Inorganic purification method of black phosphorus crystals

Abstract

The present invention discloses an inorganic purification method for black phosphorus crystals, which specifically comprises the following steps: ultrasonically cleaning the black phosphorus in hot water in sequence; ultrasonically cleaning the black phosphorus with an acid solution; ultrasonically cleaning the iodide solution containing a silicate; ultrasonically cleaning the black phosphorus with hot water, and performing vacuum drying. In the present invention, ultrasonic cleaning with hot water can effectively remove the water-soluble iodide and phosphide contained in the black phosphorus, while hot water can promote the hydrolysis of impurities, further enhancing the impurity removal effect. Ultrasonic cleaning with an acid solution can effectively remove the tin-phosphorus compounds and water-insoluble iodides contained in the black phosphorus; ultrasonic cleaning with an iodide solution can effectively remove the iodine element and red phosphorus contained in the black phosphorus, and adding a silicate can promote the reaction. The present invention only uses inorganic reagents, and compared with the traditional purification method using organic reagents, the impurity removal effect is better, and no toxic and harmful substances are generated during the use of inorganic reagents, which is safe and environmentally friendly. At the same time, the solvent can be better reused, the cost is lower, and it is suitable for large-scale black phosphorus purification.

Description

Technical Field

[0001] The present invention belongs to the field of novel material purification, and in particular relates to a method for purifying black phosphorus. Background Art

[0002] Two-dimensional materials such as graphene have been applied in many fields and are playing an increasingly important role. However, these two-dimensional materials have some shortcomings that limit their application in some areas. Compared with two-dimensional materials such as graphene, black phosphorus, an emerging two-dimensional material, has a wide and tunable direct band gap (0.3eV-2.0eV), as well as good optoelectronic properties and anisotropy, high carrier mobility, and high theoretical specific capacity. Therefore, it has promising application prospects in many fields such as catalysis, medicine, battery anodes, capacitors, and sensors.

[0003] Since the discovery of black phosphorus, various methods for preparing black phosphorus have emerged, but many methods have their shortcomings and limitations. Currently, the methods for large-scale production of black phosphorus are mainly divided into two types: chemical vapor transport and ball milling. In order to further reduce production costs and enable black phosphorus to be more widely used, no matter which method is used to prepare black phosphorus, the purity of the raw materials needs to be further reduced. Under these conditions, the purity of the black phosphorus produced will also be low. In order to facilitate the subsequent application of black phosphorus, the produced black phosphorus needs to be further purified.

[0004] Currently, there are very few patents on the purification of black phosphorus. Chinese patent CN109336073A discloses a method for purifying black phosphorus using an oxidant, and Chinese patent CN111573644A discloses a method for purifying black phosphorus using an alkali. Both methods require the use of a large amount of toxic organic solvents, which will produce toxic and harmful gases during the reaction. At the same time, the former will consume some black phosphorus. The method of this patent does not require the use of organic solvents and can purify black phosphorus using only inorganic substances. No toxic and harmful substances are produced during the purification process, making it safe and environmentally friendly. Summary of the Invention

[0005] In order to solve the problems raised in the background technology, the present invention provides a method for purifying black phosphorus using only inorganic substances. In the present invention, hot water can hydrolyze the water-soluble iodide and phosphide impurities contained in black phosphorus, the acidic solution can remove tin-phosphorus compounds and water-insoluble iodides, the iodide solution can remove elemental iodine and red phosphorus, and silicate is added to promote the reaction. This method is green and environmentally friendly, does not produce toxic and harmful gases, and only uses inorganic substances, without using toxic organic solvents, and can purify a large amount of black phosphorus at low cost and safely.

[0006] In order to achieve the purpose of safely purifying black phosphorus using inorganic substances, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for inorganic purification of black phosphorus that is simple, safe, and environmentally friendly, and specifically comprises the following steps:

[0008] (1) ultrasonically washing black phosphorus with hot water;

[0009] (2) The black phosphorus obtained in (1) was ultrasonically washed with acid.

[0010] (3) The black phosphorus obtained in (2) is ultrasonically washed with an iodide solution containing silicate.

[0011] (4) The black phosphorus obtained in (3) is ultrasonically washed with water.

[0012] (5) The black phosphorus obtained in (4) is vacuum dried.

[0013] Furthermore, the black phosphorus in step (1) is one or a combination of black phosphorus with a diameter of 0.1-5 cm.

[0014] Preferably, the black phosphorus in step (1) is one or a combination of black phosphorus with a diameter of 1-3 cm.

