A method for preparing a layered Cr2O3 crystal material

Abstract

The application discloses a preparation method of layered Cr2O3 crystal material, which uses Cr2O3 powder as raw material, uses CrCl2 as transport agent, and adopts chemical vapor transport to prepare the layered Cr2O3 crystal material. The method comprises the following steps: (1) weighing and grinding the raw material; (2) using a vacuum sealing tube machine and a hydrogen-oxygen machine to seal the tube under vacuum; (3) setting corresponding temperatures in a double-temperature zone tube furnace to make the raw material react, and the layered Cr2O3 crystal material can be obtained after cooling. The method uses CrCl2 as the transport agent, can repeatedly transport Cr2O3, is easy to operate, has controllable quality, and has high repeatability. The method provides a material basis for the layered Cr2O3 crystal material to be used as a catalyst in a hydrogen evolution reaction and an anode material of a lithium ion battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of inorganic material synthesis, and relates to a preparation method of layered Cr2O3 crystal material. BACKGROUND

[0002] In recent years, two-dimensional materials such as graphene and transition metal oxides MoS2, NbS2 and TaS2 have attracted extensive attention due to their layered structure. As a non-transition metal oxide, Cr2O3 has a layered structure in the form of hexagonal system and a non-layered structure in the form of triclinic system. This feature makes Cr2O3 the most attractive field in two-dimensional materials. The chemical properties of layered Cr2O3 are similar to those of graphene and other transition metal oxides, and it can be used as a catalyst in hydrogen evolution reaction or as an anode material for lithium ion batteries (Zhao G, Wen T, Zhang J, et al. Two-dimensional Cr 2 O 3 and interconnected graphene-Cr 2 O 3 nanosheets: synthesis and their application in lithium storage [J]. Journal of Materials Chemistry A, 2014, 2 (4): 944-948.).

[0003] In the actual production and preparation process of layered Cr2O3 crystal material, the commonly used methods are chemical vapor deposition, pulsed laser deposition and radio frequency sputtering. Among them, the chemical vapor deposition method needs to control the flow rate, pressure and other variables in the preparation process, and the pulsed laser deposition method and the radio frequency sputtering method also need to strictly control the pulse intensity and the sputtering frequency. Overall, the existing technology for preparing layered Cr2O3 crystal material has poor repeatability and unstable product quality due to the complex production process and difficult control of variable parameters. How to conveniently and quickly prepare layered Cr2O3 crystal material with required size and shape is a problem to be solved at present. SUMMARY

[0004] In view of the shortcomings of the prior art, the application provides a preparation method of layered Cr2O3 crystal material, which uses chemical vapor transport method and common raw materials and simple experimental conditions to prepare layered Cr2O3 crystal material with obvious layering, smooth surface and large size, solving the problem of poor repeatability of the prior art.

[0005] A preparation method of layered Cr2O3 crystal material, comprising the following steps:

[0006] Step 1, prepare Cr2O3 powder with purity of 99.95% and CrCl2 powder with purity of 97%, weigh and mix them in a molar ratio of 1:1, grind them uniformly, and then put them into the raw material end of a single-end opening quartz tube.

[0007] Step 2, use a vacuum sealing machine to pump air, so that the air pressure in the quartz tube drops to 10-E6 Pa, and then use a hydrogen-oxygen machine to seal the tube, and then put the quartz tube into the center area of the double-temperature zone tube furnace.

[0008] Step 3, set the double-temperature zone tube furnace to heat at a rate of 10-20 degrees per hour until the temperature of the raw material end of the quartz tube is 940℃ and the temperature of the product end is 800℃, and then start the reaction.

[0009] Step 4, maintain the reaction temperature of step 3 for 5-10 days, and then cool down to obtain layered Cr2O3 crystal material at the product end of the quartz tube.

[0010] Preferably, the weighed Cr2O3 powder and CrCl2 powder are ground and mixed under an infrared baking lamp in step 1.

[0011] Preferably, the weighing and grinding mixing of the Cr2O3 powder and the CrCl2 powder are completed in an air glove box or an argon glove box.

[0012] Preferably, the mixed Cr2O3 powder and CrCl2 powder are ground for 30 minutes to ensure uniform mixing.

[0013] Preferably, the length of the single-end opening quartz tube is 30 cm and the diameter is 12 mm.

