A method for preparing a hydrogenated diamond-like carbon powder by plasma vapor synthesis

Abstract

The application relates to the technical field of nanometer carbon material preparation, and particularly discloses a preparation method of hydrogenated diamond-like carbon powder synthesized by plasma gas phase. The application takes carbon source gas and hydrogen as reaction gas sources, introduces the carbon source gas and hydrogen into a chemical vapor deposition plasma vacuum cavity, controls radio frequency power, cavity pressure and gas proportion, makes the carbon source crack in a plasma environment, directly forms nucleation and grows in a gas phase space, does not need a solid deposition base, and collects free-state grape cluster-shaped hydrogenated diamond-like carbon powder. The carbon powder is hydrogen-containing amorphous carbon structure, the hydrogen content and sp 3 / sp 2 carbon phase ratio can be accurately controlled. The application solves the problem that a traditional PECVD process can only prepare diamond-like film and is difficult to batch synthesize hydrogenated diamond-like powder, the prepared carbon powder has excellent conductive network structure, can be applied to the fields of lithium ion battery negative electrodes, solid lubrication, water treatment adsorption and composite material modification, has strong process stability, and has large-scale development potential.

Description

Technical Field

[0001] This invention relates to the field of nano-carbon material preparation technology, specifically to a method for preparing hydrogenated diamond-like carbon powder by plasma gas-phase synthesis. Background Technology

[0002] Diamond-like carbon (DLC) materials contain sp 3 Diamond phase, sp 2 Graphite-phase amorphous carbon structure; hydride diamond-like carbon (aC:H) is typically deposited as a thin film on a solid substrate using plasma-enhanced chemical vapor deposition (PECVD) or microwave plasma-enhanced chemical vapor deposition (MPCVD). However, existing technologies have the following drawbacks: ① Traditional MPCVD equipment targets thin films as the product, requiring a substrate support, and cannot directly generate collectable free nano-carbon powders; ② Conventional nano-amorphous carbon powders (carbon black, hard carbon, soft carbon) lack controllable sp... 3 ① It lacks bound hydrogen phase, resulting in insufficient electrochemical performance and wear resistance; ② Currently, the industry lacks a process for stable batch preparation of grape-like nano-agglomerates of hydrogenated diamond-like carbon powder; ③ Existing processes struggle to precisely control the hydrogen content and sp2 content of the powder. 3 / sp 2 The proportions and material properties are inconsistent. Therefore, there is an urgent need to develop a method for the direct gas-phase synthesis of hydrogenated diamond-like carbon nanoparticles that does not rely on a deposition substrate. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a method for preparing hydrogenated diamond-like carbon powder via plasma gas-phase synthesis.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] This invention provides a method for preparing hydrogenated diamond-like carbon powder by plasma gas-phase synthesis, comprising the following steps:

[0006] Cavity pretreatment: The reaction chamber of the plasma chemical vapor deposition equipment is evacuated to a background vacuum and then argon and hydrogen are introduced for plasma cleaning.

[0007] Gas intake and ignition: The reaction gas is introduced into the pretreated reaction chamber, the gas flow rate and working pressure are adjusted, the radio frequency power supply is turned on, and a stable plasma is generated in the reaction chamber; the reaction gas includes carbon source gas, hydrogen and argon.

[0008] Gas phase nucleation and growth: The radio frequency power and gas phase temperature are controlled to carry out the reaction. The carbon source gas is decomposed in the plasma gas phase space to generate carbon free radicals. The carbon free radicals undergo homogeneous nucleation and growth in the gas phase space to form primary nanoparticles. The primary nanoparticles further self-assemble to form nano-aggregate structures, thus obtaining hydrogenated diamond-like carbon powder particles.

[0009] Powder collection: Stop the gas intake, turn off the radio frequency power supply, and collect the powder after the reaction chamber has cooled down to obtain hydrogenated diamond-like carbon powder.

[0010] Optionally, the background vacuum is -2 to 10 Pa, and the plasma cleaning time is 10 to 30 min.

[0011] Optionally, the carbon source gas is methane or acetylene; by volume fraction, the reaction gas includes 70%–85% carbon source gas, 5%–25% hydrogen, and 5%–10% argon.

