A method for high-yield preparation of large-size fullerene crystals and magnesium intercalated two-dimensional fullerene crystals

Abstract

The application belongs to the technical field of crystalline fullerene derivatives, and particularly relates to a method for preparing large-size fullerene crystals and magnesium intercalated two-dimensional fullerene crystals with high yield. 60 The crystal particles are mixed with a magnesium source, and then are placed in a reaction container. The mixture is subjected to solid-phase heat treatment under inert atmosphere or vacuum condition, so that magnesium atoms are intercalated into the fullerene crystals and adjacent fullerene molecules are induced to occur two-dimensional covalent polymerization. The product is directly collected in situ to obtain magnesium intercalated two-dimensional fullerene crystals. In the application, the fullerene raw material and the magnesium source are separately placed on one side of the reaction container, vacuum is drawn, then the raw material side is set as a high-temperature zone, the other side is set as a low-temperature zone for heating, and finally the low-temperature zone product is collected to obtain C 60 crystal particles. The application significantly improves the reactant utilization rate and the product collection efficiency through solid-phase conversion of the fullerene crystal precursor.

Description

Technical Field

[0001] This invention belongs to the technical field of crystalline fullerene derivatives, specifically relating to a method for preparing large-size fullerene crystals and magnesium-intercalated two-dimensional fullerene crystals with high yield. Background Technology

[0002] Two-dimensional fullerene materials, possessing the discrete π-electron structure, molecular-scale periodicity, and long-range order of two-dimensional covalent networks, have become an important research direction in the field of crystalline carbon materials in recent years. Among them, magnesium-intercalated two-dimensional fullerene crystals (such as Mg4C) are particularly promising. 60 It can serve as an important precursor for preparing two-dimensional fullerene layered materials, studying the structure of fullerene polymers, and developing applications of low-dimensional carbon materials.

[0003] In existing technologies, magnesium-intercalated two-dimensional fullerene crystals are typically obtained through chemical vapor deposition (CVD) or direct solid-state reaction of fullerene with magnesium. However, CVD is limited by sublimation, transport, and crystal deposition efficiency, resulting in limited product collection, which is often insufficient to meet the sample quantity requirements for subsequent structural characterization, exfoliation, or application research. When commercial fullerene powder is directly reacted with magnesium powder in a solid-state reaction, the reaction interface is inhomogeneous, the magnesium diffusion path is uncontrollable, and multiphase mixtures are easily generated, affecting product purity and crystallinity.

[0004] Therefore, there is an urgent need to develop a method for preparing magnesium-intercalated two-dimensional fullerenes that can balance yield, crystallinity, reproducibility, and scalability. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing large-size fullerene crystals and magnesium-intercalated two-dimensional fullerene crystals with high yield, so as to improve the yield and crystallinity, while having repeatability and scalability.

[0006] To achieve the above objectives, the present invention provides a method for preparing magnesium-intercalated two-dimensional fullerene crystals, comprising: C 60 After the crystal particles are mixed with the magnesium source, they are placed in a reaction vessel and subjected to solid-phase heat treatment under an inert atmosphere or vacuum. The product is then collected directly in situ to obtain magnesium-intercalated two-dimensional fullerene crystals.

[0007] Furthermore, the solid-phase heat treatment is performed at a temperature of 450-550℃ for a time of 20-96 hours.

[0008] Furthermore, the solid-state heat treatment is performed at a temperature of 480-520℃ for a duration of 40-60 hours.

[0009] Furthermore, the C 60 The mass ratio of crystal particles to magnesium source is 10:1 to 1:5; preferably 5:1 to 1:2.

[0010] Furthermore, the C 60 The average size of the crystal particles is 10 μm to 5 mm; preferably 50 μm to 2.5 mm; the magnesium source is one or more of magnesium powder, magnesium flakes, magnesium shavings, magnesium particles or magnesium foil; preferably 10-500 mesh magnesium powder.

[0011] Furthermore, the C 60 The method for preparing the crystal particles includes: separating the fullerene raw material and the magnesium source and placing them on the same side of a reaction vessel; evacuating the vessel; then setting one side of the raw material as a high-temperature zone and the other side as a low-temperature zone for heating; finally collecting the product from the low-temperature zone to obtain C. 60 Crystal grains, the C 60 The crystal size of the crystal particles is larger than that of the fullerene raw material.

