Method for the production of graphene by programmable pulsed joul heating-plasma transient thermal shock under inert atmosphere

Abstract

The application discloses a method for preparing graphene by using pulsed joule heat-plasma transient thermal shock under inert atmosphere, and relates to the technical field of graphene preparation. The method comprises the following steps: constructing a carbon-containing precursor powder layer or a particle bed layer in a reaction space and controlling the thickness and compaction degree of the bed layer; replacing the reaction space with inert gas and maintaining a set flow rate and pressure during the reaction; and executing a preset process program by a control unit to drive a pulse power to output a pulse sequence between opposite electrodes, so that the electric current forms joule heat through the bed layer and realizes transient heating and rapid cooling in milliseconds to seconds, wherein the process program at least contains one or more of peak current or voltage, pulse width, pulse interval, repetition frequency or duty cycle, segment number and output timing. The application specifies the specific requirements of inert gas, bed layer, electrode, pulse sequence, control unit and purification step, and the performance index of the product, and can efficiently prepare graphene or graphenelike materials meeting the requirements.

Description

Technical Field

[0001] This invention relates to the field of graphene preparation technology, and in particular to a method for preparing graphene by programmable pulsed Joule heating-plasma transient thermal shock under an inert atmosphere. Background Technology

[0002] Graphene and graphene-like materials, due to their excellent electrical, thermal, and mechanical properties, have shown broad application prospects in fields such as new energy, electronic information, and composite materials. In recent years, pulsed electrothermal methods have attracted widespread attention as a rapid and efficient preparation technique. This method utilizes a high-density pulsed current to generate a Joule heating effect through a conductive precursor, achieving millisecond-level transient heating, which promotes the pyrolysis and rearrangement of the carbon source, thereby generating graphene structures. Compared with traditional pyrolysis processes, pulsed electrothermal methods have advantages such as fast heating rates, low energy consumption, and relatively simple equipment, and have already achieved initial applications in the synthesis of various carbon materials.

[0003] Existing pulsed electrothermal fabrication techniques mostly employ open-loop control, where pulse parameters are pre-set and cannot be dynamically adjusted based on the actual thermal response during the reaction. Because the resistivity of carbon-containing precursors changes significantly with temperature during pyrolysis, pulse sequences with fixed parameters struggle to maintain stable Joule heating, easily leading to localized overheating or incomplete reactions, affecting the graphitization degree and structural uniformity of the product. Furthermore, the atmospheric stability in the reaction environment significantly impacts the structural evolution of carbon materials, and traditional methods still have room for optimization in atmospheric control. Therefore, achieving precise control of the pulsed electrothermal process under an inert atmosphere has become a key issue in improving the quality of graphene material preparation. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, this invention provides a method for preparing graphene by programmable pulsed Joule heating-plasma transient thermal shock under an inert atmosphere, which solves the problem that existing pulsed electrothermal technology, due to its open-loop control mode, cannot dynamically adjust the pulse parameters according to the thermal response of the precursor, thus causing local overheating or insufficient reaction, affecting the graphitization degree and structural uniformity of the product.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for preparing graphene by programmable pulsed Joule heating-plasma transient thermal shock under an inert atmosphere, comprising constructing a carbon-containing precursor powder layer or particle bed in a reaction space and controlling the bed thickness and compaction. The reaction space is replaced with an inert gas, and the set flow rate and pressure are maintained during the reaction process; The control unit executes a preset process program to drive the pulse power supply to output a pulse sequence between the opposing electrodes, so that the current passes through the bed to form Joule heating and achieve transient heating and rapid cooling in milliseconds to seconds. The process program includes at least one or more of the following: peak current or voltage, pulse width, pulse interval, repetition frequency or duty cycle, number of segments and output timing. During the pulse output process, the bed temperature and electrical parameters are acquired at high speed, and the pulse parameters are adjusted or started / stopped according to the control strategy based on the acquisition results. After the reaction was complete, the mixture was cooled under an inert atmosphere and the product was collected.