[0012] Optionally, the total inlet flow rate of the reaction gas is 580 SCCM, and the working pressure is 5 to 50 Pa.

[0013] Optionally, the RF power supply power is 800W to 6kW, and the gas phase temperature is 100 to 300℃.

[0014] Optionally, the reaction time during the gas-phase nucleation and growth process is 0.5 to 6 hours.

[0015] Optionally, it also includes post-processing, specifically: after the powder is collected, it is dried with inert gas and sieved.

[0016] The present invention also provides a gold grape cluster agglomerate (hydrogenated diamond-like carbon powder) prepared by the above method.

[0017] Optionally, the XPS carbon content of the hydrogenated diamond-like carbon powder is 90%~95%, and the oxygen content is 5%~10%; the particle size distribution of the hydrogenated diamond-like carbon powder satisfies: D10 is 0.4~1.0μm, D50 is 2.0~4.0μm, and D90 is 10.0~15.0μm; the specific surface area of ​​the hydrogenated diamond-like carbon powder is 40~100m². 2 / g. Preferably, the toner has an XPS carbon content of 90.79%, an XPS oxygen content of 9.21%, a particle size of D10 0.483μm, D50 2.806μm, D90 13.416μm, and a specific surface area of ​​62.960m². 2 / g.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] 1. This invention breaks through the limitations of traditional plasma deposition technology, which can only prepare DLC thin films, and solves the technical problem of difficulty in directly obtaining free carbon powder;

[0020] 2. This invention achieves control over the hydrogen content and sp content in toner. 3 The precise control of the carbon phase ratio allows for flexible adjustment of the material structure and composition according to application requirements;

[0021] 3. This invention yields hydrogenated diamond-like carbon powder with a grape-like nano-aggregate morphology, which, when used as a conductive electrode in lithium-ion battery anode materials, facilitates the construction of a highly efficient conductive network and improves electrochemical performance;

[0022] 4. The preparation process provided by this invention is continuous, stable, and highly repeatable, and has the potential for large-scale batch preparation. The resulting carbon powder is suitable for applications such as lithium-ion battery anodes, solid lubrication, and composite material modification. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. 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.

[0024] Figure 1 The images shown are SEM images of the gold grape cluster agglomerates (hydrogenated diamond-like carbon powder) obtained in the embodiments of the present invention. Figure A is a SEM image with a magnification of 30.00 KX, and Figure B is a SEM image with a magnification of 20.00 KX.

[0025] Figure 2 The image shows the FTIR infrared spectrum of the Agrobacterium tumefaciens (hydrogenated diamond-like carbon powder) obtained in an embodiment of the present invention.

[0026] Figure 3 The following are EDS energy dispersive spectra of the gold grape cluster agglomerate (hydrogenated diamond-like carbon powder) obtained in the embodiments of the present invention, wherein Figure A is the overall EDS spectrum and Figure B is the carbon element surface distribution diagram. Detailed Implementation

[0027] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods, and the materials and reagents used in the following embodiments are commercially available unless otherwise specified.

[0028] This invention provides a method for preparing hydrogenated diamond-like carbon powder via plasma vapor phase synthesis. Using carbon source gas, argon, and hydrogen as reaction gas sources, these gases are introduced into the cavity of a plasma chemical vapor deposition (PECVD) device. By controlling the radio frequency power, cavity pressure, and gas ratio, the reaction gases undergo pyrolysis, nucleation, and growth in the plasma gas phase space (i.e., the high-energy gas region excited by plasma), directly generating free nano-carbon particles. This process does not rely on any solid deposition substrate, and ultimately, agglomerated hydrogenated diamond-like carbon powder (aC:H) is captured in the cavity collection area. The specific steps are as follows:

[0029] 1. Cavity pretreatment

[0030] The reaction chamber of the PECVD equipment is evacuated to a background vacuum of -2 to 10 Pa, argon and hydrogen are introduced, and radio frequency plasma cleaning is performed for 10 to 30 minutes to remove impurities and adsorbates from the inner wall.

[0031] 2. Air intake and ignition

[0032] Carbon source gas, hydrogen, and argon are introduced to stabilize the flow rate and working pressure; then the radio frequency power supply is turned on to excite and form a stable spherical plasma.