[0015] Furthermore, the water in steps (1) and (4) is deionized water, and the temperature of the hot water is 40°C to 90°C.

[0016] Furthermore, in steps (1) to (4), the ultrasonic washing time is 10 min to 240 min, and the ultrasonic frequency is 20 khz to 40 khz.

[0017] Preferably, the ultrasonic washing time in steps (1) to (4) is 30 min to 60 min.

[0018] Furthermore, the mass volume ratio of black phosphorus to water in steps (1) and (4) is 1:0.1-100.

[0019] Preferably, the mass volume ratio of black phosphorus to water in steps (1) and (4) is 1:1 to 50.

[0020] Furthermore, the acid in step (2) is one or a combination of hydrochloric acid, chloric acid, perchloric acid, chromic acid, dichromic acid, nitric acid, nitrous acid, boric acid, metaboric acid, perboric acid, sulfuric acid, sulfurous acid, carbonic acid, phosphoric acid, phosphorous acid, metaphosphoric acid, hydrobromic acid, bromic acid, hydrofluoric acid, chromic acid, hydroiodic acid, silicic acid, and arsenic acid; and the solvent of the acid is deionized water. The acid concentration is 1×10 -1 mol / L~1×10 1 mol / L.

[0021] Preferably, the acid in step (2) is one or a combination of hydrochloric acid, chloric acid, perchloric acid, chromic acid, dichromic acid, nitric acid, nitrous acid, boric acid, metaboric acid, perboric acid, sulfuric acid, sulfurous acid, carbonic acid, phosphoric acid, phosphorous acid, metaphosphoric acid, hydrobromic acid, bromic acid, hydrofluoric acid, chromic acid, hydroiodic acid, silicic acid, and arsenic acid; the solvent for the acid is deionized water. The acid concentration is 1 mol / L to 5 mol / L.

[0022] Furthermore, in step (2), the mass volume ratio of black phosphorus to acid is 1:0.1-100.

[0023] Preferably, the mass volume ratio of black phosphorus to acid in step (2) is 1:1-50.

[0024] Furthermore, the iodide solution in step (3) is one or a combination of zinc iodide, magnesium iodide, potassium iodide, sodium iodide, and calcium iodide; the solvent of the iodide is deionized water, and the iodide concentration is 1×10 -1 mol / L~1×10 1 mol / L. The silicate is one or a combination of sodium silicate, calcium silicate, magnesium silicate, zinc silicate, and copper fluorosilicate; the mass-to-volume ratio of the silicate to the iodide solution is 1:0.1-100. It is understood that the iodide solution of the silicate refers to the product obtained by dissolving the silicate in an aqueous iodide solution.

[0025] Preferably, the iodide solution in step (3) is one or a combination of zinc iodide, magnesium iodide, potassium iodide, sodium iodide, and calcium iodide; the solvent for the iodide is deionized water, and the iodide concentration is 1 mol / L to 5 mol / L. The silicate is one or a combination of sodium silicate, calcium silicate, magnesium silicate, zinc silicate, and copper fluorosilicate; the mass volume ratio of the silicate to the iodide solution is 1:1 to 50.

[0026] Furthermore, the mass volume ratio of the black phosphorus to the iodide solution in step (3) is 1:0.1-100.

[0027] Preferably, the mass volume ratio of black phosphorus to iodide solution in step (2) is 1:1-50.

[0028] Furthermore, the drying in step (5) is carried out under vacuum conditions at 25°C to 150°C for 30 minutes to 240 minutes.

[0029] Preferably, the drying in step (5) is carried out under vacuum conditions at 100° C. to 120° C. for 60 min to 120 min.

[0030] The black phosphorus purified by this method can be used in catalytic reactions, medicine, battery negative electrodes, capacitors and sensors.

[0031] The method of the present invention has the following significant advantages:

[0032] (1) Use hot water ultrasonic washing to hydrolyze hydrolyzable iodides and phosphides such as tin tetraiodide and then dissolve them in water for removal. Hot water can promote the hydrolysis of impurities and further improve the impurity removal effect; it can save the amount of acid used in subsequent purification and save costs.

[0033] (2) The acid washing method of the present invention can effectively remove water-insoluble iodides and tin-phosphorus compounds, and no toxic or harmful substances are used or generated during the entire purification process, which is safe and environmentally friendly.

