A method for preparing graphene nanostructures

Abstract

The application relates to a graphene nanostructure preparation method, which comprises the following steps: providing a DNA nanostructure and a substrate with graphene; non-covalently modifying the graphene, and spreading the DNA nanostructure on the surface of the graphene; adding TMAPS and TEOS into a buffer solution to pre-hydrolyze and form a pre-hydrolysis solution, and silicifying the DNA nanostructure spread on the surface of the graphene in the pre-hydrolysis solution to grow a protective SiO2 shell on the surface of the DNA nanostructure, thereby obtaining a DNA-SiO2 mask; removing the graphene not covered by the DNA-SiO2 mask by using oxygen plasma etching; and removing the DNA-SiO2 mask to obtain the graphene nanostructure. According to the graphene nanostructure preparation method, the nano-etching technology based on the DNA-SiO2 mask solves the problem that the existing graphene nanostructure preparation technology cannot simultaneously meet the requirements of high precision, controllable morphology, low cost and large-scale preparation.

Description

TECHNICAL FIELD

[0001] The present application relates to nanomaterials, and more particularly to a method for preparing graphene nanostructures. BACKGROUND

[0002] The superior mechanical, thermal, optical, electrical and other properties of graphene make it have extremely wide application prospects in the fields of flexible electronic devices, photonic devices, sensors, composite materials and energy, etc., bringing new opportunities for the development of science and technology and the progress of society. Among them, graphene has higher electron mobility, higher thermal conductivity and higher working frequency than silicon-based semiconductors, and is expected to become a new type of semiconductor material and be applied in the field of nanoelectronics. However, the intrinsic band gap of graphene is zero, which makes it difficult to achieve a high on-off ratio for graphene-based field effect transistors. Existing literature reports show that the band gap of graphene can be opened by applying an electric field, applying high pressure, and element doping, but these methods are not conducive to large-scale manufacturing. Nanosizing graphene can effectively open the energy gap, which is an effective solution to overcome the zero band gap. Moreover, nanosizing graphene is also expected to meet the processing requirements of semiconductor materials and continue the development of device miniaturization and integration.

[0003] At present, the methods for preparing graphene nanostructures mainly include the following three types: (1) top-down etching method based on large-area single-layer graphene, including electron beam etching, block copolymer etching, nanowire etching, nanosphere etching and scanning probe etching, etc. These methods are difficult to meet the requirements of sub-10 nanometer precision, arbitrary size and morphology, large-scale graphene nanostructure preparation, and the structures obtained generally have large edge roughness, resulting in serious edge scattering effect. (2) bottom-up chemical synthesis method based on molecular precursors, including direct growth on patterned substrates and interface or liquid phase synthesis based on molecular precursors; this type of method can prepare graphene nanostructures with sub-nanometer width and atomic-level precise edge orientation, but it is currently unable to realize the preparation of structures with arbitrary size and morphology. (3) cutting method based on carbon nanotubes. This method is only limited to the preparation of graphene nanoribbons.

[0004] In recent years, DNA nanotechnology has utilized the precisely structured DNA double helix and the strict base pairing principle to fabricate atomically precise two-dimensional and three-dimensional DNA nanostructures, demonstrating application potential in numerous fields such as bioanalysis, drug delivery, photonics, plasma physics, nanopores, and nanofabrication. Among these, nanofabrication methods using DNA nanostructures as masks have attracted increasing attention. This method combines the advantages of both bottom-up and top-down approaches: low cost, mass production capability, and precise control over morphology and accuracy. Existing literature shows that using DNA nanostructures as masks can achieve customized patterning of semiconductor silicon; for example, a recently reported work used DNA array structures as plasma etching masks to fabricate 3D silicon patterns with line spacing as low as 16.2 nanometers. However, when using soft DNA templates for graphene patterning etching, these soft templates are difficult to withstand oxygen plasma etching, and the structure is prone to deformation and collapse after dehydration. Metallizing DNA templates to form hard templates can effectively overcome these challenges, but the roughness of the metallized DNA structure increases dramatically and deviates significantly from the morphology of the original DNA structure, thus causing a serious decrease in the precision of the subsequently prepared graphene nanostructures. Summary of the Invention

[0005] To address the challenge that existing graphene nanostructure preparation technologies cannot simultaneously meet the requirements of high precision, controllable morphology, low cost, and large-scale preparation, this invention provides a method for preparing graphene nanostructures.