[0007] As a preferred embodiment of the method for preparing graphene under an inert atmosphere using programmable pulsed Joule heating-plasma transient thermal shock according to the present invention, wherein: at least one stage of the pulse sequence, an electric arc plasma is induced at the interface between the electrode tip and the bed, the electric arc plasma providing transient thermal shock to the bed and working synergistically with the pulsed Joule heating.

[0008] Furthermore, in any one or more stages of the pulse sequence of programmable pulsed Joule heating, an electric arc plasma is induced to be stably generated at the interface between the counter electrode end and the carbon-based precursor bed. This electric arc plasma applies instantaneous thermal shock to the interior and surface of the bed in the form of transient high-energy heat flow, forming a composite heating effect with pulsed Joule heating that is superimposed in the field and coordinated in time, together achieving rapid high-temperature stripping and graphitization transformation of the precursor.

[0009] As a preferred embodiment of the method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in this invention, the inert gas is argon with a purity of not less than 99.9%; the inert gas replacement includes a pre-replacement stage and a maintenance stage, the pre-replacement time is 3–30 min; the inert gas flow rate is 0.5–50 mL·min⁻¹, and the reaction pressure is atmospheric pressure or slightly positive pressure.

[0010] Furthermore, high-purity argon is selected as the protective inert gas, with a purity of not less than 99.9%. The inert gas replacement process is divided into two continuous stages: pre-replacement and atmosphere maintenance. The pre-replacement stage has a ventilation time controlled between 3 and 30 minutes to thoroughly remove air and impurities from the reaction chamber. The inert gas flow rate during the reaction is set to... The internal pressure of the reaction chamber is maintained at normal pressure or slightly positive pressure to prevent external air from seeping in and to stabilize the plasma discharge environment.

[0011] As a preferred embodiment of the method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in this invention, the bed layer has a geometric thickness of 2-8 mm and a bed layer compaction pressure of 1-100 kPa; the bed current path is adjusted by vibration compaction, layered filling, or the addition of conductive components.

[0012] Furthermore, the carbon-based precursor material is constructed into a reaction bed with a geometric thickness of 2-8 mm. The overall compaction pressure of the bed is controlled at 1-100 kPa to ensure that the bed is dense and uniform and has a stable conductive path. According to the difference in the conductivity of the precursor, the current conduction path inside the bed is precisely controlled by means of vibration compaction, layered gradient filling or addition of conductive additives to avoid local current concentration or poor conductivity and ensure the uniformity of Joule heating and plasma interaction.

[0013] As a preferred embodiment of the method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in this invention, the material of the counter electrode is tungsten, electrical stainless steel or a combination thereof, and the electrode end is a flat end, a conical end or a composite end; the electrode spacing is 5-20 mm and adjustable to match the bed thickness and stabilize the discharge region.

[0014] Furthermore, the counter electrode is made of tungsten, electrical stainless steel, or a combination of both. The electrode end structure is selected as flat end, conical end, or a combination of flat and conical ends according to the discharge requirements. The initial spacing between the electrodes is set to 5-20 mm and can be finely adjusted in real time to ensure that the electrode spacing is precisely matched with the bed thickness, while constraining and stabilizing the arc plasma discharge area to prevent discharge deviation or arc extinction.

[0015] As a preferred embodiment of the method for preparing graphene by programmable pulsed Joule heating-plasma transient thermal shock under an inert atmosphere as described in this invention, the parameters of the pulse sequence include one or more of the following: peak current 10-600 A, pulse width 0.1-1000 ms, pulse interval 1-5000 ms, repetition frequency 0.1-20 Hz, duty cycle 1%-90%, and number of pulse segments 1-10; wherein the pulse interval matches the repetition frequency and / or duty cycle; the duration of a single output is 0.1-10 s or the equivalent cumulative output duration is 0.1-10 s.

