases its hydrophilicity, thereby improving the chemical activity of the material, so that the graphene as a carrier has more active centers, making it easier to react with subsequent metal nanomaterials. The appropriate defect structure can also optimize the flexibility of graphene. The oxygen treatment time of each parameter is controlled to be 30s to 5min, and the power is 20 to 100W. Several carboxyl groups, hydroxyl groups and other groups are introduced on the graphene surface, so that the graphene surface has a certain defect structure, thereby improving its surface hydrophilicity. The treatment time should not be too long, and the power should not be too high to prevent the conductivity from decreasing. The hydrophilicity of the graphene surface is improved while ensuring its conductivity, and it can still form a conductive circuit.

[0026] Preferably, in step (4), the metal nanomaterial is metal nanoparticles (NPs), and the metal nanoparticles are selected from gold, silver, platinum, palladium or copper.

[0027] Metal nanoparticles have a significant surface plasmon resonance (SPR) effect, which is due to the charge accumulation and oscillation effect generated when the nanoparticles interact with light. This effect leads to a strong local electromagnetic field enhancement, which has important applications in optical sensing, surface enhanced Raman scattering (SERS) and other fields; metal nanoparticles also have a high surface area and surface active sites, and are excellent catalysts. When these particles are deposited on graphene, their catalytic activity can be further increased because graphene provides a large specific surface area and good conductivity, which facilitates the rapid transfer of charges and the effective adsorption of reactants.

[0028] Preferably, in step (4), the metal nanoparticles are preferably platinum nanoparticles (NPs).

[0029] Platinum NPs not only have a high specific surface area and abundant active sites, which can significantly improve the efficiency of catalytic reactions, but also have high chemical stability and are not easily oxidized or corroded. This allows platinum NPs to maintain their structure and performance in various chemical environments, making them less likely to fail during long-term use, thus extending their service life. In addition, platinum NPs have low toxicity in vivo and good biocompatibility, so platinum NPs are preferred.

[0030] Preferably, in step (4), the voltage is 8 to 10 V, the dwell time is 7 to 9 s, and the load is 2 to 10 nN.

[0031] The multi-mode nanotechnology provided by the present invention has two modes in total. Under the action of Mode 1, AFM can generate high-resolution surface topography images to display the details of the sample surface, and then select a flat area without obvious defects. Subsequently, it is switched to Mode 2, where the tip will directly contact the surface of graphene or silicon substrate and slide on the sample surface. This can ensure close contact between the tip and the substrate, providing stable conditions for subsequent deposition. Subsequently, the energy dispersive spectrometer (EDS) attached to the field emission scanning electron microscope (FESEM, SU8220) is used to characterize its nanostructure.

[0032] The specific method of controllable adjustment is to control parameters such as voltage, residence time, and load. By adjusting the applied voltage, the reduction rate and deposition amount of metal nano-ions can be controlled; by controlling the residence time of the tip at each point, the deposition amount in the local area can be controlled; by adjusting the load of the silicon cantilever beam, the contact pressure between the tip and the substrate can be controlled, affecting the formation of nanostructures.

[0033] Preferably, the temperature is controlled at 27.2 °C and the humidity is 37% - 55% in steps (1) to (4).

[0034] The control of temperature and humidity throughout the process is very important for the preparation of metal nanoarrays. The relatively mild temperature provides a constant temperature condition to ensure environmental consistency; the regulation of humidity prevents uneven electrochemical reactions or the introduction of impurities caused by moisture interference. Stable temperature and humidity help to ensure the quality and uniformity of the deposited material, avoiding defects or non-uniformities caused by environmental changes.

[0035] As a general technical concept, the present invention also provides a metal nanoarray structure controllably prepared in situ on graphene, which is prepared by any of the above methods.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] (1) By using multi-mode nanotechnology, the present invention can achieve high-resolution imaging and controllably deposit the size, morphology, and distribution of platinum nanostructures on graphene and silicon substrates by precisely controlling the position and residence time or scanning speed of the AFM tip. During the deposition process, the formation of metal nanostructures is monitored in real time, and parameters are adjusted in a timely manner to ensure the quality and stability of the array structure. The preparation process is simple and easy to operate.

