Device and method for preparing graphene by delocalization electrochemical method

Abstract

The invention relates to a device and a method for preparing graphene by a delocalized electrochemical method. The device comprises a diaphragm pump, a diaphragm pump discharge port, a discharge pipe, a ball valve, a reducer pipe, a four-way pipe, a reaction kettle body, a cooling water outlet, a cooling water inlet, a pipeline sight glass, a one-way valve, a straight-through pipe, a three-way pipe, a diaphragm pump feed port and the like, and the material circulation path is from the reaction kettle body to the pipeline sight glass to the three-way pipe to the elbow pipe to the second hose to the feed port of the diaphragm pump to the diaphragm pump to the discharge port of the diaphragm pump to the reducer pipe to the four-way pipe to the reaction kettle body. The reaction kettle body and the electrolyte conveying pipeline in the device can resist the corrosion of concentrated sulfuric acid; the outlet of the diaphragm pump is buffered by a hose to relieve vibration and shaking; by adding the pipeline sight glass, the fluid state can be conveniently observed; the closed circulating cooling design is adopted, so that the cooling effect is greatly improved, and the integrated function of corrosion-resistant fluid conveying, reaction temperature control and safe discharge is realized. The device has the characteristics of simple structure, high temperature control efficiency, good consistency, safe overall structure and the like.

Description

TECHNICAL FIELD

[0001] The application relates to a device and method for preparing graphene, in particular to a device and method for preparing graphene by a delocalization electrochemical method, which are corrosion-resistant, simple in structure, high in temperature control efficiency, good in consistency and safe in overall structure. BACKGROUND

[0002] Graphene is a two-dimensional honeycomb lattice material composed of single-layer carbon atoms in sp 2 hybrid orbitals, and has a thickness of only about 0.335 nanometers. It is one of the thinnest but hardest nanomaterials known in the world at present. In 2004, it was first discovered by British scientists Andre Geim and Konstantin Novoselov through the method of repeatedly peeling off graphite by adhesive tape. The specific surface area of the material is high (~2630 m 2 / g), and the electric and thermal conductivities are good (the electron mobility is 200000 cm 2 / (V·s); the thermal conductivity (thermal conductivity 5000 W / (m·K)) is good, and the mechanical properties (Young's modulus 1000 GPa) and the chemical stability are excellent, and the material has great application potential in the fields of energy, electronics, biomedicine and chemical materials.

[0003] Large-scale preparation and quality control of graphene are the key to restricting the application of graphene materials. Conventional graphene preparation methods include more than ten preparation technologies of two major categories, i.e., top-down (mechanical peeling method, liquid phase peeling method, oxidation-reduction method) and bottom-up (SiC epitaxial growth method, CVD chemical vapor deposition method), but all have certain defects. For example, the yield of graphene obtained by the mechanical peeling method is low, and the layer is thick; the oxidation-reduction method can realize large-scale production, but the prepared product has too large defects, high oxygen content and limited application scenarios; the CVD chemical vapor deposition method can prepare few-layer high-quality graphene, but the process is complex, the cost is too high, and the large-scale production is also limited.

[0004] The traditional electrochemical method uses flake graphite as an electrolytic anode and cathode, immerses the graphite electrode in an electrolyte solution (sulfuric acid, sulfate, etc.), connects the power supply after the current flows from the graphite to the electrolyte, and the electrolyte anions are inserted into the interlayer of the anode graphite under the driving of the potential difference. With the increase of the inserted ions, the van der Waals force between the graphite layers is continuously weakened, the graphite expands, and after subsequent post-processing steps such as emulsification, homogenization, ultrasonic and centrifugation, few-layer graphene material is prepared. Compared with the mechanical peeling method, the layer number of the graphene material prepared by the method is smaller, and the oxygen content of the graphene material prepared by the method is lower than that of the graphene material prepared by the oxidation-reduction method. The method has the advantages of simple operation, low cost, environmental friendliness and easy scaling, and has been widely used in metallurgy, organic and polymer synthesis, inorganic material preparation and other aspects.

[0005] Although the traditional electrochemical method is concerned because of simple operation and environmental friendliness, the graphite electrode needs to be directly contacted with the electrolyte during the electrochemical reaction process, the ion intercalation speed is too fast during the electrochemical exfoliation process, the graphite electrode is often wasted or even collapsed, impurities are introduced into the product, the yield of graphene is too low, and the layer distribution is uneven. In addition, the cooling method of the traditional electrochemical method is water bath cooling, and the cooling water takes away the heat of the reaction solution, so that only the external area of the solution can be cooled, the internal solution is locally overheated, the intercalation material is decomposed by heat, and the electrolysis effect is poor. SUMMARY

[0006] In view of the above problems, the main purpose of the present application is to provide a device and method for preparing graphene by delocalized electrochemical method, which has corrosion resistance, simple structure, high temperature control efficiency, good consistency and safe overall structure.

[0007] The present application solves the above technical problems by the following technical scheme: a device for preparing graphene by delocalized electrochemical method, the device for preparing graphene by delocalized electrochemical method comprises:

[0008] The diaphragm pump, the diaphragm pump discharge port, the discharge pipe, the ball valve, the clamp, the reducing pipe, the four-way pipe, the reaction kettle body, the cooling water outlet, the cooling water inlet, the pipeline sight glass, the check valve, the straight pipe, the three-way pipe, the elbow pipe, the support, the kettle support plate, the hose joint, the hose and the diaphragm pump inlet are connected.

[0009] The diaphragm pump is the fluid delivery power source of the whole device, the diaphragm pump is provided with a diaphragm pump discharge port, the diaphragm pump discharge port is connected with a first hose, one way of the first hose is connected to a discharge pipe, realizing flexible connection of the pump and the rigid pipe, and the discharge pipe is provided with a ball valve for manually controlling the opening and closing of the main pipe fluid.

[0010] The other way of the first hose is locked with the larger diameter end of the reducing pipe through the clamp, and the smaller diameter end of the reducing pipe is connected to one of the interfaces of the four-way pipe.

[0011] The left side of the four-way pipe is connected with the reducing pipe, and the right end of the four-way pipe is connected to the left side of the reaction kettle body; the cooling water outlet is arranged at the upper left side of the reaction kettle body, and the cooling water inlet is arranged at the lower right side of the reaction kettle body and connected with a rubber pipe and connected to a water chiller to circulate the reaction kettle; the right side of the reaction kettle is connected with the pipeline sight glass, and the pipeline sight glass is connected with the left side of the three-way pipe; the lower end of the check valve is connected with the three-way pipe through the straight pipe, and the check valve prevents the fluid from flowing back to the pump or the four-way; the right side of the three-way pipe is connected with the elbow pipe and connected with a second hose through a hose joint, and the elbow is used for changing the direction of the pipe; and the second hose is connected to the diaphragm pump inlet, that is, a material circulation loop is constructed.