[0034] (3) Soaking black phosphorus in iodide solution can produce The reaction increases the solubility of elemental iodine in water, allowing iodine to dissolve in the iodide aqueous solution. This allows the same volume of iodine to dissolve more elemental iodine than an organic solvent. Simultaneously, the iodine and red phosphorus react to form 3I2 + 2P + 3H2O = 6HI + 2H3PO3, which removes the red phosphorus and produces only water-soluble substances, facilitating impurity separation. Adding silicate promotes both reactions, thereby simultaneously removing elemental iodine and red phosphorus impurities.

[0035] (4) The invention uses only deionized water, which has a better purification effect than organic solvents. In addition, only impurities are reacted during the purification process, and black phosphorus will not be lost.

[0036] (5) The present invention is simple to operate, each solution can be reused, and a good impurity removal effect can be achieved when the mass volume ratio of black phosphorus to solution is small, which is conducive to large-scale black phosphorus purification. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0038] Figure 1 These are photographs of black phosphorus before and after purification according to Example 2 of the present invention, wherein a is a front view of black phosphorus before purification, and b is a front view of black phosphorus after purification.

[0039] Figure 2 3 is a comparison diagram of the black phosphorus XRD before and after purification in Example 3 of the present invention, wherein a is the XRD diagram of black phosphorus before purification, and b is the XRD diagram of black phosphorus after purification.

[0040] Specific Implementation Methods The following describes the specific implementation methods of the present invention in detail. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0041] The impurities in black phosphorus are mainly compounds composed of three elements: tin, phosphorus and iodine, iodine element and red phosphorus.

[0042] Example 1

[0043] Prepare 1×10 -1 mol / L hydrochloric acid, weigh 16.6g of potassium iodide solid and dissolve it in 1L of deionized water to prepare 1×10 - 1 mol / L potassium iodide solution.

[0044] (1) Take 1 g of black phosphorus with a diameter of 0.1 cm and add it to 0.1 ml of 40°C deionized water and ultrasonically wash it for 10 min; the ultrasonic frequency is 20 kHz.

[0045] (2) Use 0.1ml 1×10 -1 The black phosphorus obtained in (1) was washed with 1 mol / L hydrochloric acid for 10 min;

[0046] (3) Add 1g sodium silicate to 0.1ml 1×10 -1 mol / L potassium iodide solution was ultrasonically washed with the black phosphorus obtained in (2) for 10 min; 0.1 ml 1×10 -1 mol / L potassium iodide solution is prepared by adding 1g of sodium silicate to 0.1ml of 1×10 -1 mol / L potassium iodide solution and stirred at 40°C for 1 h.

[0047] (4) Ultrasonic washing of black phosphorus in (3) with 0.1 ml of deionized water for 10 min;

[0048] (5) The black phosphorus obtained in (4) was placed in a vacuum drying oven and dried at 80°C for 30 min.

[0049] Table 1 shows the XRF results before and after purification. As can be seen from Table 1, the iodine and tin contents in black phosphorus were significantly reduced, significantly improving the purity of the black phosphorus after purification using this method. Soaking in deionized water can reduce the iodine content; soaking in an acid solution can reduce the iodine and tin contents; soaking in an iodide solution can further reduce the iodine content.

[0050] Table 1 is the XRF results of black phosphorus before and after purification in Example 1 of the present invention

[0051] Serial number Detection indicators Black phosphorus before purification Purified black phosphorus 1 P，％ 97.46 99.69 2 I，％ 1.208 0.088 3 Fe, % 0.073 0.012 4 Cr，％ 0.036 0 5 Sn, % 1.097 0.122 6 As, % 0.062 0.047 7 Ti, % 0.046 0.038 8 Si, % 0.013 0 9 Cu, % 0.005 0.003

[0052] Example 2

[0053] Prepare 1 mol / L hydroiodic acid solution, weigh 75g of sodium iodide solid and dissolve it in 1L of deionized water, and prepare 5×10 - 1 mol / L sodium iodide solution.

[0054] (1) Take 20 g of black phosphorus with a diameter of 2 cm and add it to 50°C deionized water for washing for 30 minutes; the ultrasonic frequency is 25 kHz.

[0055] (2) ultrasonically washing the black phosphorus obtained in (1) with 200 ml of 1 mol / L hydroiodic acid for 30 min;

[0056] (3) Add 20g of magnesium silicate to 200ml of 5×10 -1 mol / L sodium iodide solution ultrasonically (2) obtained black phosphorus 30min; said 200ml 5×10 -1 mol / L sodium iodide solution is prepared by adding 20g of magnesium silicate to 200ml of 5×10 -1 mol / L sodium iodide solution and stirred at 40°C for 1 h.

