Method for rapidly preparing black phosphorus crystal

Abstract

According to the method, 4-6 sections of temperature control areas are arranged in a vertical reactor at equal intervals, at least two sections of non-interval temperature control areas are arranged on the upper portion to serve as nucleation ends, a partition plate is adopted in the middle to form a temperature control area to serve as a transition section, and the bottom serves as a raw material end; in an inert atmosphere, respectively placing a mixture containing a phosphorus source, a catalyst and a transport agent at the raw material end and the transition section; and sequentially heating the raw material end, the transition section and the nucleation end to prepare the black phosphorus crystal. And carrying out high-temperature reaction by optimizing a heating program and the proportion of each partition material to prepare the high-quality black phosphorus crystal. On one hand, the partition plates are added to weaken the acting force between materials in the vertical space, and the gas phase-solid phase heat transfer mode in the amplification process is achieved; and on the other hand, through optimization of a heating program and the feeding proportion of the upper parts of the partition plates, the contact area between materials is increased, the reaction is accelerated, the single black phosphorus crystal yield is increased, and the reaction time is shortened.

Description

Technical Field

[0001] The invention relates to a method for rapidly preparing black phosphorus crystals. Background Art

[0002] Two-dimensional materials have many material properties because their carrier migration and heat diffusion are confined within the two-dimensional plane. They have been widely used in the fields of field effect transistors, optoelectronic devices, thermoelectric devices, etc. 2 Graphene, a single-layer two-dimensional honeycomb crystal structure in which hybrid connected carbon atoms are tightly packed, has become one of the current research hotspots. Its excellent optical, electrical and mechanical properties have important application prospects in materials science, micro-nano processing, energy, biomedicine and drug delivery. Other materials such as boron nitride, molybdenum disulfide, selenium disulfide, tungsten disulfide and other materials have wide applications in the field of condensed matter physics.

[0003] As a special two-dimensional material, black phosphorus is highly similar to graphene in appearance, performance and structure. It is black flake-shaped, has good conductivity and is layered and wrinkled. The biggest difference between the two is that black phosphorus has an energy gap, the size of which can be adjusted by the number of layers, varying continuously from 0.3 eV (bulk) to 1.51 eV (monolayer), while graphene does not have an energy gap. In terms of optical properties, black phosphorus responds in the range of visible light to near-infrared wavelengths. In the field of optoelectronics, black phosphorus has become the material of choice for most researchers.

[0004] At present, the preparation of black phosphorus is difficult, and the common methods are high-energy ball milling and red phosphorus mineralization. The conversion rate and purity need to be further improved. For example, the Chinese patent (CN 106185849 A) ​​discloses a method for preparing nano black phosphorus by ball milling with red phosphorus as raw material. Although the particle size of black phosphorus obtained by this method is 1 to 5 nm, its preparation cost is high and it is difficult to meet the needs of industrialization. Most of the process technologies such as Chinese patents CN108408703A and CN115522260 use chemical vapor phase method to promote the reaction under high temperature environment by adding catalysts such as tin and iodine. Chinese patent CN117071065A proposes to set a bracket in the lateral space to alleviate the material compaction phenomenon in the preparation of black phosphorus crystals.

[0005] As the mass of single black phosphorus gradually increases to hundreds of kilograms or even larger levels, the accumulation of materials and the heat transfer between materials in the longitudinal direction also greatly affect the volatilization of raw materials, reduce the yield of black phosphorus crystals, and restrict the further development of black phosphorus scale-up preparation technology.

[0006] Therefore, designing a new type of longitudinal built-in baffle can alleviate the material-material force and reduce the material packing density inside the reactor. By adjusting the ratio of phosphorus, catalyst and transport agent above the baffle and the heating program, the longitudinal space inside the reactor is fully utilized to achieve a faster "inert gas-material" heat transfer method, increase the contact area between materials, increase the yield of black phosphorus crystals, shorten the reaction time, and reduce the production cost of black phosphorus crystals, which is of great significance to broaden the development of black phosphorus-based materials in new energy, catalysis, biomedicine and other fields. Summary of the invention