[0038] (2) The silicon substrate with a certain thickness of the oxide layer has high mechanical strength and a very flat surface, providing a support platform for the stable attachment of graphene and the subsequently deposited metal nanoparticles. Moreover, it can provide good optical contrast and high thermal conductivity, which helps to dissipate heat quickly, ensuring that heat is transferred from the active area of graphene and metal nanoparticles to the substrate, preventing local overheating, and enhancing the stability and reliability of the material under high-temperature conditions.

[0039] (3) The periodic honeycomb conformation of graphene endows it with a high specific surface area and a series of excellent properties, making it an ideal carrier for loading metal nanoparticles. Inserting metal nanoparticles between the graphene sheets can reduce the intermolecular force between the graphene sheets, effectively avoid the aggregation of graphene sheets, enhance the overall strength and toughness of the material while improving the activity of metal nanoparticles, and prevent the aggregation of metal nanoparticles. Moreover, the honeycomb crystal structure of graphene can deposit metal nanoparticles more firmly, and they are not easily worn and fallen off during subsequent use and operation. In addition, through plasma treatment, the surface of graphene has a certain defect structure, increasing the hydrophilicity of the graphene surface. By improving the chemical activity of the material, the graphene as a carrier can have more active sites, making it easier to react with the subsequently added metal nanomaterials. At the same time, maintaining its conductivity makes the subsequent electrochemical deposition more uniform, thus preparing a more stable metal nanoarray structure. Description of the Drawings

[0040] Figure 1 It is a schematic diagram of the operation for in-situ controllable preparation of a metal nanoarray structure on graphene.

[0041] Figure 2 It is a schematic diagram of the metal nanoarray prepared on graphene in Example 1.

[0042] Figure 3 It is the energy-dispersive spectrum of platinum NPs prepared on graphene in Example 1.

[0043] Figure 4 It is the morphology diagram of platinum NPs prepared on graphene in Example 1.

[0044] Figure 5 It is the morphology diagram of platinum NPs prepared on a silicon substrate in Comparative Examples 1 - 5.

[0045] The meanings of the main reference numerals in the figures are as follows:

[0046] 1. Silicon cantilever beam, 2. Silicon substrate, 3. Graphene layer, 4. Raw material molecules. Detailed Embodiments

[0047] The technical solutions in the embodiments of the present invention will be described in detail below. The described embodiments are only partial embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention fall within the scope of protection of the present invention. The present invention will be further described below in conjunction with specific embodiments with reference to the accompanying drawings.

[0048] Unless otherwise specified, various materials involved in the present invention can be obtained from commercial channels.

[0049] As Figure 1 shown, a preparation method for in-situ controllably preparing a metal nanoarray structure on graphene includes the following steps:

[0050] (1) Preparation of a silicon cantilever 1 containing raw material molecules 4: Immerse the silicon cantilever 1 in a solution containing raw material molecules 4, and dry it with filtered compressed gas to form a silicon cantilever 1 containing raw material molecules 4;

[0051] (2) Preparation of a silicon substrate 2: Ultrasonically clean a silicon substrate 2 with a certain thickness of oxide layer in turn with acetone, ethanol, and deionized water, and then immerse it in a strong acid solution to form a clean silicon substrate 2 with H + as the terminal;

[0052] (3) Preparation of a graphene layer 3: Prepare a graphene layer 3 on the silicon substrate 2 described in step (2) by mechanical exfoliation method, and perform plasma controllable treatment on the graphene layer 3 to make the graphene have a certain degree of defective structure;

[0053] (4) Preparation of an in-situ controllably prepared metal nanoarray structure on graphene: Prepare it by multi-mode nanotechnology. First, install the silicon cantilever 1 containing raw material molecules 4 prepared in step (1) on an atomic force microscope, first scan the substrate prepared in step (3) to generate a high-resolution surface topography image, select a flat and defect-free position according to the topography map, and then make the tip of the silicon cantilever 1 contact the surface of the graphene layer 3 or the silicon substrate 2; finally, apply a positive voltage at the tip, and adjust the residence time and load so that the metal nanomaterials are deposited near the tip to form a metal nanoarray structure.

