Method for preparing graphene based on radio chemical mechanical stripping

Abstract

The invention discloses a method for preparing graphene based on radio chemical mechanical stripping, and belongs to the technical field of material preparation. The method comprises the following steps: S1, preparing a stripping solution: mixing graphite powder with a mixed solution containing electrolyte to prepare the stripping solution; s2, a radio chemical mechanical stripping device is assembled, specifically, a polishing pad is pasted to the bottom of a polishing disc with the same diameter, and the polishing pad and the polishing disc are provided with the same through holes arranged in a honeycomb array; a pair of positive and negative electrodes is arranged on the bottom wall of each through hole of the polishing disc, merged into a bus line at the top of the polishing disc and connected with positive and negative electrodes of a power supply through conductive slip rings; the polishing head clings to the polishing pad; and S3, dropping a stripping solution into the through hole, and carrying out stripping treatment on the stripping solution to prepare graphene. According to the method, expensive experimental equipment and tedious steps are not needed, extreme conditions such as high temperature, high pressure and vacuum are not involved, graphene can be efficiently prepared from the graphite raw material in a large scale within a short time, and the method has the advantages of being easy to operate, practical, convenient and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of material preparation, and provides a method for preparing graphene based on radio-chemical mechanical exfoliation, in particular to a method for preparing graphene based on radio-chemical mechanical exfoliation of graphite powder. Background Art

[0002] In recent years, the single-layer sp 2 Two-dimensional graphene, composed of hybrid carbon and specialized structures consisting of stacked monolayers, continues to be discovered to possess novel properties, expanding its potential applications. However, large-scale applications require the production of high-quality graphene in large quantities.

[0003] Electrochemical oxidation of graphite materials, which can drive anions into the interior of graphite single crystal particles to weaken the interlayer bonding, is one of the feasible methods for exfoliating graphene. For example, Chinese invention patents with application numbers CN201210314278.7, CN202211700690.2, CN201710086546.7, CN202211151441.2, CN201110439505.4, CN202010263056.1, and CN202210848291.4 disclose various methods for producing graphene by electrochemical oxidation. These methods can produce graphene from inexpensive graphite materials, but are limited to graphite raw materials with large surface area or volume, such as blocks or paper. This is because these methods rely on traditional wired electrochemistry, using wires to directly connect the graphite anode to the power supply. This limits wired connections to graphite materials with large areas or volumes. Since various inexpensive graphite materials with large areas or volumes are made by bonding and solidifying graphite powder with a binder, the graphene produced from these graphite materials inevitably contains contaminants such as the binder.

[0004] Mechanical exfoliation is another exfoliation method for graphene. Graphene was first discovered by repeatedly exfoliating bulk, highly ordered graphite using tape. Mechanical exfoliation avoids the potential for oxidation to damage the graphene structure, resulting in higher quality and finer results than electrochemical exfoliation. However, mechanical exfoliation is inefficient and, like electrochemical exfoliation, requires a large surface area or volume of graphite feedstock, making it difficult to produce large quantities of graphene from raw graphite particles.

[0005] Therefore, it is necessary to provide a method for preparing graphene by exfoliation directly from graphite particle raw materials with high exfoliation efficiency, simple process, low cost and high purity, so as to improve product purity and reduce process cost. Summary of the Invention

[0006] To achieve the aforementioned technical objectives, the present invention provides a method for preparing graphene via wireless electrochemical mechanical exfoliation. This method improves upon the wireless photoelectrochemical polishing methods disclosed in Chinese invention patents CN202110426699.8 and CN202310426153.1 (these two patents are applicable only to the polishing of semiconductor and conductive porous material workpieces, respectively). Specifically, for graphite particles, a unique powdery material, the present invention develops a highly efficient, large-scale graphene production method that combines electrochemical oxidation with mechanical friction exfoliation, which has significant application value. This method enables the direct production of graphene from graphite particle raw materials, resulting in a product that is not only highly pure but also simpler and less expensive.