[0012] In the specific embodiment of the present application, the material circulation path is: the reaction kettle body→the pipe sight glass→the three-way pipe→the elbow pipe→the second hose→the diaphragm pump feed port→the diaphragm pump→the diaphragm pump discharge port→the reducing pipe→the four-way pipe→the reaction kettle body.

[0013] In the specific embodiment of the present application, the device for preparing graphene by the delocalization electrochemical method further comprises: a support and a kettle support plate for supporting and fixing the reaction kettle body, the kettle support plate being fixed on the support.

[0014] In the specific embodiment of the present application, the first hose and the second hose are both polytetrafluoroethylene hoses.

[0015] In the specific embodiment of the present application, the diaphragm pump is a diaphragm pump for providing power for the circulation and delivery of the electrolyte, which can avoid the contact between the metal parts in the pump and the corrosive medium.

[0016] In the specific embodiment of the present application, the ball valve is a ball valve with a rotating ball with a hole in the inside, which can adjust the flow of fluid in the pipeline by controlling the opening of the switch knob.

[0017] In the specific embodiment of the present application, the four-way pipe is a pipe for delivering electrolyte and provides four directional pipe connection points, the horizontal pipe parallel to the reaction kettle is used for transmitting electrolyte, and the longitudinal pipe is internally provided with a platinum sheet, which is used as the cathode and anode of the electrochemical reaction.

[0018] A method for preparing graphene by using the above-mentioned device for preparing graphene by the delocalization electrochemical method, the method comprising the following steps:

[0019] Before the device is operated, the following preparations need to be completed:

[0020] (1) Drying: weigh the high-purity graphite and place it in a vacuum drying box for drying for about 0.3-0.75 h,

[0021] (2) Stirring: add the dried electrochemical graphite into 98% concentrated sulfuric acid and mix and stir for 1 h-2 h, the stirring speed of the stirrer being 300 r / min, and a preservative film is covered during the stirring process to prevent the splashing of sulfuric acid;

[0022] (3) Equipment inspection:

[0023] a. Check whether the inside of the reaction kettle is clean, and whether the cooling pipeline is connected perfectly;

[0024] b. Check whether the water in the circulating water cooler is sufficient, and whether there are any broken, knotted or blocked phenomena in the water outlet pipeline;

[0025] c. Check whether the electrochemical workstation can be started, whether the connection line is connected correctly, whether there are any damage or aging phenomena, and whether the electrochemical chuck is corroded;

[0026] (4) Trial operation: before the formal experiment, pour in pure water, open the diaphragm pump, and observe whether the circulating pipeline leaks water;

[0027] (5) Pour in the reaction solution: pour the mixed solution into the small bucket and then into the reaction kettle body in batches;

[0028] The specific process parameters for preparing high-quality electrochemical graphene based on the device are as follows:

[0029] (1) Electrolyte formula: 10L of 98% concentrated sulfuric acid as solvent, 250g-1kg of high-purity flake graphite as solute, and solvent mixed with solution as electrolyte;

[0030] (2) Electrolysis process: first add electrolyte until the pipeline sight glass is full, and the cathode and anode platinum pieces are completely immersed in the electrolyte by 15cm±1cm; then start the diaphragm pump, set the speed to 20rpm-40rpm, and ensure normal circulation of the electrolyte. There are no bubbles in the pipeline during the circulation process. The temperature of the electrolyte is controlled between 20℃ and 30℃;

[0031] The electrolysis process is divided into three stages per cycle, namely intercalation stage, expansion stage and peeling stage:

[0032] First stage: intercalation stage, turn on the power, set the current to 160A-180A, the voltage to 15V-18V, and the diaphragm pump speed to 20rpm-30rpm. The graphite around the anode platinum piece preferentially makes electrical contact. Under the action of the applied voltage, concentrated sulfuric acid releases persulfuric acid, HSO4· occurs electrochemical reaction, decomposes to produce SO3 and O2, escapes from the graphite interlayer, reduces the van der Waals force between the graphite interlayer, and lasts for 4.5h-6h;

[0033] Second stage: expansion stage, adjust the current value to 180A-200A, the voltage value to 18V-21V, and the diaphragm pump speed to 30rpm-40rpm; when the graphite enters the first intercalation stage, the intercalation limit is reached, and the duration is 1h-3h;

[0034] Third stage: peeling stage: adjust the current value to 200A-210A, the voltage value to 21V-24V, and the diaphragm pump speed to 35rpm-40rpm. The edge graphite is first peeled off into flaky single-layer or few-layer graphene, and then peels off layer by layer from the edge to the inside. The duration is 7h-11h;

[0035] Fourth stage: after one cycle of electrolyte circulation, repeat the first stage;

[0036] (3) Post-treatment process

[0037] After the peeling is finished, the solution is washed to PH≈7 using deionized water, and then high-quality graphene powder is obtained after emulsification, homogenization, ultrasonic, centrifugation and freeze-drying steps.

[0038] The positive progress effect of the application is that the device and method for preparing graphene by delocalization electrochemistry provided by the application have the following advantages: the reaction kettle body and electrolyte delivery pipeline in the electrolysis circulation system can resist concentrated sulfuric acid corrosion; the hose at the outlet of the diaphragm pump is used for buffering and slowing down vibration and shaking; a pipeline sight glass is added to facilitate observation of the fluid state; the closed circulation cooling design greatly improves the cooling effect, realizes the integration of corrosion-resistant fluid delivery, reaction temperature control and safe discharge, and has the characteristics of simple structure, high temperature control efficiency, good consistency and safe overall structure. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 It is a schematic diagram of the overall structure of the application.

[0040] Figure 2-1 It is a schematic diagram of the overall structure of the application.

[0041] Figure 2-2 It is a schematic diagram of the overall structure of the application. Figure 2-1

[0042] Figure 3 It is a schematic diagram of the overall structure of the application.

[0043] Figure 4 It is a schematic diagram of the overall structure of the application.

[0044] Figure 5 It is a scanning electron microscope image of the black slurry prepared in Example 1.

[0045] Figure 6 It is an image obtained by globally scanning the graphene sheet layer on the substrate using AFM.

[0046] Figure 7 It is a statistical result graph of the thickness of the graphene sheet layer.