[0006] The method for preparing graphene nanostructures according to the present invention includes the following steps: S1, providing a DNA nanostructure and a graphene-based substrate; S2, non-covalently modifying the graphene and spreading the DNA nanostructure on the modified graphene surface; S3, pre-hydrolyzing TMAPS and TEOS in a buffer solution with a pH between 7.5 and 8.5 to form a pre-hydrolysate, wherein the volume percentage concentrations of TMAPS and TEOS in the pre-hydrolysate are between 1% and 3% (V / V), and silanizing the DNA nanostructure spread on the graphene surface in the pre-hydrolysate to grow a protective SiO2 shell on the surface of the DNA nanostructure, thereby obtaining a DNA-SiO2 mask; S4, removing the graphene not covered by the DNA-SiO2 mask by oxygen plasma etching; S5, removing the DNA-SiO2 mask to obtain the graphene nanostructure.

[0007] In fact, this application is the first to propose the preparation of graphene nanostructures based on a DNA-SiO2 mask. After silanizing the DNA nanostructure, controlling the integrity of the DNA structure and the specificity of silanization at the graphene interface is a key challenge in preparing graphene nanostructures using DNA-SiO2 as a mask. Through persistent research, the inventors discovered that high-fidelity replication of the DNA nanostructure morphology using a DNA-SiO2 mask is possible only by strictly controlling the pH and concentration of the pre-hydrolyzed solution. In other words, if the pH is not within the range of 7.5-8.5 and / or the volume percentage concentration is not within the range of 1%-3%, it will lead to non-silanization and / or uneven silanization and / or graphene silanization.

[0008] Preferably, the DNA nanostructure is a DNA monomer structure or a DNA array structure. More preferably, the DNA nanostructure is a DNA triangular origami, a DNA square origami, a DNA circular origami, a DNA bowtie structure, a DNA honeycomb array, a DNA three-point star array, or a DNA box array.

[0009] Preferably, in step S1, in 1xTAE-Mg 2+ DNA nanostructures are synthesized in a buffer solution and then purified by ultrafiltration. More preferably, the ultrafiltration tube used for ultrafiltration has a molecular weight cutoff of 100 kDa.

[0010] Preferably, in step S1, monolayer graphene is prepared on a copper foil; the monolayer graphene is then transferred to a substrate to form a graphene-containing substrate. More preferably, monolayer graphene is prepared on a copper foil by chemical vapor deposition. Even more preferably, the substrate consists of a Si layer and a SiO2 layer (i.e., a SiO2 / Si substrate), and the monolayer graphene is transferred onto the SiO2 to form a graphene-containing substrate (i.e., a graphene / SiO2 / Si substrate).

[0011] Preferably, in step S2, non-covalent modification with 1-pyrene methylamine, 1-pyrene carboxylic acid, or polylysine is performed to increase the affinity between graphene and DNA nanostructures.

[0012] Preferably, in step S2, the DNA nanostructure is dropped onto the graphene surface and incubated for 30-90 seconds. More preferably, the incubation time is less than 1 minute. In fact, the inventors unexpectedly discovered that the morphology of the DNA structure after silanization begins to deform after an incubation time greater than 90 seconds, making high-fidelity information replication impossible. More preferably, after incubation, 1xTAE-Mg is used... 2+ The buffer solution washes away excess DNA nanostructures.

[0013] Preferably, in step S3, TMAPS and TEOS are slowly added to the oscillating 1xTAE-Mg, respectively.2+ The solution is fully pre-hydrolyzed in the buffer solution to form a pre-hydrolyzed solution.

[0014] Preferably, in step S3, the volume percentage concentration of TMAPS or TEOS in the pre-hydrolyzed solution is 2% (V / V).

[0015] Preferably, in step S3, the pH value of the buffer solution is 8.

[0016] Preferably, in step S4, oxygen is introduced into the plasma etching machine and etching is performed at a power of 40-60W for 5-15 seconds.

[0017] Preferably, in step S5, hydrofluoric acid and formamide are used to remove the SiO2 shell and DNA nanostructure, respectively.