[0016] Furthermore, a customized pulse sequence can be output through a programmable power supply. The core control parameters include: peak current 10-600 A, pulse width 0.1-1000 ms, pulse interval 1-5000 ms, repetition frequency 0.1-20 Hz, duty cycle 1%-90%, and number of pulse segments 1-10, which can be controlled individually or in combination. The pulse interval value is matched and adapted with the repetition frequency and duty cycle parameters to ensure the continuity of pulse output. The total output duration of a single process pulse is controlled within 0.1-10 s, or the equivalent output duration of multiple pulses is accumulated within 0.1-10 s.

[0017] As a preferred embodiment of the method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in this invention, the control unit stores multiple process programs and calls them by program number or formula name; the process programs support one or more of fixed parameter sequences, segmented sequences, voltage or current scanning sequences and polarity reversal sequences to achieve rapid switching and reproduction of different process windows.

[0018] Furthermore, the system control unit has built-in storage of multiple sets of differentiated graphene preparation process programs, which can be quickly called directly by program number or formula name; the process program mode supports one or more combinations of fixed parameter sequence, segmented multi-stage pulse sequence, voltage or current gradient scan sequence, and electrode polarity reversal sequence, so as to realize rapid switching, accurate reproduction and stable batch preparation of different reaction process windows.

[0019] As a preferred embodiment of the method for preparing graphene under programmable pulsed Joule thermal-plasma transient thermal shock in an inert atmosphere as described in this invention, the bed temperature is measured by a non-contact infrared thermometer, and the electrical parameters include at least voltage and current; the sampling frequency of temperature and electrical parameters is 100-1000Hz; the closed-loop regulation uses the temperature peak value, heating rate, energy integral threshold and discharge stability criterion as control quantities.

[0020] Furthermore, a non-contact infrared temperature measurement device is used to collect the surface and internal temperature of the bed in real time, and to collect key electrical parameters such as voltage and current simultaneously. The sampling frequency of temperature and electrical parameters is set to 100-1000Hz to ensure the real-time performance and integrity of the data. The peak bed temperature, heating rate, energy integral threshold and discharge stability are used as closed-loop control criteria to adjust the pulse parameters in real time and maintain the stable and controllable reaction process.

[0021] As a preferred embodiment of the method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere according to the present invention, the purification step includes immersion in 0.1-1 mol / L acid solution for 0.5-6 h to remove metal residues, followed by washing with water until neutral and drying at 30-80°C for 0.5-6 h.

[0022] Furthermore, the crude graphene obtained from the reaction was purified by soaking and washing it in an acidic solution with a concentration of 0.1-1 mol / L for 0.5-6 h to remove residual metal impurities introduced by the electrode and precursor. Subsequently, the product was repeatedly washed with deionized water until the washing solution was neutral, and then the neutral product was dried at 30-80℃ for 0.5-6 h to finally obtain high-purity graphene product.

[0023] As a preferred embodiment of the method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in this invention, wherein: The obtained graphene or graphene-like material satisfies at least one of the following: Raman ID / IG ratio of 0.05-1.5, I2D / IG ratio of 0.3-2.0, and XPS ratio of [missing value]. Carbon content ≥60%, total metal impurities ≤500 ppm.

[0024] Furthermore, the prepared graphene or graphene-like materials must meet at least one of the following performance indicators: the ratio of the intensity of the defect peak to the graphite peak (ID / IG) in the Raman spectrum is 0.05-1.5, and the ratio of the intensity of the second-order graphite peak to the graphite peak (I2D / IG) is 0.3-2.0; the proportion of sp² hybrid carbon in the X-ray photoelectron spectroscopy is not less than 60%; and the total content of metal impurities in the product is not higher than 500 ppm, ensuring the structural integrity and purity of the product.