[0047] The following is the name corresponding to the label in the application:

[0048] Figure 1-4 Diaphragm pump 1, diaphragm pump outlet 2, discharge pipe 3, ball valve 4, clamp 5, reducing pipe 6, four-way pipe 7, reaction kettle body 8, cooling water outlet 9, cooling water inlet 10, pipeline sight glass 11, check valve 12, straight pipe 13, three-way pipe 14, elbow pipe 15, support 16, kettle support plate 17, hose joint 18, Teflon hose 19, diaphragm pump inlet 20. DETAILED DESCRIPTION

[0049] ​The exfoliation of graphene sheets by the delocalized electrochemical method mainly experiences three stages: intercalation, expansion and exfoliation. The method selects platinum material as an electrolysis electrode, and a mixed solution of concentrated sulfuric acid and graphite as an electrolyte. After the power is turned on, the graphite around the anode platinum sheet preferentially occurs electrical contact. Under the action of an applied voltage, the concentrated sulfuric acid is released as persulfuric acid (H2S2O8, same below), and HSO4· occurs electrochemical reaction, decomposes to generate SO3 and O2 which escapes from the graphite interlayer, that is, enters the intercalation stage, and the van der Waals force between the graphite interlayer is reduced. When the graphite intercalation ends, it enters the expansion stage, and the graphite volume becomes larger and floats upward, and then quickly enters the exfoliation stage, and the edge layer graphite is first exfoliated into single or few-layer graphene, and the electrochemical reaction ends. The electrolysis circulating device adopts a closed cooling design, which changes from local cooling to global cooling, greatly improves the cooling effect, and the electrolysis intercalation effect is better. At the same time, a pressure relief port is preset on the closed internal circulation system to improve the safety of the equipment during operation. In the electrolysis reaction process, the electrolytic graphite does not directly contact the electrode, but reacts at the active sites on the surface of the electrode under the action of the electric field to generate graphene sheets. By optimizing the electrolysis conditions and electric field distribution, not only can the problem of uneven quality distribution of traditional electrochemically prepared graphene be improved, but also the subsequent screening process can be omitted, the product quality can be improved, and the process flow can be simplified.

[0050] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, to explain the technical solutions of the present application in detail, Figure 1 is a perspective view of the overall structure of the present application, Figure 2-1 is a bottom view of the overall structure of the present application, Figure 2-2 is Figure 2-1 is a partial enlarged view of Figure 3 is a front view of the overall structure of the present application, Figure 4 is a front view of the overall structure of the present application, as shown in the above figure: the device for preparing graphene by the delocalized electrochemical method proposed by the present application comprises the following components: a diaphragm pump 1, a diaphragm pump discharge port 2, a discharge pipe 3, a ball valve 4, a clamp 5, a reducing pipe 6, a four-way pipe 7, a reaction kettle body 8, a cooling water outlet 9, a cooling water inlet 10, a pipe sight glass 11, a check valve 12, a straight pipe 13, a three-way pipe 14, an elbow pipe 15, a support 16, a kettle support plate 17, a hose joint 18, a four-fluorine hose 19, and a diaphragm pump inlet 20.

[0051] The diaphragm pump 1 in the present application provides power for the circulation and delivery of the electrolyte, which can avoid the contact between the metal parts in the pump and the corrosive medium.

[0052] The diaphragm pump discharge port 2 in the present application discharges the electrolyte sucked into the diaphragm from the outlet of the pump cavity.

[0053] The discharge pipe 3 in the present application is used for discharging waste liquid, product or cleaning liquid after the reaction is completed.

[0054] The ball valve 4 in the application has a rotating ball with a hole inside, and by controlling the opening of the switch knob, the fluid flow in the pipeline is adjusted.

[0055] The clamp 5 in the application fastens the connection between the hose and the pipe fitting, ensuring the sealing and firmness of the connection, and preventing leakage.

[0056] The reducing pipe 6 in the application connects pipelines with different diameters, realizes smooth transition of pipe diameter, and changes the fluid flow rate.

[0057] The four-way pipe 7 in the application transports electrolyte pipelines and provides four-directional pipeline connection points. The transverse (parallel to the reaction kettle) pipeline is mainly used for transmitting electrolyte, and the longitudinal pipeline is internally provided with platinum sheets, which are used as cathode and anode for electrochemical reaction.

[0058] The reaction kettle body 8 in the application is an electrochemical reaction area, which contains electrodes and electrolyte inside and is internally provided with a jacket for containing cooling water. The reaction kettle body 8 in the application is made of 316L stainless steel.

[0059] The cooling water outlet 9 in the application is the outlet of the reaction kettle jacket, which discharges the cooling water with increased temperature after cooling the reaction kettle to the system.

[0060] The cooling water inlet 10 in the application connects the reaction kettle jacket and introduces cooling water to control the temperature in the reaction kettle.

[0061] The pipeline sight glass 11 in the application is installed on the pipeline and is used to directly observe the flow state, color, bubbles or impurities of the fluid in the pipeline.

[0062] The one-way valve 12 in the application only allows one-way flow of fluid and is used to protect the pump and maintain the pressure of the pipeline.

[0063] The straight-through pipe 13 in the application is used to connect two coaxial pipe fittings.

[0064] The three-way pipe 14 in the application transports electrolyte pipelines and provides three-directional pipeline connection points, which are used to divide the fluid into two branches or collect the fluid from two branches.

[0065] The elbow pipe 15 in the application is used to change the direction of the pipeline (90°) and guide the flow direction.

[0066] The bracket 16 in the application is used to support and fix the pipeline and valve, keep the pipeline system stable, and reduce vibration and stress.

[0067] The kettle support plate 17 in the application is used to support and fix the reaction kettle body, ensuring its stable placement.

[0068] The hose joint 18 in the application is used to connect the hose with the pipe fitting or equipment interface.

[0069] The four-fluorine hose 19 in the application is used for conveying corrosive electrolyte.

[0070] The diaphragm pump inlet 20 in the application sucks the electrolyte in the reaction kettle into the inlet of the diaphragm pump cavity.

[0071] The matching relationship between the components in the application is as follows:

[0072] Starting point and power source: the diaphragm pump 1 is the fluid conveying power source of the whole system. The diaphragm pump outlet 2 is connected with the polytetrafluoroethylene hose, which is connected to the discharge pipe 3, realizing flexible connection of the pump and rigid pipeline (for shock absorption and convenient docking), and the ball valve 4 is connected to the discharge pipe 3, which is used for manually controlling the opening and closing of the fluid in the main pipeline.

[0073] Main material pipeline: the other way of the polytetrafluoroethylene hose is locked with the larger diameter end of the reducing pipe 6 through the clamp 5, and the smaller diameter end of the reducing pipe 5 is connected to one of the interfaces of the four-way pipe 7 (usually one inlet in the horizontal direction).