[0007] The present invention uses a longitudinal built-in partition to participate in the whole process of preparing black phosphorus crystals, and the partition includes a circular partition (sieve shape) and a cylindrical support rod. The present invention uses a longitudinal built-in partition to cooperate with the optimization of the heating program to carry out the amplification preparation experiment of black phosphorus crystals. On the one hand, the partition increases and reduces the material stacking density and the force between the materials in the longitudinal space, increases the raw material utilization rate, and improves the preparation yield of black phosphorus crystals. On the other hand, as the scale of the amplification preparation increases, the heat transfer between the materials will gradually slow down, and the addition of the longitudinal partition changes the heat transfer mode in the reaction process from "solid phase-solid phase" to "gas phase-solid phase", increases the heat transfer rate, improves the reactor heating rate, and reduces production costs and production energy consumption. The present invention uses different material ratios, that is, from the raw material end to the partition close to the nucleation end, the catalyst content gradually increases, and the transport agent content gradually decreases. In the heating stage, the transport agent volatilizes upward, and the catalyst melts downward. The holes in the partition are used to increase the contact area between the materials and make full use of the materials.

[0008] To achieve the above object, the technical solution adopted by the present invention is: A longitudinal built-in partition for rapid preparation of black phosphorus crystals. The longitudinal partition is placed in the internal space of a reactor. The partition as a whole is composed of a plurality of sieve-shaped partitions and cylindrical support rods. A series of apertures are present on the surface of the partition.

[0009] The sieve-shaped partition plate and the cylindrical support rod are made of 304 or 316 stainless steel, with a thickness of 3 to 10 mm, preferably 5 to 8 mm.

[0010] The diameter of the sieve-shaped partition plate refers to the inner diameter of the reactor, and the diameter of the small holes on its surface is 2 to 8 mm, preferably 4 to 6 mm.

[0011] The overall height of the longitudinal partition is 1 / 4 to 3 / 5 of the length of the reactor barrel, preferably 1 / 3 to 1 / 2.

[0012] The diameter of the circular support column is 1 / 20 to 1 / 8 of the inner diameter of the reactor, preferably 1 / 20 to 1 / 10.

[0013] The specific usage steps are as follows: 1) Before feeding, determine that the lower part of the vertical reactor is the raw material end, the upper part is the nucleation end, and the middle part is the transition section, and seal the raw material end before feeding; 2) In an inert gas atmosphere, add raw phosphorus, catalyst and transport agent into the reactor in sequence, and adjust the feeding amount above each partition according to the temperature field conditions of each part of the heating device, and seal the nucleation end of the reactor; 3) Regulate the heating program of the heating device to carry out experiments and prepare high-quality black phosphorus crystals.

[0014] In view of the above technical concept, the present invention provides a method for rapidly preparing black phosphorus crystals, comprising the following steps: (1) 4-6 temperature control zones are arranged at equal distances in the vertical reactor, wherein at least two uninterval temperature control zones are arranged in the upper part as the nucleation end, a partition is arranged in the middle part as the temperature control zone as the transition section, and the bottom part is the raw material end; (2) Under an inert atmosphere, a mixture of a phosphorus source, a catalyst, and a transport agent is placed at the raw material end and the transition section respectively; (3) The raw material end, transition section, and nucleation end are heated in sequence to achieve the preparation of black phosphorus crystals.

[0015] The middle part adopts partitions to be arranged into 1-3 temperature control areas as transition sections.

[0016] The partition screen-shaped partition is made of 304 or 316 stainless steel, has a thickness of 3 to 10 mm, and a diameter of small holes on the partition surface of 2 to 8 mm.

[0017] The mass ratio of the phosphorus source, the catalyst and the transport agent in the raw material end is 10:1-9:0.5-3.

[0018] According to the temperature rising program control, more materials are put into the high temperature area, and less materials are put into the upper part of the partition in the low temperature area. The deviation of the total amount of materials in the two areas is between 10% and 20%.

[0019] The phosphorus source used is red phosphorus, and the catalyst is a compound formed by combining at least one of Sn, SnI4, and Bi with P, and the purity of the compound is above 98%.

[0020] The raw material end, transition section and nucleation end are heated to 500-560°C, and the temperature among the raw material end, transition section and nucleation end is gradually reduced, and the temperature difference range is 10-20°C.