[0057] (4) ultrasonically washing the black phosphorus in (3) with 200 ml of deionized water for 30 min;

[0058] (5) The black phosphorus obtained in (4) was placed in a vacuum drying oven at 90°C and dried for 60 min.

[0059] The front view of black phosphorus before and after purification is as follows Figure 1 As shown in the figure, it can be seen that there is a lot of red phosphorus attached to the surface of black phosphorus before purification. After purification, the red phosphorus is removed and the surface of black phosphorus reveals a metallic luster.

[0060] Example 3

[0061] Prepare a 3 mol / L phosphoric acid solution, weigh 278 g of magnesium iodide solid and dissolve it in 1 L of deionized water to prepare a 1 mol / L magnesium iodide solution.

[0062] (1) 50 g of black phosphorus with a diameter of 3 cm was added to 1000 ml of 60°C deionized water and ultrasonically washed for 60 min at an ultrasonic frequency of 30 kHz.

[0063] (2) ultrasonically washing the black phosphorus obtained in (1) with 1000 ml of 3 mol / L phosphoric acid for 60 min;

[0064] (3) Ultrasonic treatment of the black phosphorus obtained in (2) was performed for 60 minutes using 1000 ml of a 1 mol / L magnesium iodide solution containing 50 g of calcium silicate; the 1000 ml of a 1 mol / L magnesium iodide solution containing 50 g of calcium silicate was prepared by adding 50 g of calcium silicate to 1000 ml of a 1 mol / L magnesium iodide solution and stirring at 40° C. for 1 hour.

[0065] (4) ultrasonically washing the black phosphorus in (3) with 1000 ml of deionized water for 60 min;

[0066] (5) The black phosphorus obtained in (4) was placed in a vacuum drying oven at 100°C and dried for 120 min.

[0067] XRD before and after purification Figure 2 As shown in the figure, it can be seen that there are more black phosphorus impurity peaks before purification, but after purification, the black phosphorus impurity peaks become fewer and the peak intensity of the characteristic peak increases, indicating that this purification method can efficiently remove the remaining impurities without destroying the black phosphorus crystal form.

[0068] Example 4

[0069] Prepare a 5 mol / L carbonic acid solution, weigh 7975 g of zinc iodide solid and dissolve it in 5 L of deionized water to prepare a 5 mol / L zinc iodide solution.

[0070] (1) 100 g of black phosphorus with a diameter of 4 cm was added to 5000 ml of deionized water at 70°C and ultrasonically washed for 120 min at a frequency of 35 kHz.

[0071] (2) ultrasonically washing the black phosphorus obtained in (1) with 5000 ml of 5 mol / L carbonic acid for 120 min;

[0072] (3) The black phosphorus obtained in (2) was sonicated for 120 minutes using 5000 ml of a 5 mol / L zinc iodide solution containing 100 g of zinc silicate; the 5000 ml of a 5 mol / L zinc iodide solution containing 100 g of zinc silicate was prepared by adding 100 g of zinc silicate to 5000 ml of a 5 mol / L zinc iodide solution and stirring at 40° C. for 1 hour.

[0073] (4) ultrasonically washing the black phosphorus in (3) with 5000 ml of deionized water for 120 min;

[0074] (5) The black phosphorus obtained in (4) was placed in a vacuum drying oven at 120°C and dried for 180 min.

[0075] The XRF results before and after purification are shown in Table 2.

[0076] Table 2 is the XRF results of black phosphorus before and after purification in Example 4 of the present invention

[0077] Serial number Detection indicators Black phosphorus before purification Purified black phosphorus 1 P，％ 96.50 99.77 2 I，％ 1.705 0.019 3 Fe, % 0.062 0.006 4 Cr，％ 0.042 0 5 Sn, % 1.541 0.103 6 As, % 0.071 0.058 7 Ti, % 0.053 0.038 8 Si, % 0.018 0 9 Cu, % 0.008 0.006

[0078] Example 5

[0079] Prepare 1×10 1 mol / L sulfuric acid solution, weigh 3650g of calcium iodide solid and dissolve it in 1L of deionized water to prepare a 10mol / L calcium iodide solution.

[0080] (1) 10 g of black phosphorus with a diameter of 5 cm was added to 1000 ml of 80°C deionized water and ultrasonically washed for 240 min at an ultrasonic frequency of 40 kHz.

