CN102092710A - Regular graphene and preparation method thereof - Google Patents

Abstract

The invention discloses graphene with a regular shape and a preparation method thereof. The graphene with a regular shape is prepared by the chemical vapor deposition method and comprises the following steps: placing a metal foil or a substrate with a metal catalyst in a reactor without oxygen and water to ensure that the temperature of the metal foil or the substrate reaches 800-1050 DEG C, and then introducing a carbon source in the reactor to react and obtain the graphene with a regular shape. The obtained graphene in the invention has an equiangular hexagonal structure; and the method in the invention is convenient to operate, is simple and practical and can be used in mass production.

Description

A kind of regular graphene and preparation method thereof

technical field

The invention relates to a regular graphene and a preparation method thereof.

Background technique

Graphene, that is, the monoatomic layer of graphite, is a two-dimensional structure in which carbon atoms are arranged in a honeycomb shape, and is also the basic unit of other low-dimensional carbon materials such as fullerenes and carbon nanotubes. According to the number of layers, graphene can be divided into single-layer graphene, double-layer graphene, and few-layer graphene. Graphene has been studied for a long time, but the truly independent and stable graphene was obtained by Geim et al. from the University of Manchester in the United Kingdom by stripping highly oriented graphite through adhesive tape. Since the discovery of graphene, due to its excellent performance and huge application prospects, it has triggered a research boom in the fields of physics and material science. However, the problem of controllable synthesis of graphene materials with specific functions and applications remains unsolved. These issues include large-area graphene with a controllable layer number, patterning, lattice perfection of graphene, and graphene with regular geometries. Material. For these reasons, graphene research remains in the realm of basic research. At present, the main methods for preparing graphene are mechanical exfoliation of graphite (Novoselov, K.S.; Geim, A.K.; Morozov, S.V.; Jiang, D.; Zhang, Y.; Dubonos, S.V.; Grigorieva, I.V.; Firsov, A.A., Science 2004 , 306, 666), epitaxial growth (C.Berger, Z.M.Song, Science 2006, 312, 1191), graphite oxidation and reduction method (McAllister, M.J.; Li, J., Adamson, D.H.; Schniepp, H.C.; Abdala, A.A , Liu, J.; Herrera-Alonso, M.; Milius, D.L.; Car, R.; Prudhomme, R.K.; Aksay, I.A., Chem.Mater.2007, 19, 4396) and chemical vapor deposition methods (Li, X.S.; Cai, W.W.; An, J.; Kim, S.; Nah, J.; Yang, D.; Piner, R.; L.; Ruoff, R.S. Science 2009, 324, 1312-1314.). However, how to synthesize graphene with regular geometric boundaries in a large-scale and controllable manner has never been discovered and reported.

Chemical vapor deposition is one of the most commonly used deposition techniques in the semiconductor industry. The principle of this method is to use various energy sources such as heating, plasma excitation or light radiation to chemically react gaseous or vaporous chemical substances in the gas phase or gas-solid interface to form solid-state deposition in the reactor. technology of things.

Contents of the invention

The purpose of the present invention is to provide a method for preparing graphene with regular morphology.

The graphene with regular morphology provided by the present invention is prepared by chemical vapor deposition according to the method comprising the following steps: putting metal foil or a substrate with a metal catalyst into an oxygen-free and water-free reactor , making the temperature of the metal foil or the substrate reach 800-1050° C. (preferably 900-1050° C.), and then introducing a carbon source into the reactor for reaction to obtain graphene with regular morphology.

The metal foil can be purchased directly. The substrate with the metal catalyst can be prepared according to existing methods, such as the metal can be deposited on the substrate by any one of the following six methods to obtain the substrate with the metal catalyst: chemical vapor deposition, physical Vapor deposition, vacuum thermal evaporation, magnetron sputtering, plasma enhanced chemical vapor deposition, electroplating and printing.

Wherein, the metal may be one of copper, gold, silver, nickel, cobalt and iron or any combination thereof.

The carbon source can specifically be one or any combination of methane, carbon monoxide, methanol, acetylene, ethanol, benzene, toluene, cyclohexane and phthalocyanine.

The graphene with regular morphology provided by the present invention is graphene with hexagonal structure.

The flow rate of the carbon source is 5-100 sccm; in order to obtain graphene with an ideal equiangular hexagonal structure, the flow rate of the carbon source is preferably 5-20 sccm. The reaction time of the reaction is 0.5-1000 minutes, preferably 20-60 minutes. Generally speaking, the growth rate of this equilateral hexagonal graphene along the diagonal direction is in the range of 100-200 nm/min, and its final size depends on the reaction time.