[0021] The raw material end is heated from room temperature to 540-560°C in 0.5-1 h, kept at this temperature for 1-4 h, and cooled to room temperature in 2-4 h; The transition stage is to heat from room temperature to 520-550°C in 0.5-1 h, keep warm for 1-4 h, and cool to room temperature in 2-4 h; The nucleation end is heated from room temperature to 500-530°C over 0.5-1 h, kept at this temperature for 1-4 h, and cooled to room temperature over 2-4 h.

[0022] In some embodiments, the middle part of the present invention is configured as two temperature-controlled areas using partitions as transition sections, and five temperature-controlled areas are arranged at equal distances from the bottom to the top in the vertical reactor, wherein at least two uninterval-free temperature-controlled areas are arranged in the top as nucleation ends, the two middle sections are configured as temperature-controlled areas using partitions as transition sections, and the bottom is used as the raw material end.

[0023] In the five temperature control zones that are equidistant from the bottom to the top, the raw material settings and temperature rise procedures are as follows: Stage 1: The ratio of phosphorus source: catalyst: transport agent is 10:1:1.5, and the heating program is: heating to 550-560 °C in 1 h at room temperature, keeping the temperature for 1-4 h, and cooling to room temperature in 2-4 h; The second stage: the ratio of phosphorus source: catalyst: transport agent is 10:3:1, and the heating program is: heating to 540-550 °C in 1 h at room temperature, keeping it at this temperature for 1-4 h, and cooling it to room temperature in 2-4 h; Stage 3: The ratio of phosphorus source: catalyst: transport agent is 10:5:0.5, and the heating program is: heating to 530-540 °C in 1 h at room temperature, keeping it at that temperature for 1-4 h, and cooling to room temperature in 2-4 h; Stage 4: No material is added, and the heating program is as follows: heat to 520-530 °C within 1 h at room temperature, keep warm for 1-4 h, and cool to room temperature within 2-4 h.

[0024] Stage 5: No material is added, and the heating program is as follows: heat to 500-520 °C after 1 h at room temperature, keep warm for 1-4 h, and cool to room temperature after 2-4 h.

[0025] Preferably, the specific heating program is: 1) Stage 1: heating to 560 °C over 1 h at room temperature, keeping at that temperature for 2 h, and cooling to room temperature over 2 h; 2) Stage 2: Heating to 550 °C at room temperature for 1 h, keeping at this temperature for 2 h, and cooling to room temperature for 2 h; 3) Stage 3: heating to 540 °C over 1 h at room temperature, keeping at that temperature for 2 h, and cooling to room temperature over 2 h; 4) Stage 4: heating to 530 °C over 1 h at room temperature, keeping at that temperature for 2 h, and cooling to room temperature over 2 h; 5) Stage 5: Heat to 520 °C at room temperature for 1 h, keep at this temperature for 2 h, and cool to room temperature for 2 h.

[0026] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention adopts longitudinal partitions to reduce the packing density of materials, increase the air volume between materials, and utilize air heat transfer. Compared with the existing metal partition heat transfer and heat transfer between materials, the heat transfer speed is greatly improved, the heating rate is indirectly increased, and the transport and transformation of materials to the nucleation end is promoted.

[0027] 2. The present invention regulates the temperature rise procedure, accurately controls the temperature around each baffle area, fully utilizes the longitudinal space inside the reactor, increases the available area of ​​the raw material end area, enables more materials to reach the reaction temperature during the temperature rise stage, greatly shortens the reaction time, and reduces the hardening of materials after the reaction. At the same time, the temperature difference of each baffle area from the raw material end to the nucleation end is about 10°C, which is conducive to the formation of the temperature field between the raw material end and the nucleation end.

[0028] 3. The present invention regulates the material ratio of each partition area, and the catalyst content gradually increases and the transport agent content gradually decreases from the raw material end to the upper part of the partition at the nucleation end. The melting point of the commonly used catalyst Sn is 231.89°C. When it reaches 100°C, the commonly used transport agent iodine completely volatilizes. In the present invention, during the heating stage, the transport agent volatilizes and moves toward the nucleation end, and the catalyst melts and moves toward the raw material end, increasing the contact area of ​​the transport agent-catalyst-phosphorus source, promoting the reaction, and increasing the yield of black phosphorus preparation.