[0018] According to the graphene nanostructure preparation method of the present invention, a simple, efficient, and reproducible method for customizing graphene nanostructures is established based on a high-fidelity, chemically stable DNA-SiO2 hard template, using oxygen plasma etching to transfer the template pattern to graphene. Compared with existing nanofabrication techniques, it has the following advantages: the DNA-SiO2 template faithfully replicates the morphological information of the DNA nanostructure and has sufficient mechanical strength to resist oxygen plasma etching, giving it an advantage as a nanofabrication mask; by editing the morphology of the DNA nanostructure, graphene nanostructures of specific shapes, including monomers and arrays, can be customized; by designing the size of the DNA nanostructure, the nanofabrication precision can be controlled, achieving the preparation of graphene nanostructures with a high precision of 6.3 nm; the present invention also has advantages such as low cost, high throughput, and no need for large-scale equipment. In summary, the graphene nanostructure preparation method of the present invention, using nano-etching technology based on a DNA-SiO2 mask to prepare graphene nanostructures, solves the problem that existing graphene nanostructure preparation techniques cannot simultaneously meet the requirements of high precision, controllable morphology, low cost, and large-scale preparation. Attached Figure Description

[0019] Figure 1 This is a flowchart of the DNA-SiO2 nanoetching method according to a preferred embodiment of the present invention.

[0020] Figure 2 HS-AFM imaging shows the rapid adsorption of hydrolyzed clusters in solution onto DNA triangular origami.

[0021] Figure 3 This is a SEM image of a siliconized DNA triangle origami on graphene.

[0022] Figure 4The similarity distribution is shown under different incubation times, pH, and TMAPS+TEOS concentrations.

[0023] Figure 5 The Young's modulus of DNA nanostructures before and after siliconization is shown.

[0024] Figure 6 The images show the siliconized DNA nanostructure (SEM image), the nanostructure after plasma etching (SEM image), and the corresponding graphene nanostructure (TEM image). The scale bar in the SEM image is 200 nm, and the scale bar in the TEM image is 25 nm.

[0025] Figure 7 The results show a comparison of the morphological fidelity of semiconductor nanostructures obtained from DNA template-based semiconductor fabrication experiments to DNA templates. The references are: J. Am. Chem. Soc. 135, 6778-6781, (2013); J. Am. Chem. Soc. 135, 6778-6781, (2013); Chem. Mater. 27, 1692-1698, (2015); Science Advances 4, 8978 (2018); Nat. Commun. 4, 1663, (2013).

[0026] Figure 8 The statistical analysis of the characteristic dimensions of graphene nanostructures is shown.

[0027] Figure 9 These are XPS characterizations of the graphene samples after each etching step.

[0028] Figure 10 These are Raman characters of the graphene samples after each etching step. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto. The pharmaceuticals and reagents used in the embodiments can be purchased from chemical pharmaceutical companies or prepared by methods disclosed in the art.

[0030] like Figure 1 As shown, the graphene nanostructure preparation method according to the present invention is based on a DNA-SiO2 mask and is a DNA-SiO2 nano-etching method.

[0031] The method for preparing graphene nanostructures first involves transferring large monolayer graphene synthesized by chemical vapor deposition from copper foil to a SiO2 / Si substrate, followed by non-covalent modification of the graphene to increase its affinity for DNA nanostructures. The reagent used for non-covalent modification here is 1-pyrenemethylamine; however, it should be understood that other non-covalent modification reagents such as 1-pyrenecarboxylic acid and polylysine can also be used in this invention.

[0032] The method for preparing graphene nanostructures then includes synthesizing and purifying DNA nanostructures and spreading them onto a non-covalently modified graphene surface. The DNA nanostructures can be DNA monomer structures or DNA array structures. DNA monomer structures and DNA array structures include DNA triangular origami, DNA square origami, DNA circular origami, DNA bowtie structures, DNA honeycomb arrays, DNA three-point star arrays, and DNA box arrays. However, it should be understood that other morphologies of DNA monomers and periodic DNA arrays can also be used in this invention. The buffer solution used for synthesizing the DNA nanostructures is 1xTAE-Mg. 2+ The buffer solution contained 40 mM Tris, 20 mM acetate, 2 mM EDTA, and 12.5 mM magnesium acetate. Purification here refers to ultrafiltration. The ultrafiltration tube used had a molecular weight cutoff of 100 kDa, the centrifuge speed was 3000 rcf, the centrifugation time was 10 minutes, and the number of centrifugations was 3. Spreading here refers to incubating the DNA nanostructures onto the graphene surface. The incubation times were 1 min, 5 min, 10 min, and 30 min. Adjusting the incubation time of DNA on graphene can optimize and improve the morphological fidelity of the DNA-SiO2 mask.

