CN111254494A

CN111254494A - Preparation method for realizing cheap black phosphorus single crystal by using low-purity red phosphorus

Info

Publication number: CN111254494A
Application number: CN202010226768.6A
Authority: CN
Inventors: 李旻鸶; 李维汉; 孙学良; 李德军
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-03-27
Filing date: 2020-03-27
Publication date: 2020-06-09

Abstract

The invention discloses a method for preparing black phosphorus single crystal by using low-purity red phosphorus, which uses the low-purity red phosphorus as a raw material and a plurality of mineralizer combinations (including tin, iodine and tin tetraiodide) to prepare the black phosphorus. Specifically, cheap low-purity red phosphorus (50-99 wt%), a mineralizer (a mixture of tin powder and iodine powder, and a mixture of tin powder and tin tetraiodide) are used as raw materials, and a black phosphorus single crystal block with a high-purity phase is prepared by a gas phase transmission reaction under a lower pressure by controlling the temperature condition. The invention has simple and easy operation steps for preparing high purity red phosphorus, adopts cheap low-purity red phosphorus, can greatly reduce the production cost and achieves the aim of high conversion rate black scale mass production. And the prepared black phosphorus has the characteristics of good purity, high crystallinity and the like. The preparation method of the black phosphorus provided by the invention has a prospect of large-scale application.

Description

Preparation method for realizing cheap black phosphorus single crystal by using low-purity red phosphorus

Technical Field

The invention belongs to the technical field of chemical single crystal preparation, and relates to a method for preparing black phosphorus single crystal by using low-purity red phosphorus.

Background

Black phosphorus crystals were first synthesized in 1914 by Percy w. With the rapid development of two-dimensional materials, black phosphorus and phosphorus alkene materials exhibit special properties in the aspects of electricity, optics, hotspot science and catalysis, so that the black phosphorus and phosphorus alkene materials are rapidly developed in the last two decades. Moreover, due to the good various performances of the black phosphorus, the black phosphorus has good application prospects in the fields of electrical devices, optical devices and electrocatalysis. However, its high material cost is a major bottleneck for its rapid development and large-scale application.

Historically, the preparation of black phosphorus crystals has undergone a long time of development. After the first report of black phosphorus crystal preparation in 1914 by Percy w. Bridgman, the preparation of large blocks of black phosphorus crystals was achieved by high pressure equipment. In addition, the preparation of the black phosphorus single crystal is also realized by using mercury or bismuth as a catalyst. Recently, Nilges et al first reported in 2008 that Sn-Au alloys and tin tetraiodide were used as mineralizers to achieve conversion of high purity red phosphorus to black phosphorus. Subsequently, Nilges et al realized the growth of black phosphorus using tin powder and tin tetraiodide as mineralizers. Similarly, in the recent work of realizing the growth of black phosphorus by using a tin powder-tin tetraiodide combination or a tin powder-iodine powder as a mineralizer, high-purity red phosphorus (the mass fraction of phosphorus is more than 99 wt%) is required to be used as a raw material, wherein the price of the high-purity red phosphorus with the phosphorus content of 99.99-99.999% is up to 250 RMB/g. In this calculation, the high cost of black phosphorus is mainly due to the high price of high-purity red phosphorus raw material. The black phosphorus preparation methods disclosed in CN104310326A, CN105133009B, CN105460910A and CN105565289A all require high-purity red phosphorus (phosphorus content mass fraction is greater than 99 wt%) as raw material, and these methods cannot reduce the black phosphorus cost fundamentally.

Disclosure of Invention

The invention aims to provide a method for preparing a high-purity black phosphorus single crystal with low cost.

In order to achieve the above object, the present invention provides a way to distinguish all previous black phosphorus preparation methods.

A method for preparing black phosphorus single crystal by using low-purity red phosphorus is characterized by comprising the steps of mixing the low-purity red phosphorus with two mineralizer combinations (one is a mixture of tin powder and iodine powder, and the other is a mixture of tin powder and tin tetraiodide) respectively under a vacuum condition, carrying out gas phase transport reaction in a high-temperature furnace with a temperature gradient, wherein the temperature of a reaction end is increased to 450-900 ℃, and growing black phosphorus single crystal particles at a low-temperature end after a meteorological transport reaction occurs;

the red phosphorus: the mass ratio of the mineralizer is 5-100: 1, preferably 5-20: 1.

The mineralizer refers to: the molar ratio of the tin powder to the iodine powder is 1: 10 to 0.01 or

The molar ratio of the tin powder to the tin tetraiodide mixture is 1: 10 to 0.17.

The purity range of the low-purity red phosphorus raw material is 1-99 wt%. The high-temperature furnace with the temperature gradient is characterized in that the temperature of a growth section in the vacuum tube is lower than that of a reaction end, wherein the temperature difference between the reaction end and the growth end is 50-300 ℃.

