A counter electrode device for preparing graphene by electrochemical exfoliation

Abstract

The invention discloses a counter electrode device for preparing graphene by electrochemical stripping, comprising a metal counter electrode plate, the electrode plate being placed in an insulating ion exchange membrane support frame, the portion of the electrode plate extending from the ion exchange membrane support frame forming a strip-shaped conductive electrode ear, the conductive electrode ear being clamped by an insulating plate, the insulating plate and the conductive electrode ear being mirror-symmetrical in shape and the conductive electrode ear being consistent in shape with the symmetrical portion of the conductive electrode ear as the insulating electrode ear, the conductive electrode ear and the insulating electrode ear being provided with semicircular holes with the same radius and the same diameter of the conductive busbar at the ends facing outward in the same direction, the semicircular hole portion of the conductive electrode ear extending outward from the insulating plate, the ion exchange membrane support frame being provided with a group of partition frames on both sides parallel to the working surface of the counter electrode plate, each partition frame being provided with an ion exchange membrane sealed and connected to the partition frame, and the ion exchange membrane support frame being provided with a group of air guide holes and a group of liquid guide holes. This device has the advantages of low cost, safety, high efficiency, simple operation, and the ability to realize continuous production.

Description

Technical Field

[0001] The invention relates to a technology for large-scale production of graphene by electrochemical method, in particular to a counter electrode device for preparing graphene by electrochemical exfoliation. Background Art

[0002] Graphene is a two-dimensional crystalline material composed of a layer of carbon atoms, and its main source of preparation is graphite. Professor Geim and Professor Novoselov of the University of Manchester in the UK successfully prepared a single layer of crystalline graphene from native graphite, proving that graphene can exist in the natural environment. Graphene has excellent mechanical, electrical, thermal and optical properties.

[0003] Compared with other methods, the electrochemical exfoliation of graphite to produce graphene has the advantages of low cost, green safety, and high efficiency. It is a new method for the industrial production of graphene. In the electrostripping process of the water system, the oxygen generated at the anode expands the graphite sheets to produce graphene. Because the electrochemical exfoliation is carried out in an aqueous solution, the cathode will also produce hydrogen. In large-scale production, a large amount of gas will be produced. If no measures are taken to separate the gases generated by the positive and negative electrodes during the electrostripping process, the oxygen generated at the anode and the hydrogen generated at the cathode will directly contact each other, and an explosion may occur in the presence of a tiny spark, which poses a great safety hazard to the large-scale production process. Therefore, avoiding the contact between the oxygen generated at the anode and the hydrogen generated at the cathode during the electrostripping process is the key to avoiding explosions during the electrostripping process. Summary of the invention

[0004] The purpose of the present invention is to provide a counter electrode device for preparing graphene by electrochemical exfoliation in view of the shortcomings of the prior art. The device has the advantages of low cost, safety, high efficiency, simple operation and continuous production.

[0005] The technical solution for achieving the purpose of the present invention is:

[0006] A counter electrode device for preparing graphene by electrochemical stripping includes a metal counter electrode plate, the electrode plate is placed in an insulating ion exchange membrane support frame, the portion of the electrode plate extending from the ion exchange membrane support frame forms a strip-shaped conductive electrode ear, the conductive electrode ear is clamped by an insulating plate, the insulating plate and the conductive electrode ear are mirror-symmetrical parts, and the shape of the conductive electrode ear is consistent with the shape of the symmetrical part of the conductive electrode ear, the conductive electrode ear and the insulating electrode ear are provided with semicircular holes with the same direction and radius as the conductive busbar wire diameter at the outward ends, the semicircular hole portion of the conductive electrode ear extends out of the insulating plate, the ion exchange membrane support frame is provided with a group of partition frames on both sides parallel to the working surface of the counter electrode plate, each partition frame is provided with an ion exchange membrane sealed and connected to the partition frame, the ion exchange membrane support frame is provided with a group of air guide holes at the upward end when it extends into the electrode slot, and the ion exchange membrane support frame is provided with a group of liquid guide holes at the lower part of the electrode slot, and the counter electrode device is fixed to the busbar in a hanging manner.

[0007] The insulating plate and the ion exchange membrane support frame are made of acrylic plate, polypropylene plastic plate or wooden plate, and their function is insulation. When the acrylic plate is used, the adhesive used for the acrylic plate is dichloromethane.

[0008] The ion exchange membrane is made of a material that allows electrolyte ions to pass freely while isolating the cathode and anode gas products from contacting each other. The ion exchange membrane prevents the oxygen produced by the anode and the hydrogen produced by the cathode from contacting each other, thus avoiding the risk of explosion. The ion exchange membrane allows ions to pass through while isolating the gas from passing through, and performs intercalation reactions on the rapid passage of ions and the migration of ions to the graphite electrode.