[0029] 4. The present invention regulates the temperature of the nucleation end, realizes the temperature difference of the nucleation end, increases the heating rate of the nucleation end, weakens the temperature surge phenomenon in the subsequent constant temperature stage, maintains the stability of the nucleation end, maintains the appropriate growth temperature of the black phosphorus crystal, and increases the yield of the black phosphorus crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is an overall schematic diagram of the longitudinal partition used for rapid preparation of black phosphorus crystals and a temperature zone distribution diagram in the embodiment, wherein: 1. reactor, 2. partition, 21. circular partition, 22. cylindrical support rod, 23. circular partition surface aperture, forming a "sieve-shaped partition".

[0031] Figure 2 This is the X-ray diffraction pattern of the black phosphorus crystals obtained in Example 1.

[0032] Figure 3 The mass of black phosphorus crystals prepared in Example 1 and Comparative Examples 1, 2, 3, and 4.

[0033] Figure 4 This is the quality of black phosphorus crystals obtained in Example 2 and Example 3. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below in conjunction with implementation cases and drawings, but the examples given are not intended to limit the present invention.

[0035] Among them, we indirectly explained the crystallinity of the black phosphorus crystal in Implementation Case 1 using the XRD spectrum test results. Generally speaking, under the same characteristic peak, the greater the peak intensity, the higher the crystal crystallinity.

[0036] Comparative Example 1 A horizontal reactor was used to conduct a rapid preparation experiment of 30 kg of black phosphorus crystals. The specific experimental operations were as follows: (1) The horizontal reactor is evenly divided into three sections: the left end is the raw material end, the right end is the nucleation end, and the middle end is the transition end. The raw material end is sealed before feeding.

[0037] (2) Add 98% phosphorus source, 98% pure Sn and 98% pure SnI4 into the reactor in turn, and the feeding is carried out in three times. Divide the materials into three portions, and the material ratio of each portion is about 10:1:1.5 (12 kg: 1.2 kg: 1.8 kg), 10:3:1 (12 kg: 3.6 kg: 1.2 kg) and 10:5:0.5 (6 kg: 3 kg: 0.3 kg). Add the three portions of materials into the reactor in turn, seal the core end, and rotate the reactor to achieve vertical feeding and horizontal reaction.

[0038] (3) The experiment was carried out by optimizing the heating program, as follows: the raw material end was heated to 560 °C for 1 h at room temperature, kept at this temperature for 1 h, and cooled to room temperature for 2 h; the transition end was heated to 540 °C for 1 h at room temperature, kept at this temperature for 1 h, and cooled to room temperature for 2 h; the nucleation end was heated to 520 °C for 1 h at room temperature, kept at this temperature for 1 h, and cooled to room temperature for 2 h. After the reaction, 5.2 kg of high-quality black phosphorus crystals were finally obtained, with an overall yield of 17.3%.

[0039] Comparative Example 2 The 30 kg black phosphorus crystal rapid preparation experiment was carried out using the partition described in Example 1. The specific experimental operation was as follows: (1) The bottom of the vertical reactor is used as the raw material end, the top is used as the nucleation end, and the middle is used as the transition end. The raw material end is sealed before feeding.

[0040] (2) A 98% phosphorus source, 98% pure Sn and 98% pure SnI4 were added into the reactor in sequence. The weight of red phosphorus added to the first, second and third stages was 12 kg, 12 kg and 6 kg respectively. The material ratios of the first, second and third stages were 10:1:1.5 (12 kg: 1.2 kg: 1.8 kg), 10:3:1 (12 kg: 3.6 kg: 1.2 kg) and 10:5:0.5 (6 kg: 3 kg: 0.3 kg).

[0041] (3) Carry out the experiment by optimizing the heating program as follows: The first stage is heated to 560 °C at room temperature for 1 h, kept at this temperature for 2 h, and cooled to room temperature for 2 h; The second stage was heated to 550 °C at room temperature for 1 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h; The third stage was heated to 540 °C at room temperature for 2 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h; The temperature of the fourth and fifth sections was raised to 530 °C at room temperature for 1 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h.

[0042] After the reaction, 15.3 kg of high-quality black phosphorus crystals were obtained, with an overall yield of 51.0%.

[0043] Comparative Example 3 The separator mentioned in Example 1 was used to quickly prepare 30 kg of black phosphorus crystals. The specific experimental operation was as follows: (1) The bottom of the vertical reactor is used as the raw material end, the top is used as the nucleation end, and the middle is used as the transition end. The raw material end is sealed before feeding.

