TWI522314B - Large-scale production apparatus for preparing graphene and graphene oxide and the method thereof - Google Patents

Description

Apparatus for producing graphene and graphene oxide by mass production and method thereof

The invention relates to a process equipment and a method for graphene and graphene oxide, in particular to a process equipment and method for mass production of graphene and graphene oxide.

Graphene is a monoatomic layer of graphite, each of which is sp ² mixed with adjacent three atoms to form a bond and extends into a honeycomb two-dimensional structure. It is known that graphene has a carrier mobility of up to 200,000 cm ² /V‧s, and also has good thermal conductivity and high transmittance. Therefore, it has been widely used in semiconductors and touch panels. Or in the field of solar cells.

Conventional techniques for producing graphene include mechanical exfoliation, epitaxial growth, chemical vapor deposition (CVD), and chemical exfoliation. Among them, the mechanical exfoliation method and the epitaxial growth method can produce graphene of better quality, but neither method can synthesize graphene over a large area. In the preparation of chemical vapor deposition, it is necessary to use nearly 1000 degrees of high temperature and expensive metal substrates, and it takes several hours to complete. The chemical stripping method mainly oxidizes the graphite first, and finally the step of high temperature reduction causes the graphene to return to its original lattice shape to make it electrically conductive. However, the oxidation process causes the crystal lattice of graphene to be destroyed, and not all of the graphene oxide can be effectively reduced. The shortcomings of these methods limit the production and subsequent application of graphene.

Therefore, how to provide a method for production at room temperature, low cost, simple process and rapid production of high quality graphene has become one of the important topics. U.S. Patent 7,790,285 provides a method for making a nano-scaled grapheme platelet comprising interweaving a carbon fiber or a graphite fiber in an intercalation between layers and then being The embedded fibers are peeled off to become graphene sheets or graphene flakes; then the graphene sheets are further separated to obtain nano-scale graphene sheets.

Further, U.S. Patent No. 7,892,514 provides a method of stripping a layered material such as graphite or graphite oxide to produce a nanoplatelet having an average thickness of from 0.34 to 1.02 nm. The method comprises intercalating a layer of powder at a temperature above a halogen melting point or sublimation point at a specific vapor pressure; and then allowing a second temperature above the boiling point of the halogen The embedded halogen atoms extend between the layers of the compound to exfoliate the compound into platelets; or the embedded compound is dissolved in a liquid matrix to ultrasonically strip the compound into small pieces. Wherein the halogen may be, for example, Cl ₂ , Br ₂ , I ₂ , ICl, IBr, BrCl, IF ₅ , BrF ₃ , ClF ₃ , or a mixture thereof, please refer to column 4, lines 10-18 of the specification.

In addition, the applicant further discloses a method for preparing graphene by using a chemical peeling method, using ions in an electrochemical electrolyte as an insert and supplemented by a method of preparing graphene in the Republic of China Patent Application No. 100115655. The voltage embeds the ions and then strips the graphene with different voltages.

The content of the manufacture of graphene disclosed in the above prior art is only to prepare a small amount of graphene by the method disclosed therein. However, in view of the current demand for technological development in the fields of semiconductors, touch panels and solar cells, the design of simple, large-scale, and continuous scale-scale graphene preparation has become increasingly important. The present invention provides a design and method for rapidly producing high quality graphene manufacturing equipment for the purpose of large-scale preparation. The same electrolysis method can also be used to produce graphene oxide.

In view of the above problems, it is an object of the present invention to provide a manufacturing apparatus for graphene and graphene oxide which is low in cost, simple in process, and fast in producing high quality.

Another object of the present invention is to provide a method for mass production of graphene and graphene oxide, which is based on an electrochemical stripping method known in the art to produce graphene and graphene oxide.

A manufacturing apparatus of graphene and graphene oxide according to the present invention, comprising: a first electrode comprising an electrode holder comprising a graphite starting material, a second electrode, an electrolytic cell, a power supply, and a A module for filtering and separating products. In one embodiment of the invention, the first electrode is an electrode holder comprising a graphite starting material, and the second electrode system is also an electrode holder or a metal comprising a graphite starting material. The so-called graphite starting material also contains a mixture of graphite and metal.

For the purpose of electrochemically stripping graphene, the manufacturing apparatus of the present invention is provided with a first electrode and a second electrode in an electrolyte, the first electrode being an electrode holder comprising a graphite starting material; And performing a step of embedding the graphite material; performing a stripping step of the graphite material under the second bias; and finally removing the solid product in the electrolyte.