[0054] Specific embodiments are as follows:

[0055] Example 1

[0056] A preparation method for in-situ controllably preparing a metal nanoarray structure on graphene,

[0057] including the following steps:

[0058] (1) Immerse a silicon cantilever with a spring constant of 2.8 N / m, a resonance frequency of 75 kHz, and coated with a 25-nm-thick PtIr into H with a mass fraction of 2 wt%2 PtCl 6 The solution was dried with filtered compressed argon for 15 min to form H 2 PtCl 6 coated silicon cantilever beam;

[0059] (2) A p-type silicon wafer with an oxide layer thickness of 300 nm was cleaned in an ultrasonic device with acetone, ethanol, and deionized water for 5 min, and then immersed in a 10% HF solution for 60 s to form a clean HF solution. + A silicon substrate for the terminal;

[0060] (3) preparing a graphene layer on the silicon substrate described in step (2) by a mechanical exfoliation method, and subjecting the graphene layer to plasma treatment, oxygen treatment for 2 min, power of 50 W, so that the graphene has a certain degree of defective structure;

[0061] (4) First, the H prepared in step (1) 2 PtCl 6 The coated silicon cantilever is mounted on an atomic force microscope, and the substrate prepared in step (3) is first scanned to generate a high-resolution surface morphology image. After selecting a flat position without obvious defects according to the morphology image, the tip of the silicon cantilever is brought into contact with the surface of the graphene or silicon substrate; then a positive voltage of 8 V is applied to the tip, the dwell time is adjusted to 7 s, and a load of 10 nN is set to allow platinum NPs to be deposited near the tip to form a metal nanoarray structure, such as Figure 2 and Figure 3 As shown, platinum NPs are uniformly deposited on the graphene honeycomb crystal structure.

[0062] The temperature was maintained at 27.2°C and the humidity was 45% throughout the process.

[0063] Example 2

[0064] A method for preparing a metal nanoarray structure in situ and controllably on graphene,

[0065] The following steps are involved:

[0066] (1) A silicon cantilever beam with a spring constant of 2.8 N / m, a resonant frequency of 75 kHz, and a 25 nm thick PtIr coating was immersed in a 1 wt% H 2 PtCl 6 The solution was dried with filtered compressed argon for 10 min to form H 2 PtCl 6 coated silicon cantilever beam;

[0067] (2) A p-type silicon wafer with an oxide layer thickness of 200 nm was cleaned in an ultrasonic device with acetone, ethanol, and deionized water for 10 min, and then immersed in a 5% HF solution for 30 s to form a clean HF solution. + A silicon substrate for the terminal;

[0068] (3) preparing a graphene layer on the silicon substrate described in step (2) by a mechanical exfoliation method, and subjecting the graphene layer to plasma treatment, oxygen treatment for 1 min, power of 20 W, so that the graphene has a certain degree of defective structure;

[0069] (4) First, the H prepared in step (1) 2 PtCl 6 The coated silicon cantilever is mounted on an atomic force microscope, and the substrate prepared in step (3) is first scanned to generate a high-resolution surface morphology image. After selecting a flat position without obvious defects according to the morphology image, the tip of the silicon cantilever is brought into contact with the surface of the graphene or silicon substrate; then a positive voltage of 9 V is applied to the tip, the dwell time is adjusted to 7 s, and a load of 6 nN is set to allow platinum NPs to be deposited near the tip to form a metal nanoarray structure.

[0070] The temperature was maintained at 27.2°C and the humidity was 37% throughout the process.