[0074] Reaction kettle connection and circulation: the left side of the four-way pipe 7 is connected with the reducing pipe 6, and the right end of the four-way pipe 7 is connected to the left side of the reaction kettle body 8; the cooling water outlet 9 is arranged at the upper left side of the reaction kettle body 8, and the cooling water inlet 10 is arranged at the lower right side, which is connected with the rubber pipe and connected to the water cooler to circulate and cool the reaction kettle; the reaction kettle 8 is connected with the pipeline sight glass 11 at the right side, the pipeline sight glass 11 is connected with the left side of the three-way pipe 14, the reaction kettle body 8 is supported by the kettle support plate 17, the kettle support plate 17 is fixed on the support 16, the lower end of the one-way valve 12 is connected with the three-way pipe 14 through the 13 straight pipe, and the one-way valve prevents the fluid from flowing back to the pump or the four-way pipe; the right side of the three-way pipe 14 is connected with the elbow pipe 15 and connected with the polytetrafluoroethylene hose 19 through the hose joint 18, and the elbow is used to change the direction of the pipeline; the polytetrafluoroethylene hose 9 is connected to the diaphragm pump inlet 20, that is, the material circulation loop is constructed, and the material circulation path is: the reaction kettle body 8→the pipeline sight glass 11→the three-way pipe 14→the elbow pipe 15→the polytetrafluoroethylene hose 19→the diaphragm pump inlet 20→the diaphragm pump 1→the diaphragm pump outlet 2→the reducing pipe 6→the four-way pipe 7→the reaction kettle body 8.

[0075] Before the device is operated, the following preparations need to be completed:

[0076] 1. Drying: high-purity graphite is weighed and placed in a vacuum drying box for drying for about 0.5 h (80℃).

[0077] 2. Stirring: the dried electrochemical graphite is added into 98% concentrated sulfuric acid, mixed and stirred for 1 h, the stirring speed of the stirrer is 300 r / min, and the stirring process is covered with plastic wrap to prevent sulfuric acid from splashing.

[0078] 3. Equipment inspection:

[0079] a. Check whether the inside of the 8th reaction kettle is clean, and whether the cooling pipeline is connected perfectly.

[0080] b. Check whether the circulating water machine has sufficient water, and whether the water outlet pipeline has any breakage, knot, or blockage.

[0081] c. Check whether the electrochemical workstation can be started, whether the connection line is connected correctly, whether there is any damage or aging, and whether the electrochemical chuck is corroded.

[0082] 4. Trial operation: Before the formal experiment, pour in pure water, turn on the diaphragm pump, and observe whether the circulating pipeline leaks.

[0083] 5. Pour in the reaction solution: Pour the mixed solution into a 2.5L bucket and pour it into the reaction kettle in batches.

[0084] The specific process parameters for preparing high-quality electrochemical graphene based on this equipment are as follows:

[0085] 1. Electrolyte formula: 10L of 98% concentrated sulfuric acid as solvent, 250g-1kg of high-purity flake graphite as solute, and the mixture of solvent and solution as electrolyte.

[0086] 2. Electrolysis process: First, add electrolyte until the pipeline sight glass is full, and the cathode and anode platinum pieces are completely immersed in the electrolyte about 15cm±1cm. Then turn on the diaphragm pump, set the speed to 20rpm-40rpm, and ensure that the electrolyte circulates normally. There should be no bubbles in the pipeline during the circulation process. The temperature of the electrolyte should be controlled between 20℃ and 30℃.

[0087] The electrolysis process is divided into three stages, namely intercalation, expansion, and exfoliation.

[0088] First stage: intercalation stage. Turn on the power, set the current to 160A-180A, the voltage to 15V-18V, and the diaphragm pump speed to 20rpm-30rpm. The graphite around the anode platinum piece preferentially makes electrical contact. Under the action of the applied voltage, concentrated sulfuric acid releases persulfuric acid (H2S2O8, same below), HSO4· occurs electrochemical reaction, decomposes to produce SO3 and O2, which escapes from the graphite interlayer, reduces the van der Waals force between the graphite layers, and continues for 4.5h-6h.

[0089] Second stage: expansion stage. The current value is adjusted to 180A-200A, the voltage value is adjusted to 18V-21V, and the diaphragm pump speed is adjusted to 30rpm-40rpm. Wait for the graphite to enter the first intercalation stage (GIC-I) for intercalation limit, duration 1h-3h. (Intercalated graphite can be divided into first-order intercalation compounds, second-order intercalation compounds, …, n-order intercalation compounds according to the insertion state. The orderly insertion of one layer of intercalation reactants between the layers of graphite is called first-order intercalation compound.)

[0090] Third stage: exfoliation stage. The current value is adjusted to 200A-210A, the voltage value is adjusted to 21V-24V, and the diaphragm pump speed is adjusted to 35rpm-40rpm. The edge graphite is first exfoliated into flaky single-layer or few-layer graphene, and then exfoliated layer by layer from the edge to the inside. Duration 7h-11h.

[0091] Fourth stage: After one cycle of electrolyte circulation, repeat the first stage.

[0092] 3. Post-processing process

[0093] After the exfoliation is completed, the solution is rinsed with deionized water to PH≈7, and then subjected to emulsification, homogenization, ultrasonic, centrifugation and freeze-drying steps to obtain high-quality graphene powder.

[0094] Example one:

[0095] Take 10L volume fraction 98% concentrated sulfuric acid as solvent, add 250g high-purity flake graphite as solute to the solvent, and mix the solvent and solution by stirring to complete the electrolyte configuration. Add the electrolyte anode and cathode platinum pieces to completely immerse in the electrolyte about 15cm±1cm, then start the diaphragm pump, set the speed to 20rpm, and ensure that there is no air bubble in the pipeline during the electrolyte circulation. The electrolyte temperature is controlled at 20℃.

[0096] The electrolysis process is divided into three stages and is cycled.

[0097] First stage: intercalation stage. Turn on the power, set the current to 160A, the voltage to 15V, and the diaphragm pump speed to 25rpm. The graphite around the anode platinum piece preferentially occurs electrical contact, and under the action of the applied voltage, the concentrated sulfuric acid releases H2S2O8, HSO4· occurs electrochemical reaction, decomposes to produce SO3 and O2 escapes from the interlayer of graphite, reduces the van der Waals force between the layers of graphite, and lasts for 4.5h.

[0098] Second stage: expansion stage. The current value is adjusted to 180A, the voltage value is adjusted to 18V, and the diaphragm pump speed is adjusted to 30rpm. Wait for the graphite to enter the first intercalation stage (GIC-I) for intercalation limit, duration 1h.

[0099] The third stage: peeling stage. The current value is adjusted to 200 A, the voltage value is adjusted to 21 V, the diaphragm pump speed is adjusted to 35 rpm, the edge graphite is first peeled into a sheet single-layer or few-layer graphene, and then peeling occurs layer by layer from the edge to the inside, with a duration of 7 h.

[0100] The fourth stage: after the electrolyte circulates for one week and flows back to the vicinity of the electrode, the first stage is repeated.

[0101] After peeling, the solution is washed to PH≈7 using deionized water, and then high-quality graphene powder is obtained after emulsification, homogenization, ultrasonic, centrifugation and freeze-drying steps.