In the present invention, the graphite starting material comprises natural graphite having a graphite layer structure, artificial graphite, a composite material made of graphite powder, or a combination thereof. In particular, the graphite starting material contains natural graphite and high directivity. Highly-oriented pyrolytic graphite (HOPG), pitch-based graphite (resin-based graphite), carbon fiber (PAN-and pitch-based carbon fibers), charcoal, or other carbon containing layered or scaly graphite material. It may be a graphite layer crystal material of a block, a chip, a powder, and an irregular shape, or may be a block in which the above-mentioned topography of the graphite material is bonded by an adhesive body (having a conductive property).

In the present invention, in order to achieve mass production efficiency, the two poles of the electrode may be graphite starting materials or electrode holders containing graphite starting materials, and are arranged in a series connection manner such as array or parallel arrangement.

In the present invention, the first electrode is not limited to only one, and a plurality of parallel first electrodes can be simultaneously inserted.

In the present invention, the second electrode is not limited to only one, and a plurality of parallel second electrodes can be simultaneously inserted.

In one embodiment of the present invention, the metal is an acid-base precious metal such as platinum (Pt), silver (Ag), gold (Au), iridium (Ir), osmium (Os), palladium (Pd). ), 铑 (Rh), or 钌 (Ru), etc. It may also include, but is not limited to, a conductive material that is not easily chemically etched, such as copper (Cu), stainless steel, glassy carbon, conducting polymer, and the like.

In an embodiment of the present invention, the electrolysis cell of the device is a container capable of filling an electrolyte, and the material thereof may be a polymer material such as glass, acrylic, PP, PS, PVC, stainless steel or other metal. a container made of materials.

In one embodiment of the invention, the electrolyte comprises hydrogen bromide, hydrochloric acid, or sulfuric acid.

In one embodiment of the invention, the electrolyte is added with potassium hydroxide.

In one embodiment of the invention, the electrolyte further comprises an oxidizing agent comprising potassium dichromate, permanganic acid, or potassium permanganate.

In an embodiment of the present invention, in order to improve the efficiency or product quality of the electroplated graphene and graphene oxide, the electrolysis process may be supplemented by heating, ultrasonic vibration, microwave or high-energy light source, as needed. In the electrolyte solution, a rotor or the like is manufactured by a rotor to assist in stripping off graphene and graphene oxide.

In the present invention, in order to achieve the purpose of the continuous process, the stripped product can be fed to a module for filtering and separating the product. The first member of the module is a microporous screen having a size of 18 Between 1,250 meshes, preferably between 35 and 500 meshes, for filtering unpeeled coarse-grained graphite particles, and by screening to obtain products of appropriate size; The second member is a filter membrane having a pore size from 200 to 1,200 nm, preferably from 300 to 800 nm, for the purpose of collecting the graphene sheet product through the screen. In addition, the graphene product collected on the second member can be followed by a large amount of deionized water to remove the residual electrolyte, or other ionic solution (such as HCl) that can dissolve and replace residual ions (such as K ⁺ or SO ₂ ^- ). Wait).

In the present invention, the bias voltage is provided by a power supply, which may be a direct current or an alternating current supply. In one embodiment of the invention, the first bias voltage is between +0.5 volts and +10 volts, preferably between +2.5 volts and +5 volts. In one embodiment of the invention, the second bias voltage is between +5 volts to +220 volts, preferably between +10 volts and +100 volts.

In summary, the present invention provides a method for producing mass-produced graphene and graphene oxide by electrochemical stripping, that is, embedding can be completed by changing the transmission voltage at room temperature. The step of stripping the graphite material eliminates the need for additional high temperature for reduction, so that the process can be simplified, and graphene having a small number of layers, a large lateral dimension, and a high degree of graphitization can be produced in a short time. Conducive to industrial mass production and application in various fields.

The method for producing the mass-produced graphene and the graphene oxide comprises: disposing a first electrode and a second electrode in an electrolyte; the first electrode is an electrode holder comprising a graphite starting material, and the second electrode is An electrode holder comprising a graphite starting material or a metal (the so-called graphite starting material also comprises a mixture of graphite and metal); performing the embedding step of the graphite starting material under a first bias; and performing the graphite under a second bias a stripping step of the starting material; and feeding the stripped product to a module for filtering and separating the product, the module comprising a first member, which is a microporous screen, and a second member, which is a filter membrane The graphene product and the graphene oxide are collected on the filter membrane.

The preparation method described above is as follows: a first electrode and a second electrode are provided as an anode and a cathode, respectively, and are immersed in an electrolyte through the electrode wire. First, the first bias is used to perform the step of embedding the graphite material, so that the anions such as sulfate, nitrate ions, etc. in the electrolyte are intercalated between adjacent two layers of graphite layers and On the grain boundary, wherein the first bias voltage is between +0.5 volts and +10 volts, preferably between +2.5 volts and +5 volts, and the action time is about 1 to 30 minutes, preferably 1 to 5 minute.