[0033] 3. Gas-phase nucleation and growth

[0034] By adjusting the radio frequency power, working gas pressure, gas ratio and gas phase temperature, the carbon source is decomposed in the radio frequency plasma, and carbon free radicals nucleate and grow in the gas phase to form primary nanoparticles, which then self-assemble into grape-like aggregate structures. The CH bonds are retained inside the particles to obtain hydrogenated amorphous diamond-like structures.

[0035] Key process parameters are as follows: gas ratio (volume fraction): carbon source gas 70%–85%, hydrogen 5%–25%, argon 5%–10%; working pressure: 5–50 Pa; radio frequency: 13.56 MHz, radio frequency power 800 W–6 kW; gas phase temperature: 100–300 ℃; background vacuum: -2–10 Pa; reaction time 30 min–6 h.

[0036] 4. Powder collection and post-processing

[0037] Stop the air intake and RF power supply, and allow the cavity to cool to room temperature; use a cavity collection device / filter membrane to collect toner.

[0038] Optional post-treatment: inert gas drying and simple sieving to remove a small amount of coarse particles.

[0039] Example 1

[0040] A method for preparing hydrogenated diamond-like carbon powder by plasma gas-phase synthesis includes the following steps:

[0041] 1. Cavity pretreatment

[0042] The cavity of the PECVD equipment is evacuated to a background vacuum of -2 to 10 Pa, argon and hydrogen are introduced, and radio frequency plasma cleaning is started for 20 minutes to remove impurities and adsorbates from the inner wall.

[0043] 2. Air intake and ignition

[0044] Carbon source gas, hydrogen, and argon are introduced to stabilize the flow rate and working pressure; then the radio frequency power supply is turned on to excite and form a stable spherical plasma.

[0045] 3. Gas-phase nucleation and growth

[0046] By adjusting the radio frequency power, working gas pressure, gas ratio and gas phase temperature, the carbon source is decomposed in the radio frequency plasma, and carbon free radicals nucleate and grow in the gas phase to form primary nanoparticles, which then self-assemble into grape-like aggregate structures. The CH bonds are retained inside the particles to obtain hydrogenated amorphous diamond-like structures.

[0047] Key process parameters are as follows: gas ratio (volume fraction): carbon source gas (methane) 80%, hydrogen 10%, argon 10%; total inlet flow rate of reaction gas 580 SCCM; working pressure: 5~50 Pa; radio frequency: 13.56 MHz; radio frequency power 2 kW; gas phase temperature: 200 ℃; background vacuum: -2~10 Pa; reaction time 2 h.

[0048] 4. Powder collection and post-processing

[0049] Stop the air intake and RF power supply, and allow the cavity to cool to room temperature; use a cavity collection device / filter membrane to collect toner.

[0050] Optional post-treatment: inert gas drying and simple sieving to remove a small amount of coarse particles.

[0051] The *Gnaphalium affine* (hydrogenated diamond-like carbon) powder prepared in this embodiment has an XPS carbon content of 90.79%, an XPS oxygen content of 9.21%, a particle size of D10 0.483 μm, D50 2.806 μm, D90 13.416 μm, and a specific surface area of ​​62.960 m². 2 / g.

[0052] The characteristics of the gold grape spherical cluster agglomerate (hydrogenated diamond-like carbon powder) prepared in Example 1 of this invention are as follows: (1) Phase structure: amorphous carbon matrix, containing sp 3 Hybrid carbon (diamond phase) and sp 2Hybrid carbon (graphite phase) contains chemically bonded hydrogen; (2) Microstructure: Primary nanoparticles are interconnected to form grape-like chain-like aggregates. The hydrogenated diamond-like carbon powder prepared in this embodiment was characterized by SEM, FTIR, and EDS, and the results correspond to Figure 1 , Figure 2 , Figure 3 .

[0053] Figure 1 The image shows the SEM (scanning electron microscope) morphology of the gold grape spherical cluster agglomerate (hydrogenated diamond-like carbon powder) obtained in Example 1 of the present invention, which shows that the powder is a grape-like cluster of quasi-spherical nanoparticles. Figure 1 The SEM images show that the powder consists of a large number of quasi-spherical nanoparticles agglomerated into grape-like aggregates, without graphene sheet structure or diamond angular single crystal morphology, and the particle size is concentrated in the range of hundreds of nanometers.