[0012] Furthermore, the fullerene raw material is a fullerene crystal with an average size of 1-3 μm; the temperature of the high-temperature zone is 600-700 ℃, and the temperature of the low-temperature zone is 80-120 ℃ lower than that of the high-temperature zone; the heating time is 12-96 h.

[0013] This invention also provides a method for preparing large-size fullerene crystals, comprising: separating the fullerene raw material and the magnesium source and placing them on the same side of a reaction vessel; evacuating the vessel; then setting one side of the raw material as a high-temperature zone and the other side as a low-temperature zone for heating; finally collecting the product from the low-temperature zone to obtain C. 60 Crystal grains, the C 60 The crystal size of the crystal particles is larger than that of the fullerene raw material.

[0014] Furthermore, the fullerene raw material is a fullerene crystal with an average size of 1-3 μm; the C 60 The average size of the crystal particles is 10 μm to 5 mm; preferably, the C 60 The crystal particles contain 0.1wt%-0.5wt% magnesium, the temperature of the high-temperature zone is 600-700 ℃, and the temperature of the low-temperature zone is 80-120 ℃ lower than that of the high-temperature zone; the heating time is 12-96 h.

[0015] Furthermore, a magnesium source is placed inside a large quartz tube, and a fullerene raw material is placed inside a small quartz tube, with one end closed and the other open. The closed end is placed next to the magnesium source inside the large quartz tube, and then the large quartz tube is placed in a dual-temperature zone tube furnace for heating. The large quartz tube is 200-300 mm long and has an inner diameter of 8-15 mm; the small quartz tube is 60-100 mm long and has an inner diameter of 3-6 mm.

[0016] The present invention also provides a large-size fullerene crystal obtained by the preparation method described above.

[0017] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages: (1) The present invention collects the product in situ through solid-phase heat treatment, which can significantly improve the yield of magnesium intercalated two-dimensional fullerene crystals compared with the traditional chemical vapor transport method that collects the product in the low temperature region.

[0018] (2) The process of this invention is simple, reproducible and suitable for large-scale preparation, providing an effective route for the large-scale preparation of magnesium intercalated two-dimensional fullerene crystals and subsequent two-dimensional fullerene materials.

[0019] (3) The product obtained by in-situ collection in this invention has similar properties to Mg4C. 60 The simulated XRD characteristic peaks consistent with powder crystals, the layered stacking morphology, and the Raman characteristic peaks characterizing the covalent bonds between fullerenes can be used for subsequent research on two-dimensional fullerenes, fullerene polymers, low-dimensional carbon materials, and related functional materials.

[0020] (4) Further, by setting the solid-phase heat treatment temperature to 450-550℃ and the time to 20-96h, the present invention can improve the crystal quality while appropriately reducing the temperature of the high-temperature zone and extending the holding time compared with the traditional chemical vapor transport method.

[0021] (5) Furthermore, by using large-size fullerene crystals as precursors, the growth of fullerene crystals is decoupled from the magnesium intercalation / two-dimensional polymerization process, avoiding the problem of low product deposition in one-step gas-phase transport. Compared with commercial fullerene powders, the crystals have higher order and more continuous reaction interfaces, which is conducive to the diffusion, intercalation and two-dimensional covalent polymerization of magnesium in the crystals, thereby obtaining Mg4C with better crystallinity. 60 Crystal.

[0022] (6) Further, the present invention utilizes magnesium powder and amorphous fullerene C 60 The powder is separated and placed in the high-temperature zone, allowing for the collection of larger C particles in the low-temperature zone. 60 The presence of magnesium powder in the crystals contributes to the improved yield, thus enabling the preparation of large-sized C crystals. 60 The crystals can be used for the in-situ preparation of magnesium-intercalated two-dimensional fullerene crystals, which helps to improve product quality and yield. Attached Figure Description