[0025] The beneficial effects of this invention are as follows: a carbon-containing precursor bed is constructed in the reaction space and its thickness and compaction are controlled; the reaction space is replaced with an inert gas and the set gas flow rate and pressure are maintained during the reaction; the control unit executes a preset process program to drive the pulse power supply to output a pulse sequence, so that the current passes through the bed to form Joule heating and achieve transient heating and cooling; during the pulse output process, the bed temperature and electrical parameters are collected at high speed and the pulse parameters are adjusted in a closed loop according to the collection results; after the reaction, the product is collected by cooling under an inert atmosphere; in at least one stage of the pulse sequence, an arc plasma is induced at the electrode end and the bed interface, which works synergistically with the pulse Joule heating; the specific requirements of inert gas, bed, electrode, pulse sequence, control unit, purification steps and product performance indicators are also clarified, which can efficiently prepare graphene or graphene-like materials that meet the requirements. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This invention relates to a method for preparing graphene using programmable pulsed Joule heating-plasma transient thermal shock under an inert atmosphere.

[0028] Figure 2 This is a schematic diagram of the real-time monitoring and display interface during the preparation process of this invention.

[0029] Figure 3 The figure shows the characterization results of graphene / graphene-like materials prepared using the method of this invention.

[0030] Figure 4 The method of this invention is used to obtain electron micrographs and selected area electron diffraction patterns of graphene / graphene-like materials.

[0031] Figure 5 The image shows the energy dispersive spectroscopy (EDS) results of graphene / graphene-like materials prepared using the method of this invention.

[0032] Figure 6 These are atomic force microscopy (AFM) morphology and thickness characterization images of graphene / graphene-like materials prepared using the method of this invention. Detailed Implementation

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0034] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0035] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0036] Reference Figures 1-6This is one embodiment of the present invention, which provides a method for preparing graphene by programmable pulsed Joule heating-plasma transient thermal shock under an inert atmosphere, comprising the following steps: Example 1:

[0037] 1) Raw material selection and pretreatment Graphite powder was selected as the precursor material, with a purity of over 99% and a particle size of 60 mesh. The graphite powder was placed in a vacuum drying oven and dried at 70°C for 3 hours to reduce the impact of moisture and volatile impurities on discharge stability.

[0038] Preferably, the graphite powder is sealed and stored after drying to avoid moisture absorption that could cause fluctuations in bed conductivity.

[0039] 2) Electrode preparation and installation Tungsten rods were used as electrodes, which were cleaned and lightly polished before use. The electrodes were then assembled into the clamping positions within the reaction vessel, maintaining an adjustable spacing and stable clamping. The distance between the two electrodes was set to 15 mm to ensure that the discharge channel could be repeatedly established.

[0040] Preferably, the electrode is clamped by a conductive clamping block or by a threaded clamping method to reduce contact resistance and improve discharge stability during thermal shock; more preferably, the electrode end is shaped as a flat end or a tapered end to meet different arc initiation stability requirements.

[0041] Alternatively, stainless steel electrodes or tungsten needle electrodes can be used as electrode materials, with tungsten needle electrodes used to enhance arc initiation stability and improve discharge repeatability.

[0042] 3) Reaction vessel preparation and atmosphere control The reaction vessel is made of quartz glass, with a quartz tube having an inner diameter of 6mm, a wall thickness of 1.5mm, and a length of 7cm. Custom designs are available to meet specific process requirements. High-purity argon gas (purity >99.999%) is introduced into the reaction vessel, with the argon gas flow rate controlled at 5mL / min. -1 This is used to reduce the risk of oxidation and stabilize heat transfer and escape pathways.

[0043] Preferably, the establishment of the inert atmosphere includes a pre-displacement stage and a maintenance stage: the pre-displacement stage continuously displaces the reaction chamber at a set flow rate to reduce the residual oxygen content, and the maintenance stage continuously supplies gas during the thermal shock process to stabilize the reaction interface; optionally, an abnormal pressure release and safety protection are achieved through a safety valve.

[0044] More preferably, the reaction chamber maintains a slightly positive pressure or a stable pressure range throughout the preparation process to reduce the probability of external air and moisture intrusion.