[0071] Example 3

[0072] A method for preparing a metal nanoarray structure in situ and controllably on graphene,

[0073] The following steps are involved:

[0074] (1) A silicon cantilever beam with a spring constant of 2.8 N / m, a resonant frequency of 75 kHz, and a 25 nm thick PtIr coating was immersed in a 10 wt% H 2 PtCl 6 The solution was dried with filtered compressed argon for 40 min to form H 2 PtCl 6 coated silicon cantilever beam;

[0075] (2) A p-type silicon wafer with an oxide layer thickness of 400 nm was cleaned in an ultrasonic device with acetone, ethanol, and deionized water for 6 min, and then immersed in a 7% HF solution for 10 s to form a clean HF solution. + A silicon substrate for the terminal;

[0076] (3) preparing a graphene layer on the silicon substrate described in step (2) by a mechanical exfoliation method, and subjecting the graphene layer to plasma treatment, oxygen treatment for 5 min, power of 100 W, so that the graphene has a certain degree of defective structure;

[0077] (4) First, the H prepared in step (1) 2 PtCl 6 The coated silicon cantilever is mounted on an atomic force microscope, and the substrate prepared in step (3) is first scanned to generate a high-resolution surface morphology image. After selecting a flat position without obvious defects according to the morphology image, the tip of the silicon cantilever is brought into contact with the surface of the graphene or silicon substrate; then a positive voltage of 10 V is applied to the tip, the dwell time is adjusted to 7 s, and a load of 4 nN is set to allow platinum NPs to be deposited near the tip to form a metal nanoarray structure.

[0078] The temperature was maintained at 27.2°C and the humidity was 55% throughout the process.

[0079] Example 4

[0080] A method for preparing a metal nanoarray structure in situ and controllably on graphene,

[0081] The following steps are involved:

[0082] (1) A silicon cantilever beam with a spring constant of 2.8 N / m, a resonant frequency of 75 kHz, and a 25 nm thick PtIr coating was immersed in a 5 wt% H 2 PtCl 6 The solution was dried with filtered compressed argon for 35 min to form H 2 PtCl 6 coated silicon cantilever beam;

[0083] (2) A p-type silicon wafer with an oxide layer thickness of 150 nm was cleaned in an ultrasonic device with acetone, ethanol, and deionized water for 8 min, and then immersed in a 40% HF solution for 3 min to form a clean H + A silicon substrate for the terminal;

[0084] (3) preparing a graphene layer on the silicon substrate described in step (2) by a mechanical exfoliation method, and subjecting the graphene layer to plasma treatment, oxygen treatment for 2 min, power of 40 W, so that the graphene has a certain degree of defective structure;

[0085] (4) First, the H prepared in step (1) 2 PtCl 6 The coated silicon cantilever is mounted on an atomic force microscope, and the substrate prepared in step (3) is first scanned to generate a high-resolution surface morphology image. After selecting a flat position without obvious defects according to the morphology image, the tip of the silicon cantilever is brought into contact with the surface of the graphene or silicon substrate; then a positive voltage of 8 V is applied to the tip, the dwell time is adjusted to 7 s, and a load of 10 nN is set to allow platinum NPs to be deposited near the tip to form a metal nanoarray structure.

[0086] The temperature was maintained at 27.2°C and the humidity was 40% throughout the process.

[0087] Example 5

[0088] A method for preparing a metal nanoarray structure in situ and controllably on graphene,

[0089] The following steps are involved:

[0090] (1) A silicon cantilever beam with a spring constant of 2.8 N / m, a resonant frequency of 75 kHz, and a 25 nm thick PtIr coating was immersed in a 3 wt% H 2 PtCl 6 The solution was dried with filtered compressed argon for 11 min to form H 2 PtCl 6 coated silicon cantilever beam;

[0091] (2) A p-type silicon wafer with an oxide layer thickness of 120 nm was cleaned in an ultrasonic device with acetone, ethanol, and deionized water for 7 min, and then immersed in a 20% HF solution for 4 min to form a clean H + A silicon substrate for the terminal;

[0092] (3) preparing a graphene layer on the silicon substrate described in step (2) by a mechanical exfoliation method, and subjecting the graphene layer to plasma treatment, oxygen treatment for 50 seconds at a power of 70 W, so that the graphene has a certain degree of defective structure;

[0093] (4) First, the H prepared in step (1) 2 PtCl 6 The coated silicon cantilever is mounted on an atomic force microscope, and the substrate prepared in step (3) is first scanned to generate a high-resolution surface morphology image. After selecting a flat position without obvious defects according to the morphology image, the tip of the silicon cantilever is brought into contact with the surface of the graphene or silicon substrate; then a positive voltage of 8 V is applied to the tip, the dwell time is adjusted to 8 s, and a load of 4 nN is set to allow platinum NPs to be deposited near the tip to form a metal nanoarray structure.

