CN109573991B - Method for preparing graphene arrays with different lattice point thicknesses by using composite metal template - Google Patents

Abstract

The invention relates to a method for preparing graphene arrays with different array point thicknesses by using a composite metal template, which comprises the steps of plating a nickel array on a copper foil by using a mask (or plating a copper array on a nickel foil), heating at high temperature to change the surface of the copper array into a copper-nickel alloy array, introducing a carbon source at the growth temperature of a CVD (chemical vapor deposition) process, growing the graphene array on the surface of a composite metal film during cooling, controlling the number of layers of graphene in different areas by using the composite metal film, preparing a high-quality graphene array with a thick middle edge and a thin middle edge or a graphene array with a thick middle edge, solving the problem that the thickness of each array point of the graphene array is uniform by using the conventional method, meeting the special requirements of applications such as an acceleration sensor and a pressure sensor on the graphene, and obtaining the high-quality graphene array.

Description

A method for preparing graphene arrays with different lattice point thicknesses using composite metal templates

technical field

The invention relates to a method for preparing graphene arrays with different lattice point thicknesses by using a composite metal template, and belongs to the technical field of graphene array preparation.

Background technique

Graphene is a new carbonaceous material composed of carbon atoms tightly packed into a two-dimensional honeycomb lattice structure. It has excellent electrical, optical, thermal and mechanical properties. It is expected to be used in high-performance nanoelectronic devices, composite materials, and field emission materials. It has been widely used in fields such as photodetectors, gas sensors and energy storage, and has broad application prospects in industry, power industry and electronics industry.

At present, the commonly used preparation methods of graphene single crystals mainly fall into two categories, one is chemical vapor deposition (CVD) method, and the other is high temperature SiC pyrolysis method. The chemical vapor deposition (CVD) method mainly uses metal as the substrate, uses carbon-containing compounds such as methane as the carbon source, and grows graphene by decomposing the carbon source on the surface of the substrate at high temperature. The CVD method is relatively simple in process and low in cost, and is one of the common methods for preparing graphene. Tang Jun et al. reported a method for growing graphene on 6H-SiC silicon surface. The equipment used is molecular beam epitaxy equipment. The method is to deposit a layer of silicon at 750 °C under vacuum, and then raise it to 1300 °C for epitaxy generation. Graphene (see Tang Jun et al., Effect of annealing time on the morphology and structure of epitaxial graphene on 6H-SiC(0001) surface, Acta Phys. Chem., 2010, 26(1), 253-258).

However, most of the graphene prepared by chemical vapor deposition is randomly nucleated and grown, and its spatial distribution is poorly controllable, resulting in large-sized single-layer and uniform multi-layer graphene, and it is difficult to prepare specific arrays Graphene. However, graphene-based electronic devices usually require arrayed graphene.

Chinese patent document 201210008150.8 discloses a method for preparing a controllable graphene array. Two silicon substrates with the same crystal orientation are used for small-angle bonding to form a square grid-shaped screw dislocation, and the stress distribution on the silicon surface is caused by the dislocation. Uneven, using stress selective etching to etch the vertical corresponding area affected by dislocation lines to form a square grid-shaped patterned silicon island, using electron epitaxy to form metal nanoparticles with segregation characteristics, and finally using chemical Graphene arrays were prepared by vapor deposition and segregation methods. However, the thickness of each lattice point of the graphene array prepared by this method is uniform, which cannot meet the needs of new acceleration sensors, pressure sensors, vector sensors and other applications: acceleration sensors and pressure sensors are widely used in military applications, and their sensing films require Breathable, light-transmitting, thin and thick-edge graphene film in the middle, while the vector sensor requires a graphene film with a thick middle and thin edge, rather than a thin and uniform graphene film material.

Therefore, it is necessary to establish a scientific and high-quality preparation method for graphene arrays whose center and edge layers can be controlled.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the present invention provides a method for preparing graphene arrays with different lattice point thicknesses by using a composite metal template.