[0023] Figure 1 Large-sized C prepared for Example 1 60 A photograph of a crystal. Figure 2 Large-sized C prepared for Example 1 60 A photograph of crystals dissolved in toluene. Figure 3 The Mg4C prepared by the large single crystal solid-state method in Example 2 of this invention 60 Mg4C prepared by traditional gas-phase transport method 60 and Mg4C 60 Powder X-ray diffraction pattern simulating powder crystals; Figure 4 Mg4C prepared at different temperatures using the large single-crystal solid-state method in Examples 2 and 3 of this invention. 60 Powder X-ray diffraction pattern; Figure 5 X-ray diffraction patterns of the high-temperature region products prepared at different temperatures and times for Comparative Example 2; Figure 6 Mg4C prepared by the conventional gas-phase transport method in this embodiment of the invention 60 Scanning electron microscope image; Figure 7 Mg4C prepared by the large single crystal solid-state method in this embodiment of the invention. 60 Scanning electron microscope image; Figure 8 Mg4C prepared by the large single crystal solid-state method and the traditional gas-phase transport method in the embodiments of the present invention 60 Raman spectrum comparison diagram; Figure 9 This invention provides a method for preparing Mg4C compared to traditional gas-phase transport methods. 60 A diagram showing the process and yield comparison. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0025] like Figure 9 This invention provides a method for preparing magnesium-intercalated two-dimensional fullerene crystals, comprising: C 60 After the crystal particles are mixed with the magnesium source, they are placed in a reaction vessel and subjected to solid-phase heat treatment under an inert atmosphere or vacuum. The product is then collected directly in situ to obtain magnesium-intercalated two-dimensional fullerene crystals.

[0026] This invention uses C 60 Using crystal particles as raw materials for in-situ reaction can significantly improve the yield of magnesium-intercalated two-dimensional fullerene crystals. The yield of existing technologies is generally below 10%, while that of this invention can reach over 70%.

[0027] The solid-state heat treatment is performed at a temperature of 450-550 °C for 20-96 h. Preferably, the solid-state heat treatment is performed at a temperature of 480-520 °C for 40-60 h. If the temperature is too high, the product will partially carbonize, reducing the yield and purity. If the time is too low, the in-situ reaction may be incomplete. When the purity and yield requirements are not so high, the temperature can be extended to 400-650 °C for in-situ collection, with a holding time of 12-96 h, preferably 24-72 h.

[0028] The reaction vessel is a quartz tube, and the vacuum level before sealing is no higher than 10. -2 Pa; preferably not higher than 10 Pa; -4 Pa; more preferably about 10 Pa; -5 Pa. The sample loading process is carried out in an inert atmosphere with H2O content less than 10 ppm and O2 content less than 10 ppm; preferably, both H2O content and O2 content are less than 0.1 ppm.

[0029] In some embodiments, the solid-phase heat treatment is performed using a dual-zone tube furnace, containing C 60 The crystal particles and magnesium source are located in the high-temperature region, with a temperature of 450–550 °C. The low-temperature region has a temperature 50–150 °C lower than the high-temperature region. Finally, the product from the high-temperature region is collected in situ.

[0030] The C 60 The mass ratio of crystal particles to magnesium source is 10:1 to 1:5; preferably 5:1 to 1:2; more preferably 2:1. This invention C 60 The yield of crystal particles is above 50%, preferably not less than 60%, and more preferably not less than 70%. The yield is mainly optimized by adjusting the magnesium source, temperature, and time.

[0031] The C 60 The average size of the crystal particles is 10 μm to 5 mm; preferably 50 μm to 2.5 mm; that is, the C used in this invention. 60 The crystal particles are large-sized fullerene crystals, prepared by chemical vapor transport, sublimation recrystallization, temperature gradient sublimation, or solution recrystallization; preferably, prepared by chemical vapor transport. Preferably, the C... 60 The method for preparing the crystal particles includes: placing the fullerene raw material and the magnesium source separately on one side of a reaction vessel, evacuating the vessel, then setting one side of the raw material as a high-temperature zone and the other side as a low-temperature zone for heating, causing the fullerene to sublimate from the high-temperature zone and recrystallize in the low-temperature zone to obtain large-sized fullerene crystals; finally, collecting the product from the low-temperature zone to obtain C1. 60Crystal particles. This invention first prepares large-sized fullerene crystals, and then performs a secondary solid-state heat treatment on the crystal precursor with a magnesium source, separating the fullerene crystal growth process from the magnesium intercalation / two-dimensional polymerization process, thereby significantly improving the yield and collection efficiency of the target product.

[0032] Furthermore, the fullerene raw material is a fullerene crystal with an average size of 1-3 μm; the temperature of the high-temperature zone is 600-700 ℃, and the temperature of the low-temperature zone is 80-120 ℃ lower than that of the high-temperature zone; the heating time is 12-96 h.