[0094] The temperature was maintained at 27.2°C and the humidity was 38% throughout the process.

[0095] Example 6

[0096] A method for preparing a metal nanoarray structure in situ and controllably on graphene,

[0097] The following steps are involved:

[0098] (1) A silicon cantilever beam with a spring constant of 2.8 N / m, a resonant frequency of 75 kHz, and a 25 nm thick PtIr coating was immersed in a H 2 PtCl 6 The solution was dried with filtered compressed argon for 26 min to form H 2 PtCl 6 coated silicon cantilever beam;

[0099] (2) A p-type silicon wafer with an oxide layer thickness of 250 nm was cleaned in an ultrasonic device with acetone, ethanol, and deionized water for 9 min, and then immersed in a 15% HF solution for 40 s to form a clean HF solution. + A silicon substrate for the terminal;

[0100] (3) preparing a graphene layer on the silicon substrate described in step (2) by a mechanical exfoliation method, and subjecting the graphene layer to plasma treatment, oxygen treatment for 2 min, power of 30 W, so that the graphene has a certain degree of defective structure;

[0101] (4) First, the H prepared in step (1) 2 PtCl 6 The coated silicon cantilever is mounted on an atomic force microscope, and the substrate prepared in step (3) is first scanned to generate a high-resolution surface morphology image. After selecting a flat position without obvious defects according to the morphology image, the tip of the silicon cantilever is brought into contact with the surface of the graphene or silicon substrate; then a positive voltage of 8 V is applied to the tip, the dwell time is adjusted to 10 s, and a load of 4 nN is set to allow platinum NPs to be deposited near the tip to form a metal nanoarray structure.

[0102] The temperature was maintained at 27.2°C and the humidity was 42% throughout the process.

[0103] Comparative Example 1

[0104] A method for preparing a metal nanoarray structure in situ and controllably on a silicon substrate.

[0105] The following steps are involved:

[0106] (1) A silicon cantilever beam having a spring constant of 2.8 N / m, a resonance frequency of 75 kHz and coated with a 25 nm thick PtIr layer was immersed in a 2 wt% H2PtCl6 solution and dried with filtered compressed argon for 15 min to form a H2PtCl6 coated silicon cantilever beam;

[0107] (2) A p-type silicon wafer with an oxide layer thickness of 300 nm was cleaned in an ultrasonic device with acetone, ethanol, and deionized water for 5 min, and then immersed in a 10% HF solution for 60 s to form a clean silicon substrate with H+ as the terminal;

[0108] (3) The H2PtCl6-coated silicon cantilever prepared in step (1) is first mounted on an atomic force microscope, and the substrate prepared in step (2) is first scanned to generate a high-resolution surface morphology image. After selecting a flat position according to the morphology image, the tip of the silicon cantilever is then brought into contact with the surface of the silicon substrate; a positive voltage of 4 V is then applied to the tip, the scanning speed is adjusted to 50 nm / s, and a load of 10 nN is set to allow platinum NPs to be deposited near the tip.

[0109] The temperature was maintained at 27.2°C and the humidity was 45% throughout the process.

[0110] Comparative Example 2

[0111] A method for preparing a metal nanoarray structure in situ and controllably on a silicon substrate.