Brief description of the invention:

In the present invention, a mask is used to coat a metal nickel array on a copper foil (or a metal copper array is plated on the nickel foil), and then heated at a high temperature to make the surface of the copper-nickel alloy array, and then at the growth temperature of the CVD process, carbon is introduced When the temperature is lowered, a graphene array is grown on the surface of the composite metal film. The composite metal film is used to control the number of graphene layers in different regions to prepare high-quality middle-thick-edge-thin graphene arrays or middle-thin-edge-thick graphene arrays. , which solves the problem that the thickness of each lattice point of the graphene array obtained by the existing method is uniform, and satisfies the special needs of the applications such as acceleration sensors and pressure sensors for graphene, and can obtain high-quality graphene arrays.

Terminology Explanation:

Optical reticle: A structure in which various functional patterns are created and precisely positioned on a film, plastic, or glass substrate for selective exposure of a photoresist coating.

Electroplating: The process of plating a thin layer of other metals on a metal surface using the principle of electrolysis.

Electron beam evaporation: The evaporation material is placed in a water-cooled crucible, and the evaporation material is vaporized and condensed on the substrate to form a thin film by direct heating of the electron beam.

Plasma sputtering: The rare gas is ionized into plasma by means of direct current or radio frequency, and then the target is bombarded by means of bias, so that the atoms on the target have enough ability to be detached and fall on the substrate to form a thin film.

Detailed description of the invention:

The present invention is achieved through the following technical solutions:

A method for preparing graphene arrays with different lattice point thicknesses by using a composite metal template, comprising the following steps:

(1) providing a metal foil, cleaning, removing surface impurities, and obtaining the metal foil after removing impurities;

(2) electroplating or depositing other metal arrays on the impurity-removed metal foil by electroplating or deposition to obtain a metal array substrate;

(3) Place the metal array substrate on the quartz boat sample stage of the CVD growth furnace, evacuate, heat up to 200-300°C, pass high-purity argon gas, control the pressure at 100-300mbar, and keep the temperature for 1-5min; then The temperature is raised to 550-650°C, high-purity hydrogen is introduced, the pressure is controlled at 100-300mbar, and the temperature is kept for 10-60min, and the composite metal array substrate is obtained after annealing;

(4) The obtained composite metal array substrate is continuously heated to 1000-1100° C. and kept for 10-60 minutes; then high-purity carbon source gas is introduced, the pressure is controlled at 100-300 mbar, and the graphene array is grown for 5-60 minutes at a temperature of 5-60 minutes. After completion, turn off the carbon source gas, continue to pass high-purity argon gas, control the pressure at 100-300mbar, pull the heating zone to the other side, quickly cool down to 500-600°C, and then naturally cool down to room temperature, and place a lining on the composite metal array. Graphene arrays are grown on the bottom surface;

(5) removing the composite metal from the composite metal substrate of the graphene array obtained in step (4) or separating the graphene from the substrate, cleaning and drying to obtain graphene arrays with different lattice point thicknesses.

Preferably in the present invention, in step (1), the metal foil is nickel foil, copper foil, platinum foil, iron foil, cobalt foil; the thickness of the metal foil is 0.010mm-0.10mm, and the purity is >99.9%; the The cleaning is to ultrasonically clean the metal foil with deionized water and absolute ethanol in sequence.

Preferably in the present invention, in step (2), the other metal arrays are copper arrays or nickel arrays, which is different from the metal of the metal foil in step (1), when the metal foil in step (1) is nickel foil, step ( In 2), the other metal arrays are copper arrays; when the metal foils in step (1) are copper foils, the other metal arrays in step (2) are nickel arrays.

Preferably in the present invention, in step (2), the metal array substrate is obtained in one of the following two ways:

a. Cover the metal foil with a metal porous mask, the holes on the metal porous mask are circular holes, and electroplating or deposit a layer of other metals on the metal porous mask by electroplating or deposition, and remove the metal Porous mask, metal arrays of other metals are obtained on the metal foil, and the diameter of the metal array dots is 10-500 μm;

b. Paste an optical mask on the upper surface of the metal foil, expose the optical mask, the holes on the optical mask are circular holes, remove the glue at the exposure point, and use electroplating or deposition at the exposure point A layer of other metals is electroplated or deposited on the metal porous mask, and the remaining glue is removed to obtain metal arrays of other metals on the metal foil, and the diameter of the metal array dots is 10-500 μm.