Then, the second bias voltage is used to perform the stripping step of the graphite material, wherein the second bias voltage is greater than the first bias voltage and is between +5 volts and +220 volts, preferably between +10 volts and +100 volts. There is no limit to the duration of action. It should be noted that the method for producing graphene and graphene oxide of the present invention may further comprise: performing a stripping step of the graphite material under a third bias. That is, in addition to the second biasing for a period of time to perform the stripping step, the stripping step may be performed using a third bias different from the second bias. For example, the polarity of the third bias may be opposite to the polarity of the second bias, or the polarity may be the same, but the size may be different, wherein the second bias and the third bias may be direct current or alternating current, respectively. If the polarity of the third bias is opposite to the polarity of the second bias, the forward voltage can be used to promote stripping and oxidation of graphene, and then the negative voltage can reduce the oxidized graphene. In one embodiment of the invention, the second biasing system uses +10 volts and the third biasing system uses -10 volts, the operating time is 2 seconds and 5 seconds, respectively, and alternates for a period of time.

In addition, the embedding step and the stripping step of the present invention can be converted using different first bias voltages and second bias conditions depending on the electrolyte composition and pH used to achieve the best quality and yield.

After the stripping step, the stripped product can pass through the feed end to a module for filtering and separating the product. The first member of the module is a microporous screen (35 mesh) for filtering unpeeled coarse The graphite particles of the particle size and the product of appropriate size are obtained by screening; the second component of the module is a 400 nm pore filter membrane, the purpose of which is to collect the graphene sheet product through the screen. In addition, the graphene product and the graphene oxide collected on the second member may be followed by a large amount of deionized water to remove the residual electrolyte, or other dissolved or substituted residual ions (such as K ⁺ or SO ₂ ^- ). An ionic solution (such as HCl) is used to remove the residual electrolyte. The module mainly uses an air extracting device S12 to accelerate the step of suction filtration. This example was subjected to filtration and separation by vacuum filtration.

In this document, the singular forms "a" and "the" are also used in the plural. The use of any and all examples and exemplifications (such as "such as") are intended to be illustrative of the invention and are not intended to limit the scope of the invention. The components may form an essential component in the practice of the invention.

Hereinafter, a method for producing graphene and graphene oxide according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings, wherein the same elements will be described with the same reference numerals.

Figure 1, which is a schematic diagram of one of the devices for preparing graphene and graphene oxide. A first electrode S02 and a second electrode S11 are disposed as an anode and a cathode, respectively, and are immersed in an electrolyte S04 through the electrode wires. The first electrode S02 is a graphite material or an electrode holder containing graphite, and the second electrode S11 may also be a graphite material, an electrode holder containing graphite, or a metal. Among them, in addition to graphite, the graphite material may be highly oriented pyrolytic graphite (HOPG), pitch graphite, or carbon charcoal, etc., and the metal is a precious metal that is not easily chemically etched, such as platinum. , silver, gold, rhodium, ruthenium, palladium, iridium, or osmium, or other conductive materials, such as copper, stainless steel, glassy carbon, conductive polymers. Further, in the embodiment, the first electrode is a graphite starting material, and the second electrode is also a graphite starting material. The graphite starting material may be a graphite layer crystalline material of a block, a chip, a powder and an irregular shape, or may be a block in which the graphite material of the above-mentioned morphology is bonded by an adhesive body (having a conductive property). In an embodiment of the present invention, in order to achieve mass production efficiency, the graphite initial materials of the two electrodes are arranged in a series connection manner such as array or parallel arrangement.

In the present invention, the electrolysis cell of the device is a container S01 which can be filled with an electrolyte, and the material thereof can be made of high-molecular polymer materials such as glass, acrylic, PP, PS, PVC, stainless steel or other metal materials. Container. What is used in this embodiment is a glass container.

In the present invention, in order to improve the efficiency or product quality of the electroplated graphene, the electrolysis process may be supplemented by heating, ultrasonic oscillating, microwave or high-energy light source, and a vortex is formed in the electrolyte by a rotor. Etc. to assist in stripping out graphene. In the present embodiment, the rotor S05 and the temperature controller S06 are used to assist in stripping off the graphene.

This embodiment supplies a bias voltage with a DC bias. The first bias voltage is between +0.5 volts and +10 volts and the second bias voltage is between +5 volts and +220 volts.