[0045] 4) Pulse Joule heating—Plasma transient thermal shock Pretreated graphite powder was placed between two electrodes to form a powder layer approximately 5 mm thick. A programmable pulse power supply was then connected, applying a current of 200 A with a pulse width of 1000 ms and a single application time of 1 s. The powder layer was then subjected to transient thermal shock, raising its temperature to 3000 °C. Infrared thermometry and electrical parameter acquisition were performed simultaneously throughout the process.

[0046] Preferably, the powder layer can be compacted, vibrated, or layered to form a stable bed porosity, so as to reduce discharge drift caused by accumulation fluctuations; the powder layer thickness is preferably controlled in the range of 2-8 mm.

[0047] Preferably, the external controller is used to set the pulse time, pulse interval time, peak current / current parameters and output mode, and to record the pulse sequence parameters; the non-contact infrared temperature probe is used to acquire the apparent temperature of the bed or the temperature change trend; the electrical parameter acquisition is used to synchronously record the voltage / current / power / energy integral curves, thereby achieving time alignment of temperature and electrical parameters and process traceability.

[0048] Optionally, the system is equipped with a real-time observation display screen to display one or more of the following: temperature readings, pulse sequence operation status, and electrical parameter curves, so that the operator can interpret the status of the thermal shock process in real time.

[0049] Optionally, the system is connected to an external thermal imager to acquire temperature distribution information at different spatial locations in the reaction zone, in order to assess thermal uniformity and serve as a basis for optimizing bed construction parameters, electrode spacing, or pulse sequences.

[0050] In one alternative implementation, when temperature exceeds the limit, energy integration exceeds the limit, discharge is abnormal, or inert atmosphere is abnormal, an interlocking strategy is triggered to perform load reduction, suspension, or shutdown protection.

[0051] 5) Product collection and purification The product was naturally cooled to room temperature under argon protection and then removed. It was soaked in dilute hydrochloric acid (0.5 mol / L) for 3 hours to remove any possible residual metal impurities, washed repeatedly with deionized water until neutral, and dried at 50°C for 2 hours to obtain pure graphene powder.

[0052] Preferably, after washing to neutrality, filtration / centrifugation can be used to improve solid-liquid separation efficiency; after drying, the sample is sealed and stored to avoid moisture absorption and fluctuations in oxygen-containing functional groups on the surface caused by impurities in the air.

[0053] 6) Graphene product performance testing methods The graphene powder obtained in this invention was characterized and its performance was tested using the following methods: ① Raman spectroscopy: Laser wavelength set at 532 nm, scanning range 800-3200 cm⁻¹ -1 Through the D peak (approximately 1350 cm)-1 G peak (approximately 1580 cm) -1 ) and 2D peak (approximately 2700 cm) -1 ),calculate I D / I G 、I 2D / I G Parameters characterize the degree of defect and the number of layers; ②X-ray diffraction (XRD): A copper target was used, with a scanning range of 2θ = 10~80° and a scanning rate of 10°·min. -1 The interlayer spacing and grain size are estimated based on the position and half-width of peak (002). ③X-ray photoelectron spectroscopy (XPS): Fitting the C1s spectrum and decomposing it into sp... 2 sp 3 And oxygen-containing functional group peaks, calculate sp 2 Carbon percentage is used to evaluate the degree of graphitization; ④ Transmission electron microscopy (TEM) and selected area electron diffraction (SAED): Observe the morphology and lattice fringes of the sample, and determine the degree of crystal order and number of layers by combining SAED patterns; ⑤ Atomic Force Microscopy (AFM): After being dispersed in ethanol and sonicated for 20-30 min, the graphene sheets were drop-coated onto a SiO2 / Si substrate and allowed to dry naturally. A scanning area of ​​0.5-5 μm was selected, and the sheet thickness and surface roughness were measured according to the height plot truncation line to determine the single-layer or few-layer (≤5 layers) graphene sheets and their morphology.