Further preferably, in step (2), the diameter of the holes on the mask plate is 100-500 μm, the thickness of the array dots of the metal array is 10 nm-800 nm, and the mass ratio of the total mass of the array dots to the metal foil is 1:10- 1:5000.

Preferably, the diameter of the holes on the mask is 200-500 μm, the thickness of the array dots of the metal array is 200 nm-400 nm, and the mass ratio of the total mass of the array dots to the metal foil is 1:500-1:2000.

The spacing of the holes on the porous mask plate is determined according to requirements, and the spacing used in the present invention is 1-5 mm.

Preferably in the present invention, in step (2), the electroplating is an anode of an electrochemical workstation for metal foil, which is placed in other metal salt solutions, and a copper sheet is used as a cathode, and a layer of other metal arrays is electroplated on the metal foil.

Preferably in the present invention, in step (2), the deposition is deposition by electron beam evaporation or plasma sputtering.

Preferably in the present invention, in step (3), the vacuum degree of evacuation is 10 ^-4 to 10 ^-6 Pa, the heating rate to 200-300°C is 5-20°C/min, and the flow rate of high-purity argon is It is 10-100sccm; the heating rate to 550-650℃ is 5-20℃/min, and the flow rate of high-purity hydrogen is 4-20sccm; high-purity argon and high-purity hydrogen are greater than or equal to 5N argon, greater than or equal to 5N hydrogen.

Preferably in the present invention, in step (4), the temperature rising rate to 1000-1100°C is 1-10°C/min, the flow rate of the high-purity carbon source gas is 1-20sccm, and the high-purity carbon source gas It is methane or propane gas greater than or equal to; after the growth is completed, the flow rate of high-purity argon gas is 10-100sccm, and the rapid cooling rate is 120-240℃/min.

Preferably of the present invention, in step (5), remove the composite metal or separate the graphene from the substrate and adopt one of the following methods to carry out:

e. Add 1% polymethyl methacrylate solution dropwise to the composite metal of the grown graphene array, spin off the glue and dry it, and then put the sample into 1 mol/L FeCl ₃ and nitric acid (FeCl ₃ and nitric acid) The mass ratio is 1:1) in the mixed solution, soaked for 2h-10h to remove the composite metal; take out the graphene array with a glass slide and put it into deionized water, clean it, take it out with a silicon wafer, and dry it; repeatedly use The PMMA was removed by hot acetone, and finally washed with deionized water and ethanol, and finally dried with a nitrogen gun.

f. Add 1% polymethyl methacrylate solution dropwise to the composite metal of the grown graphene array, spin off the glue and dry it, take the composite metal foil as the anode of the electrochemical workstation, put it in the salt solution, and use copper The sheet was used as a cathode, and the composite metal and the graphene array were separated by bubbling; the graphene array was pulled out with a glass slide into deionized water, cleaned, and then pulled out with a silicon wafer, and dried; the PMMA was repeatedly removed with hot acetone , and finally washed with deionized water and ethanol respectively, and finally dried with a nitrogen gun.

g. Put the composite metal of the grown graphene array into a mixed solution of 1 mol/L FeCl ₃ and nitric acid (the mass ratio of FeCl ₃ and nitric acid is 1:1), soak for 2h-10h, and remove the composite metal; use a glass slide The graphene array was taken out of the sheet into deionized water. After cleaning, the substrates of the pressure and acceleration sensors were taken out, and dried. Finally, they were cleaned with deionized water and alcohol respectively, and finally dried with a nitrogen gun.

In the preparation method of the present invention, step (4) is evacuated and heated to 200-300° C. to pre-bake the composite metal and the interior of the reaction chamber, so that the gas adsorbed on the surface of the composite metal and the interior of the chamber is desorbed and discharged. cavity to reduce the residual oxygen content in the cavity and further improve the vacuum degree.