[0007] In a first aspect, the present invention provides a method for preparing graphene based on radio-chemical mechanical exfoliation, the specific steps of which are as follows: S1: preparing a stripping solution: mixing graphite powder with a mixed solution containing an electrolyte to prepare a stripping solution; S2: Assembling the radio-chemical mechanical exfoliation device: The polishing pad is attached to the bottom of a polishing plate with the same diameter, wherein the polishing pad and the polishing plate have through holes arranged in the same honeycomb array; A pair of positive and negative electrodes are provided on the bottom wall of each through hole of the polishing plate. Each of the positive and negative electrodes is connected to the bus line of the positive and negative electrode bus line area on the top of the polishing plate through a wire, and is connected to the positive and negative electrodes of the power supply through a conductive slip ring; The polishing head is close to the polishing pad; S3: dropping a stripping liquid into the through hole, and performing a stripping treatment on the stripping liquid using the device of S2 to obtain graphene.

[0008] Furthermore, during the stripping process, the stripping liquid drips onto the surface of the polishing head through the through hole, and the stripping liquid, the positive and negative electrodes and the polishing head together form an electrolytic cell, and the positive and negative electrodes are separated from the polishing head by the polishing pad.

[0009] Furthermore, during the stripping process, upon application of voltage, the graphite powder in each electrolytic cell is electrochemically oxidized.

[0010] Furthermore, during the stripping process, the polishing disc and the polishing pad rotate simultaneously with the polishing head so that the stripping liquid alternates evenly between electrochemical oxidation and mechanical friction, thereby achieving electrochemical mechanical stripping.

[0011] Furthermore, during the stripping process, the stripping liquid is collected in a stripping liquid recovery tank and then re-entered the radio-chemical mechanical stripping device through a stripping liquid nozzle for a cyclic stripping process until the stripping is complete. In the present invention, the standard for complete stripping is that only a single layer or a base layer of graphene remains.

[0012] Furthermore, the stripping solution contains graphite powder at a weight percentage of 5-30%, preferably 5%, 10%, 15%, 20%, 25%, or 30%. If the graphite powder content in the stripping solution is too low, the preparation efficiency will be too low. If the graphite powder content is too high, solid graphite particles will accumulate in the through-holes, forming a solid conductive loop between the positive and negative electrodes (positive and negative electrodes), causing a short circuit.

[0013] Furthermore, the stripping liquid can be a water-based suspension or an organic medium suspension. When the stripping liquid is an organic medium suspension, the organic medium can be a mixture of one or more of acetonitrile, ethylene carbonate, and propylene carbonate.

[0014] Furthermore, in the stripping solution, the mixed solution containing electrolyte accounts for 70~95% by weight. Furthermore, the mixed solution containing electrolyte can be any conventional electrolyte, and any electrolyte that can achieve the purpose of the present invention is within the scope of protection.

[0015] Furthermore, the electrolyte-containing mixed solution can be a water-based suspension containing 0.1-2M Na2SO4 or 0.1-2M K2SO4; or it can be an organic medium suspension containing 0.1-1M LiPF6 solution. The electrolyte content of the electrolyte-containing mixed solution should not be too low, as this will prevent the electric field from being formed quickly and effectively. The electrolyte content should not be too high, as this will result in excessive current in the electrolytic cell and severe heat generation.

[0016] Furthermore, the stripping liquid is dripped into the through-hole at a rate of 10 mL / min to 120 mL / min, preferably 10 mL / min, 50 mL / min, 100 mL / min, or 120 mL / min. If the stripping liquid is dripped into the through-hole at a rate that is too low, an electrolytic cell structure cannot be effectively formed on the surface of the polishing head, and electrochemical oxidation cannot be achieved. If the stripping liquid is dripped into the through-hole at a rate that is too high, the cross-sectional area of ​​the electrolyte in the electrolytic cell is too large, resulting in excessive current and severe heat generation.

[0017] Furthermore, the polishing head and the polishing pad are both made of insulating materials.

[0018] Furthermore, the polishing head is pressed against the polishing pad with a certain pressure, wherein the pressure is 1.7-10 psi, preferably 1.7 psi, 2 psi, 2.5 psi, 3 psi, 3.36 psi, 3.5 psi, 4 psi, 4.5 psi, 5 psi, 6 psi, 7 psi, 8 psi, 9 psi, or 10 psi. Too high a pressure will result in excessive friction between the polishing head and the polishing pad, thereby causing unstable operation of the device. Too low a pressure will prevent electrochemical mechanical exfoliation from being achieved.