[0102] Example Two:

[0103] Take 10L volume fraction 98% concentrated sulfuric acid as solvent, add 300g high-purity flake graphite as solute, and mix the solvent and solution by stirring to complete the electrolyte configuration. The anode and cathode platinum pieces are completely immersed in the electrolyte by about 15cm±1cm, and then the diaphragm pump is started, with a speed of 25rpm, to ensure that there is no bubble in the pipeline during the circulation of the electrolyte. The electrolyte temperature is controlled at 25℃.

[0104] The electrolysis process is divided into three stages and is cycled.

[0105] The first stage: intercalation stage. Turn on the power, set the current to 165 A, the voltage to 16 V, and the diaphragm pump speed to 26 rpm. The graphite around the anode platinum piece preferentially occurs electrical contact, and under the action of the applied voltage, the concentrated sulfuric acid releases H2S2O8, HSO4· occurs electrochemical reaction, decomposes to produce SO3 and O2, which escapes from the graphite interlayer, reduces the van der Waals force between the graphite interlayer, and lasts for 5h.

[0106] The second stage: expansion stage. The current value is adjusted to 185 A, the voltage value is adjusted to 19 V, and the diaphragm pump speed is adjusted to 31 rpm. When the graphite enters the first intercalation stage (GIC-I) to the intercalation limit, the duration is 1.5h.

[0107] The third stage: peeling stage. The current value is adjusted to 201 A, the voltage value is adjusted to 22 V, and the diaphragm pump speed is adjusted to 36 rpm. The edge graphite is first peeled into a sheet single-layer or few-layer graphene, and then peeling occurs layer by layer from the edge to the inside, with a duration of 7.5h.

[0108] The fourth stage: after the electrolyte circulates for one week and flows back to the vicinity of the electrode, the first stage is repeated.

[0109] After peeling, the solution is washed to PH≈7 using deionized water, and then high-quality graphene powder is obtained after emulsification, homogenization, ultrasonic, centrifugation and freeze-drying steps.

[0110] Example Three

[0111] Take 10L volume fraction 98% of concentrated sulfuric acid as solvent, add 400g high purity flake graphite as solute in the solvent, and mix the solvent and solution by stirring to complete the electrolyte configuration. Add the electrolyte to completely immerse the platinum sheet of the anode and cathode in the electrolyte by 15cm±1cm, then start the diaphragm pump, set the rotating speed to 26rpm, and ensure that there is no bubble in the pipeline during the circulation of the electrolyte. The temperature of the electrolyte is controlled at 25℃.

[0112] The electrolysis process is divided into three stages and is carried out in a cycle.

[0113] The first stage is intercalation stage. Turn on the power, set the current to 170A and the voltage to 17V, adjust the rotating speed of the diaphragm pump to 27rpm, and the graphite around the anode platinum sheet preferentially occurs electrical contact. Under the action of the applied voltage, the concentrated sulfuric acid releases H2S2O8, HSO4· occurs electrochemical reaction, decomposes to produce SO3 and O2, and escapes from the interlayer of graphite, which reduces the van der Waals force between the interlayers of graphite, and lasts for 5h.

[0114] The second stage is expansion stage. The current value is adjusted to 186A, the voltage value is adjusted to 20V, and the rotating speed of the diaphragm pump is adjusted to 32rpm. When the graphite enters the first intercalation stage (GIC-I) and reaches the intercalation limit, the duration is 2h.

[0115] The third stage is exfoliation stage. The current value is adjusted to 202A, the voltage value is adjusted to 23V, and the rotating speed of the diaphragm pump is adjusted to 37rpm. The edge graphite is first exfoliated into flaky single-layer or few-layer graphene, and then the exfoliation occurs layer by layer from the edge to the inside, and the duration is 8h.

[0116] The fourth stage is that after one cycle of electrolyte circulation, the electrolyte flows back to the vicinity of the electrode, and the first stage is repeated.

[0117] After the exfoliation is completed, the solution is washed with deionized water to PH≈7, and then high-quality graphene powder is obtained after emulsification, homogenization, ultrasonic, centrifugation and freeze-drying steps.

[0118] Example Four

[0119] Take 10L volume fraction 98% of concentrated sulfuric acid as solvent, add 500g high purity flake graphite as solute in the solvent, and mix the solvent and solution by stirring to complete the electrolyte configuration. Add the electrolyte to completely immerse the platinum sheet of the anode and cathode in the electrolyte by 15cm±1cm, then start the diaphragm pump, set the rotating speed to 27rpm, and ensure that there is no bubble in the pipeline during the circulation of the electrolyte. The temperature of the electrolyte is controlled at 26℃.

[0120] The electrolysis process is divided into three stages and is carried out in a cycle.

[0121] The first stage: intercalation stage. Turn on the power, set the current to 175 A and the voltage to 17.5 V, adjust the speed of the diaphragm pump to 28 rpm, and the graphite around the anode platinum sheet preferentially makes electrical contact. Under the action of the applied voltage, concentrated sulfuric acid releases H2S2O8, and HSO4· occurs electrochemical reaction, decomposes to produce SO3 and O2, which escapes from the interlayer of graphite, reducing the van der Waals force between the interlayers of graphite, and lasts for 5.5 h.

[0122] The second stage: expansion stage. Adjust the current value to 187 A and the voltage value to 21 V, and adjust the speed of the diaphragm pump to 33 rpm. When the graphite enters the first intercalation stage (GIC-I) as the intercalation limit, the duration is 2.5 h.

[0123] The third stage: exfoliation stage. Adjust the current value to 203 A and the voltage value to 23 V, and adjust the speed of the diaphragm pump to 38 rpm. The edge graphite is first exfoliated into flaky single-layer or few-layer graphene, and then exfoliates layer by layer from the edge to the inside, with a duration of 8.5 h.

[0124] The fourth stage: after one cycle of electrolyte circulation, repeat the first stage.

[0125] After the exfoliation is completed, use deionized water to rinse the solution to PH≈7, and then go through the steps of emulsification, homogenization, ultrasonic, centrifugation and freeze-drying to obtain high-quality graphene powder.

[0126] Example Five:

[0127] Take 10L volume fraction 98% concentrated sulfuric acid as the solvent, add 600g high-purity flake graphite as the solute, and mix the solvent and the solution to complete the electrolyte configuration. Add the electrolyte, and immerse the anode and cathode platinum sheets in the electrolyte by about 15cm±1cm. Then start the diaphragm pump and set the speed to 27rpm to ensure that there are no bubbles in the pipeline during the circulation of the electrolyte. The temperature of the electrolyte is controlled at 26℃.

[0128] The electrolysis process is divided into three stages and is cycled.