[0033] First, large-sized fullerene crystals obtained through crystal growth are provided. Then, the large-sized fullerene crystals are mixed with a magnesium source in an inert environment and subsequently heat-treated in a vacuum environment. This allows magnesium atoms to intercalate into the fullerene crystals and induces adjacent fullerene molecules to form a two-dimensional covalent polymer structure, resulting in magnesium-intercalated two-dimensional fullerene crystals. This process simultaneously solves the problems of low yield and difficulty in scaling up existing chemical vapor transport methods, as well as the tendency for direct solid-state reactions of fullerene powder to produce multiphase products.

[0034] The magnesium source is one or more of magnesium powder, magnesium flakes, magnesium shavings, magnesium particles, or magnesium foil; preferably, it is magnesium powder with a mesh size of 10-500.

[0035] The Mg4C obtained in this invention 60 The crystal exhibits similarities to Mg4C in the powder X-ray diffraction pattern. 60 The simulated powder crystals showed the principal diffraction peaks and other diffraction peaks corresponding to the (200) crystal plane, and C was absent in the Raman spectrum. 60 It has the characteristic peak of A2 g, as well as the bridging peak that characterizes the covalent connection between fullerene molecules and the characteristic peaks of H7 g and H8 g.

[0036] The magnesium-intercalated two-dimensional fullerene crystals exhibit a layered stacked morphology, with crystal sizes ranging from micrometers to millimeters.

[0037] The magnesium-intercalated two-dimensional fullerene crystals obtained in this invention can be used to prepare two-dimensional fullerenes, fullerene polymers, low-dimensional carbon materials, energy storage materials, catalytic materials, heat transport materials, or electronic device materials.

[0038] This invention also provides a method for preparing fullerene crystals, comprising: placing fullerene raw materials and a magnesium source separately on one side of a reaction vessel, evacuating the vessel, then setting one side of the raw materials as a high-temperature zone and the other side as a low-temperature zone for heating, and finally collecting the product from the low-temperature zone to obtain C. 60 Crystal particles.

[0039] Furthermore, the temperature of the high-temperature zone is 600–700 °C, and the temperature of the low-temperature zone is 80–120 °C lower than that of the high-temperature zone; the heating time is 12–96 h.

[0040] In this invention, "large-size fullerene crystals" refer to fullerene crystal particles with larger crystal size and higher crystal order compared to commercial fullerene powders, preferably with a longest dimension of not less than 10 μm, and more preferably 50 μm to 2 mm. In this invention, the "large single-crystal solid-state method" refers to a method of first obtaining large-size fullerene crystals, and then mixing the large-size fullerene crystals with a magnesium source to carry out solid-state intercalation and polymerization reactions.

[0041] Example 1: Large-size C 60 Crystal preparation 60 mg of magnesium powder (300 mesh, 99.5% purity) was packed into a large quartz tube, 230 mm long, 13 mm outer diameter, and 10 mm inner diameter. 120 mg of fullerene C was packed into a small quartz tube, 80 mm long, 7 mm outer diameter, and 5 mm inner diameter. 60 (Average size approximately 2μm, purity 99.5%), and place the small quartz tube inside the large quartz tube, closer to the magnesium powder side, so that the magnesium powder and C... 60 The particles are spatially separated without direct contact; the small quartz tube is closed at one end near the magnesium powder and open at the other. The above operation is carried out in a glove box filled with argon gas, where the O2 content is less than 0.01 ppm and the H2O content is less than 0.01 ppm.

[0042] The quartz tube after sample loading was evacuated to approximately 10. -5 After Pa, the tube was sealed and placed in a dual-temperature zone tube furnace for heating. One end containing the filler was located in the high-temperature zone (650 °C), and the other end was located in the low-temperature zone (550 °C). The heating time was 130 min, and the holding time was 48 h. After the reaction, the tube was allowed to cool naturally to room temperature. The tube was then opened, and the black single-crystal particles generated in the low-temperature zone were collected, yielding large-size C2 crystals. 60 Crystal.