The above method also includes a step of purifying the prepared graphene to remove the metal catalyst.

When iron, cobalt, and nickel are used as catalysts in the preparation process, they can be removed by acid solution (such as hydrochloric acid, sulfuric acid, nitric acid, etc.); The catalyst is removed by its displacement reaction with a salt solution (such as ferric nitrate, ferric chloride, etc.).

The invention prepares the graphene with the regular shape through the chemical vapor deposition method, and the method is easy to operate, simple and feasible, and can be used for large-scale production.

Description of drawings

Fig. 1 is a schematic diagram of a chemical vapor deposition device, wherein, 1 is a metal foil or a substrate with a metal catalyst, 2 is a tube furnace, and 3 is a quartz tube.

2 is a scanning electron micrograph of regular graphene deposited on a copper surface by chemical vapor deposition in Example 1.

Fig. 3 is the Raman spectrum of depositing regular graphene on copper surface by chemical vapor deposition method in embodiment 1

4 is an atomic force microscope photo of regular graphene deposited on a copper surface by chemical vapor deposition in Example 1.

FIG. 5 is a scanning electron micrograph of regular graphene after removing copper in Example 1. FIG.

6 is a transmission electron microscope and a selected area electron diffraction photo of regular graphene after removing copper in Example 1.

FIG. 7 is a scanning electron micrograph of regular graphene deposited on a copper surface by chemical vapor deposition in Example 2. FIG.

FIG. 8 is a scanning electron micrograph of regular graphene deposited on a copper surface by chemical vapor deposition in Example 3. FIG.

FIG. 9 is a scanning electron micrograph of regular graphene deposited on a copper surface by chemical vapor deposition in Example 4. FIG.

Detailed ways

The method of the present invention will be described below through specific examples, but the present invention is not limited thereto.

The experimental methods described in the following examples, unless otherwise specified, are conventional methods; the reagents and materials, unless otherwise specified, can be obtained from commercial sources.

The present invention is described in detail below in conjunction with accompanying drawing:

The first step, the preparation of catalyst:

The substrate is ultrasonically cleaned with deionized water, ethanol, and acetone in sequence, and then oven-dried, and then processed by chemical vapor deposition, physical vapor deposition, vacuum thermal evaporation, magnetron sputtering, plasma-enhanced chemical vapor deposition, electrochemical method or Deposition techniques such as printing deposit a layer of metal on the substrate surface, or directly use commercial metal foils (such as gold, silver, copper, iron, cobalt, nickel, etc.) as catalysts.

The second step, the vapor deposition device is shown in Figure 1. Place the metal-deposited substrate or metal foil in the middle of a clean quartz tube, and put the quartz tube into the electric furnace so that the middle of the quartz tube is just in the center of the electric furnace. area. First use a mechanical pump to pump out the air and moisture in the quartz tube, then pass 100-2000 sccm non-oxidizing gas (such as hydrogen, argon, etc.) into the quartz tube for 1-1000 minutes, then start heating;

Step 3: When the temperature in the central area of the electric furnace reaches 800-1050°C, feed carbonaceous substances (such as carbon monoxide, methane, acetylene, ethanol, benzene, toluene, cyclohexane, phthalocyanine, etc.) into the non-oxidizing gas As a carbon source, the reaction begins, and carbon is deposited on the surface of the catalyst to form graphene;

The fourth step, after the reaction has been carried out for 0.5 to 1000 minutes, stop feeding the carbon-containing compound, turn off the electric furnace at the same time, and continue feeding non-oxidizing gas to cool to room temperature;

The fifth step, carry out purification treatment:

When using iron, cobalt, nickel and other catalysts that can react with acid, the purification method is to soak the substrate in an acid solution (such as hydrochloric acid, sulfuric acid, nitric acid, etc.) for 0.5 to 1000 minutes to remove the catalyst, and then wash it with deionized water After cleaning, dry; when using gold, silver, copper and other catalysts that are difficult to react with acid, remove the catalyst through displacement reaction with salt solution (such as ferric nitrate, ferric chloride, etc.).

Embodiment 1, preparation regular graphene

In the first step, a 25um thick copper foil (purity 99.8%) is ultrasonically cleaned with deionized water, ethanol and acetone, and then dried in an oven.