[0044] (2) A 98% phosphorus source, 98% pure Sn, and 98% pure SnI4 were sequentially added into the reactor, and the weight of red phosphorus added to the first, second, and third stages was 10 kg. The material ratios of the first, second, and third stages were all 10:3:1 (10 kg: 3 kg: 1 kg).

[0045] (3) Carry out the experiment by optimizing the heating program as follows: The first stage is heated to 560 °C at room temperature for 1 h, kept at this temperature for 1 h, and cooled to room temperature for 2 h; The second stage was heated to 550 °C at room temperature for 1 h, kept at that temperature for 1 h, and then cooled to room temperature for 2 h; The third stage was heated to 540 °C at room temperature for 1 h, kept at that temperature for 1 h, and then cooled to room temperature for 2 h; The fourth stage was heated to 530 °C at room temperature for 1 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h; The fifth section was heated to 520 °C at room temperature for 1 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h.

[0046] After the reaction, 19.0 kg of high-quality black phosphorus crystals were obtained, with an overall yield of 63.3%.

[0047] Comparative Example 4 The separator mentioned in Example 1 was used to prepare 30 kg of black phosphorus crystals. The specific experimental operation was as follows: (1) The bottom of the vertical reactor is used as the raw material end, the top is used as the nucleation end, and the middle is used as the transition end. The raw material end is sealed before feeding.

[0048] (2) A 98% phosphorus source, 98% pure Sn and 98% pure SnI4 were sequentially added into the reactor, and the weight of red phosphorus added to the first, second and third stages was 12 kg, 12 kg and 6 kg respectively. The material ratios of the first, second and third stages were 10:1:1.5 (12 kg: 1.2 kg: 1.8 kg), 10:3:1 (12 kg: 3.6 kg: 1.2 kg) and 10:5:0.5 (6 kg: 3 kg: 0.3 kg).

[0049] (3) Carry out the experiment by optimizing the heating program as follows: The first stage is heated to 560 °C at room temperature for 1 h, kept at this temperature for 1 h, and cooled to room temperature for 2 h; The second stage was heated to 550 °C at room temperature for 1 h, kept at that temperature for 1 h, and then cooled to room temperature for 2 h; The third stage was heated to 540 °C at room temperature for 1 h, kept at that temperature for 1 h, and then cooled to room temperature for 2 h; The fourth stage was heated to 530 °C at room temperature for 1 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h; The fifth section was heated to 520 °C at room temperature for 1 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h.

[0050] After the reaction, 8.5 kg of high-quality black phosphorus crystals were finally obtained, with an overall yield of 28.3%.

[0051] Example 1 A built-in longitudinal partition for rapid preparation of black phosphorus crystals, such as Figure 1 As shown, the partition as a whole is composed of a plurality of sieve-shaped partitions 21 and cylindrical support rods 22; there are a series of apertures 23 on the surface of the partition.

[0052] The sieve-shaped partition and cylindrical support rod are made of 304 or 316 stainless steel with a thickness of 6 mm.

[0053] The diameter of the sieve-shaped baffle is based on the inner diameter of the reactor, and the diameter of the small holes on its surface is 6 mm.

[0054] The overall height of the longitudinal partition is 5 / 12 of the length of the reactor barrel.

[0055] The diameter of the circular support column is 3 / 40 of the inner diameter of the reactor.

[0056] The longitudinal partition was used to quickly prepare 30 kg of black phosphorus crystals. The specific experimental operation was as follows: (1) The bottom of the vertical reactor is used as the raw material end, the top is used as the nucleation end, and the middle is used as the transition end. The raw material end is sealed before feeding.

[0057] (2) A 98% phosphorus source, 98% pure Sn and 98% pure SnI4 were sequentially added into the reactor, and the weight of red phosphorus added to the first, second and third stages was 12 kg, 12 kg and 6 kg respectively. The material ratios of the first, second and third stages were 10:1:1.5 (12 kg: 1.2 kg: 1.8 kg), 10:3:1 (12 kg: 3.6 kg: 1.2 kg) and 10:5:0.5 (6 kg: 3 kg: 0.3 kg).