Wherein the temperature is increased to 500-900 ℃ in the reaction section in the reaction process, preferably 600-800 ℃, and the temperature is kept for 1-32 hours. After the heat preservation process, the cooling rate is set to be 1-30 ℃/h. The pressure in the vacuum tube is less than 1 Pa.

The invention further discloses application of the prepared black phosphorus single crystal in effectively reducing the production cost of black phosphorus, and experimental results show that: the price of high-purity red phosphorus (the mass fraction of phosphorus content is 99.99-99.999 wt%) is close to 250 RMB/g, and the price of low-purity red phosphorus (taking red phosphorus with the phosphorus content of 97wt% as an example) is only 0.5RMB/g, and the price difference is nearly 500 times. When the cost is calculated, other consumables (mineralizer and vacuum cavity) and the power consumption are calculated together, and the synthesis cost of the high-purity black phosphorus can be reduced by 90%. On the other hand, the purity of the prepared black phosphorus is up to 99.9 wt% determined by X-ray diffraction spectrum (XRD) and energy dispersive X-ray spectroscopy (EDX), and the purity can completely match that of black phosphorus single crystals prepared by other methods. Therefore, the method can realize the cheap preparation of the high-purity black phosphorus single crystal.

The invention is described in more detail below:

firstly, mixing low-purity red phosphorus and mineralizers (two mineralizers are combined, one mineralizer is a mixture of tin powder and iodine powder, and the other mineralizer is a mixture of tin powder and tin tetraiodide) according to a certain mass ratio. The mixing proportion is red phosphorus: the mass ratio of the mineralizer is 5-100: 1, preferably 5-20: 1. And (3) filling the mixed raw materials into a quartz tube, vacuumizing to a pressure of less than 1 Pa, and sealing the opening section of the quartz tube in a vacuum state. And putting the mixture into a tubular furnace, heating to 500-900 ℃ in a reaction section, preferably 600-800 ℃, preserving heat for 1-32 hours, and ensuring that the temperature difference between a low-temperature crystallization end and a high-temperature reaction section is 50-300 ℃. And then, cooling to room temperature for 10-30 h to obtain the black phosphorus crystal.

The invention mainly solves the problem of limitation of the requirement of high-purity red phosphorus raw materials in the conventional black phosphorus single crystal preparation process, mainly inspects the process problem of taking low-purity red phosphorus as the high-purity black phosphorus single crystal preparation raw material, and has the main difficulty of realizing automatic separation of phosphorus atoms and impurities in the low-purity red phosphorus in the black phosphorus single crystal growth process.

Compared with the prior chemical transport method for synthesizing black phosphorus, the method for preparing the black phosphorus single crystal by using the low-purity red phosphorus disclosed by the invention has the advantages that the low-purity red phosphorus is used as a reactant, and compared with the method for synthesizing the black phosphorus by using the high-purity red phosphorus, the production cost can be greatly reduced on the premise of ensuring the crystal quality.

Drawings

FIG. 1 shows the characterization results of black phosphorus obtained in example 1, wherein (A) is a scanning electron microscope image, (B) is an energy dispersive X-ray spectrum, (C) is an X-ray diffraction spectrum, and (D) is a Raman spectrum.

Detailed Description

The invention is described below by means of specific embodiments. Unless otherwise specified, the technical means used in the present invention are well known to those skilled in the art. In addition, the embodiments should be considered illustrative, and not restrictive, of the scope of the invention, which is defined solely by the claims. It will be apparent to those skilled in the art that various changes or modifications in the components and amounts of the materials used in these embodiments can be made without departing from the spirit and scope of the invention. The raw materials used in the invention are pure red phosphorus, tin powder, iodine powder, tin tetraiodide and the like which are sold in the market.

Example 1

Low-purity red phosphorus (phosphorus content: 97 wt%), iodine, and tin powder were mixed in a ratio of 10: 0.15: 0.05 mass percent of the mixture is put into a quartz tube, the open end section is sealed under the vacuum condition, and the sealed quartz tube is put into a tube furnace. Setting the speed of the reaction section to be 1 ℃ per min, heating to 670 ℃, preserving the heat for 20h at 670 ℃, and then cooling to room temperature within 20 h. After the temperature reduction process is finished, the high-purity black phosphorus crystal can be obtained.

The purity of the black phosphorus prepared by X-ray diffraction spectrum (XRD), energy dispersion X-ray spectrum (EDX) and Raman spectrum (Raman) is up to 99.9 wt%,

the used instruments are: BRUKER, Germany, D8 ADVANCE X-ray diffractometer from AXS, Hiahitachi, Japan, model S-4800, field emission Scanning Electron microscope (Fieldemission Scanning Electron microscope) model S-4800, HORIBA Scientific LabRAM HR Raman spectrometer

The test method comprises the following steps: x-ray powder diffraction, secondary electron scanning electron microscope images, energy dispersive X-ray spectroscopy and Raman spectroscopy.