In the second step, the copper foil is placed in the middle of a clean quartz tube, and the quartz tube is put into an electric furnace so that the middle of the quartz tube is located in the central area of the electric furnace, and then 120 sccm of argon gas is passed into the quartz tube, 5 After ~10 minutes, the argon sparging was stopped. Turn on the vacuum pump to start vacuuming. When the pressure in the reaction chamber is 3 to 10 Pa, turn off the vacuum pump, and then feed the mixed gas of 100 sccm of argon and 300 sccm of hydrogen until the pressure in the reaction chamber is consistent with the external atmospheric pressure, and then stop feeding the argon. Only use 300sccm hydrogen as the carrier gas, and start heating after 10 minutes of ventilation;

In the third step, when the temperature in the central area of the electric furnace reaches 1000°C, 10 sccm methane is introduced into the carrier gas as a carbon source, and the reaction begins;

In the fourth step, after the reaction was carried out for 40 minutes, stop feeding methane, turn off the electric furnace at the same time, and continue feeding 300 sccm hydrogen to lower the temperature to room temperature. The scanning electron microscope photo of the product is shown in Figure 2, and the copper surface can be observed from the figure There are uniformly dispersed equiangular hexagonal substances, which are graphene. The Raman spectrum of the product is shown in Figure 3, where the red line indicates multilayer, the blue line indicates single layer, and the black line indicates the copper region without graphene. The above results prove that equiangular hexagonal graphene is a high-quality monolayer or multilayer. The atomic force microscope photo is shown in Figure 4, and a regular hexagonal substance is observed from the figure, which is regular graphene;

In the fifth step, the substrate deposited with graphene is soaked in 1 mole per liter of ferric nitrate solution for 60 minutes to remove copper, and then washed and dried with deionized water. The scanning electron microscope photograph of product is shown in Figure 5, can find regular hexagonal structure from the figure, and this material is graphene; The transmission electron microscope photograph (left) and selected area electron diffraction photograph (right) of product are as shown in Figure 6 It can be seen from the figure that the product is a two-dimensional equiangular hexagonal regular structure, indicating that the product is graphene.

Embodiment 2, preparation regular graphene

The preparation method is basically the same as in Example 1, except that when the temperature of the electric furnace reaches 1000° C., 20 sccm of methane is introduced as the carbon source, and the scanning electron micrograph of the product is as shown in Figure 7, and it can still be seen from the figure Two-dimensional hexagonal structure, but its shape begins to deviate from the ideal equiangular hexagonal structure. This fact is general, that is, as the flow rate of the carbon source is increased, or equivalently, the growth rate is increased, the shape of graphene shifts towards a more and more irregular direction.

Embodiment 3, preparation regular graphene

The preparation method is basically the same as Example 1, except that: when the temperature in the central area of the electric furnace reaches 1050° C., 5 sccm of methane is then introduced as a carbon source. The scanning electron microscope photo of the product is shown in Figure 8, and the regular hexagonal structure can be seen from the figure, indicating that the product is regular graphene.

Preparation of Regular Graphene at 900°C in Example 4

The preparation method is basically the same as Example 1, except that: when the temperature in the central area of the electric furnace reaches 900° C., 50 sccm of methane is then introduced as a carbon source. The scanning electron micrograph of the product is shown in Figure 9, and the regular hexagonal structure can be seen from the figure, indicating that the product is regular graphene.

Claims (8)

1. method for preparing Graphene with regular morphology, adopt chemical Vapor deposition process to be prepared, may further comprise the steps: tinsel or the substrate that has a metal catalyst are put into the anhydrous reactor of anaerobic, make tinsel or substrate temperature reach 800～1050 ℃, in described reactor, feed carbon source then and react, obtain having the Graphene of regular morphology.

2. method according to claim 1 is characterized in that: described metal is a kind of or its arbitrary combination in copper, gold and silver, nickel, cobalt and the iron.

3. method according to claim 1 and 2 is characterized in that: described carbon source is a kind of or its arbitrary combination in methane, carbon monoxide, methyl alcohol, acetylene, ethanol, benzene, toluene, hexanaphthene and the phthalocyanine.

4. according to each described method among the claim 1-3, it is characterized in that: the flow that feeds described carbon source in the described reaction is 5-100sccm; Be preferably 5-50sccm.

5. according to each described method among the claim 1-4, it is characterized in that: the reaction times of described reaction is 0.5～1000 minute, preferred 20-60 minute.

6. according to each described method among the claim 1-5, it is characterized in that: described Graphene with regular morphology is the Graphene with hexagonal structure.

7. according to each described method among the claim 1-6, it is characterized in that: described method comprises that also the Graphene with regular morphology to preparation carries out the step that purifying is removed metal catalyst.

8. the Graphene for preparing according to each described method among the claim 1-7 with regular morphology.

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