[0019] Furthermore, the simultaneous rotation includes co-directional rotation or counter-directional rotation. Further, the rotation speed of the polishing disc is 0-400 rpm, and the rotation speed of the polishing head is 0-400 rpm, and the rotation speeds of the polishing disc and the polishing head are preferably 0 rpm, 20 rpm, 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, and 400 rpm, respectively.

[0020] Furthermore, the simultaneous rotation speed is 20 to 400 rpm, preferably 20 rpm, 50 rpm, 100 rpm, 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, or 400 rpm. If the simultaneous rotation speed is too low, graphite particles in the stripping solution may accumulate in the through-holes, which may easily cause a short circuit between the positive and negative electrodes. If the simultaneous rotation speed is too high, the equipment will operate unstable, hindering the stripping process. In the present invention, the relative speed generated by the simultaneous rotation refers to the speed difference caused by the different radii of the polishing disc and polishing head at the same speed.

[0021] Furthermore, the applied voltage is 3 V to 40 V, preferably 3 V, 5 V, 10 V, 15 V, 20 V, 25 V, 30 V, 35 V, or 40 V. If the applied voltage is too low, electrochemical oxidation is difficult to occur; if the applied voltage is too high, the electrolytic cell will generate severe heat, affecting the reaction.

[0022] Furthermore, the method further comprises filtering the collected stripping liquid, washing the filter powder, and drying to obtain graphene.

[0023] In a second aspect, the present invention provides a wireless chemical mechanical stripping device comprising a stripping liquid recovery tank, a polishing head, a power supply, a polishing pad, a polishing plate, positive and negative electrodes, a positive and negative electrode busbar area, a stripping liquid nozzle, a conductive slip ring, and a circulating liquid supply system; The polishing pad is pasted on the bottom of the polishing disk with the same diameter, and the polishing pad and the polishing disk have the same honeycomb array of through holes; the polishing head is close to the polishing pad; a pair of positive and negative electrodes are set on the bottom wall of each through hole of the polishing disk, and the positive and negative electrodes are incorporated into the bus lines of the positive and negative electrode bus line area on the top of the polishing disk, and are connected to the positive and negative poles of the power supply through a conductive slip ring; the bottom ends of the positive and negative electrodes are separated from the polishing head by the polishing pad; the circulating liquid supply system is connected to the stripping liquid recovery tank and the stripping liquid nozzle through a reflux pipeline; the stripping liquid nozzle is set directly above the polishing disk, which is conducive to spraying the stripping liquid into the through hole; the polishing disk and the polishing head are respectively driven to rotate by motors.

[0024] Furthermore, the circulating liquid supply system includes a pump or other power device and a reflux pipeline, and any power device that can realize the stripping liquid entering the stripping liquid nozzle from the stripping liquid recovery tank can be used.

[0025] Furthermore, the polishing head, polishing pad and polishing disk are all made of electrically insulating materials, and more preferably, they are SUBA800 polishing pads (polyurethane material), and the polishing head and polishing disk are all made of polyetheretherketone (PEEK) material.

[0026] Furthermore, the polishing pad and the polishing plate have through holes of the same diameter and arranged in a honeycomb array. The diameter of the polishing pad and the polishing plate is 20 cm to 100 cm, preferably 23 cm, and the area of ​​each through hole is 0.07 cm. 2 ~1cm 2 , further preferably: the diameter is 23 cm, and the diameter of each circular through hole is 0.6 cm.

[0027] Furthermore, the polishing disc has a thickness of 2.0 to 5 cm, preferably 2 cm.

[0028] Furthermore, the diameter of the polishing head is 2.0-5 cm, preferably 5 cm.

[0029] Furthermore, a pair of positive and negative electrodes are provided on the bottom wall of each through hole of the polishing plate, and the electrode material is an alloy formed by one or more of platinum, tantalum, ruthenium, iridium or niobium, and more preferably metal platinum.

[0030] Furthermore, the positive and negative electrodes are in the shape of disk, line or sheet, or a combination thereof, and the electrode area is 0.1 mm 2 ~10mm 2 , further preferably a linear electrode, and further preferably a diameter of 0.3 mm and a length of 2 mm.

[0031] Furthermore, the positive and negative electrodes are incorporated into the bus bar and connected to the positive and negative ends of the power supply through a conductive slip ring. The conductive connection uses a wire wrapped with a waterproof insulation layer, and more preferably a copper wire wrapped with polytetrafluoroethylene, and further preferably a copper conductive diameter of 0.5 mm.