All raw materials in the method of the present invention are commercially available products. For the parts that are not particularly limited, reference can be made to the prior art.

Since the present invention adopts nickel/copper foil as the substrate, its production cost is very low, and there are many specifications on the market.

The nickel/copper foil used in the present invention has no damage layer after ultrasonic cleaning and annealing treatment, and undergoes hydrogen etching treatment in the subsequent step (4) heating process, and the surface is very smooth.

The technical characteristics and excellent effects of the present invention are:

1. In the preparation method of the present invention, a mask is used to coat a metal nickel array on a copper foil (or a metal copper array on the nickel foil), and then heated at a high temperature to make the surface become a copper-nickel alloy array, which can induce the growth of the graphene array. Then, at the growth temperature of the CVD process, a carbon source is introduced, and a graphene array is grown on the surface of the composite metal film when the temperature is lowered. The composite metal film is used to control the number of graphene layers in different regions to prepare high-quality The middle thick edge thin graphene array or the middle thin edge thick graphene array solves the problem that the thickness of each lattice point of the graphene array obtained by the existing method is uniform, and satisfies the special needs for graphene in applications such as acceleration sensors and pressure sensors. , high-quality graphene arrays can be obtained.

2. Compared with the traditional graphene array preparation method, the present invention has high graphene coverage at each lattice point, the graphene array is more controllable, and the number of layers in different regions is more controllable; this method can also solve the traditional graphene preparation method. Graphene has the problem that the number of layers in different regions is difficult to control, which satisfies the special needs of graphene for applications such as acceleration sensors and pressure sensors, and can obtain high-quality graphene arrays.

3. The present invention obtains a high-quality middle-thick-edge-thin graphene array or a middle-thin-edge-thick graphene array by combining the hole diameter on the mask plate with the thickness of the array point of the metal array and the growth method.

4. The present invention controls the number of layers of graphene by precisely controlling the temperature and the heating and cooling rate, and using the intelligent composite metal array on the surface of the metal foil alloy (by controlling the different thicknesses of the copper and nickel arrays) to adjust the composition of the composite metal array; It solves the problem that the number of layers in different regions of graphene is difficult to control.

Description of drawings

FIG. 1 is a schematic diagram of the present invention plating a copper array on a nickel foil to prepare a thin-edge-thick graphene array in the middle.

FIG. 2 is a schematic diagram of the present invention plating a nickel array on a copper foil to prepare a thin-edge-thick graphene array in the middle.

FIG. 3 is an SEM image of the graphene arrays grown in Example 1 and Example 2. FIG. a is the SEM image of the graphene array of Example 1, and b is the SEM image of the graphene array of Example 2.

FIG. 4 is the XRD pattern of the graphene array grown in Example 1. FIG. The test point is area 3 in Figure 3a.

FIG. 5 is the Raman spectra of graphene arrays grown at different positions in Example 1. FIG. The abscissa is the Raman shift (cm ⁻¹ ), and the ordinate is the intensity (au). Regions 1, 2, and 3 are regions 1, 2, and 3 in Fig. 3a.

Detailed ways

The present invention will be further described below in conjunction with the embodiments, but not limited thereto.

The slide rail tube type CVD growth furnace used in the embodiment is Hefei Kejing OTF-1200 type CVD furnace, the heating rate can reach 30°C/min, and the cooling rate can reach 300°C/min at the fastest.

The copper foil and nickel foil used are commercially available products, thickness: 0.010mm-0.1mm, and purity >99.9%.

Example 1:

A method for preparing graphene arrays with different lattice point thicknesses by using a composite metal template, comprising the following steps:

(1) the nickel foil with a size of 1 square centimeter is ultrasonically cleaned with deionized water and absolute ethanol successively to remove impurities on the surface of the nickel foil;

(2) Apply glue on the nickel foil cleaned in step (1), expose under the optical mask, wash off the glue at the exposure point, as the anode of the electrochemical workstation, put it into a 1 mol/L CuCl ₂ solution, with The copper sheet was used as the cathode, reacted at room temperature for 20 minutes, electroplated a layer of copper array on the nickel foil, removed the excess glue, and obtained a copper metal array substrate.