[0014] The present application has the following beneficial effects:

[0015] The present application uses chemical vapor transport to prepare layered Cr2O3 crystal material, uses common raw materials and experimental equipment, and is simple to operate. Only the temperature in the double-temperature zone tube furnace needs to be controlled during the reaction to ensure stable reaction. The quality of the final product is controllable, the preparation method has high repeatability, energy consumption is low, and raw materials can be recycled and reused, which provides a prerequisite for large-area application of layered Cr2O3 crystal material. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 Figure 1 is a schematic diagram of the preparation of layered Cr2O3 crystal material using chemical vapor transport method;

[0017] Figure 2 Figure 4 is a product morphology diagram of the layered Cr2O3 crystal material prepared in Example 1;

[0018] Figure 3The schematic diagram of the product selected for elemental ratio analysis in Example 1;

[0019] Figure 4 The elemental ratio analysis diagram of the layered Cr2O3 crystal material prepared in Example 1. DETAILED DESCRIPTION

[0020] The application will be further explained in conjunction with the accompanying drawings;

[0021] In the following examples, Cr2O3 powder with a purity greater than 99.95% and CrCl2 powder with a purity greater than 97% are used as the reaction raw materials.

[0022] Example 1

[0023] A preparation method of a layered Cr2O3 crystal material, comprising the following steps:

[0024] Step 1, weigh 0.5107g of Cr2O3 and 0.4129g of CrCl2, mix and grind under an infrared baking lamp for 30 minutes, and then transfer to the bottom of a single-end opening quartz tube with a length of 30cm and a diameter of 12mm, as shown in Figure 1 .

[0025] Step 2, repeatedly wash the gas three times in a vacuum sealing machine, and then use a hydrogen-oxygen machine to seal the quartz tube opening when the vacuum degree is 10E-6Pa.

[0026] Step 3, place the quartz tube into a double-temperature-zone tube furnace, set the temperature rising rate to 20℃ / h, until the temperature of the raw material end of the quartz tube is 940℃ and the temperature of the product end is 800℃.

[0027] Step 4, keep warm for 5 days until the reaction is completed, and then obtain the layered Cr2O3 crystal material at the product end after cooling to room temperature, open the quartz tube and collect the product. The obtained layered Cr2O3 crystal material is shown in Figure 2 , it can be seen that the shape of the obtained material presents a hexagonal shape, and the layered structure can be clearly seen in the field of view. As shown in Figure 3 , the product at the position of the square box in the figure is selected for EDS test, and the energy spectrum diagram is shown in Figure 4 , the analysis of the energy spectrum diagram can obtain the element ratio results shown in Table 1, wherein Cr:O≈2:3, and no Cl element is introduced, which can prove that the CrCl2 powder is only used as a transport agent in the experimental process.

[0028]

[0029] Table 1

[0030] Example 2

[0031] Step 1, 0.5107g of Cr2O3 and 0.4129g of CrCl2 were weighed in an argon glove box, mixed and ground under an infrared baking lamp for 30 minutes, and then transferred to the bottom of a single-end opening quartz tube with a length of 30 cm and a diameter of 12 mm.

[0032] Step 2, repeatedly purging three times in a vacuum sealing machine, and then sealing the quartz tube opening using a hydrogen-oxygen machine when the vacuum degree is 10E-6 Pa.

[0033] Step 3, the quartz tube was placed in a double-temperature-zone tube furnace, and the temperature rising rate was set to 20℃ / h until the temperature of the raw material end of the quartz tube was 940℃ and the temperature of the product end was 800℃.

[0034] Step 4, after 5 days of heat preservation until the reaction was completed, the layered Cr2O3 crystal material was obtained at the product end after cooling to room temperature, the quartz tube was opened, and the product was collected.

[0035] Example 3

[0036] Step 1, 0.5107g of Cr2O3 and 0.4129g of CrCl2 were weighed in an argon glove box, mixed and ground under an infrared baking lamp for 30 minutes, and then transferred to the bottom of a single-end opening quartz tube with a length of 30 cm and a diameter of 12 mm.

[0037] Step 2, repeatedly purging three times in a vacuum sealing machine, and then sealing the quartz tube opening using a hydrogen-oxygen machine when the vacuum degree is 10E-6 Pa.

[0038] Step 3, the quartz tube was placed in a double-temperature-zone tube furnace, and the temperature rising rate was set to 20℃ / h until the temperature of the raw material end of the quartz tube was 940℃ and the temperature of the product end was 800℃.

[0039] Step 4, after 5 days of heat preservation until the reaction was completed, the layered Cr2O3 crystal material was obtained at the product end after cooling to room temperature, the quartz tube was opened, and the product was collected.

[0040] Example 4

[0041] Step 1, 0.5107g of Cr2O3 and 0.4129g of CrCl2 were weighed in an argon glove box, mixed and ground under an infrared baking lamp for 30 minutes, and then transferred to the bottom of a single-end opening quartz tube with a length of 30 cm and a diameter of 12 mm.

[0042] Step 2, repeatedly purging three times in a vacuum sealing machine, and then sealing the quartz tube opening using a hydrogen-oxygen machine when the vacuum degree is 10E-6 Pa.

[0043] Step 3, the quartz tube was placed in a double-temperature-zone tube furnace, and the temperature rising rate was set to 20℃ / h until the temperature of the raw material end of the quartz tube was 940℃ and the temperature of the product end was 800℃.