[0043] like Figure 1 Large size C 60 The crystal size is approximately 2-3.5 mm. From Figure 2 It can be seen that the large-size C 60 The crystals can dissolve in toluene, turning the colorless toluene solution purple, indicating that large-sized C crystals... 60 The crystals did not cross-link under the action of magnesium powder to form magnesium-intercalated two-dimensional fullerenes because the magnesium-intercalated two-dimensional fullerenes Mg4C 60The polymer cannot dissolve in toluene in its molecular state. Furthermore, the large-size C2 particles in aqua regia digested by ICP-OES (Inductively Coupled Plasma-Optical Emission Spectroscopy) were analyzed. 60 Tests on the digestion solution of the crystals showed that large-sized C 60 The magnesium content in the crystal is 0.23 wt%. The above results indicate that large-size C... 60 A small amount of metallic Mg was incorporated into the crystal, while Mg4C 60 It contains 11.89 wt% metallic Mg and large-sized C. 60 The small amount of Mg incorporated into the crystal may promote the subsequent covalent crosslinking of the two-dimensional fullerene. Therefore, this invention utilizes magnesium powder and amorphous fullerene C... 60 Powder undergoes gas-phase transport reaction to obtain large-size C 60 Crystals, with a yield as high as 70%.

[0044] Table 1 Quantitative analysis of magnesium content using ICP-OES

[0045] The present invention also conducted the same experiment as in Example 1, except that magnesium powder was not placed. Although large-sized C atoms could still be collected in the low-temperature region at this time... 60 Crystalline forms, but with a low yield of approximately 5%. Therefore, this invention utilizes magnesium powder and amorphous fullerene C... 60 The powder is placed separately in the high-temperature zone, preventing the direct formation of magnesium-intercalated two-dimensional fullerenes Mg4C in the low-temperature zone. 60 Instead, it yields large-size C-type ... 60 Crystal.

[0046] Example 2: High-yield preparation of Mg4C 60 crystal The 120 mg large-size C obtained in Example 1 60 The crystal particles were mixed with 60 mg of magnesium powder and then packed into a quartz tube 230 mm long, 13 mm outer diameter, and 10 mm inner diameter. The above operation was carried out in a glove box filled with argon gas, where the O2 content was less than 0.01 ppm and the H2O content was less than 0.01 ppm.

[0047] The quartz tube after sample loading was evacuated to approximately 10. -5After Pa, the tube was sealed and placed in a dual-temperature zone tube furnace for secondary solid-state heat treatment. One end containing the mixture was located in the high-temperature zone at 500 °C; the other end was located in the low-temperature zone at 400 °C. The heating time was 100 min, and the holding time was 48 h. After the reaction was completed, the temperature was allowed to cool naturally to room temperature. The tube was then opened, and the black particles in the high-temperature zone were collected, yielding magnesium-intercalated two-dimensional fullerene crystals Mg4C. 60 With initial C 60 The yield calculation in this embodiment is based on step C of embodiment 1. 60 The yield of two-dimensional fullerenes calculated from the feed amount is approximately 70%. The first step involves the growth of large-sized C4 cells. 60 The crystal yield was 70%, and the second step synthesized Mg4C. 60 The yield was close to 100%, meaning that in the second step, Mg powder and large-sized C... 60 After the crystal mixture is pyrolyzed, no further separation is required; the product Mg4C can be obtained directly. 60 .

[0048] Example 3 The 120 mg large-size C obtained in Example 1 60 The crystal particles were mixed with 60 mg of magnesium powder and then packed into a quartz tube 230 mm long, 13 mm outer diameter, and 10 mm inner diameter. The above operation was carried out in a glove box filled with argon gas, where the O2 content was less than 0.01 ppm and the H2O content was less than 0.01 ppm.

[0049] The quartz tube after sample loading was evacuated to approximately 10. -5 After Pa, the tube was sealed and placed in a dual-temperature zone tube furnace for secondary solid-phase heat treatment. One end containing the mixture was located in the high-temperature zone at 600 °C; the other end was located in the low-temperature zone at 500 °C. The heating rate was 5 °C / min, and the holding time was 48 h. After the reaction was completed, the tube was allowed to cool naturally to room temperature, the tube was opened, and the black particles in the high-temperature zone were collected.