[0032] Furthermore, the polishing head is pressed against the polishing pad with a certain pressure, and the pressure is 1.7~10 psi; preferably 1.7 psi, 2 psi, 2.5 psi, 3 psi, 3.36 psi, 3.5 psi, 4 psi, 4.5 psi, 5 psi, 6 psi, 7 psi, 8 psi, 9 psi, and 10 psi.

[0033] In a third aspect, the present invention provides graphene prepared using the method of the present invention.

[0034] Furthermore, the graphene has an area greater than 5×5 μm 2 Single-layer graphene.

[0035] The principle of the method provided by the present invention is to achieve electrochemical oxidation of graphite powder particles based on the principle of bipolar electrochemistry and further exfoliate the oxidized and softened graphite particles based on mechanical friction. Specifically, although each graphite particle in the electrolyte layer is not in direct contact with the positive and negative electrodes, it is in the electric field between the two electrodes. Driven by the electric field force, for the same graphite particle, the electrons in the particle flow from the side close to the negative electrode to the side close to the positive electrode, causing the side with fewer electrons to become the anode, and an oxidation reaction of anion embedding occurs, thereby weakening the interlayer bonding force within the particle; while the other side of the graphite particle with more electrons becomes the cathode, and a reduction reaction occurs at the same time, avoiding excessive oxidation of the graphite particles and reducing the quality of graphene, which is why it is called bipolar electrochemistry. Because the graphite particle material has a large surface area / volume ratio, the efficiency of electrochemical oxidation to weaken the interlayer bonding force is very high. Simultaneously, the rotation of the polishing disc / pad and polishing head draws the graphite oxide particles between the pad and the polishing head, causing mechanical frictional exfoliation. The rough surface of the soft polishing pad effectively holds the particles, enabling efficient mechanical exfoliation of the graphite oxide particles. Furthermore, the process utilizes a circulating stripping solution, ensuring that each graphite particle in the solution continuously undergoes a two-step process of electrochemical oxidation and mechanical exfoliation until complete exfoliation. Therefore, the combined electrochemical oxidation and mechanical exfoliation method provided by the present invention allows for the efficient production of graphene from raw graphite particles.

[0036] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects: (1) The radio-chemical mechanical exfoliation method for preparing graphene provided by the present invention does not require expensive experimental equipment and cumbersome steps, nor does it involve extreme conditions such as high temperature, high pressure and vacuum. Graphene can be prepared from graphite particle raw materials under mild and environmentally friendly conditions, and has the advantages of simple operation and practical convenience.

[0037] (2) The radio-chemical mechanical exfoliation method for preparing graphene provided by the present invention can efficiently produce high-quality graphene in large quantities within a short period of time (1 hour). In the preparation method of the present invention, the product is prepared directly from graphite powder, without the presence of contaminants such as adhesives, and the product purity is high. The mechanical exfoliation after the graphite powder particles are electrochemically softened does not damage the graphene, resulting in higher quality and finer results. The graphene produced has a large area, enabling large-scale exfoliation.

[0038] (3) The method provided by the present invention can efficiently and pollution-freely prepare graphene from cheap graphite powder at room temperature and pressure without using an oxidant, and has broad application prospects.

[0039] Terminology Certain embodiments of the present invention are now described in detail, examples of which are illustrated by the accompanying structural formulas and chemical formulae. The present invention is intended to encompass all substitutions, modifications, and equivalent technical solutions, which are all included within the scope of the invention as defined in the claims. Those skilled in the art will recognize that many methods and materials similar or equivalent to those described herein can be used to practice the present invention. The present invention is in no way limited to the methods and materials described herein. In the event that one or more of the combined documents, patents, and similar materials differ from or contradict the present application (including but not limited to defined terms, term applications, described technologies, etc.), the present application shall prevail.

[0040] It will be further appreciated that certain features of the invention, which, for clarity, are described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which, for brevity, are described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

[0041] Unless otherwise specified, all technical terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. All patents and publications related to the present invention are incorporated herein by reference in their entirety.