[0009] The number of the gas guide holes and liquid guide holes is at least 2. The gas generated by the electrode is discharged through the gas guide holes and can be collected and reused. The arrangement of the liquid guide holes allows the electrolyte in the electrolytic cell to enter the ion exchange membrane support frame, which facilitates the exchange of the electrolyte in the cell with the electrolyte in the ion exchange membrane support frame to mitigate concentration polarization.

[0010] The counter electrode device is a cathode when working in an aqueous electro-stripping environment, and is an anode when working in an organic electro-stripping environment.

[0011] The ion exchange membrane will swell when immersed in the electrolyte, and the ion exchange membrane support frame fixes the ion exchange membrane to achieve stable production.

[0012] The working process of the device is as follows: two busbars are placed in parallel on the body of the electrolytic cell, and then N graphite electrode devices and N+1 counter electrode devices are arranged at intervals on the conductive busbars, the graphite electrode devices and the counter electrode devices are relatively parallel, and adjacent electrode devices have a pole distance, the electrolyte is injected into the electrolytic cell, the busbars in the electrolytic cell are connected to a DC power supply with a wire, and the power supply output is set to 1V-60V. The counter electrode device exchanges liquid through two liquid guide tubes at the bottom, which is beneficial to slowing down the concentration polarization of the electrolyte. After power is turned on, under the action of the electric field, the cations in the electrolyte migrate to the cathode, and the anions migrate to the anode to intercalate the graphite; the anode and cathode undergo a gas evolution reaction to produce Gas, a large amount of gas is produced on the cathode side, and a large number of bubbles emerge upward along the electrode plate. In the presence of the ion exchange membrane, the gas is restricted to one side of the electrode device and cannot diffuse to the graphite electrode side and is discharged through the two air ducts on the upper part of the electrode device, thereby achieving the isolation of the anode and cathode gases. The electrical stripping time is 1-8h, and the anode graphite electrode is completely stripped into a large amount of graphene. From the beginning to the end, the gas generated in the electrode device is only discharged from the air duct and collected. The graphite electrode is stripped into graphene slurry, and the electrode device can be recycled. After the stripping is completed, the electrode device is ultrasonically cleaned for 10 minutes and soaked in deionized water for next use.

[0013] The technical solution uses a layer of ion exchange membrane between the positive and negative electrodes to prevent the oxygen generated by the anode and the hydrogen generated by the cathode from contacting each other, thus avoiding the risk of explosion; the electrode plate is suspended at both ends of the busbar, one end of which is conductive, and the other end is connected to the electrode by using an insulating material, so that one end of the electrode is insulated to avoid the risk of short circuit; when preparing graphene, if the diaphragm is set on the side of the graphite working electrode, the complexity of the graphite working electrode device will increase, and at the same time, the product of the graphite electrode will adhere to the ion exchange membrane, causing contamination of the ion exchange membrane and difficulty in cleaning. The ion exchange membrane is set on one side of the electrode device to simplify the structural complexity of the graphite electrode device; when the ion exchange membrane reaches the end of its service life and needs to be replaced, it is simple to replace the ion exchange membrane.

[0014] This device has the advantages of low cost, safety, high efficiency, easy operation and the ability to achieve continuous production. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of an embodiment;

[0016] Figure 2 This is a SEM image of the product peeled off in the example;

[0017] Figure 3 This is a TEM image of the product peeled off in Example.

[0018] In the figure, 1. electrode plate 2. ion exchange membrane support frame 3. conductive electrode ear 4. insulating plate 5. insulating electrode ear 6. partition frame 7. ion exchange membrane 8. air guide hole 9. liquid guide hole. Specific embodiments

[0019] The content of the present invention is further described below in conjunction with the drawings and embodiments, but the present invention is not limited thereto.

[0020] Example:

[0021] Reference Figure 1, a counter electrode device for preparing graphene by electrochemical exfoliation, comprising a metal counter electrode plate 1, the electrode plate 1 is placed in an insulating ion exchange membrane support frame 2, the portion of the electrode plate 1 extending from the ion exchange membrane support frame 2 forms a strip-shaped conductive electrode ear 3, the conductive electrode ear 3 is clamped by an insulating plate 4, the insulating plate 4 and the conductive electrode ear 3 are in the shape of a mirror-symmetrical portion, and the shape of the symmetrical portion of the conductive electrode ear 3 is consistent with the shape of the conductive electrode ear 3 as an insulating electrode ear 5, the conductive electrode ear 3 and the insulating electrode ear 5 are provided with semicircular holes with the same direction and the same radius as the conductive busbar wire diameter at the outward ends, the semicircular hole portion of the conductive electrode ear 3 extends out of the insulating plate 4, the ion exchange membrane support frame 2 is provided with a group of partition frames 6 on both sides parallel to the working surface of the counter electrode plate 1, each partition frame 6 is provided with an ion exchange membrane 7 sealed and connected to the partition frame 6, the ion exchange membrane support frame 2 is provided with a group of gas guide holes 8 at the upward end when it extends into the electrode slot, and the ion exchange membrane support frame 2 is provided with a group of liquid guide holes 9 at the lower part of the electrode slot, and the counter electrode device is fixed to the busbar in a hanging manner.