[0050] like Figure 4 It can be seen that using a large-size C 60 The positions of the main diffraction peaks (200) and other secondary diffraction peaks of the high-temperature product obtained after reacting powder crystals at 500 °C for 48 h are similar to those of Mg4C. 60 The good correspondence between the simulated powder crystals and the actual crystals indicates the successful preparation of magnesium-intercalated two-dimensional fullerene crystals via the large single-crystal solid-state method. The sharp diffraction peaks suggest good crystallinity of the obtained product. After increasing the reaction temperature from 500 ℃ to 600 ℃, the Mg4C collected in the high-temperature region... 60The corresponding main diffraction peaks disappeared and weakened, while a peak of graphitized amorphous carbon appeared at 25°, indicating that high temperature destroys the carbon structure of fullerenes and leads to their graphitization. The optimal experimental conditions for the large single-crystal solid-state method were 500 °C for 48 h.

[0051] As can be seen, this invention uses a large-size C 60 Powdered crystals, while simultaneously lowering the temperature in the high-temperature zone, allow for direct in-situ collection of products from the high-temperature zone. Compared to collecting products from the low-temperature zone without gas-phase transport, the Mg4C obtained by this invention... 60 The crystals are directly high in density, and the yield is also much higher than that of existing technologies.

[0052] It should be noted that since this invention collects the product in the high-temperature zone in situ, the temperature of the low-temperature zone has little impact on this invention. It is just that a commonly used dual-temperature zone tube furnace is used, so a low-temperature zone temperature is set. It should be understood that this invention can obtain the corresponding product by only setting the high-temperature zone temperature.

[0053] Example 3 Using commercial small-size C 60 Powdered crystals (average size approximately 2 μm) and magnesium powder were mixed and vacuum-sealed into a tube, then placed in a dual-temperature zone tube furnace for heating. The raw material was located at the bottom of the quartz tube, corresponding to the high-temperature zone. The high-temperature zone temperature was 500 ℃ or 600 ℃, and the low-temperature zone temperature was 100 ℃ lower than the high-temperature zone temperature. The holding time was... Figure 5 The heating time was as shown, the heating rate was 5 ℃ / min, and finally the product in the high-temperature zone was collected.

[0054] from Figure 5 It can be seen that using a small-sized C 60 After the powder crystals were reacted at 500 °C for 48 h, the X-ray diffraction pattern of the product showed a wider full width at half maximum (FWHM), indicating poor crystallinity. Compared to Mg4C, the peak widths were also wider. 60 The simulated powder crystals exhibit shifted and impurity peaks. With increasing pyrolysis temperature and reaction time, the product diffraction peaks gradually broaden and disappear, finally showing a peak at 25° representing graphitized amorphous carbon. These results indicate that under the same conditions as the large single-crystal solid-state method, large-size C… 60 Replace the crystal grains with smaller C 60 Powder crystals cannot synthesize Mg4C with good crystallinity. 60 This indicates that the large size C 60 Crystal particles are a necessary condition for in-situ preparation.

[0055] Comparative Example 1: Preparation of Mg4C by Traditional Gas-Phase Transport Method 60 Following the traditional chemical vapor transport route, Mg and C... 60 Mg4C is directly generated in a sealed tube through gas phase transport and deposition. 60Crystals (collecting products from the low-temperature region). This method can obtain Mg4C. 60 Crystals can be formed, but the product collection rate is low due to limitations in gas phase transport and crystal deposition efficiency. Example 2 of this invention uses large-size C0.05 crystals. 60 The crystal precursor reacts directly with Mg powder in a solid phase, which significantly improves the yield compared to Comparative Example 1. In this example, the yield is increased to about 70%.

[0056] Product characterization Figure 3 The powder X-ray diffraction results show that the positions of the main diffraction peaks (200) and other secondary diffraction peaks of the product obtained in Example 2 of this invention are similar to those of Mg4C. 60 The good correspondence between the simulated powder crystals and the actual crystals indicates the successful preparation of magnesium-intercalated two-dimensional fullerene crystals via the large single-crystal solid-state method. The sharp diffraction peaks suggest good crystallinity of the obtained product. This is consistent with Mg4C obtained via the traditional vapor transport method. 60 In comparison, the diffraction peak positions of the two methods correspond well, indicating that the products obtained by the two methods have the same or essentially the same crystal structure.

[0057] Figure 6 and 7 Scanning electron microscopy results showed that Mg4C prepared by the conventional vapor transport method... 60 Mg4C prepared by the method of the present invention 60 All exhibit a layered stacked structure with crystal sizes in the micrometer range. The crystals obtained by the method of this invention also possess a clear layered morphology, indicating its suitability for obtaining collectable and further processed crystalline Mg4C. 60 Material.