[0033] The method for preparing graphene nanostructures then involves preparing a pre-hydrolysis solution using N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride (TMAPS) and tetraethyl orthosilicate (TEOS). DNA nanostructures spread on the graphene surface are then placed in the pre-hydrolysis solution for silanization, allowing a protective SiO2 shell to grow on the DNA surface, thereby preparing a DNA-SiO2 mask. The morphological fidelity of the DNA-SiO2 mask is optimized by adjusting the pH and concentration of the pre-hydrolysis solution. The pre-hydrolysis solution is prepared by slowly adding TMAPS and TEOS to a shaking 1xTAE-Mg solution. 2+ The solution is formed by thorough pre-hydrolysis in a buffer solution. The 1xTAE-Mg used to prepare the pre-hydrolyzed solution... 2+The pH values ​​of the buffer solutions were 6.5, 7.0, 7.5, 8.0, 8.5, and 9.0. The concentrations of the pre-hydrolyzed solution were 0.1% (V / V), 0.5% (V / V), 1% (V / V), 2% (V / V), 4% (V / V), and 8% (V / V). The DNA-SiO2 mask with the highest morphology fidelity was obtained when the incubation time was 1 min, the pH was 8.0, and the concentration was 2% (V / V). Here, morphology fidelity refers to the shape similarity between the source and target images calculated using a shape matching algorithm based on contour vectorization developed in this invention. The matching criteria are as follows: During matching, the contour point set is first discretized, making multiple sets of vectors linearly approximate the contour. The similarity of each corresponding vector in the source and target images is calculated using a weighted summation formula, and the average of the vector similarities is used to obtain the matching result. This invention uses a standard model of DNA nanostructures as the source image and a DNA-SiO2 mask as the target image, and then performs a matching operation in MATLAB software.

[0034] The method for preparing graphene nanostructures then involves using oxygen plasma etching to remove the graphene not covered by the DNA-SiO2 mask, thereby defining the spatial information of the final graphene nanostructure.

[0035] The final step in this graphene nanostructure preparation method involves removing a DNA-SiO2 mask to obtain the graphene nanostructure, ultimately transferring the spatial information of the DNA structure to the graphene. The removal of the DNA-SiO2 mask is achieved by using 2% hydrofluoric acid and 99.5% deionized formamide to remove the SiO2 shell and the DNA nanostructure, respectively.

[0036] When DNA nanostructures are in the form of DNA monomers, graphene monomer structures are obtained. A series of DNA monomer structures with different morphologies and sizes were designed and synthesized, and then siliconized to form DNA-SiO2 masks. Using graphene nanofabrication processes based on DNA-SiO2 masks, a series of monolayer graphene nanopatterns with customized shapes and characteristic dimensions were fabricated. The microstructure and properties (geometric morphology, characteristic dimensions, defects, etc.) of graphene were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS).

[0037] When DNA nanostructures are transformed into DNA array structures, graphene array structures are obtained. Large-scale DNA array structures with different periods and edge widths were designed and synthesized. These DNA array structures were then siliconized to form precise and stable large-scale mask templates. Using graphene nano-etching technology based on DNA-SiO2 mask templates, two-dimensional periodic array structures with sub-10 nanometer feature sizes were custom-fabricated. The graphene array structure and properties (morphology, size, defects, etc.) were characterized using AFM, SEM, TEM, XPS, and Raman spectroscopy.

[0038] Example 1

[0039] Fabrication of graphene interface high-fidelity DNA-SiO2 mask

[0040] Synthetic DNA triangular origami. This involves the controlled assembly of DNA structures using a common and well-established thermal denaturation technique: dissolving purchased DNA strands, and then mixing staple strands and scaffold strands in a 10:1 molar ratio in 1xTAE-Mg... 2+ The DNA was mixed in buffer to prepare a DNA triangular origami solution with a final concentration of 5 nM. The mixture was then annealed in a PCR instrument, where the DNA underwent both denaturation and annealing processes, ultimately forming the DNA triangular origami. The origami was purified using an ultrafiltration tube with a molecular weight cutoff of 100 kDa, and washed three times by centrifugation at 3000 rcf. Table 1 shows the annealing procedure for the self-assembly of the triangular origami structure (each step represents a temperature change of 1 °C):