In the present invention, in order to achieve the purpose of the continuous process, the stripped product is transferred from the feeding end S01 to the module S08 for filtering and separating the product by the pumping motor S07, and the first component S09 of the module is a micro A mesh screen (35 mesh) for filtering unpeeled coarse-grained graphite particles and a product of appropriate size by screening; the second member S10 of the module is a 400 nm pore filter membrane, the purpose of which is The graphene sheet product passing through the screen is collected. In addition, the graphene product collected on the second member can be followed by a large amount of deionized water to remove the residual electrolyte, or other ionic solution (such as HCl) that can dissolve and replace residual ions (such as K ⁺ or SO ₂ ^- ). Etc.) to remove residual electrolyte. The module mainly uses an air extracting device S12 to accelerate the step of suction filtration. This example was subjected to filtration and separation by vacuum filtration.

2 is a schematic view of an electrode holder device including a graphite starting material. If the initial material is a block of the centimeters (above) scale, the electrode may be directly connected to form an electrode; if the initial material is a chip or a powder, the electrode holder shown in FIG. 2 must be used, and the member can be used as the first electrode. S02 or second electrode S11. The graphite starting material S13 may be a graphite layer crystalline material which is a chip, a powder and other fine particles which are not easily connected directly to the conductive line. The isolation net S14 is a filter (pore size: 0.1 to 5 mm), a porous film, or a member having a hole, and its main functions are three: one. The scattered graphite initial material is kept in a state of being tight and mutually conductive, and the metal electrode S15 forms a path and is connected to the power supply; Make the electrolyte S04 easy to enter and exit, effectively produce electrochemical stripping; The decomposed graphene product is easily diffused into the solution to facilitate subsequent reaction of the electrolyte with the unreacted graphite starting material. The choice of the size of the isolation mesh is related to the initial material size so as not to pass unreacted material. The isolation network is an acid and alkali resistant insulator composed of glass, acrylic, PE, PP, etc. or other high molecular polymers, or metal materials treated by insulation and corrosion protection. The metal electrode S15 is intended to be a connection between the graphite starting material and an external circuit, and a fixed pressure can be applied to the graphite material S13 to make the conductive effect better.

3 is a dispersion solution of graphene obtained in the present example in dimethylformamide (DMF).

Fig. 4 is a graphene solid powder obtained by the present embodiment.

In the present embodiment, a scanning electron microscope (SEM, JEOL-6330F) or an atomic force microscope (AFM, Veeco Dimension-Icon system) was used to observe the appearance of the graphene sheet. Figure 5 is a scanning electron micrograph of the graphene flake solid powder in the present embodiment. The graphene powder obtained in the present example is shown to be a layered stacked and high-purity graphene. A graphene ink was formed on a substrate of cerium oxide (SiO ₂ ) by drop plating to form a thin film, and the morphology of the graphene sheets was observed by an atomic force microscope. As shown in FIG. 6, in the obtained graphene dispersion, the thickness of the graphene sheet is less than or equal to 3 nm, and about 65% of the graphene sheets have a thickness of less than 2 nm, which can be seen from the present embodiment. The thickness of the graphene sheets is very small.

Please refer to FIG. 7 , which is a graph of graphs of graphene sheets analyzed by a NT-MDT confocal Raman microscopic system. In this example, a graphene sheet having a thickness of 1.6 nm was observed by AFM, and the molecular bonding structure of graphene was analyzed by Raman spectroscopy at a wavelength of 473 nm. As shown in the figure, the appearance of the G peak at about 1580 cm ^-1 exhibiting a narrower and higher intensity shows that the graphene obtained by the production method of the present invention has a better graphite graphitization. In general, the 2D/G intensity ratio of a single layer of graphene is usually greater than the 2D/G intensity ratio of the bilayer graphene, and the 2D peak at 2720 cm ^-1 observed in Figure 7, the ratio to the G peak is The ratio of the reduced graphene oxide produced in the conventional method is large, and thus the graphene of the present invention is again proved to have better graphitization.

In the preparation process, the electrolytic DC bias is increased or the acidity of the electrolyte is increased, and the graphene oxide can be produced. The purification process only needs to be filtered and washed, and the production steps and raw material equipment are the same as the above preparation. Description of graphene. The graphene oxide prepared by this method has a Raman spectrometer characteristic peak as shown in FIG.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the present invention should be included in the scope of the appended claims.