[0054] Example 2: Comparative Example To illustrate the importance of key process parameters in this invention, the following comparative experiment is provided. Unless otherwise specified, the raw material pretreatment method, inert atmosphere conditions, pulse control method, monitoring and recording method, and post-processing purification steps in the comparative experiment are the same as those in Example 1.

[0055] In each comparative example, the temperature change trend and electrical parameter curves (voltage / current / power / energy integral) of infrared thermography were recorded simultaneously, and combined with Raman spectroscopy. I D / I G 、I 2D / I G and XPS SP 2 The carbon ratio is used to evaluate the product.

[0056] Comparative Example 1: The powder layer thickness is too large When the powder layer thickness is increased to about 10 mm, after applying a pulse, local overheating, arc sputtering or unstable discharge are likely to occur in the outer layer of the bed, while the temperature rise inside the bed is relatively small, resulting in uneven temperature distribution and uneven reaction.

[0057] The reason may be that the excessive thickness of the bed causes the electro-thermal coupling and plasma interaction zone to be mainly concentrated on the surface, while the energy coupling in the central region is insufficient, making it difficult to achieve the temperature-time history required for graphitization rearrangement.

[0058] Therefore, when the powder layer thickness exceeds the preferred range of 2-8 mm, it is easy to cause uneven thermal shock and reduce product quality and consistency.

[0059] Comparative Example 2: Using a non-conductive precursor without treatment Insulating polymer powder was selected as the precursor, and no carbon black was added. After applying a pulse voltage, almost no effective current passed through the powder layer. The electrical parameter curve showed that the current response was weak or close to zero. The powder temperature did not rise significantly, and the powder morphology and color did not change after the reaction.

[0060] The reason is that the overall conductivity of the bed is insufficient, making it impossible to form a stable current path, thus making it difficult to generate effective Joule heating and plasma-induced thermal shock.

[0061] Therefore, when the intrinsic conductivity of the selected precursor is low, it is necessary to pre-treat the precursor by carbonization / pyrolysis or by adding conductive components to construct a current path before it can enter the effective process window of this invention.

[0062] Comparison Group 3: Electrode spacing too far When the electrode spacing is increased from 5 mm to 10 mm and a pulse is applied, phenomena such as unstable arc initiation, unstable arc generation only in local areas, or discharge interruption are likely to occur, making it difficult to form a uniform and repeatable plasma interaction zone; the bed temperature response fluctuates greatly, indicating that the energy coupling process is unstable.

[0063] The reason may be that the excessive electrode spacing leads to a mismatch between the discharge path and the geometric position of the bed, causing the arc action area to drift or concentrate in a local area, making it impossible to uniformly cover the bed with heat and plasma impact.

[0064] Therefore, the electrode spacing should be matched with the bed thickness and the supporting structure (quartz boat / quartz tube insertion positioning) to improve discharge stability and thermal shock uniformity.

[0065] As can be seen from the above comparative examples, bed thickness, construction of conductive pathways in the bed, and matching of electrode spacing are key conditions for obtaining stable graphene / graphene-like products in this invention. By controlling the powder layer thickness within a preferred range, regulating the conductive pathways of the low-conductivity precursor, and matching the electrode spacing with the bed / support structure, discharge stability, thermal shock uniformity, and product consistency can be significantly improved, thereby entering the curable process window.

[0066] In summary, this invention constructs a carbon-containing precursor bed within a reaction space and controls its thickness and compaction. The reaction space is replaced with an inert gas, and a set gas flow rate and pressure are maintained during the reaction. A control unit executes a preset process program to drive a pulse power supply to output a pulse sequence, causing current to flow through the bed and generate Joule heating, achieving transient temperature rise and fall. During pulse output, the bed temperature and electrical parameters are rapidly acquired, and the pulse parameters are adjusted in a closed loop based on the acquisition results. After the reaction, the product is cooled and collected under an inert atmosphere. In at least one stage of the pulse sequence, an electric arc plasma is induced at the electrode tip and the bed interface, working synergistically with the pulsed Joule heating. The invention also clarifies the specific requirements for the inert gas, bed, electrode, pulse sequence, control unit, purification steps, and product performance indicators, enabling the efficient preparation of graphene or graphene-like materials that meet the requirements.