[0058] (3) Carry out the experiment by optimizing the heating program as follows: The first stage is heated to 560 °C at room temperature for 1 h, kept at this temperature for 1 h, and cooled to room temperature for 2 h; The second stage was heated to 550 °C at room temperature for 1 h, kept at that temperature for 1 h, and then cooled to room temperature for 2 h; The third stage was heated to 540 °C at room temperature for 1 h, kept at that temperature for 1 h, and then cooled to room temperature for 2 h; The fourth stage was heated to 530 °C at room temperature for 1 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h; The fifth section was heated to 520 °C at room temperature for 1 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h.

[0059] After the reaction, 24.6 kg of high-quality black phosphorus crystals were obtained, with an overall yield of 82.0%.

[0060] It should also be noted that, referring to the various technical features described in the above case, the reactor size and the longitudinal partition size can be enlarged in a certain proportion to realize a single black phosphorus crystal scale-up preparation experiment.

[0061] Compared with Comparative Example 1, Example 1 shows that on the road to large-scale production of black phosphorus crystals, the vertical device can further promote the transportation of materials to the nucleation end and realize the efficient preparation of black phosphorus crystals. Compared with Comparative Example 2, the experimental conditions of Example 1 set a temperature difference between the fourth and fifth sections, and the gradient temperature increase improves the temperature stability of the nucleation end, avoids the temperature surge phenomenon, and improves the yield of black phosphorus crystals. Compared with Comparative Example 3, the experimental conditions of Example 1 adjusted the proportion of materials above the applied partition to achieve most of the catalyst above the material, and flow downward after heating and melting, and most of the transport agent is below the material, and sublimates when heated. The two jointly promote the reaction while reducing the packing density between materials after amplification, increasing the contact area between materials, and promoting the growth of black phosphorus crystals.

[0062] Example 2 The longitudinal partition in the above-mentioned Example 1 was used to quickly prepare 30 kg of black phosphorus crystals. The specific experimental operation was as follows: (1) The bottom of the vertical reactor is used as the raw material end, the top is used as the nucleation end, and the middle is used as the transition end. The raw material end is sealed before feeding.

[0063] (2) A 98% phosphorus source, 98% pure Sn and 98% pure SnI4 were sequentially added into the reactor, and the weight of red phosphorus added to the first, second and third stages was 12 kg, 12 kg and 6 kg respectively. The material ratios of the first, second and third stages were 10:1:1.5 (12 kg: 1.2 kg: 1.8 kg), 10:3:1 (12 kg: 3.6 kg: 1.2 kg) and 10:5:0.5 (6 kg: 3 kg: 0.3 kg).

[0064] (3) Carry out the experiment by optimizing the heating program as follows: The first stage is heated to 550 °C at room temperature for 1 h, kept at that temperature for 1 h, and cooled to room temperature for 2 h; The second stage was heated to 540 °C at room temperature for 1 h, kept at that temperature for 1 h, and then cooled to room temperature for 2 h; The third stage was heated to 530 °C at room temperature for 1 h, kept at this temperature for 1 h, and then cooled to room temperature for 2 h; The fourth stage was heated to 520 °C at room temperature for 1 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h; The fifth section was heated to 500 °C at room temperature for 1 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h.

[0065] After the reaction, 26.5 kg of high-quality black phosphorus crystals were obtained, with an overall yield of 88.3%.

[0066] Example 3 The longitudinal partition in the above-mentioned Example 1 was used to quickly prepare 30 kg of black phosphorus crystals. The specific experimental operation was as follows: (1) The bottom of the vertical reactor is used as the raw material end, the top is used as the nucleation end, and the middle is used as the transition end. The raw material end is sealed before feeding.

[0067] (2) A 98% phosphorus source, 98% pure Sn and 98% pure SnI4 were sequentially added into the reactor. The weight of red phosphorus added to the first, second and third stages was 12 kg, 12 kg and 6 kg respectively. The material ratios of the first, second and third stages were 10:1:3 (12 kg: 1.2 kg: 3.6 kg), 10:5:1.5 (12 kg: 6 kg: 1.8 kg) and 10:9:0.5 (6 kg: 5.4 kg: 0.3 kg).