[0129] The first stage: intercalation stage. Turn on the power, set the current to 175 A and the voltage to 17.5 V, adjust the speed of the diaphragm pump to 28 rpm, and the graphite around the anode platinum sheet preferentially makes electrical contact. Under the action of the applied voltage, concentrated sulfuric acid releases H2S2O8, and HSO4· occurs electrochemical reaction, decomposes to produce SO3 and O2, which escapes from the interlayer of graphite, reducing the van der Waals force between the interlayers of graphite, and lasts for 5.5 h.

[0130] The second stage: expansion stage. Adjust the current value to 187 A and the voltage value to 21 V, and adjust the speed of the diaphragm pump to 33 rpm. When the graphite enters the first intercalation stage (GIC-I) as the intercalation limit, the duration is 2.5 h.

[0131] The third stage: the peeling stage. The current value is adjusted to 204A, the voltage value is adjusted to 24V, and the diaphragm pump speed is adjusted to 39rpm. The edge graphite is peeled into sheet-like single-layer or few-layer graphene first, and then peeling occurs layer by layer from the edge to the inside, lasting for 9 hours.

[0132] Fourth stage: After the electrolyte circulates once, it flows back to the vicinity of the electrode, and the first stage is repeated.

[0133] After the exfoliation is completed, the solution is rinsed with deionized water until the pH is approximately 7. After emulsification, homogenization, sonication, centrifugation and freeze-drying, high-quality graphene powder is obtained.

[0134] Example 6:

[0135] Use 10L of 98% concentrated sulfuric acid as the solvent, and add 700g of high-purity flake graphite as the solute. Mix the solvent and solution to prepare the electrolyte. Add the electrolyte, ensuring the anode and cathode platinum sheets are completely submerged in the electrolyte to approximately 15cm ± 1cm. Then, turn on the diaphragm pump and set the speed to 28rpm, ensuring no air bubbles in the pipeline during electrolyte circulation. Maintain the electrolyte temperature at 27℃.

[0136] The electrolysis process is divided into three stages, which are carried out in a cycle.

[0137] Phase 1: Intercalation Phase. Turn on the power, set the current to 177A and the voltage to 19V, and adjust the diaphragm pump speed to 30rpm. The graphite around the anode platinum sheet preferentially makes electrical contact. Under the action of the applied voltage, concentrated sulfuric acid is released as H2S2O8, releasing HSO4· which undergoes an electrochemical reaction, decomposing to produce SO3 and O2 that escape from the graphite interlayer, reducing the van der Waals forces between the graphite layers, and this process continues for 6 hours.

[0138] Second stage: Expansion stage. The current value is adjusted to 189A, the voltage value to 21V, and the diaphragm pump speed to 35rpm. The intercalation limit is reached when the graphite enters the first-order intercalation stage (GIC-Ⅰ), which lasts for 3 hours.

[0139] The third stage: the peeling stage. The current value is adjusted to 205A, the voltage value is adjusted to 24V, and the diaphragm pump speed is adjusted to 40rpm. The edge graphite is peeled into sheet-like single-layer or few-layer graphene first, and then peeling occurs layer by layer from the edge to the inside, lasting for 9.5 hours.

[0140] Fourth stage: After the electrolyte circulates once, it flows back to the vicinity of the electrode, and the first stage is repeated.

[0141] After the exfoliation is completed, the solution is rinsed with deionized water until the pH is approximately 7. After emulsification, homogenization, sonication, centrifugation and freeze-drying, high-quality graphene powder is obtained.

[0142] Example Seven

[0143] Take 10L volume fraction 98% of concentrated sulfuric acid as solvent, add 800g high purity flake graphite as solute in the solvent, and mix the solvent and solution by stirring to complete the electrolyte configuration. Add the electrolyte to completely immerse the platinum sheet of the anode and cathode in the electrolyte by about 15cm±1cm, then start the diaphragm pump, set the speed to 29rpm, and ensure that there are no bubbles in the pipeline during the circulation of the electrolyte. The electrolyte temperature is controlled at 28℃.

[0144] The electrolysis process is divided into three stages and is cycled.

[0145] First stage: intercalation stage. Turn on the power supply, set the current to 178A and the voltage to 17V, adjust the diaphragm pump speed to 30rpm, and the graphite around the anode platinum sheet preferentially makes electrical contact. Under the action of the applied voltage, concentrated sulfuric acid releases H2S2O8, HSO4· occurs electrochemical reaction, decomposes to produce SO3 and O2, escapes from the interlayer of graphite, reduces the van der Waals force between the interlayers of graphite, and lasts for 5.5h.

[0146] Second stage: expansion stage. Adjust the current value to 190A, the voltage value to 21V, and the diaphragm pump speed to 36rpm. When the graphite enters the first intercalation stage (GIC-I), the intercalation limit is reached, and the duration is 1.5h.

[0147] Third stage: exfoliation stage. Adjust the current value to 206A, the voltage value to 23V, and the diaphragm pump speed to 41rpm. The edge graphite is first exfoliated into flaky single-layer or few-layer graphene, and then exfoliation occurs layer by layer from the edge to the inside. The duration is 10h.

[0148] Fourth stage: After one cycle of electrolyte circulation, repeat the first stage.

[0149] After the exfoliation is completed, use deionized water to rinse the solution to PH≈7, and then go through the steps of emulsification, homogenization, ultrasonic, centrifugation and freeze-drying to obtain high-quality graphene powder.

[0150] Example Eight

[0151] Take 10L volume fraction 98% of concentrated sulfuric acid as solvent, add 900g high purity flake graphite as solute in the solvent, and mix the solvent and solution by stirring to complete the electrolyte configuration. Add the electrolyte to completely immerse the platinum sheet of the anode and cathode in the electrolyte by about 15cm±1cm, then start the diaphragm pump, set the speed to 26rpm, and ensure that there are no bubbles in the pipeline during the circulation of the electrolyte. The electrolyte temperature is controlled at 29℃.

[0152] The electrolysis process is divided into three stages and is cycled.

[0153] The first stage: intercalation stage. Turn on the power, set the current to 179 A and the voltage to 18 V, adjust the speed of the diaphragm pump to 30 rpm, and the graphite around the anode platinum sheet will preferentially make electrical contact. Under the action of the applied voltage, concentrated sulfuric acid releases H2S2O8, and HSO4· occurs electrochemical reaction, decomposes to produce SO3 and O2, which escapes from the interlayer of graphite, reducing the van der Waals force between the interlayers of graphite, and lasts for 6 h.

[0154] The second stage: expansion stage. Adjust the current value to 190 A and the voltage value to 21 V, and adjust the speed of the diaphragm pump to 37 rpm. When the graphite enters the first intercalation stage (GIC-I) as the intercalation limit, the duration is 2 h.

[0155] The third stage: exfoliation stage. Adjust the current value to 207 A and the voltage value to 23 V, and adjust the speed of the diaphragm pump to 40 rpm. The edge graphite is first exfoliated into sheet-shaped single-layer or few-layer graphene, and then exfoliates layer by layer from the edge to the inside, with a duration of 10.5 h.