The black phosphorus single crystal parameters are calculated as a = 3.332 Å, b = 10.523 Å and c =4.432 Å.

Example 2

Low-purity red phosphorus (phosphorus content: 90 wt%), tin, and iodine powder were mixed in a ratio of 10: the quartz tube was charged in a mass ratio of 0.15: 0.05, and the sealed quartz tube was placed in a tube furnace by sealing the open end section under vacuum. Setting the speed of the reaction section to be 1 ℃ per min, heating to 780 ℃, preserving the heat at 780 ℃ for 10h, and then cooling to room temperature within 20 h. After the temperature reduction process is finished, the high-purity black phosphorus crystal can be obtained.

Example 3

Low-purity red phosphorus (phosphorus content: 70 wt%), tin, and iodine powder were mixed in a ratio of 10: the quartz tube was charged in a mass ratio of 0.15: 0.05, and the sealed quartz tube was placed in a tube furnace by sealing the open end section under vacuum. Setting the speed of the reaction section to be 1 ℃ per min, heating to 670 ℃, preserving the heat for 20h at 670 ℃, and then cooling to room temperature within 20 h. After the temperature reduction process is finished, the high-purity black phosphorus crystal can be obtained.

Example 4

Low-purity red phosphorus (phosphorus content: 97 wt%), tin, and iodine powder were mixed in a ratio of 10: 0.05: 0.03 mass percent of the mixture is put into a quartz tube, the opening section is sealed under the vacuum condition, and the sealed quartz tube is put into a tube furnace. Setting the speed of the reaction section to be 1 ℃ per min, heating to 780 ℃, preserving the heat at 780 ℃ for 20h, and then cooling to room temperature within 20 h. After the temperature reduction process is finished, the high-purity black phosphorus crystal can be obtained.

Example 5

The low-purity red phosphorus (phosphorus content: 97 wt%), tin powder, and tin tetraiodide were mixed in a ratio of 10: 1: 0.2 mass ratio, and putting the sealed quartz tube into a tube furnace by sealing the open end section under vacuum condition. Setting the speed of the reaction section to be 1 ℃ per min, heating to 780 ℃, preserving the heat at 780 ℃ for 20h, and then cooling to room temperature within 20 h. After the temperature reduction process is finished, the high-purity black phosphorus crystal can be obtained.

Example 6

The low-purity red phosphorus (phosphorus content: 97 wt%), tin powder, and tin tetraiodide were mixed in a ratio of 10: 0.5: 0.2 mass ratio, and putting the sealed quartz tube into a tube furnace by sealing the open end section under vacuum condition. Setting the speed of the reaction section to be 1 ℃ per min, heating to 670 ℃, preserving the heat for 20h at 670 ℃, and then cooling to room temperature within 20 h. After the temperature reduction process is finished, the high-purity black phosphorus crystal can be obtained.

Example 6

Comparative test

The conclusion is that the process can successfully realize the preparation of high-purity black phosphorus from low-purity red phosphorus, and can greatly reduce the preparation cost of black phosphorus single crystals by about 500 times.

Claims

1. A method for preparing black phosphorus single crystal by using low-purity red phosphorus is characterized in that under the vacuum condition, the low-purity black phosphorus is respectively mixed with two mineralizers, and gas phase transport reaction is carried out in a high-temperature furnace with temperature gradient, wherein the temperature of a reaction end is increased to 450-900 ℃, and black phosphorus single crystal particles grow at a low-temperature end after the meteorological transport reaction occurs;

the mass ratio of the pure black phosphorus to the mineralizer is 5-100: 1;

2. The method of claim 1, wherein the low purity red phosphorus material has a purity of 1 to 99 wt%.

3. The preparation method of claim 1, wherein the high temperature furnace with the temperature gradient is characterized in that the temperature of the growth section in the vacuum tube is lower than that of the reaction end, and the temperature difference between the reaction end and the growth end is 50-300 ℃.

4. The preparation method of claim 1, wherein the temperature of the reaction section is raised to 500-900 ℃ in the reaction process, and the temperature is maintained for 1-32 hours.

5. The method of claim 1, wherein the temperature of the reaction zone is raised to 600-800 ℃ during the reaction.

6. The method according to claim 5, wherein the temperature reduction rate is set to 1 to 30 ℃/h after the heat-retaining step.

7. The method according to claim 1 to 6, wherein the pressure in the vacuum tube is in the range of 1 to 10^-5Pa。

8. The use of a black phosphorus single crystal produced by the method of claim 1 to effectively reduce the cost of black phosphorus production.