[0112] The following steps are involved:

[0113] (1) A silicon cantilever beam having a spring constant of 2.8 N / m, a resonance frequency of 75 kHz and coated with a 25 nm thick PtIr layer was immersed in a 4 wt% H2PtCl6 solution and dried with filtered compressed argon for 21 min to form a H2PtCl6 coated silicon cantilever beam;

[0114] (2) A p-type silicon wafer with an oxide layer thickness of 240 nm was cleaned in an ultrasonic device with acetone, ethanol, and deionized water in sequence for 7 min, and then immersed in a 24% by volume HF solution for 55 s to form a clean silicon substrate with H+ as the terminal;

[0115] (3) The H2PtCl6-coated silicon cantilever prepared in step (1) is first mounted on an atomic force microscope, and the substrate prepared in step (2) is first scanned to generate a high-resolution surface morphology image. After selecting a flat position according to the morphology image, the tip of the silicon cantilever is then brought into contact with the surface of the silicon substrate; a positive voltage of 4 V is then applied to the tip, the scanning speed is adjusted to 40 nm / s, and a load of 10 nN is set to allow platinum NPs to be deposited near the tip.

[0116] The temperature was maintained at 27.2°C and the humidity was 47% throughout the process.

[0117] Comparative Example 3

[0118] A method for preparing a metal nanoarray structure in situ and controllably on a silicon substrate.

[0119] The following steps are involved:

[0120] (1) A silicon cantilever beam having a spring constant of 2.8 N / m, a resonance frequency of 75 kHz and coated with a 25 nm thick PtIr layer was immersed in a 5 wt% H2PtCl6 solution and dried with filtered compressed argon for 33 min to form a H2PtCl6 coated silicon cantilever beam;

[0121] (2) A p-type silicon wafer with an oxide layer thickness of 230 nm was cleaned in an ultrasonic device with acetone, ethanol, and deionized water in sequence for 6 min, and then immersed in a 25% by volume HF solution for 15 s to form a clean silicon substrate with H+ as the terminal;

[0122] (3) The H2PtCl6-coated silicon cantilever prepared in step (1) is first mounted on an atomic force microscope, and the substrate prepared in step (2) is first scanned to generate a high-resolution surface morphology image. After selecting a flat position according to the morphology image, the tip of the silicon cantilever is then brought into contact with the surface of the silicon substrate; a positive voltage of 4 V is then applied to the tip, the scanning speed is adjusted to 30 nm / s, and a load of 10 nN is set to allow platinum NPs to be deposited near the tip.

[0123] The temperature was maintained at 27.2°C and the humidity was 41% throughout the process.

[0124] Comparative Example 4

[0125] A method for preparing a metal nanoarray structure in situ and controllably on a silicon substrate.

[0126] The following steps are involved:

[0127] (1) A silicon cantilever beam with a spring constant of 2.8 N / m, a resonant frequency of 75 kHz, and a 25 nm thick PtIr coating was immersed in a 4 wt% H 2 PtCl 6 The solution was dried with filtered compressed argon for 36 min to form H 2 PtCl 6 coated silicon cantilever beam;

[0128] (2) A silicon wafer with an oxide layer thickness of 240 nm was cleaned in an ultrasonic device with acetone, ethanol, and deionized water for 7 min, and then immersed in a 45% HF solution for 36 s to form a clean HF solution. + A silicon substrate for the terminal;

[0129] (3) The H2PtCl6-coated silicon cantilever prepared in step (1) is first mounted on an atomic force microscope, and the substrate prepared in step (2) is first scanned to generate a high-resolution surface morphology image. After selecting a flat position according to the morphology image, the tip of the silicon cantilever is then brought into contact with the surface of the silicon substrate; a positive voltage of 4 V is then applied to the tip, the scanning speed is adjusted to 20 nm / s, and a load of 10 nN is set to allow platinum NPs to be deposited near the tip.

[0130] The temperature was maintained at 27.2°C and the humidity was 53% throughout the process.

[0131] Comparative Example 5

[0132] A method for preparing a metal nanoarray structure in situ and controllably on a silicon substrate.