(3) placing the nickel-copper composite metal array substrate in step (2) on the quartz boat sample stage of the slide rail tubular CVD growth furnace; the tubular CVD growth furnace is evacuated to 10 ^-4 Pa with a mechanical pump and a molecular pump , heat up to 200 °C, the heating rate is 20 °C/min, pass high-purity argon gas, the flow rate is 20sccm, the pressure is controlled at 100-300 mbar, and the temperature is maintained for 5 minutes; then heat up to 550 °C, the heating rate is 20 °C/min, Enter hydrogen at a flow rate of 10 sccm, control the pressure at 100-300 mbar, and keep the temperature at 10 min; then heat up to 1100 ° C, the heating rate is 10 ° C/min, and keep the temperature for 20 min; Keep warm for 20min;

After the growth is completed, turn off the carbon source gas, continue to pass argon gas, the flow rate is 30sccm, the pressure is controlled at 100-300mbar, the heating range is pulled to the other side, and the temperature is quickly cooled to 600 °C, and the cooling rate can reach 120-240 °C/min ; Then the temperature is naturally cooled to room temperature, and a graphene array with a thin middle and a thick edge is grown on the surface of the nickel-copper composite metal array substrate;

(4) drop 1% PMMA solution on the composite metal of the graphene array grown in step (3), spin off the glue and dry, and then put the sample into 1 mol/L FeCl ₃ and nitric acid (1:1) In the mixed solution, treat for more than 2 hours to remove the composite metal; remove the graphene array with a glass slide into deionized water, clean it, remove it with a silicon wafer, and dry it; remove the PMMA with repeated hot acetone, and finally remove it separately. Ionized water and alcohol were used for cleaning, and finally dried with a nitrogen gun; a graphene array with thin edges and thick edges was obtained.

Example 2:

A method for preparing graphene arrays with different lattice point thicknesses by using a composite metal template, comprising the following steps:

(1) The copper foil with a size of 1 square centimeter is ultrasonically cleaned with deionized water and anhydrous alcohol in turn to remove impurities on the surface of the copper foil;

(2) Apply glue to the copper foil cleaned in step (1), expose under the optical mask, wash off the glue at the exposure point, use electron beam evaporation to deposit 200nm nickel, remove the excess glue, and obtain a nickel metal array lining At the bottom, the diameter of metal array dots is about 300μm, the thickness is 300nm, and the spacing is 2mm;

(3) placing the copper-nickel composite metal array substrate in step (2) on the quartz boat sample stage of the slide-rail tubular CVD growth furnace; the tubular CVD growth furnace is evacuated to 10 ^-4 with a mechanical pump and a molecular pump Pa, heat up to 200 °C, the heating rate is 20 °C/min, high-purity argon gas is introduced, the flow rate is 20sccm, the pressure is controlled at 100-300 mbar, and the temperature is maintained for 10 minutes; Introduce hydrogen at a flow rate of 10sccm, control the pressure at 100-300mbar, and keep the temperature at 10min; then heat up to 1050°C, with a heating rate of 10°C/min, and keep the temperature for 20min; feed methane gas, the flow rate is 10sccm, and the pressure is controlled at 100-300mbar , keep warm for 30min;

After the growth is completed, turn off the carbon source gas, continue to pass argon gas, the flow rate is 30sccm, the pressure is controlled at 100-300mbar, the heating range is pulled to the other side, and the temperature is quickly cooled to 600 °C, and the cooling rate can reach 120-240 °C/min ; Then the temperature is naturally cooled to room temperature, and a graphene array with a thick middle and a thin edge is grown on the surface of the copper-nickel composite metal array substrate;

(4) drop 1% PMMA solution on the composite metal of the graphene array grown in step (3), spin off the glue and dry it, take the composite metal foil as the anode of the electrochemical workstation, put it into the salt solution, and use The copper sheet is used as the cathode, and the composite metal and the graphene array are separated by the bubbling method; the graphene array is taken out with a glass slide into deionized water, cleaned, and then taken out with a silicon wafer, and dried; with repeated hot acetone The PMMA was removed, washed with deionized water and alcohol, and finally dried with a nitrogen gun to obtain a graphene array with a thick middle and a thin edge.