[0156] The fourth stage: after one cycle of electrolyte circulation, repeat the first stage.

[0157] After the exfoliation is completed, use deionized water to rinse the solution to PH≈7, and then go through the steps of emulsification, homogenization, ultrasonic, centrifugation and freeze-drying to obtain high-quality graphene powder.

[0158] Example Nine:

[0159] Take 10L volume fraction 98% concentrated sulfuric acid as the solvent, add 950g high-purity flake graphite as the solute, and mix the solvent and the solution to complete the electrolyte configuration. Add the electrolyte, and immerse the anode and cathode platinum sheets in the electrolyte by about 15cm±1cm. Then start the diaphragm pump and set the speed to 26rpm to ensure that there are no bubbles in the pipeline during the circulation of the electrolyte. The temperature of the electrolyte is controlled at 30℃.

[0160] The electrolysis process is divided into three stages and is cycled.

[0161] The first stage: intercalation stage. Turn on the power, set the current to 179 A and the voltage to 18 V, adjust the speed of the diaphragm pump to 30 rpm, and the graphite around the anode platinum sheet will preferentially make electrical contact. Under the action of the applied voltage, concentrated sulfuric acid releases H2S2O8, and HSO4· occurs electrochemical reaction, decomposes to produce SO3 and O2, which escapes from the interlayer of graphite, reducing the van der Waals force between the interlayers of graphite, and lasts for 6 h.

[0162] The second stage: expansion stage. Adjust the current value to 190 A and the voltage value to 21 V, and adjust the speed of the diaphragm pump to 37 rpm. When the graphite enters the first intercalation stage (GIC-I) as the intercalation limit, the duration is 2 h.

[0163] The third stage is a peeling stage. The current value is adjusted to 208 A, the voltage value is adjusted to 24 V, and the diaphragm pump speed is adjusted to 40 rpm. The edge graphite is first peeled into a sheet-shaped single-layer or few-layer graphene, and then peels layer by layer from the edge to the inside. The duration is 10 h.

[0164] The fourth stage is that the electrolyte flows back to the vicinity of the electrode after circulating for one week, and the first stage is repeated.

[0165] After the peeling is completed, the solution is washed to PH ≈ 7 using deionized water, and then high-quality graphene powder is obtained after emulsification, homogenization, ultrasonic, centrifugation and freeze-drying steps.

[0166] Example Ten:

[0167] 10 L of concentrated sulfuric acid with a volume fraction of 98% is taken as a solvent, and 1000 g of high-purity flake graphite is added as a solute. The solvent and the solution are stirred and mixed to complete the electrolyte configuration. The cathode and anode platinum pieces are completely immersed in the electrolyte by about 15 cm ± 1 cm. Then the diaphragm pump is started, and the speed is set to 27 rpm to ensure that there are no bubbles in the pipeline during the circulation of the electrolyte. The temperature of the electrolyte is controlled at 30°C.

[0168] The electrolysis process is divided into three stages and is circulated.

[0169] The first stage is an intercalation stage. The power is turned on, the current is set to 180 A, the voltage is set to 16 V, and the diaphragm pump speed is adjusted to 30 rpm. The graphite around the anode platinum piece preferentially occurs electrical contact. Under the action of the applied voltage, the concentrated sulfuric acid releases H2S2O8, and HSO4· occurs electrochemical reaction to decompose SO3 and O2 to escape from the graphite interlayer, reducing the van der Waals force between the graphite interlayer. The duration is 4.5 h.

[0170] The second stage is an expansion stage. The current value is adjusted to 190 A, the voltage value is adjusted to 21 V, and the diaphragm pump speed is adjusted to 35 rpm. When the graphite enters the intercalation limit of the first stage (GIC-I), the duration is 2 h.

[0171] The third stage is a peeling stage. The current value is adjusted to 210 A, the voltage value is adjusted to 24 V, and the diaphragm pump speed is adjusted to 40 rpm. The edge graphite is first peeled into a sheet-shaped single-layer or few-layer graphene, and then peels layer by layer from the edge to the inside. The duration is 11 h.

[0172] The fourth stage is that the electrolyte flows back to the vicinity of the electrode after circulating for one week, and the first stage is repeated.

[0173] After the peeling is completed, the solution is washed to PH ≈ 7 using deionized water, and then high-quality graphene powder is obtained after emulsification, homogenization, ultrasonic, centrifugation and freeze-drying steps.

[0174] Figure 5 A scanning electron microscope image of the black paste prepared in Example 1, Figure 6 An image obtained by globally scanning the graphene sheet layer on the substrate using an AFM, Figure 7 A statistical result graph of the thickness of the graphene sheet layer. Refer to Figure 5-7 , Figure 5 It can be seen that the product is a sheet structure, showing a typical graphene morphology, indicating that the product prepared by the method of the application is a graphene sheet layer. In order to accurately determine the thickness and number of layers of the graphene prepared by the delocalization electrochemical method, the graphene sheet layer on the substrate is globally scanned using an AFM, and the image shown in Figure 6 It can be seen that the graphene sheet layer is thin and small in size, and the thickness statistical result is shown in Figure 7 It can be seen that the graphene prepared by the delocalization electrochemical method has a low number of layers, with 55.4% of the graphene having 10 layers or less and 32.9% of the graphene having 10-20 layers, indicating that the graphene prepared by this method has high quality. Figure 7

[0175] The application provides a method and device for realizing non-contact peeling of graphene from an electrode by delocalization electric field to prepare high-quality graphene material. The application designs a novel closed circulation cooling mode to improve the cooling efficiency. Under the action of an electric field, the active sites of graphite on the surface of an electrode react to generate graphene sheet layers. By optimizing the electrolysis conditions and electric field distribution, the problems of uneven quality distribution of graphene prepared by a traditional electrochemical method can be solved, and the subsequent screening process can be omitted, and the problems of electrode pollution, uneven product, and scale limitation in the traditional electrochemical method can be solved.

[0176] In the device provided by the application, the reaction kettle body and the electrolyte delivery pipeline can resist concentrated sulfuric acid corrosion. The hose at the outlet of the diaphragm pump is used for buffering and slowing down the vibration and shaking. The pipeline sight glass is added to facilitate observation of the fluid state. The closed circulation cooling design greatly improves the cooling effect, realizes the integration of corrosion-resistant fluid delivery, reaction temperature control, and safe discharge, and has the characteristics of simple structure, high temperature control efficiency, good consistency, and safe overall structure.