[0133] The following steps are involved:

[0134] (1) A silicon cantilever beam with a spring constant of 2.8 N / m, a resonant frequency of 75 kHz, and a 25 nm thick PtIr coating was immersed in a 2 wt% H 2 PtCl 6 The solution was dried with filtered compressed argon for 24 min to form H 2 PtCl 6 coated silicon cantilever beam;

[0135] (2) A p-type silicon wafer with an oxide layer thickness of 280 nm was cleaned in an ultrasonic device with acetone, ethanol, and deionized water for 10 min, and then immersed in a 16% HF solution for 45 s to form a clean H + A silicon substrate for the terminal;

[0136] (3) The H2PtCl6-coated silicon cantilever prepared in step (1) is first mounted on an atomic force microscope, and the substrate prepared in step (2) is first scanned to generate a high-resolution surface morphology image. After selecting a flat position according to the morphology image, the tip of the silicon cantilever is then brought into contact with the surface of the silicon substrate; a positive voltage of 4 V is then applied to the tip, the scanning speed is adjusted to 10 nm / s, and a load of 10 nN is set to allow platinum NPs to be deposited near the tip.

[0137] The temperature was maintained at 27.2°C and the humidity was 51% throughout the process.

[0138] From the morphology images of the platinum NPs prepared in Examples 1 to 6 and Comparative Examples 1 to 5, the height and diameter data are extracted, as shown in Table 1:

[0139] Table 1 Height and diameter values ​​of platinum NPs prepared in Examples 1 to 6 and Comparative Examples 1 to 5

[0140] Height (nm) Diameter (nm) Example 1 1.91±0.54 24.68±6.30 Example 2 2.14±0.63 28.78±7.41 Example 3 3.01±0.39 34.03±5.64 Example 4 3.27±1.45 35.07±6.23 Example 5 3.49±1.69 40.25±2.36 Example 6 4.34±2.01 43.08±5.68 Comparative Example 1 2.35±1.05 70.45±7.34 Comparative Example 2 3.87±2.04 80.25±3.45 Comparative Example 3 4.12±0.98 95.24±6.28 Comparative Example 4 5.56±1.25 100.21±4.25 Comparative Example 5 9.48±1.23 105.23±4.12

[0141] Combined with Table 1, Figure 4 As with Examples 1 to 3, the size change of platinum NPs was tested by changing the voltage. As the voltage increased, the height and diameter of the platinum NPs also increased, which means that the size of the platinum NPs increased with the increase of the voltage, because the rate of the reduction reaction is directly affected by regulating the voltage. A higher voltage will increase the electric field strength, thereby accelerating the reduction reaction of platinum ions, so that more platinum ions are reduced to platinum atoms and deposited on graphene, thereby forming larger-sized nanoparticles. The maximum height of the platinum NPs formed was 3.01±0.39nm, and the maximum diameter was 34.03±5.64.

[0142] Combining Table 1 with Examples 4 to 6, this is an experiment to test the size change of platinum NPs by changing the residence time. As the residence time increases, the height and diameter of the platinum NPs also increase, which means that the size of the platinum NPs increases with the increase in residence time, and compared with Examples 1 to 3 in which the voltage is changed, the size change of the platinum NPs is more obvious, and the growth rate is also greater. The minimum height of the platinum NPs formed in Examples 4 to 6 is 3.27±1.45, and the minimum diameter is 35.07±6.23, both of which are larger than the size of the platinum NPs prepared in Examples 1 to 3. By adjusting the residence time, the residence time of the tip on the substrate is changed. A longer residence time means that more platinum ions have more time to be reduced and deposited at this position. The longer the residence time, the larger the platinum NPs formed.

[0143] Combining Table 1 with Examples 1 to 5 and Comparative Examples 1 to 6, it is found that as the load changes, the change in load has a certain effect on the platinum NPs, but the effect is not significant.

[0144] Combining Table 1 with Comparative Examples 1 to 5, since it only contains a silicon substrate and no graphene layer, the height and diameter of the prepared platinum NPs are significantly larger than those of Examples 1 to 6, that is, the size of the platinum NPs directly deposited on the silicon substrate is larger, but the large-sized platinum NPs will reduce the overall specific surface area, reduce the surface activity, and further reduce the catalytic activity and adsorption capacity of the material; when the particle size increases to a certain extent, the movement of electrons is no longer significantly restricted, and the energy level changes from discrete to continuous. This leads to the weakening or disappearance of the quantum size effect, thereby affecting the optical, electrical and magnetic properties of the material. Combining Figure 5 , we can see that larger nanoparticles are more likely to agglomerate and form larger aggregates. Agglomeration further reduces the specific surface area and may block active sites, thereby reducing the performance of the material.