[0042] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0043] In the following description, all numbers disclosed herein are approximate, regardless of whether the word "about" or "approximately" is used. The numerical value of each number may vary by 1%, 2%, 5%, 7%, 8%, 10%, 15%, or 20%. Whenever a number having a value of N is disclosed, any number having a value of N+ / -1%, N+ / -2%, N+ / -3%, N+ / -5%, N+ / -7%, N+ / -8%, N+ / -10%, N+ / -15%, or N+ / -20% is expressly disclosed, where "+ / -" means plus or minus. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0045] Figure 1 This is a schematic diagram of the wireless chemical mechanical stripping device used in Example 1 of the present invention. In the figure, 1 is the stripping liquid recovery tank, 2 is the polishing head, 3 is the power supply, 4 is the polishing pad, 5 is the polishing plate, 6 is the positive and negative electrodes, 7 is the positive and negative electrode busbar area, 8 is the stripping liquid nozzle, and 9 is the conductive slip ring.

[0046] Figure 2 This is a schematic diagram of the structure of the electrochemical electrolytic cell at the bottom of the polishing plate through hole in Example 1 of the present invention.

[0047] Figure 3 This is a scanning electron microscope image of graphene prepared in Example 2 of the present invention.

[0048] Figure 4 This is the Raman spectrum of the graphene and graphite particle raw materials prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0049] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the following examples. The specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention in any way. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion about the concepts of the present disclosure. Such structures and technologies are also described in many publications.

[0050] The reagents used in the present invention can be purchased from the market or prepared by the method described in the present invention.

[0051] Example 1 like Figure 1 The schematic diagram of the radio chemical mechanical stripping device shown is as follows: it includes a stripping liquid recovery tank 1, a polishing head 2, a power supply 3, a polishing pad 4, a polishing disc 5, positive and negative electrodes 6, a positive and negative electrode bus line area 7, a stripping liquid nozzle 8, a conductive slip ring 9 and a circulating liquid supply system; the polishing pad 4 is adhered to the bottom of the polishing disc 5, and the polishing pad 4 and the polishing disc 5 have through holes arranged in the same honeycomb array; the positive and negative electrodes 6 are arranged on the bottom wall of the through hole, and the positive and negative electrodes 6 are connected to the positive and negative electrode bus line area 7 through wires, and the wires of the positive and negative electrode bus line area 7 are respectively connected to the positive and negative poles of the power supply 3 through the conductive slip ring 9 (in some embodiments, the power supply 3 is a DC power supply); the bottom ends of the positive and negative electrodes 6 are separated from the polishing head 2 by the polishing pad 4; the diameter of the polishing head 2 is less than or equal to the radius of the polishing disc 5, or the edge of the polishing head 2 is not It is arranged across the central axis of the polishing disc 5 to ensure that the stripping liquid flows smoothly into the stripping liquid recovery tank 1; the stripping liquid nozzle 8 is arranged directly above the polishing disc 5, which is conducive to spraying the stripping liquid into the through hole; the polishing disc 5 and the polishing head 2 are respectively driven to rotate by a motor; during processing, the stripping liquid nozzle 8 drips the stripping liquid into the through hole, and the stripping liquid, the positive and negative electrodes 6 and the polishing head 4 form an electrolytic cell; when voltage is applied, the graphite powder in the electrolyte layer undergoes anion insertion oxidation reaction in the electric field of the positive and negative poles, and the bonding force between the graphite layers is weakened; when the motor is energized, the polishing head 2 is prompted to rotate in the same direction or opposite direction as the polishing disc 5 and the polishing pad 4. When rotating in the same direction, a relative speed is generated due to the different radii of the polishing head 2, the polishing disc 5 and the polishing pad, and the stripping liquid is rotated into the contact gap between the polishing pad 4 and the polishing head 2, so that the graphite powder in the stripping liquid can be mechanically stripped. During the processing, the stripping liquid that flows out is recovered through the stripping liquid recovery tank 1, and then the stripping liquid is returned to the stripping liquid nozzle 8 through the reflux pipeline by the pump or other power device in the circulating liquid supply system, thereby realizing the repeated circulation processing process of the graphite powder in the stripping liquid until it is completely stripped.