[0054] Figure 2 The FTIR Fourier transform infrared spectrum of the Agrobacterium tumefaciens (hydrogenated diamond-like carbon powder) obtained in Example 1 of this invention; Figure 2 The FTIR infrared spectrum at 2930.13 cm⁻¹ -1 A characteristic absorption peak for the saturated CH stretching vibration appears at 1631.30 cm⁻¹, along with a peak at 1631.30 cm⁻¹. -1 1452.41cm -1 1400.37cm -1 The characteristic peaks of aliphatic hydrocarbons prove that there are chemically bonded hydrogens inside the powder, indicating a hydrogenated amorphous carbon structure.

[0055] Figure 3 The images show the EDS energy-dispersive X-ray spectra and carbon element surface distribution mapping of the Agrobacterium tumefaciens (hydrogenated diamond-like carbon) carbon powder obtained in Example 1 of this invention. Figure 3 The EDS spectrum only detected carbon as the main peak, with only trace amounts of oxygen present. No metal impurities such as Fe, Ni, and Cu were detected. The carbon element surface scan showed that carbon was uniformly distributed throughout the entire particle area, indicating high powder purity.

[0056] This invention uses methane as the carbon source gas, argon as the carrier gas, and hydrogen as the structure control gas. The volumetric flow rate ratio of methane, hydrogen, and argon is precisely controlled using a mass flow meter. Increasing the hydrogen-to-methane flow rate ratio increases the hydrogen content of the carbon powder, thus improving the sp... 3 Increased proportion of hybrid bonds, sp 3 / sp 2 The ratio increases; decreasing the hydrogen ratio and increasing the argon ratio leads to a decrease in hydrogen content and sp. 2 The proportion of graphitized structures has increased.

[0057] The cavity pressure of this invention is controlled to a low-pressure environment of -2 to 10 Pa, resulting in uniform gas phase nucleation and toner sp.3 / sp 2 The proportional fluctuation deviation is ≤5%, achieving precise and uniform control.

[0058] The post-processing control of this invention is as follows: a trace amount of oxygen can be introduced for gentle etching to selectively remove sp. 3 Hybrid structure, targeted enhancement of sp 2 The carbon content is reduced, while the hydrogen content is decreased simultaneously.

[0059] Example 2

[0060] A method for preparing hydrogenated diamond-like carbon powder by plasma gas phase synthesis, prepared according to the method described in Example 1, with the following differences: the plasma cleaning time is 30 min; the reaction gas includes 70% carbon source gas, 25% hydrogen, and 5% argon by volume fraction; the radio frequency power supply is 1 kW, and the gas phase temperature is 300 °C; optionally, the reaction time in the gas phase nucleation and growth process is 1 h.

[0061] Example 3

[0062] A method for preparing hydrogenated diamond-like carbon powder by plasma gas phase synthesis, prepared according to the method described in Example 1, with the difference being: by volume fraction, the reaction gas includes 85% carbon source gas, 10% hydrogen, and 5% argon; the radio frequency power supply is 4kW, and the gas phase temperature is 100℃; optionally, the reaction time in the gas phase nucleation and growth process is 4h.

[0063] This invention discloses a method for preparing hydrogenated diamond-like carbon powder via plasma gas-phase synthesis, belonging to the field of nanomaterial preparation technology. The invention uses carbon source gas along with argon and hydrogen as reaction gases, introduced into a plasma vacuum chamber. By controlling the radio frequency power, chamber pressure, and gas ratio, the carbon source is decomposed in a plasma environment, directly nucleating and growing in the gas phase space without the need for a solid deposition substrate, resulting in the collection of free, grape-like, hydrogenated diamond-like carbon nanoparticles. This carbon powder has a hydrogen-containing amorphous carbon structure and also contains sp... 3 Diamond phase and sp 2 Graphite phase allows for precise control of hydrogen content and sp content. 3 / sp 2 Carbon phase ratio. This invention solves the problem that traditional PECVD processes can only prepare diamond-like carbon films and are difficult to synthesize hydrogenated diamond-like carbon powder in batches. The carbon powder prepared has an excellent conductive network structure and can be applied to lithium-ion battery anodes, solid lubrication, water treatment adsorption, composite material modification and other fields. The process has strong stability and has the potential for large-scale development.