[0067] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing graphene by programmable pulsed Joule heating-plasma transient thermal shock under an inert atmosphere, characterized in that: This includes constructing a carbon-containing precursor powder or particle bed within the reaction space and controlling the bed thickness and compaction. The reaction space is replaced with an inert gas, and the set flow rate and pressure are maintained during the reaction process; The control unit executes a preset process program to drive the pulse power supply to output a pulse sequence between the opposing electrodes, so that the current passes through the bed to form Joule heating and achieve transient heating and rapid cooling in milliseconds to seconds. The process program includes at least one or more of the following: peak current or voltage, pulse width, pulse interval, repetition frequency or duty cycle, number of segments and output timing. During the pulse output process, the bed temperature and electrical parameters are acquired at high speed, and the pulse parameters are adjusted or started / stopped according to the control strategy based on the acquisition results. After the reaction was complete, the mixture was cooled under an inert atmosphere and the product was collected.

2. The method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in claim 1, characterized in that: In at least one stage of the pulse sequence, an arc plasma is induced at the interface between the electrode tip and the bed, the arc plasma providing transient thermal shock to the bed and acting in synergy with pulsed Joule heating.

3. The method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in claim 2, characterized in that: The inert gas is argon with a purity of not less than 99.9%; the inert gas replacement includes a pre-replacement stage and a maintenance stage, with a pre-replacement time of 3–30 min; the inert gas flow rate is 0.5–50 mL·min⁻¹, and the reaction pressure is atmospheric pressure or slightly positive pressure.

4. The method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in claim 3, characterized in that: The bed has a geometric thickness of 2-8 mm and a compaction pressure of 1-100 kPa; the bed current path is adjusted by vibration compaction, layered filling, or the addition of conductive components.

5. The method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in claim 4, characterized in that: The material of the counter electrode is tungsten, electrical stainless steel or a combination thereof, and the electrode end is a flat end, a conical end or a composite end; the electrode spacing is 5-20 mm and adjustable to match the bed thickness and stabilize the discharge area.

6. The method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in claim 5, characterized in that: The parameters of the pulse sequence include one or more of the following: peak current 10-600 A, pulse width 0.1-1000 ms, pulse interval 1-5000 ms, repetition frequency 0.1-20 Hz, duty cycle 1%-90%, and number of pulse segments 1-10; wherein the pulse interval matches the repetition frequency and / or duty cycle; the duration of a single output is 0.1-10 s or the equivalent cumulative output duration is 0.1-10 s.

7. The method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in claim 6, characterized in that: The control unit stores multiple process programs and calls them by program number or recipe name; the process programs support one or more of the following: fixed parameter sequence, segmented sequence, voltage or current scanning sequence, and polarity reversal sequence, so as to realize the rapid switching and reproduction of different process windows.

8. The method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in claim 6, characterized in that: The bed temperature is measured by a non-contact infrared thermometer, and the electrical parameters include at least voltage and current; the sampling frequency of temperature and electrical parameters is 100-1000Hz; the closed-loop regulation uses the temperature peak, heating rate, energy integral threshold and discharge stability criterion as control variables.

9. The method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in claim 6, characterized in that: The purification steps include immersion in 0.1-1 mol / L acid solution for 0.5-6 h to remove metal residues, followed by washing with water until neutral and drying at 30-80°C for 0.5-6 h.

10. The method for preparing graphene under programmable pulsed Joule heating-plasma transient thermal shock in an inert atmosphere as described in claim 6, characterized in that: The obtained graphene or graphene-like material satisfies at least one of the following: Raman ID / IG is 0.05-1.5, I2D / IG is 0.3-2.0, sp2 carbon content in XPS is ≥60%, and total metal impurities are ≤500 ppm.

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