[0052] like Figure 2 The schematic diagram of the electrochemical cell structure at the bottom of the polishing plate through-holes shows: Two 0.3mm diameter platinum wires are vertically installed at the bottom of each through-hole on the polishing plate and fixed at both ends of the through-hole diameter, with the ends of the platinum wires and the bottom of the polishing plate restrained. Conductive adhesive is bonded to a Teflon-coated copper wire, and epoxy adhesive is then used to coat the platinum wires and the conductive bonding area, leaving only 2mm of each platinum wire end exposed. The copper wires converge at the positive and negative electrode busbar area 7 and are further connected to the positive and negative terminals of the power supply 3 via conductive slip rings 9. The stripping liquid is an electrolyte containing graphite powder.

[0053] The polishing pad and polishing disc are both made of electrically insulating materials. The polishing pad is a SUBA800 polishing pad (made of polyurethane), and the polishing disc is a polyetheretherketone (PEEK) polishing disc (with a thickness of 2.0 cm).

[0054] The specific process of preparing graphene includes: sticking a polishing pad with a through hole to the bottom of a polishing plate with the same diameter and the same through hole; setting a pair of positive and negative electrodes on the bottom wall of each through hole, and connecting the two electrodes in each through hole to the bus line of the positive and negative electrode bus line area on the top of the polishing plate, and connecting the bus line to the positive and negative poles of the power supply through a conductive slip ring; pressing a polishing head made of insulating material against the polishing pad at the bottom of the polishing plate with a certain pressure; during the preparation process, an electrolytic cell consisting of an electrolyte layer containing graphite powder, positive and negative electrodes, and the surface of the polishing head is formed in the through hole at the bottom of the polishing plate; after applying voltage, the electrolytic cell is The graphite powder in the liquid layer undergoes anion intercalation oxidation reaction in the electric field of the positive and negative poles, and the bonding force between the graphite layers is weakened; when the motor is energized, the polishing disc and the polishing head are caused to rotate in the same or opposite directions. When rotating in the same direction, a relative rotation speed is generated due to the different radii of the polishing head 2, the polishing disc 5 and the polishing pad, so that the oxidized graphite powder in the through hole is rotated into the space between the polishing pad and the polishing head, and the graphene is peeled off by mechanical friction; the electrolyte collected under the polishing head is dripped onto the surface of the polishing head, and the graphite particles continue to undergo a cycle of electrochemical oxidation and mechanical friction peeling until they are completely peeled off.

[0055] During the processing and preparation process, the positive and negative electrodes are separated from the polishing head by the polishing pad, and the stripping liquid drips through the through hole onto the surface of the polishing head to form an electrolyte layer, and the electrodes and the electrolyte layer constitute an electrolytic cell; During the processing and preparation process, when the motor is energized, the polishing head and the polishing pad or the polishing disk rotate simultaneously. After voltage is applied, the graphite particles in the electrolyte layer are electrochemically oxidized in the electrolytic cell, and then rotated between the polishing head and the polishing pad and peeled off by mechanical friction. The stripping liquid collected under the polishing head is dripped onto the surface of the polishing head, and the graphite particles undergo a cycle of electrochemical oxidation and mechanical friction stripping until they are completely stripped off.

[0056] Example 2 Graphite powder particles with a median particle size of 150 μm were mixed with an aqueous solution containing 0.1 M Na2SO4 to form a stripping solution with a solid content of 8 wt%; A polishing pad (SUBA800) and a polyetheretherketone (PEEK) polishing disk (2.0 cm thick) were used to machine 131 identical through-holes with a diameter of 0.6 cm in a Fibonacci array. The polishing pad and polishing disc, both with a diameter of 23 cm, were glued together in such a way that the through holes overlapped; A pair of platinum wire positive and negative electrodes are arranged on the bottom wall of the through hole, the positive and negative electrodes are merged into the bus bar on the top of the polishing plate, and connected to the positive and negative electrodes of the power supply through a conductive slip ring; A 5 cm diameter polishing head made of polyetheretherketone (PEEK) was pressed against the polishing pad at the bottom of the polishing plate at a pressure of 3.36 psi; Turn on the circulating liquid supply system and continuously drip the stripping liquid onto the polishing plate at a rate of 100 ml / min, through the through hole and onto the surface of the polishing head; Power on the motor so that the polishing disc and polishing head rotate in the same direction at 100 rpm; turn on the power supply, apply a 15V DC voltage, and start processing; The electrolyte collected under the polishing head is dripped onto the polishing plate at a rate of 100 ml / min, passing through the through hole and dripping onto the surface of the polishing head; After 1 hour of continuous processing, turn off the power supply, motor and circulating liquid supply system in turn; filter the collected electrolyte, and rinse the filter powder on the filter membrane with 500ml ultrapure water and 100ml anhydrous ethanol in turn, and then rinse with 90 o After drying at C for 5 h, the graphene product was obtained.