[0145] In summary, the method for preparing a metal nanoarray provided by the present invention can accurately and flexibly adjust the size, morphology and position of metal nanoparticles deposited on graphene by adjusting the voltage and residence time, so that it can be better applied to electronic devices, catalysis, sensor technology, energy conversion, optical applications, biomedicine and other fields.

[0146] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for in-situ controllable preparation of a metal nanoarray structure on graphene, characterized in that: The following steps are involved: (1) Preparing a silicon cantilever beam containing a raw material molecule: immersing the silicon cantilever beam in a solution containing the raw material molecule, and drying the solution with filtered compressed gas to form a silicon cantilever beam containing the raw material molecule, wherein the raw material molecule is hexachloroplatinic acid; (2) Preparation of silicon substrate: The silicon substrate containing the oxide layer was ultrasonically cleaned with acetone, ethanol, and deionized water in sequence, and then immersed in a strong acid solution to form a clean H + A silicon substrate for the terminal; (3) Preparing a graphene layer: preparing a graphene layer on the silicon substrate described in step (2) by a mechanical exfoliation method, and performing a plasma controllable treatment on the graphene layer so that the graphene has a defective structure; (4) In-situ controllable preparation of metal nanoarray structures on graphene: Preparation is performed using multi-mode nanotechnology. The silicon cantilever containing the raw material molecules prepared in step (1) is first mounted on an atomic force microscope, and the substrate prepared in step (3) is scanned to generate a high-resolution surface morphology image. A flat position without obvious defects is selected based on the morphology image; then the tip of the silicon cantilever is brought into contact with the surface of the graphene or silicon substrate; Finally, a positive voltage is applied to the tip, and the dwell time and load are adjusted to allow the metal nanomaterial to be deposited near the tip to form a metal nanoarray structure. The voltage is 8-10 V, the dwell time is 7-9 s, and the load is 2-10 nN.

2. The method for in-situ controllable preparation of a metal nanoarray structure on graphene according to claim 1, characterized in that: In the step (1), the tip of the silicon cantilever beam is coated with a 25 nm thick layer of platinum-iridium alloy, the spring constant of which is 2.8 N / m and the resonance frequency is 75 kHz.

3. The method for in-situ controllable preparation of a metal nanoarray structure on graphene according to claim 1, characterized in that: In the step (1), the compressed gas is argon; the drying time is 10 to 40 minutes; and the mass percentage of the hexachloroplatinic acid solution is 1 to 10 wt%.

4. The method for in-situ controllable preparation of a metal nanoarray structure on graphene according to claim 1, characterized in that: In the step (2), the silicon substrate is selected from a p-type silicon wafer, and the thickness of the silicon substrate oxide layer is 100-400 nm.

5. The method for in-situ controllable preparation of a metal nanoarray structure on graphene according to claim 1, characterized in that: The ultrasonic cleaning time in step (2) is 5 to 10 minutes each time, the strong acid solution is a hydrofluoric acid solution, the volume fraction of the hydrofluoric acid solution is 5% to 50%, and the immersion time is 10 seconds to 5 minutes.

6. The method for in-situ controllable preparation of a metal nanoarray structure on graphene according to claim 1, characterized in that: In step (3), the parameters of the plasma controllable treatment are: oxygen treatment time 30s~5min, power 20~100W.

7. The method for in-situ controllable preparation of a metal nanoarray structure on graphene according to claim 1, characterized in that: In steps (1) to (4), the temperature is controlled at 27.2° C. and the humidity is controlled at 37% to 55%.

8. A metal nanoarray structure controllably prepared in situ on graphene, characterized in that: The method is prepared by any one of claims 1 to 7.

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