Example 3:

A method for preparing graphene arrays with different lattice point thicknesses by using a composite metal template, comprising the following steps:

(1) The copper foil with a size of 1 square centimeter is ultrasonically cleaned with deionized water and anhydrous alcohol in turn to remove impurities on the surface of the copper foil;

(2) paste a metal porous mask on the copper foil cleaned in step (1), and deposit 300nm nickel by electron beam evaporation or plasma sputtering to obtain a nickel metal array substrate, and the diameter of the metal array spot is about 500 μm, The thickness is 300nm and the spacing is 2mm;

(3) placing the copper-nickel composite metal array substrate in step (2) on the quartz boat sample stage of the slide-rail tubular CVD growth furnace; the tubular CVD growth furnace is evacuated to 10 ^-4 with a mechanical pump and a molecular pump Pa, heat up to 200 °C, the heating rate is 20 °C/min, high-purity argon gas is introduced, the flow rate is 20sccm, the pressure is controlled at 100-300 mbar, and the temperature is maintained for 10 minutes; Introduce hydrogen at a flow rate of 10sccm, control the pressure at 100-300mbar, and keep the temperature at 10min; then heat up to 1030°C, the heating rate is 10°C/min, and keep the temperature for 20min; feed methane gas, the flow rate is 10sccm, and the pressure is controlled at 100-300mbar , keep warm for 60min;

After the growth is completed, turn off the carbon source gas, continue to pass argon gas, the flow rate is 30sccm, the pressure is controlled at 100-300mbar, the heating range is pulled to the other side, and the temperature is quickly cooled to 600 °C, and the cooling rate can reach 120-240 °C/min ; Then the temperature is naturally cooled to room temperature, and a graphene array with a thick middle and a thin edge is grown on the surface of the copper-nickel composite metal array substrate;

(4) Put the composite metal on which the graphene array is grown in step (3) into a mixed solution of 1 mol/L FeCl ₃ and nitric acid (1:1), and treat for more than 2 hours to remove the composite metal; take out the graphite with a glass slide The graphene array is placed in deionized water, cleaned, and then taken out with pressure, acceleration and other sensor substrates, and dried; finally cleaned with deionized water and alcohol, and finally dried with a nitrogen gun; the graphene with thick edges and thin edges is obtained. array.

Experimental example:

A detection experiment was carried out on the products of the above-mentioned Examples 1-3.

The SEM images of the graphene arrays grown in Examples 1 and 2 are shown in FIG. 3 : in FIG. 3 a is the SEM image of the graphene array of Example 1, and b is the SEM image of the graphene array of Example 2. From the SEM image of Example 1, it can be seen that the first area is the copper foil substrate is single-layer graphene, and the second and third areas are graphene arrays. It can be seen that the number of layers becomes thicker, and the third area is the thickest (the Raman in Figure 5). The figure also proves that the copper foil substrate is single-layer graphene in region one, and the thickest region three is), so the present invention successfully forms a graphene array with a thick middle and a thin edge, and the size of a single array can reach 200-300 μm; Example The SEM of 2 in Figure 3b shows that the outer area is nickel foil and the substrate is multi-layer graphene, and the central area is a graphene array. It can be seen that the number of layers becomes thinner, forming a graphene array with thin edges and thick edges. The size of a single array can be up to 300 μm. The graphene arrays are of good quality.

The XRD pattern of the graphene array grown by the steps described in Example 1 is shown in FIG. 4 . From the above Figure 4, the XRD pattern of the graphene array sample grown in Example 1, compared with the nickel foil, at 25o-30o, there is an obvious protrusion, which is the diffraction peak of the aggregated carbon, indicating that there are graphene generated; Examples 2-3 were similar.