[0064] This invention has the following advantages:

[0065] 1. Free hydrogenated DLC powder is prepared by direct gas-phase synthesis without the need for a deposition substrate, which is fundamentally different from traditional thin film deposition processes that rely on solid substrates for growth;

[0066] 2. It allows for precise control of the hydrogen content and SP content in the toner. 3 / sp 2 Proportion allows for flexible design of material structure and performance;

[0067] 3. The product has a grape-like nano-aggregate structure, which is beneficial for building a highly efficient conductive network and improving electrochemical performance when used as a conductive electrode in lithium-ion battery anode materials;

[0068] 4. The process is based on a mature PECVD equipment platform, requiring no additional development of dedicated equipment, making it easy to scale up the process and achieve large-scale production.

[0069] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the inventive concept of the present invention, can make other changes and modifications to these embodiments, all of which fall within the scope of the present invention.

[0070] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If such modifications and variations fall within the scope of equivalents of this invention, then this invention is also intended to include these modifications and variations.

Claims

1. A method for preparing hydrogenated diamond-like carbon powder by plasma vapor phase synthesis, characterized in that, Includes the following steps: Chamber pretreatment: The reaction chamber of the chemical vapor deposition equipment is evacuated to a background vacuum and then argon and hydrogen are introduced for plasma cleaning; Gas intake and ignition: The reaction gas is introduced into the pretreated reaction chamber, the gas flow rate and working pressure are adjusted, the radio frequency power supply is turned on, and a stable plasma is generated in the reaction chamber; the reaction gas includes carbon source gas, hydrogen and argon. Gas phase nucleation and growth: The radio frequency power and gas phase temperature are controlled to carry out the reaction. The carbon source gas is decomposed in the plasma gas phase space to generate carbon free radicals. The carbon free radicals undergo homogeneous nucleation and growth in the gas phase space to form primary nanoparticles. The primary nanoparticles further self-assemble to form nano-aggregate structures, thus obtaining hydrogenated diamond-like carbon powder particles. Powder collection: Stop the gas intake, turn off the radio frequency power supply, and collect the powder after the reaction chamber has cooled down to obtain hydrogenated diamond-like carbon powder.

2. The method for preparing hydrogenated diamond-like carbon powder by plasma vapor phase synthesis according to claim 1, characterized in that, The background vacuum is -2 to 10 Pa, and the plasma cleaning time is 10 to 30 minutes.

3. The method for preparing hydrogenated diamond-like carbon powder by plasma vapor phase synthesis according to claim 1, characterized in that, The carbon source gas is methane or acetylene; by volume fraction, the reaction gases include 70%–85% carbon source gas, 5%–25% hydrogen, and 5%–10% argon.

4. The method for preparing hydrogenated diamond-like carbon powder by plasma vapor phase synthesis according to claim 1, characterized in that, The total inlet flow rate of the reactant gas is 580 SCCM.

5. The method for preparing hydrogenated diamond-like carbon powder by plasma vapor phase synthesis according to claim 1, characterized in that, The working air pressure is 5-50 Pa.

6. The method for preparing hydrogenated diamond-like carbon powder by plasma vapor phase synthesis according to claim 1, characterized in that, The RF power supply has a power of 800W to 6kW and a vapor phase temperature of 100 to 300℃.

7. The method for preparing hydrogenated diamond-like carbon powder by plasma vapor phase synthesis according to claim 1, characterized in that, The reaction time during gas-phase nucleation and growth is 0.5 h to 6 h.

8. The method for preparing hydrogenated diamond-like carbon powder by plasma vapor phase synthesis according to claim 1, characterized in that, It also includes post-processing, specifically: after collecting the powder, it is dried with inert gas and then sieved.

9. A hydrogenated diamond-like carbon powder prepared by the method according to any one of claims 1 to 8.

10. The hydrogenated diamond-like carbon powder according to claim 9, characterized in that, The hydrogenated diamond-like carbon powder has a carbon content of 90% to 95% and an oxygen content of 5% to 10%.

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