[0068] (3) Carry out the experiment by optimizing the heating program as follows: The first stage is heated to 560 °C at room temperature for 1 h, kept at this temperature for 1 h, and cooled to room temperature for 2 h; The second stage was heated to 550 °C at room temperature for 1 h, kept at that temperature for 1 h, and then cooled to room temperature for 2 h; The third stage was heated to 540 °C at room temperature for 1 h, kept at that temperature for 1 h, and then cooled to room temperature for 2 h; The fourth stage was heated to 530 °C at room temperature for 1 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h; The fifth section was heated to 520 °C at room temperature for 1 h, kept at this temperature for 2 h, and then cooled to room temperature for 2 h.

[0069] After the reaction, 27.3 kg of high-quality black phosphorus crystals were obtained, with an overall yield of 91.0%.

Claims

1. A method for rapidly preparing black phosphorus crystals, characterized in that: The steps include: (1) 4-6 temperature control zones are arranged at equal distances in the vertical reactor, wherein at least two uninterval temperature control zones are arranged in the upper part as the nucleation end, a partition is arranged in the middle part as the temperature control zone as the transition section, and the bottom part is the raw material end; (2) Under an inert atmosphere, a mixture of a phosphorus source, a catalyst, and a transport agent is placed at the raw material end and the transition section respectively; (3) The raw material end, transition section, and nucleation end are heated in sequence to achieve the preparation of black phosphorus crystals.

2. The method for rapidly preparing black phosphorus crystals according to claim 1, characterized in that: The middle part adopts partitions to be arranged into 1-3 temperature control areas as transition sections.

3. The method for rapidly preparing black phosphorus crystals according to claim 2, characterized in that: The partition screen-shaped partition is made of 304 or 316 stainless steel, has a thickness of 3 to 10 mm, and a diameter of small holes on the partition surface of 2 to 8 mm.

4. The method for rapidly preparing black phosphorus crystals according to claim 3, characterized in that: The mass ratio of the phosphorus source, the catalyst and the transport agent in the raw material end is 10:1-9:0.5-3.

5. The method for rapidly preparing black phosphorus crystals according to claim 4, characterized in that: The raw material end, transition section and nucleation end are heated to 500-560°C, and the temperature among the raw material end, transition section and nucleation end is gradually reduced, and the temperature difference range is 10-20°C.

6. The method for rapidly preparing black phosphorus crystals according to claim 5, characterized in that: The raw material end is heated from room temperature to 540-560°C in 0.5-1 h, kept at this temperature for 1-4 h, and cooled to room temperature in 2-4 h; The transition stage is to heat from room temperature to 520-550°C in 0.5-1 h, keep warm for 1-4 h, and cool to room temperature in 2-4 h; The nucleation end is heated from room temperature to 500-530°C over 0.5-1 h, kept at this temperature for 1-4 h, and cooled to room temperature over 2-4 h.

7. The method for rapidly preparing black phosphorus crystals according to claim 6, characterized in that: The middle part is configured into two temperature control areas using partitions as transition sections, and five temperature control areas are arranged at equal distances from the bottom to the top in the vertical reactor, wherein at least two uninterval temperature control areas are arranged in the top as nucleation ends, the two middle sections are configured into temperature control areas using partitions as transition sections, and the bottom is used as the raw material end.

8. The method for rapidly preparing black phosphorus crystals according to claim 7, characterized in that: In the five temperature control zones that are equidistant from the bottom to the top, the raw material settings and temperature rise procedures are as follows: Stage 1: The ratio of phosphorus source: catalyst: transport agent is 10:1:1.5, and the heating program is: heating to 550-560 °C in 1 h at room temperature, keeping the temperature for 1-4 h, and cooling to room temperature in 2-4 h; The second stage: the ratio of phosphorus source: catalyst: transport agent is 10:3:1, and the heating program is: heating to 540-550 °C in 1 h at room temperature, keeping it at this temperature for 1-4 h, and cooling it to room temperature in 2-4 h; Stage 3: The ratio of phosphorus source: catalyst: transport agent is 10:5:0.5, and the heating program is: heating to 530-540 °C in 1 h at room temperature, keeping it at that temperature for 1-4 h, and cooling to room temperature in 2-4 h; Stage 4: No material is added, and the heating program is as follows: heat to 520-530 °C within 1 h at room temperature, keep warm for 1-4 h, and cool to room temperature within 2-4 h. Stage 5: No material is added, and the heating program is as follows: heat to 500-520 °C within 1 h at room temperature, keep warm for 1-4 h, and cool to room temperature within 2-4 h.

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