The Raman spectra of different positions of the graphene array obtained by the steps described in Example 1 are shown in FIG. 5 .

From the above-mentioned Figure 5, the Raman characteristic peaks 2D peaks and _G peaks of the three regions of the graphene array obtained by the growth of Example 1 are very obvious. _2D = 0.35-2) and the value of the 2D peak width at half maximum FWHM, the number of layers of graphene grown in three regions is 1, 3, and 5 layers, forming a graphene array with thick middle and thin edges and high quality. The corresponding formula between the width at half maximum and the number of layers: FWHM=(-45×(1/n))+88 (n is the number of graphene layers).

Comparative Test:

Using the method of the invention, using _CH4 or _C3H8 external carbon source and different ratios of mixed gas to prepare graphene arrays, similar results were obtained (the results of ₄ and 5 in Table 1 are similar). Table 1 shows the results of preparing graphene arrays under different conditions. The comparison shows that under the same conditions, the number of graphene layers prepared by traditional CVD method is single-layer or uniform multi-layer, while the graphene arrays are prepared by using composite metal template. The new method quality of middle-thin-edge-thick and middle-thick-edge-thin graphene arrays demonstrates that in the growth of graphene, copper-nickel composite metal assisted control of the external carbon source makes the growth easier to control. Therefore, the difficult-to-control problems in the preparation of graphene arrays by traditional CVD methods are expected to be significantly improved, and the performance of the corresponding graphene arrays is also expected to be significantly improved.

Table 1. Comparison of the results of growing graphene arrays under different conditions.

To sum up, the novel method for preparing graphene arrays using the composite metal template of the present invention can prepare high-quality middle-thin-edge-thick and middle-thick-edge-thin graphene arrays on commercially available nickel foils (copper foils). Compared with the traditional preparation of graphene arrays, this method has significant advantages.

Claims (4)

1. A method for preparing graphene arrays with different lattice point thicknesses by using a composite metal template comprises the following steps:

(1) providing a metal foil, cleaning, and removing surface impurities to obtain an impurity-removed metal foil;

(2) electroplating or depositing other metal arrays on the metal foil after impurity removal in an electroplating or depositing mode to obtain a metal array substrate; the other metal arrays are copper arrays or nickel arrays, and are different from the metal of the metal foil in the step (1), when the metal foil in the step (1) is nickel foil, the other metal arrays in the step (2) are copper arrays; when the metal foil in the step (1) is copper foil, the other metal arrays in the step (2) are nickel arrays;

the metal array substrate is specifically obtained in one of two ways:

a. covering a metal foil with a metal porous mask plate, wherein the holes on the metal porous mask plate are circular holes, electroplating or depositing a layer of other metal on the metal porous mask plate by adopting an electroplating or depositing mode, removing the metal porous mask plate, and obtaining a metal array of other metals on the metal foil, wherein the diameter of a metal array point is 10-500 mu m; the diameter of the hole on the mask plate is 200-500 mu m, the thickness of the array point of the metal array is 200-400 nm, and the mass ratio of the total mass of the array point to the metal foil is 1:500-1: 2000;

b. adhering an optical mask plate on the upper surface of the metal foil, exposing the optical mask plate, wherein holes on the optical mask plate are circular holes, removing glue at exposure points, electroplating or depositing a layer of other metal on the metal porous mask plate at the exposure points in an electroplating or depositing mode, removing the rest glue, and obtaining a metal array of the other metal on the metal foil, wherein the diameter of the metal array points is 10-500 mu m; the diameter of the hole on the mask plate is 200-500 mu m, the thickness of the array point of the metal array is 200-400 nm, and the mass ratio of the total mass of the array point to the metal foil is 1:500-1: 2000;