[0041] Table 1

[0042] Temperature Time / step 90℃ 30 sec 86-71℃ 1 min / step 70-60℃ 10 min / step 59-30℃ 15 min / step 29-26℃ 10 min / step 25℃ 25 min 4℃ hold

[0043] Transferring a large monolayer graphene film to a SiO2 / Si substrate. The transfer steps are as follows: A layer of PMMA is spin-coated onto the graphene surface on a copper foil at 3000 rpm for 1 min. The surface is then heated to 120°C and dried for 10 min. The PMMA / graphene / copper foil is suspended in an ammonium persulfate solution, and the copper foil is etched away, leaving the PMMA / graphene suspended on the surface. The PMMA / graphene is washed three times with Milli-Q water, then the PMMA / graphene is removed from the solution using the SiO2 / Si substrate. The PMMA / graphene / SiO2 / Si substrate is then baked at 120°C for 30 min. Finally, the PMMA is removed with acetone, completing the transfer of graphene from the copper foil to the SiO2 / Si substrate.

[0044] DNA origami spreading on the graphene film surface. Graphene / SiO2 / Si was immersed in 1-pyrene methylamine solution for 30 min, then washed with ethanol and Milli-Q water, and dried with nitrogen. 5 μL of DNA origami was dropped onto the graphene surface and incubated for 1 min, 5 min, 10 min, and 30 min. Finally, 1xTAE-Mg was used for the spreading. 2+ Wash away excess DNA folds with buffer solution.

[0045] DNA origami was silanized on a graphene film. Various concentrations of TMAPs and TEOS (0.1% (V / V), 0.5% (V / V), 1% (V / V), 2% (V / V), 4% (V / V), and 8% (V / V)) were slowly added to a shaken 1xTAE-Mg film. 2+ Prepare pre-hydrolysis buffers in buffer solutions (pH = 6.5, 7.0, 7.5, 8.0, 8.5, 9.0). Add the prepared pre-hydrolysis buffers to suitable containers (glass dishes or centrifuge tubes). Place the graphene sample incubated with DNA origami in the pre-hydrolysis buffer and allow it to stand at room temperature for 16 hours for silanization. Then wash away excess reagents with Milli-Q water and dry with nitrogen gas.

[0046] Structural and property characterization of graphene interface DNA-SiO2 mask

[0047] In-situ reactions between DNA and hydrolyzed clusters were detected using fast atomic force microscopy (HS-AFM). Clusters were observed to rapidly attach to the DNA origami surface within seconds, and within less than one minute, the adsorbed clusters caused a significant increase in height, such as... Figure 2 As shown.

[0048] Images of the prepared DNA-SiO2 mask were obtained using SEM. The results showed that the morphology of the DNA structure after silanization after incubation on the graphene surface for 1 min maintained the original DNA structure. However, with prolonged incubation, the morphology underwent severe deformation, such as… Figure 3 As shown.

[0049] A shape matching algorithm based on contour vectorization was used to calculate the morphological matching degree between SEM images of DNA-SiO2 masks and ideal DNA structural models. The results showed that the highest morphological matching degree was obtained with pH = 8.0, TMAPS and TEOS concentrations of 2% (V / V), and an incubation time of 1 min, indicating that high-fidelity masks can be obtained under these conditions. Figure 4 As shown.

[0050] The side length, side width, and height of the mask, as determined by AFM characterization, were 123.7±3.0 nm, 27.9±2.1 nm, and 5.3±0.8 nm, respectively. Young's modulus analysis revealed that the DNA-SiO2 mask possessed higher mechanical stiffness than DNA origami, such as... Figure 5 As shown.