[0044] Step 4: Keep warm for 5 days until the reaction is complete. After cooling to room temperature, layered Cr2O3 crystal material is obtained at the product end. Open the quartz tube and collect the product.

[0045] Example 5

[0046] Step 1: Weigh 0.5107g of Cr2O3 and 0.4129g of CrCl2, mix and grind them under an infrared lamp for 30 minutes, and then transfer them to the bottom of a single-ended open quartz tube with a length of 30cm and a diameter of 12mm.

[0047] Step 2: Repeat the gas washing three times in the vacuum tube sealing machine, and then use a hydrogen-oxygen generator to seal the quartz tube opening at a vacuum of 10E-6Pa.

[0048] Step 3: Place the quartz tube into a dual-temperature zone tube furnace and set the heating rate to 15℃ / h until the temperature at the raw material end of the quartz tube reaches 940℃ and the temperature at the product end reaches 800℃.

[0049] Step 4: Keep warm for 10 days until the reaction is complete. After cooling to room temperature, layered Cr2O3 crystal material is obtained at the product end. Open the quartz tube and collect the product.

[0050] Example 6

[0051] Step 1: Weigh 0.5107g of Cr2O3 and 0.4129g of CrCl2, mix and grind them under an infrared lamp for 30 minutes, and then transfer them to the bottom of a single-ended open quartz tube with a length of 30cm and a diameter of 12mm.

[0052] Step 2: Repeat the gas washing three times in the vacuum tube sealing machine, and then use a hydrogen-oxygen generator to seal the quartz tube opening at a vacuum of 10E-6Pa.

[0053] Step 3: Place the quartz tube into a dual-temperature zone tube furnace, set the heating rate to 20℃ / h, until the temperature at the raw material end of the quartz tube is 940℃ and the temperature at the product end is 800℃.

[0054] Step 4: Keep warm for 10 days until the reaction is complete. After cooling to room temperature, layered Cr2O3 crystal material is obtained at the product end. Open the quartz tube and collect the product.

[0055] Example 7

[0056] Step 1: Weigh 0.5107g of Cr2O3 and 0.4129g of CrCl2, mix and grind them under an infrared lamp for 30 minutes, and then transfer them to the bottom of a single-ended open quartz tube with a length of 30cm and a diameter of 12mm.

[0057] Step 2: Repeat the gas washing three times in the vacuum tube sealing machine, and then use a hydrogen-oxygen generator to seal the quartz tube opening at a vacuum of 10E-6Pa.

[0058] Step 3: Place the quartz tube into a dual-temperature zone tube furnace and set the heating rate to 15℃ / h until the temperature at the raw material end of the quartz tube reaches 940℃ and the temperature at the product end reaches 800℃.

[0059] Step 4: Keep warm for 5 days until the reaction is complete. After cooling to room temperature, layered Cr2O3 crystal material is obtained at the product end. Open the quartz tube and collect the product.

Claims

1. A method of producing a layered Cr203 crystal material, characterized by: The method comprises the following steps: Step 1: prepare Cr2O3 powder with a purity of 99.95% and CrCl2 powder with a purity of 97%, and mix the two powders in a molar ratio of 1:1, then grind the mixture and put it into a single-end opening quartz tube at the raw material end of the bottom of the tube; Step 2: use a vacuum sealing machine to reduce the air pressure in the quartz tube to 10e-6 Pa, and then use a hydrogen-oxygen machine to seal the tube, and then put the quartz tube into the center area of a double-temperature zone tube furnace; Step 3: set the double-temperature zone tube furnace to heat at a rate of 10-20 degrees per hour until the temperature of the raw material end of the quartz tube is 940 DEG C and the temperature of the product end of the quartz tube is 800 DEG C, and then start the reaction; Step 4: maintain the reaction temperature of step 3, and after 5-10 days, the reaction is completed, and then the layered Cr2O3 crystal material is obtained at the product end of the quartz tube after cooling.

2. The method for preparing a layered Cr2O3 crystal material as described in claim 1, characterized in that: In step 1, the weighed Cr2O3 powder and CrCl2 powder are ground and mixed under an infrared baking lamp.

3. The method for preparing a layered Cr2O3 crystal material as described in claim 1, characterized in that: The weighing and grinding of the Cr2O3 powder and the CrCl2 powder are completed in an air glove box or an argon glove box.

4. The method of claim 1 to 3, wherein the layered Cr203 crystal material is prepared by the following steps: (1) preparing a precursor of Cr203; (2) mixing the precursor with a solvent to form a mixture; (3) heating the mixture to obtain a layered Cr203 crystal material. The mixed Cr2O3 powder and CrCl2 powder are ground for 30 minutes to make them uniformly mixed.

5. The method for preparing a layered Cr2O3 crystal material as described in claim 1, characterized in that: The length of the single-end opening quartz tube is 30 cm, and the diameter is 12 mm.

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