[0081] (2) Use 1000ml 1×10 1 The black phosphorus obtained in (1) was ultrasonically washed with a mol / L sulfuric acid solution for 240 min;

[0082] (3) The black phosphorus obtained in (2) was ultrasonically washed for 240 min using 1000 ml of a 10 mol / L calcium iodide solution containing 10 g of copper fluorosilicate; the 1000 ml of a 10 mol / L zinc iodide solution containing 10 g of copper fluorosilicate was prepared by adding 10 g of copper fluorosilicate to 1000 ml of a 10 mol / L zinc iodide solution and stirring at 40° C. for 1 h.

[0083] (4) ultrasonically washing the black phosphorus in (3) with 1000 ml of deionized water for 240 min;

[0084] (5) The black phosphorus obtained in (4) was placed in a vacuum drying oven at 150°C and dried for 240 min.

[0085] The XRF results before and after purification are shown in Table 3.

[0086] Table 3 is the XRF results of black phosphorus before and after purification in Example 5 of the present invention

[0087]

[0088]

[0089] In summary, hot water hydrolyzes water-soluble iodide and phosphide impurities in black phosphorus, an acidic solution removes tin-phosphorus compounds and water-insoluble iodides, and an iodide solution removes elemental iodine and red phosphorus. This method is low-cost, uses no organic solvents, is non-toxic and pollution-free, and is environmentally friendly. The solvent is reusable, making it suitable for large-scale black phosphorus purification.

[0090] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various replacements and changes can be made to the technical solutions of the present invention, and these replacements and changes all fall within the scope of protection of the present invention.

[0091] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will no longer describe various possible combinations one by one.

Claims

1. A method for inorganic purification of black phosphorus, characterized in that: The specific steps include: (1) ultrasonically washing black phosphorus with hot water; (2) ultrasonically washing the black phosphorus obtained in (1) with an acid; the acid is one or a combination of hydrochloric acid, chloric acid, perchloric acid, chromic acid, dichromic acid, nitric acid, nitrous acid, boric acid, metaboric acid, perboric acid, sulfuric acid, sulfurous acid, carbonic acid, phosphoric acid, phosphorous acid, metaphosphoric acid, hydrobromic acid, bromic acid, hydrofluoric acid, chromic acid, hydroiodic acid, silicic acid, and arsenic acid, and the concentration of the acid is 1×10 -1 mol / L~1×10 1 mol / L, the mass volume ratio of black phosphorus to acid is 1:0.1-100; (3) ultrasonically washing the black phosphorus obtained in (2) with an iodide solution containing silicate; the iodide solution is one or a combination of zinc iodide, magnesium iodide, potassium iodide, sodium iodide, and calcium iodide; the silicate is one or a combination of sodium silicate, calcium silicate, magnesium silicate, zinc silicate, and copper fluorosilicate; the iodide concentration is 1×10 -1 mol / L~1×10 1 mol / L, the mass volume ratio of silicate to iodide solution is 1:0.1-100, and the mass volume ratio of black phosphorus to iodide solution is 1:0.1-100; (4) ultrasonically washing the black phosphorus obtained in (3); (5) The black phosphorus obtained in (4) is vacuum dried.

2. The method for inorganic purification of black phosphorus according to claim 1, characterized in that: The diameter of the black phosphorus in step (1) is 0.1-5 cm.

3. The method for inorganic purification of black phosphorus according to claim 1, characterized in that: The water in steps (1) and (4) is deionized water, the mass ratio of black phosphorus to water is 1:0.1-100, and the temperature of the hot water is 40°C-90°C.

4. The method for inorganic purification of black phosphorus according to claim 1, characterized in that: The ultrasonic washing time in steps (1) to (4) is 10 min to 240 min, and the ultrasonic frequency is 20 khz to 40 khz.

5. The method for inorganic purification of black phosphorus according to claim 1, characterized in that: The acid concentration in step (2) is 1 mol / L to 5 mol / L.

6. The method for inorganic purification of black phosphorus according to claim 1, characterized in that: The mass volume ratio of black phosphorus to acid in step (2) is 1:1 to 50.

7. The method for inorganically purifying black phosphorus according to claim 1, characterized in that: The solvent of the iodide in step (3) is deionized water, and the iodide concentration is 1 mol / L to 5 mol / L.

8. The method for inorganic purification of black phosphorus according to claim 1, characterized in that: The mass volume ratio of silicate to iodide solution is 1:1-50.

9. The method for inorganically purifying black phosphorus according to claim 1, characterized in that: The mass volume ratio of black phosphorus to iodide solution in step (3) is 1:1-50.

10. The method for inorganically purifying black phosphorus according to claim 1, characterized in that: The drying in step (5) is carried out under vacuum conditions at 80°C to 150°C for 30 minutes to 240 minutes.

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