[0051] Example 2

[0052] Fabrication of graphene monolayer and array based on DNA-SiO2 mask

[0053] Synthesis of DNA monomers and array structures. The DNA monomer structures used included DNA triangular origami, DNA square origami, DNA circular origami, and DNA bowtie origami; the DNA array structures included DNA honeycomb arrays, DNA box arrays, and DNA three-point star arrays. Notably, the DNA origami structures (DNA triangular origami, DNA square origami, DNA circular origami, DNA bowtie origami, DNA honeycomb array, and DNA box array) were synthesized by using staple chains and scaffold chains at a molar ratio of 10:1 in 1xTAE-Mg 2+ The DNA is obtained by mixing in a buffer solution and then annealing the mixture in a PCR instrument. The synthesis of the DNA box array involves first preparing DNA box monomers A and B, then mixing A and B in a 1:1 molar ratio, and annealing the mixture for 7 days. The synthesis of the DNAtile structure (DNA three-point star array) involves mixing multiple short DNA strands in a specific molar ratio in a 1xTAE-Mg buffer solution. 2+ Mix in buffer, then anneal the prepared sample in a PCR instrument. The prepared DNA nanostructure solution is then ultrafiltered three times in an ultrafiltration tube (100 kDa MWCO) to remove excess DNA strands. Notably, DNA box arrays and DNA triangular arrays do not require ultrafiltration purification.

[0054] The spreading of DNA structures on the graphene surface. Graphene transferred to a SiO2 / Si substrate was immersed in 1-pyrene methylamine solution for 30 min, then removed and washed with ethanol and Milli-Q water, respectively, and dried with nitrogen. 5 μL of DNA structure solution was dropped onto the graphene and incubated (DNA monomers for 1 min, DNA arrays for 10 min), and then treated with 1xTAE-Mg... 2+ Wash away excess DNA folds with buffer solution.

[0055] Silicification of DNA structures on graphene surfaces. 2% (v / v) TMAPs and 2% (v / v) TEOS were slowly added to a shaken 1xTAE-Mg solution. 2+Pre-hydrolyze the sample in a buffer solution (pH = 8.0) to ensure thorough pre-hydrolysis. Add a suitable amount of the pre-hydrolyzed solution to a suitable container (glass dish or centrifuge tube). Place the graphene sample containing the DNA structure in the pre-hydrolyzed solution and incubate at room temperature for 16 hours. Wash away excess reagents with Milli-Q water and dry with nitrogen.

[0056] Oxygen plasma etching. The siliconized sample is placed in a plasma etching machine, and oxygen is introduced to etch at a power of 50W for 10 seconds. The DNA-SiO2 mask acts as a positive mask in the oxygen plasma etching process, protecting the graphene it covers from being etched, while the uncovered graphene is etched away.

[0057] Mask removal. The sample etched by oxygen plasma was placed in hydrofluoric acid to remove the SiO2 shell on the surface of the DNA structure. Then, the sample was immersed in formamide to remove the DNA structure on the graphene surface, finally exposing the graphene nanostructure covering the template.

[0058] Structural and property characterization of graphene monolayer and array

[0059] SEM and TEM were used to characterize the following structures: the silanized DNA monomers and arrays, the structure after plasma etching, and the graphene monomers and arrays obtained after mask removal. The results show that DNA-SiO2 replicates the geometric information of various DNA monomers and array structures and transfers it to graphene with high fidelity. Figure 6 As shown.

[0060] A shape matching algorithm was used to match SEM images of graphene nanostructures with corresponding DNA structure models. The average shape similarities obtained were 0.56±0.03 (graphene cubes), 0.54±0.06 (graphene triangles), and 0.57±0.05 (graphene rings). Compared with experimental work on semiconductor nanofabrication based on DNA templates reported in the literature, the graphene nanostructures obtained in this invention achieve the highest fidelity in replicating the morphology of DNA templates, such as... Figure 7 As shown.

[0061] By statistically analyzing the feature sizes of graphene nanostructures, the smallest feature size was found to be 6.3 nm, which exhibits higher precision than the EBL-patterned graphene reported in the literature. Figure 8 As shown.

[0062] XPS was used to detect changes in the chemical composition and compound states of graphene samples during etching. The obtained XPS spectra showed six main peaks: O 2s, Si 2p, Si 2s, C 1s, O 1s, and O KLL. After Tougaard-type inelastic background correction and fitting with a Gaussian-Lorentz function, the graphene sample exhibited the sharpest peak at the C=C bond, with smaller peaks at the CO, C=O, and OC=O bonds. The main peak at the C=C bond indicates that most C atoms are arranged in a honeycomb lattice. The weaker CO, C=O, and OC=O peaks are mainly attributed to partial oxidation of the graphene. Figure 9 As shown. a) XPS full-spectrum scanning of monolayer graphene on SiO2 / Si substrate (i), functionalized 1-pyrene methylamine (ii), deposited DNA nanostructure (iii), silanized DNA nanostructure (iv), plasma etching (v), and sample after mask removal (vi). b) Corresponding fine C1s spectral scanning. All C1s spectra were fitted with Gaussian-Lorentz functions after background subtraction.