[0057] Scanning electron microscopy was used to examine the morphology (e.g. Figure 3 As shown in Figure 2), it shows that the method used in the present invention can obtain an area larger than 5×5 μm 2 Single-layer graphene product. Figure 3 It can be seen that no substance remains and high-purity graphene is obtained.

[0058] Example 3 Graphite particles with a median particle size of 50 μm were mixed with an acetonitrile solution containing 0.2 M LiPF6 to form a stripping solution with a solid content of 5 wt%; A polishing pad (SUBA800) and a polyetheretherketone (PEEK) polishing disc (2.0 cm thick) were machined to form 131 identical through-holes with a diameter of 0.6 cm in a Fibonacci array. The polishing pad and disc, both with a diameter of 23 cm, were then glued together so that the through-holes overlapped. A pair of platinum wire positive and negative electrodes are arranged on the bottom wall of the through hole, the positive and negative electrodes are merged into the bus bar on the top of the polishing plate, and connected to the positive and negative electrodes of the power supply through a conductive slip ring; A PEEK polishing head with a diameter of 5 cm was pressed against the polishing pad at the bottom of the polishing plate at a pressure of 3.36 psi; Turn on the circulating liquid supply system and continuously drip the stripping liquid onto the polishing plate at a rate of 50 ml / min, through the through hole and onto the surface of the polishing head; Power on the motor so that the polishing disc and polishing head rotate in the same direction at 60 rpm; Turn on the power supply, apply a 10 V DC voltage, and start processing. The electrolyte collected under the polishing head is dripped onto the polishing plate at a rate of 60 ml / min, passing through the through hole and dripping onto the surface of the polishing head. After 1 hour of continuous processing, turn off the power supply, motor and circulating liquid supply system in turn; After the electrolyte was collected, it was filtered and the filter powder on the filter membrane was washed with 500ml ultrapure water and 100ml anhydrous ethanol. o After drying at C for 5 h, the graphene product was obtained.

[0059] After testing, no substance was left, and high-purity graphene was obtained.

[0060] Collect Raman spectra to characterize the structure Figure 4 As shown ( Figure 4 The curve shown in Figure 1) is compared with the Raman spectrum of the graphite particle raw material ( Figure 4 Compared with the curve shown in Figure 2, the two -1 The G peak at is high and narrow, indicating that both have highly complete sp 2 Conjugated structure, but the graphene product obtained in the present invention should be at 1350 cm -1 The D peak at Figure 3 1), indicating that the distance between graphite layers is significantly enlarged, showing that the method used in the present invention obtains a graphene product with several layers stacked.

[0061] Example 4 The difference from Example 1 is that the polishing plate and the polishing head both rotate in opposite directions at a rotation speed of 100 rpm.

[0062] Example 5 The difference from Example 2 is that the polishing plate and the polishing head both rotate in opposite directions at a rotation speed of 60 rpm.

[0063] The methods of the present invention have been described through preferred embodiments. It is apparent that those skilled in the art will be able to modify or appropriately alter and combine the methods and applications described herein within the scope, spirit, and spirit of the present invention to implement and apply the technology of the present invention. Those skilled in the art may refer to the disclosure herein and appropriately modify the process parameters to achieve the desired effect. It is particularly important to note that all similar substitutions and modifications apparent to those skilled in the art are considered encompassed by the present invention.

Claims

1. A method for preparing graphene based on radio-chemical mechanical exfoliation, characterized in that: The specific steps are as follows: S1: preparing a stripping solution: mixing graphite powder with a mixed solution containing an electrolyte to prepare a stripping solution; S2: Assembling the radio-chemical mechanical exfoliation device: The polishing pad is attached to the bottom of a polishing plate with the same diameter, wherein the polishing pad and the polishing plate have through holes arranged in the same honeycomb array; A pair of positive and negative electrodes are provided on the bottom wall of each through hole of the polishing plate. Each of the positive and negative electrodes is connected to the bus line of the positive and negative electrode bus line area on the top of the polishing plate through a wire, and is connected to the positive and negative electrodes of the power supply through a conductive slip ring; The polishing head is close to the polishing pad; S3: dropping a stripping liquid into the through hole, and performing a stripping treatment on the stripping liquid using the device of S2 to obtain graphene.