S01. . . Electrolytic cell

S02. . . First electrode

S03. . . Power Supplier

S04. . . Electrolyte

S05. . . Rotor

S06. . . Temperature Controller

S07. . . Pumping motor

S08. . . Module for filtering and separating products

S09. . . First member

S10. . . Second member

S11. . . Second electrode

S12. . . Air suction device

S13. . . Graphite material

S14. . . Isolation network

S15. . . Metal electrode

Figure 1. Schematic diagram of the process equipment for graphene of the present invention

Figure 2. Schematic diagram of an electrode holder device containing graphite starting material

Figure 3. Graphene solution (dispersed in 250mL DMF solution)

Figure 4. Graphene solids after separation and filtration

Figure 5. Scanning electron microscope image of graphene solids

Figure 6. Atomic force microscopy image of graphene

Figure 7. Signals for graphene analysis of its bond type by Raman spectroscopy

Figure 8. Signals for the bonding of graphene oxides by Raman spectroscopy

S01. . . Electrolytic cell

S02. . . First electrode

S03. . . Power Supplier

S04. . . Electrolyte

S05. . . Rotor

S06. . . Temperature Controller

S07. . . Pumping motor

S08. . . Module for filtering and separating products

S09. . . First member

S10. . . Second member

S11. . . Second electrode

S12. . . Air suction device

Claims (19)

A manufacturing apparatus for mass-produced graphene and graphene oxide, comprising: a first electrode comprising an electrode holder of a graphite starting material, and a second electrode comprising an electrode seat of a graphite starting material, a metal, Or comprising a mixture of graphite and metal, and an electrolytic cell, wherein the electrolyte is filled, the first electrode and the second electrode are disposed in the electrolyte and connected to a power supply, wherein the power supply provides a first bias A pressure and a second bias, and a module for filtering and separating the product for collecting graphene and graphene oxide products. The apparatus of claim 1, wherein the graphite starting material comprises natural graphite, high-parallel graphite, pitch graphite, carbon fiber, carbon charcoal, or other carbon material containing layered or scaly graphite. The device of claim 1, wherein the first and second electrode systems each comprise an electrode holder of a graphite starting material, and are arranged in an array or parallel arrangement of clusters. The device of claim 1, wherein the first electrode is a plurality of first electrodes connected in parallel. The device of claim 1, wherein the second electrode is a plurality of second electrodes connected in parallel. The apparatus of claim 1 wherein the metal is an acid-base resistant precious metal or other electrically conductive material. The device of claim 1, wherein the electrolyte comprises hydrogen bromide, hydrochloric acid, Or sulfuric acid. The apparatus of claim 1 further comprising a pumping device. The apparatus of any one of claims 1 to 8, wherein the module for filtering and separating the product comprises a first member which is a microporous screen; and a second member which is a filter membrane; Wherein the microporous screen has a size between 18 and 1,250 mesh, and wherein the filter membrane has a pore size of 200 to 1,200 nm. A method for manufacturing graphene and graphene oxide, comprising: disposing a first electrode and a second electrode in an electrolytic bath filled with an electrolyte, the first electrode being an electrode holder comprising a graphite starting material, the second electrode a lead holder comprising a graphite starting material or a metal or a mixture comprising graphite and metal, connecting a power supply to the first electrode and the second electrode; and performing the graphite initial material under a first bias And an embedding step; and performing a stripping step of the graphite starting material under a second bias, wherein the second biasing system is greater than the first bias voltage; and feeding the stripped product to a module for filtering and separating the product, The module comprises a first member, which is a microporous screen, and a second member, which is a filter membrane; collects graphene products and graphene oxide on the filter membrane; wherein the first biasing system is between + 0.5 volts to +10 volts; and the second bias voltage therein is between +10 volts to +220 volts. The method of claim 10, wherein the graphite starting material comprises natural graphite, high-parallel graphite, asphalt graphite, carbon fiber, carbon charcoal, or the like Carbon material containing layered or scaly graphite. The method of claim 10, wherein the first electrode and the second electrode system each comprise an electrode holder of a graphite starting material, and are arranged in an array or parallel arrangement of clusters. The method of claim 10, wherein the first electrode is a plurality of first electrodes connected in parallel. The method of claim 10, wherein the second electrode is a plurality of second electrodes connected in parallel. The method of claim 10, wherein the metal is an acid-base resistant precious metal, or other electrically conductive material. The method of claim 10, wherein the electrolyte comprises hydrogen bromide, hydrochloric acid, or sulfuric acid, or other electrically conductive material. The method of claim 10, further comprising a pumping device. The method of claim 10, wherein the bias is supplied in direct current or alternating current. The method of any one of claims 10 to 17, wherein the module for filtering and separating the product comprises a first member which is a microporous screen; and a second member which is a filter membrane; Wherein the microporous screen has a size between 18 and 1,250 mesh, and wherein the filter membrane has a pore size of 200 to 1,200 nm.