[0063] Raman spectroscopy was used to detect electronic and structural changes in graphene samples during etching. The obtained Raman spectra showed three main characteristic peaks: D, G, and 2D. For graphene sheets transferred to a SiO2 / Si substrate, the G and 2D peaks exhibited symmetrical Lorentz shapes, indicating the high crystalline order of defect-free graphene. Graphene functionalized with 1-pyrene methylamine showed a peak density of 1237.0 cm⁻¹. -1 1390.3cm -1 and 1626.3cm -1 Three Raman peaks were introduced. After laying DNA nanostructures on graphene, silanizing, and plasma etching, the peak intensity ratio and full width at half maximum (FWHM) of the D and G peaks increased, indicating that the intact graphene was etched into small discrete crystallites, leading to the generation of numerous defects and the destruction of symmetry. Furthermore, the relationship between the peak positions of the D and G peaks and stress and doping revealed that the graphene sample was generally subjected to hole doping and compressive stress during the etching process. Figure 10 As shown. a, Raman characterization of monolayer graphene on SiO2 / Si substrate (i), functionalized 1-pyrene methylamine (ii), deposited DNA nanostructure (iii), silanized DNA nanostructure (iv), plasma etching (v), and sample after mask removal (vi). b, Fitting of corresponding D, G, and 2D peaks. Lorentz functions are fitted to all Raman peaks after background subtraction.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A method for preparing graphene nanostructures, characterized in that, The method for preparing this graphene nanostructure includes the following steps: S1 provides a DNA nanostructure and a graphene-based substrate, respectively; S2, non-covalent modification of graphene, spreads DNA nanostructures on the surface of the modified graphene. S3, by adding TMAPS and TEOS to a buffer solution with a pH value between 7.5 and 8.5 to pre-hydrolyze and form a pre-hydrolysate, wherein the volume percentage concentration of TMAPS and TEOS in the pre-hydrolysate is between 1% and 3%, respectively, the DNA nanostructure spread on the graphene surface is placed in the pre-hydrolysate for silanization, so that a protective SiO2 shell grows on the surface of the DNA nanostructure, thus obtaining a DNA-SiO2 mask; S4, using oxygen plasma etching to remove graphene not covered by the DNA-SiO2 mask; S5, the DNA-SiO2 mask is removed to obtain the graphene nanostructure.

2. The method for preparing graphene nanostructures according to claim 1, characterized in that, DNA nanostructures can be either DNA monomer structures or DNA array structures.

3. The method for preparing graphene nanostructures according to claim 1, characterized in that, In step S1, in 1xTAE-Mg 2+ DNA nanostructures were synthesized in a buffer solution and then purified by ultrafiltration.

4. The method for preparing graphene nanostructures according to claim 1, characterized in that, In step S1, a single layer of graphene is prepared on a copper foil; the single layer of graphene is transferred to a substrate to form a substrate with graphene.

5. The method for preparing graphene nanostructures according to claim 1, characterized in that, In step S2, non-covalent modification with 1-pyrene methylamine, 1-pyrene carboxylic acid, or polylysine is performed to increase the affinity between graphene and DNA nanostructures.

6. The method for preparing graphene nanostructures according to claim 1, characterized in that, In step S2, the DNA nanostructure is dropped onto the graphene surface and incubated for a period of 30-90 seconds.

7. The method for preparing graphene nanostructures according to claim 1, characterized in that, In step S3, the volume percentage concentrations of TMAPS and TEOS in the pre-hydrolyzed solution are both between 2%.

8. The method for preparing graphene nanostructures according to claim 1, characterized in that, In step S3, the pH of the buffer solution is 8.

9. The method for preparing graphene nanostructures according to claim 1, characterized in that, In step S4, oxygen is introduced into the plasma etching machine and etching is performed at a power of 40-60W for 5-15 seconds.

10. The method for preparing graphene nanostructures according to claim 1, characterized in that, In step S5, hydrofluoric acid and formamide are used to remove the SiO2 shell and DNA nanostructure, respectively.

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