[0022] The insulating plate 4 and the ion exchange membrane support frame 2 are made of acrylic plate, polypropylene plastic plate or wooden plate, and their function is insulation. In this example, an acrylic plate is used, and the adhesive used for the acrylic plate is dichloromethane.

[0023] The ion exchange membrane 7 is made of a material that allows electrolyte ions to pass freely while isolating the cathode and anode gas products from contacting each other. The ion exchange membrane 7 prevents the oxygen produced by the anode and the hydrogen produced by the cathode from contacting each other, thereby avoiding the risk of explosion. The ion exchange membrane 7 allows ions to pass through while isolating the gas from passing through, and performs intercalation reactions on the rapid passage of ions and the migration of ions to the graphite electrode. In this example, the ion exchange membrane 7 is a perfluorosulfonic acid ion exchange membrane.

[0024] The number of the gas guide holes 8 and the liquid guide holes 9 is at least 2. The gas generated by the electrode 1 is discharged through the gas guide holes 8 and can be collected and reused. The setting of the liquid guide holes 9 allows the electrolyte in the electrolytic cell to enter the ion exchange membrane support frame 2, which facilitates the exchange of the electrolyte in the cell with the electrolyte in the ion exchange membrane support frame 2 to mitigate concentration polarization.

[0025] The counter electrode device is a cathode when working in an aqueous electro-stripping environment, and is an anode when working in an organic electro-stripping environment.

[0026] The working process of this device is as follows: two busbars are placed in parallel on the body of the electrolytic cell, and then N graphite electrode devices and N+1 counter electrode devices are arranged at intervals on the conductive busbars. The graphite electrode devices and the counter electrode devices are in relatively parallel positions, and adjacent electrode devices have a pole distance. The electrolyte is injected into the electrolytic cell, and the busbars in the electrolytic cell are connected to a DC power supply with a wire. The power supply output is set to 1V-60V. The counter electrode device exchanges liquid through the two liquid guide tubes at the bottom, which is beneficial to slowing down the concentration polarization of the electrolyte. After power is turned on, under the action of the electric field, the cations in the electrolyte migrate to the cathode, and the anions migrate to the anode to intercalate graphite; gas evolution reaction occurs at the anode and cathode to produce gas, a large amount of gas is produced on the cathode side, and a large number of bubbles emerge upward along the electrode plates. In the presence of the ion exchange membrane, the gas is The gas is restricted on one side of the counter electrode device and cannot diffuse to the graphite electrode side and is discharged through the two air ducts on the upper part of the electrode device, thereby realizing the isolation of the anode and cathode gases. The electrical stripping time is 1-8h, and the anode graphite electrode is completely stripped into a large amount of graphene. From the beginning to the end, the gas generated in the counter electrode device is only discharged from the air duct 7 and collected. The graphite electrode is stripped into graphene slurry. The counter electrode device can be recycled. After the stripping is completed, the counter electrode device is ultrasonically cleaned for 10 minutes and soaked in deionized water for next use. The SEM and TEM images of the products of preparing graphene by electrochemical stripping of the device are shown as follows: Figure 2 , Figure 3 shown.

Claims

1. A counter electrode device for preparing graphene by electrochemical exfoliation, It is characterized in that It includes a metal counter electrode plate, which is placed in an insulating ion exchange membrane support frame. The portion of the electrode plate extending from the ion exchange membrane support frame forms a strip-shaped conductive electrode ear, which is clamped by an insulating plate. The shape of the mirror-symmetrical portion of the insulating plate and the conductive electrode ear is consistent with the shape of the symmetrical portion of the conductive electrode ear, which is the insulating electrode ear. The ends of the conductive electrode ear and the insulating electrode ear facing outward are provided with semicircular holes with the same direction and the same radius as the conductive busbar wire diameter. The semicircular hole portion of the conductive electrode ear extends out of the insulating plate. A group of partition frames are provided on both sides of the ion exchange membrane support frame parallel to the working surface of the counter electrode plate, and an ion exchange membrane sealed and connected to the partition frame is provided in each partition frame. When the ion exchange membrane support frame extends into the electrode slot, a group of air guide holes are provided at the upward end, and a group of liquid guide holes are provided at the lower part of the ion exchange membrane support frame extending into the electrode slot. The counter electrode device is fixed to the busbar in a hanging manner. The insulating plate and the ion exchange membrane support frame are made of acrylic plate, polypropylene plastic plate or wooden plate; The ion exchange membrane is made of a material that allows electrolyte ions to pass freely while isolating the cathode and anode gas products from contacting each other; The number of the air guide holes and the liquid guide holes is at least 2.

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