(3) placing the metal array substrate on a quartz boat sample table of a CVD growth furnace, vacuumizing, heating to 200-; then heating to 550-650 ℃, introducing high-purity hydrogen, controlling the pressure at 100-300mbar, preserving the heat for 10-60min, and annealing to obtain a composite metal array substrate; the vacuum degree of the vacuum pumping is 10^-4～10^-6Pa, the heating rate of heating to 200-300 ℃ is 5-20 ℃/min, and the flow of the high-purity argon is 10-100 sccm; the temperature rise rate is 5-20 ℃/min when the temperature rises to 550-650 ℃, and the flow of the high-purity hydrogen is 4-20 sccm; the high-purity argon and the high-purity hydrogen are argon with the purity of more than or equal to 5N and hydrogen with the purity of more than or equal to 5N;

(4) the obtained composite metal array substrate is continuously heated to 1000-1100 ℃, and the temperature is kept for 10-60 min; then introducing high-purity carbon source gas, controlling the pressure at 300mbar for 100-; the heating rate is 1-10 ℃/min when the temperature is increased to 1000-1100 ℃, the flow of the high-purity carbon source gas is 1-20sccm, and the high-purity carbon source gas is methane or propane gas; after the growth is finished, introducing high-purity argon at a flow rate of 10-100sccm, and rapidly cooling at a rate of 120-;

(5) and (4) removing composite metal from the composite metal substrate of the graphene array obtained in the step (4) or separating the graphene from the substrate, and cleaning and drying to obtain the graphene array with different lattice point thicknesses.

2. The method for preparing graphene arrays with different lattice thicknesses by using a composite metal template according to claim 1, wherein in the step (1), the thickness of the metal foil is 0.010mm-0.10mm, and the purity is more than 99.9%; the cleaning is to perform ultrasonic cleaning on the metal foil by using deionized water and absolute ethyl alcohol in sequence.

3. The method for preparing graphene arrays with different lattice point thicknesses by using the composite metal template as claimed in claim 1, wherein in the step (2), the electroplating is to use an anode of an electrochemical workstation for the metal foil, put the metal foil into other metal salt solution, use a copper sheet as a cathode, and electroplate a layer of other metal arrays on the metal foil; the deposition is electron beam evaporation or plasma sputtering deposition.

4. The method for preparing graphene arrays with different lattice thicknesses by using a composite metal template as claimed in claim 1, wherein the step (5) of removing the composite metal or separating the graphene from the substrate is performed by using one of the following methods:

e. dripping 1% polymethyl methacrylate solution on the composite metal with the graphene array grown, whirl coating and drying, and then putting the sample into 1mol/L FeCl₃Soaking in mixed solution of nitric acid for 2-10 h, and adding FeCl in the mixed solution₃Removing the composite metal with the mass ratio of nitric acid being 1: 1; fishing out the graphene array into deionized water by using a glass slide, cleaning the graphene array, fishing out the graphene array by using a silicon wafer, and drying the graphene array; removing PMMA by using hot acetone repeatedly, and finally respectively removing ionsWashing with water and ethanol, and blow-drying with a nitrogen gun;

f. dripping 1% polymethyl methacrylate solution on the composite metal with the graphene array grown, spinning and drying, putting the composite metal foil as an anode of an electrochemical workstation into a salt solution, taking a copper sheet as a cathode, and separating the composite metal from the graphene array by a bubbling method; fishing out the graphene array into deionized water by using a glass slide, cleaning the graphene array, fishing out the graphene array by using a silicon wafer, and drying the graphene array; repeatedly using hot acetone to remove PMMA, finally respectively cleaning with deionized water and ethanol, and finally drying with a nitrogen gun;

g. putting the composite metal of the grown graphene array into 1mol/L FeCl₃Soaking in mixed solution of nitric acid for 2-10 h, and adding FeCl in the mixed solution₃Removing the composite metal with the mass ratio of nitric acid being 1: 1; fishing out the graphene array into deionized water by using a glass slide, cleaning, fishing out by using a pressure and acceleration sensor substrate, and drying; and finally, respectively cleaning with deionized water and alcohol, and finally drying with a nitrogen gun.

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