[0177] The above shows and describes the basic principles and main features of the application and the advantages of the application. Those skilled in the art should understand that the application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the application. Without departing from the spirit and scope of the application, various changes and improvements can be made to the application, and these changes and improvements all fall within the scope of the claimed application. The scope of protection of the application is defined by the appended claims and their equivalents.​

Claims

1. An apparatus for preparing graphene by delocalized electrochemical method, characterized in that: The apparatus for preparing graphene by delocalized electrochemical method includes: Diaphragm pump, diaphragm pump outlet, discharge pipe, ball valve, clamp, reducer, four-way pipe, reactor body, cooling water outlet, cooling water inlet, pipe sight glass, check valve, straight pipe, tee pipe, elbow pipe, bracket, reactor support plate, hose connector, hose, diaphragm pump inlet; The diaphragm pump is the power source for fluid transport in the entire device. The diaphragm pump is equipped with a diaphragm pump outlet, which is connected to the first hose. One of the first hoses is connected to the discharge pipe, realizing a flexible connection between the pump and the rigid pipeline. The discharge pipe is equipped with a ball valve for manually controlling the opening and closing of the fluid in the main pipeline. The other end of the first flexible hose is locked to the larger diameter end of the reducer via a clamp, and the smaller diameter end of the reducer is connected to one of the ports of the four-way pipe. The left side of the four-way pipe connects to the reducer, and the right end of the four-way pipe connects to the left side of the reactor body. The upper left of the reactor body is the cooling water outlet, and the lower right is the cooling water inlet, which connects to the rubber hose and then to the chiller for circulating cooling of the reactor. The right side of the reactor body connects to the pipe sight glass, which connects to the left side of the three-way pipe. The lower end of the check valve connects to the three-way pipe through a straight pipe. The check valve prevents fluid from flowing back to the pump or the four-way pipe. The right side of the three-way pipe connects to an elbow pipe and then to a second hose through a hose connector. The elbow is used to change the direction of the pipeline. The second hose connects to the diaphragm pump inlet, thus forming a material circulation loop.

2. The apparatus for preparing graphene by delocalized electrochemical method according to claim 1, characterized in that: The material circulation path is as follows: reactor body → pipe sight glass → tee pipe → elbow pipe → second flexible hose → diaphragm pump inlet → diaphragm pump → diaphragm pump outlet → reducer → four-way pipe → reactor body.

3. The apparatus for preparing graphene by delocalized electrochemical method according to claim 1, characterized in that: The apparatus for preparing graphene by delocalized electrochemical method also includes: a support and a vessel support plate mounted on the support for supporting and fixing the reaction vessel body, the vessel support plate being fixed on the support.

4. The apparatus for preparing graphene by delocalized electrochemical method according to claim 1, characterized in that: Both the first and second hoses are polytetrafluoroethylene (PTFE) hoses.

5. The apparatus for preparing graphene by delocalized electrochemical method according to claim 1, characterized in that: A diaphragm pump is a pump that provides power for the circulation and delivery of electrolyte, and avoids contact between the metal parts inside the pump and corrosive media.

6. The apparatus for preparing graphene by delocalized electrochemical method according to claim 1, characterized in that: A ball valve is a valve with an internal rotating ball and a perforated hole. The flow rate of fluid in a pipeline is adjusted by controlling the opening of a switch knob.

7. The apparatus for preparing graphene by delocalized electrochemical method according to claim 1, characterized in that: The four-way pipe is used to transport the electrolyte and provides pipe connection points in four directions. The horizontal pipe, parallel to the reactor, is used to transport the electrolyte; the vertical pipe has a built-in platinum sheet, which is used as the cathode and anode of the electrochemical reaction.

8. A method for preparing graphene using an apparatus for preparing graphene by any one of claims 1-7, characterized in that: The method includes the following steps: The following preparatory work needs to be completed before the device is put into operation: (1) Drying: Weigh out high-purity graphite and place it in a vacuum drying oven to dry for approximately 0.3-0.75 hours. (2) Stirring: Add the dried electrochemical graphite to 98% concentrated sulfuric acid and stir for 1-2 hours. The stirring speed is 300 r / min. Cover with plastic wrap during the stirring process to prevent sulfuric acid from splashing. (3) Equipment inspection: a. Check whether the inside of the reactor is clean and whether the cooling pipes are properly connected; b. Check whether the water volume inside the circulating chiller is sufficient, and whether there are any breaks, knots, or obstructions in the water outlet pipe; c. Check whether the electrochemical workstation can be started, whether the connection lines are connected correctly, whether there is any damage or aging, and whether the electrochemical chuck is corroded. (4) Trial run: Before the formal experiment, pour in pure water, turn on the diaphragm pump, and observe whether the circulation pipeline leaks. (5) Pour the reaction solution: Pour the mixed solution into a small bucket and then pour it into the reaction vessel in batches; The specific process parameters for preparing high-quality electrochemical graphene based on this device are as follows: (1) Electrolyte formulation: 10L of 98% concentrated sulfuric acid by volume is used as solvent, and 250g to 1kg of high-purity flake graphite is added to the solvent as solute. The solvent and solution are mixed to form the electrolyte. (2) Electrolysis process: First, add electrolyte until the pipe sight glass is full, and the anode and cathode platinum sheets are completely immersed in the electrolyte for 15cm±1cm; then turn on the diaphragm pump and set the speed to 20rpm~40rpm to ensure normal circulation of electrolyte, and no air bubbles in the pipeline during the circulation process; the electrolyte temperature is controlled between 20℃~30℃. Each cycle of the electrolysis process is divided into three stages: the intercalation stage, the expansion stage, and the stripping stage. First stage: Intercalation stage. Turn on the power, set the current to 160A~180A and the voltage to 15V~18V, and adjust the diaphragm pump speed to 20rpm~30rpm. The graphite around the anode platinum sheet preferentially makes electrical contact. Under the action of the applied voltage, concentrated sulfuric acid is released into persulfate, releasing HSO4· and undergoing an electrochemical reaction. The decomposition produces SO3 and O2 that escape from the graphite interlayer, reducing the van der Waals forces between the graphite layers. This lasts for 4.5h~6h. Second stage: expansion stage, the current value is adjusted to 180A~200A, the voltage value is adjusted to 18V~21V, and the diaphragm pump speed is adjusted to 30rpm~40rpm; the intercalation limit is reached when the graphite enters the first intercalation stage, which lasts for 1h~3h. The third stage: the peeling stage: the current value is adjusted to 200A~210A, the voltage value is adjusted to 21V~24V, the diaphragm pump speed is adjusted to 35rpm~40rpm, the edge graphite is peeled into sheet-like single layer or few layers of graphene first, and then peeling occurs layer by layer from the edge to the inside, lasting 7h~11h. Fourth stage: After the electrolyte circulates once, it flows back to the vicinity of the electrode, and the first stage is repeated; (3) Post-processing technology After the exfoliation was completed, the solution was rinsed with deionized water until the pH was approximately 7. After emulsification, homogenization, sonication, centrifugation and freeze-drying, high-quality graphene powder was obtained.

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