2. The method according to claim 1, characterized in that During the stripping process, the stripping liquid drips onto the surface of the polishing head through the through hole, and the stripping liquid, the positive and negative electrodes and the polishing head together form an electrolytic cell, and the positive and negative electrodes are separated from the polishing head by the polishing pad; Further preferably, during the stripping process, after voltage is applied, the graphite powder in each electrolytic cell is electrochemically oxidized.

3. The method according to claim 1, characterized in that During the stripping process, the polishing disc and the polishing pad rotate simultaneously with the polishing head so that the stripping liquid alternates evenly between electrochemical oxidation and mechanical friction, thereby achieving electrochemical mechanical stripping.

4. The method according to claim 1, characterized in that During the stripping process, the stripping liquid is collected in the stripping liquid recovery tank and then enters the radio-chemical mechanical stripping device again through the stripping liquid nozzle to perform a cyclic stripping process until the stripping is complete.

5. The method according to claim 1, characterized in that In the stripping solution, the content of graphite powder is 5-30% by weight, and the rest is a mixed solution containing electrolyte; Further preferably, the mixed solution containing the electrolyte is selected from at least one of a water-based suspension containing 0.1~2M Na2SO4 or 0.1~2M K2SO4 or an organic medium suspension containing 0.1~1 M LiPF6.

6. The method according to claim 1, characterized in that The stripping liquid is dripped into the through hole at a rate of 10 mL / min to 120 ml / min.

7. The method according to claim 1, characterized in that The polishing head, polishing pad and polishing disk are all made of electrically insulating materials; further preferably, the polishing pad is a SUBA800 polishing pad, and the polishing head and polishing disk are both made of polyetheretherketone; Further preferably, the polishing head is pressed against the polishing pad with a certain pressure, and the pressure is 1.7 to 10 psi; Further preferably, the simultaneous rotation includes rotation in the same direction or rotation in opposite directions; Further preferably, the simultaneous rotation speed is 20-400 rpm.

8. The method according to claim 2, characterized in that: The voltage of the applied voltage is 3 V to 40 V; Further preferably, the method further comprises filtering the collected stripping liquid, washing the filter powder, and drying to obtain graphene.

9. A radio chemical mechanical exfoliation device for use in the method according to any one of claims 1 to 8, characterized in that: It includes a stripping liquid recovery tank, a polishing head, a power supply, a polishing pad, a polishing disc, positive and negative electrodes, a positive and negative electrode busbar area, a stripping liquid nozzle, a conductive slip ring and a circulating liquid supply system; The polishing pad is pasted on the bottom of the polishing disk with the same diameter, and the polishing pad and the polishing disk have the same honeycomb array of through holes; the polishing head is close to the polishing pad; a pair of positive and negative electrodes are set on the bottom wall of each through hole of the polishing disk, and the wires of the positive and negative electrodes are merged into the bus lines of the positive and negative electrode bus line area on the top of the polishing disk, and are connected to the positive and negative poles of the power supply through the conductive slip ring; the bottom ends of the positive and negative electrodes are separated from the polishing head by the polishing pad; the circulating liquid supply system is connected to the stripping liquid recovery tank and the stripping liquid nozzle through the reflux pipeline; the stripping liquid nozzle is set directly above the polishing disk, which is conducive to spraying the stripping liquid into the through hole; the polishing disk and the polishing head are respectively driven to rotate by motors.

10. The radio chemical mechanical exfoliation device according to claim 9, characterized in that: The circulating liquid supply system includes a pump or other power device and a return pipeline; Further preferably, the polishing head, polishing pad and polishing plate are all made of electrically insulating materials; Further preferably, the polishing pad and the polishing plate both have through holes of the same diameter and arranged in a honeycomb array; Further preferably, the polishing head is pressed against the polishing pad with a certain pressure, and the pressure is 1.7-10 psi.

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