[0058] Figure 8 The Raman spectroscopy results show that the Mg4C prepared by the method of the present invention... 60 Compared with Mg4C obtained by conventional gas-phase transport method 60 C did not appear in any of them. 60 The A2 g peak indicates that the product contains virtually no unreacted C. 60 Impurities. Also, located at approximately 900 cm... -1 The bridging double peaks at the 1400–1600 cm⁻¹ indicate the formation of carbon-carbon covalent bonds between adjacent fullerene spheres; -1 The characteristic peaks of H7g and H8g in the region indicate that the Mg4C obtained by the method of this invention... 60 Compared with Mg4C obtained by conventional gas-phase transport method 60 It has structural consistency.

[0059] In summary, this invention first prepares large-size C 60 A two-step strategy of crystal formation followed by Mg solid-phase intercalation and two-dimensional polymerization was employed to achieve Mg4C crystal formation. 60High-yield preparation of crystals. This route overcomes the problems of low yield and insufficient sample collection in traditional chemical vapor transport methods, while maintaining the target Mg4C. 60 The crystal exhibits good crystallinity and a layered structure.

[0060] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing magnesium-intercalated two-dimensional fullerene crystals, characterized in that, include: C 60 After the crystal particles are mixed with the magnesium source, the mixture is subjected to solid-state heat treatment under an inert atmosphere or vacuum, and the product is collected directly in situ to obtain magnesium intercalated two-dimensional fullerene crystals.

2. The method for preparing magnesium-intercalated two-dimensional fullerene crystals according to claim 1, characterized in that, The solid-state heat treatment is performed at a temperature of 450-550℃ for a time of 20-96 hours.

3. The method for preparing magnesium-intercalated two-dimensional fullerene crystals according to claim 2, characterized in that, The solid-state heat treatment is performed at a temperature of 480-520℃ for a duration of 40-60 hours.

4. The method for preparing magnesium-intercalated two-dimensional fullerene crystals according to claim 1, characterized in that, The C 60 The mass ratio of crystal particles to magnesium source is 10:1 to 1:5; preferably 5:1 to 1:

2.

5. The method for preparing magnesium-intercalated two-dimensional fullerene crystals according to any one of claims 1-4, characterized in that, The C 60 The average size of the crystal particles is 10 μm to 5 mm; preferably 50 μm to 2.5 mm. The magnesium source is one or more of magnesium powder, magnesium flakes, magnesium shavings, magnesium particles, or magnesium foil; preferably, it is magnesium powder with a mesh size of 10-500.

6. The method for preparing magnesium-intercalated two-dimensional fullerene crystals according to claim 5, characterized in that, The C 60 The method for preparing the crystal particles includes: separating the fullerene raw material and the magnesium source and placing them on the same side of a reaction vessel; evacuating the vessel; then setting one side of the raw material as a high-temperature zone and the other side as a low-temperature zone for heating; finally collecting the product from the low-temperature zone to obtain C. 60 Crystal grains, the C 60 The crystal size of the crystal particles is larger than that of the fullerene raw material.

7. The method for preparing magnesium-intercalated two-dimensional fullerene crystals according to claim 6, characterized in that, The fullerene raw material is a fullerene crystal with an average size of 1-3 μm; the C 60 The average size of the crystal particles is 10 μm to 5 mm; The temperature of the high-temperature zone is 600-700 ℃, and the temperature of the low-temperature zone is 80-120 ℃ lower than that of the high-temperature zone; the heating time is 12-96 h.

8. A method for preparing large-size fullerene crystals, characterized in that, include: The fullerene feedstock and magnesium source were separated and placed on the same side of the reaction vessel. A vacuum was applied, and the feedstock side was set as a high-temperature zone while the other side was set as a low-temperature zone for heating. Finally, the product from the low-temperature zone was collected to obtain C. 60 Crystal grains, the C 60 The crystal size of the crystal particles is larger than that of the fullerene raw material.

9. The method for preparing large-size fullerene crystals according to claim 8, characterized in that, The fullerene raw material is a fullerene crystal with an average size of 1-3 μm; The temperature of the high-temperature zone is 600-700 ℃, and the temperature of the low-temperature zone is 80-120 ℃ lower than that of the high-temperature zone; the heating time is 12-96 h.

10. A large-size fullerene crystal obtained by the preparation method according to claim 8 or 9.

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