Preparation method of M-phase vanadium dioxide

Abstract

The invention discloses a preparation method of M-phase vanadium dioxide, which comprises the following steps: dispersing V2O5 into deionized water to obtain an aqueous dispersion of V2O5; the preparation method comprises the following steps: adding N2H4. HCl and HCl into an aqueous dispersion of V2O5, stirring until the solution becomes blue from yellow, adding an aqueous suspension of NH4HCO3 in a CO2 atmosphere, and continuously stirring for reaction and purification to obtain oxygen vanadium (IV) basic ammonium carbonate; and placing the oxygen vanadium (IV) basic ammonium carbonate in a protective gas atmosphere for high-temperature heat treatment to obtain the M-phase vanadium dioxide. The M-phase vanadium dioxide is uniform in morphology, is of a monoclinic system structure and has high optical absorptivity, and when the M-phase vanadium dioxide is applied to the Ti < 3 > C < 2 > T < x > MXene material, the transmittance of the Ti < 3 > C < 2 > T < x > MXene material to a visible light-near infrared wavelength band can be regulated and controlled by means of M-phase VO2, and controllable photothermal conversion is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of vanadium dioxide synthesis, and particularly relates to a method for preparing M-phase vanadium dioxide. Background Art

[0002] M-phase vanadium dioxide (VO2) exhibits semiconductor properties at low temperatures, and undergoes a metallic phase transition when the temperature rises to a specific critical temperature, accompanied by a significant increase in electrical conductivity. This phase transition property makes M-phase vanadium dioxide an ideal photothermal regulation material with broad application prospects in the photothermal field. By controlling the structure and composition of M-phase vanadium dioxide, high absorption and low emission in the infrared region can be achieved, so that it can be used to prepare equipment such as solar collectors and thermal radiation regulators to improve energy utilization efficiency, and is widely used in fields such as photothermal electricity conversion.

[0003] The main methods for preparing VO2 nanopowders reported so far are: water (solvent) thermal method, chemical precipitation method, sol-gel method, thermal decomposition method, vapor deposition method, etc. For example, China CN104071843A discloses a method for preparing monodisperse M-phase vanadium dioxide nanoparticles, and obtains monodisperse M-phase vanadium dioxide nanoparticles with a particle size of 60 to 80 nm, but the method requires the use of a strong reducing agent oxalic acid, which may cause excessive reduction of vanadium pentoxide to generate vanadium trioxide. Chinese patent CN202211559919.5 discloses an M-phase vanadium dioxide and a preparation method thereof, specifically disclosing the preparation of M-phase vanadium dioxide by decomposing tetravalent vanadium salts by thermal decomposition, and obtaining vanadium dioxide powder with small particle size and uniform morphology, but the method may produce by-products, affecting the purity of the product. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention aims to provide a method for preparing M-phase vanadium dioxide. The method has the characteristics of safe and simple process steps, low cost, and applicability to industrial production.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for preparing M-phase vanadium dioxide, comprising the following steps:

[0007] S1. Preparation of Vanadyl (IV) Basic Ammonium Carbonate:

[0008] S11, dispersing V2O5 in deionized water to obtain an aqueous dispersion of V2O5;

[0009] S12, adding N2H4·HCl and HCl to the aqueous dispersion of V2O5, stirring until the solution changes from yellow to blue, adding the aqueous suspension of NH4HCO3 while maintaining the CO2 atmosphere, continuing to stir the reaction, purifying, and obtaining vanadyl (IV) basic ammonium carbonate;

[0010] Preparation of S2 and M phase vanadium dioxide (VO2):

[0011] Vanadyl (IV) ammonium carbonate hydroxide is placed in a protective gas atmosphere for high temperature heat treatment to obtain M phase vanadium dioxide.

[0012] Preferably, in step S1, the molar ratio of V2O5 to N2H4·HCl is 1:1-2.

[0013] Preferably, the continued stirring reaction time is 25 to 40 minutes.

[0014] Preferably, in step S12, the purification includes: filtering and washing the reaction product;

[0015] Preferably, the washing treatment is to repeatedly wash with a saturated NH4HCO3 solution until no Cl is detected. - .

[0016] Preferably, in step S2, the high temperature heat treatment temperature is 500-800° C., and the heat treatment time is 1-3 hours.

[0017] Preferably, the protective gas is N2 or Ar.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention first prepares vanadyl (IV) ammonium carbonate hydroxide using V2O5 and N2H4·HCl as raw materials, and then successfully prepares M-phase vanadium dioxide by subjecting the vanadyl (IV) ammonium carbonate hydroxide to high-temperature heat treatment. The obtained M-phase vanadium dioxide has high purity, uniform morphology, and a monoclinic crystal structure.

[0020] (2) The preparation method of the present invention has the characteristics of simple process, easy control of process conditions, low cost, and suitability for industrial production.

[0021] (3) The M-phase VO2 prepared by the present invention has a high optical absorptivity and can be applied to Ti3C2T x MXene materials can regulate the transmittance of visible light to near-infrared wavelengths to achieve controllable photothermal conversion, so they have broad application prospects in photothermal fields such as solar panels. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 is the XRD pattern of M-phase VO2 prepared in Example 1-3;

[0024] Figure 2 The following are: (a) SEM image of 0-VO2; (b) SEM image of 1.0-VO2; (c) TEM image of 1.0-VO2; (d) HRTEM image of 1.0-VO2;

[0025] Figure 3 In order to apply the M-phase VO2 prepared in Example 1 to Ti3C2T x UV-visible-infrared spectral absorption results in MXene materials. DETAILED DESCRIPTION

[0026] In the following description, for the purpose of illustration rather than limitation, specific details such as specific system structures and technologies are provided to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may also be implemented in other embodiments without these specific details.

[0027] Example 1

[0028] A method for preparing M-phase vanadium dioxide comprises the following steps:

[0029] S1. Preparation of Vanadyl (IV) Basic Ammonium Carbonate:

[0030] 5.46 g of V2O5 was added to a three-necked flask containing 15 mL of deionized water and stirred until completely dispersed; 2.68 g of N2H4·HCl and 9.6 ml of HCl were slowly and alternately added to the above dispersion in a CO2 atmosphere. After the solution changed from yellow to blue, 20 ml of NH4HCO3 solution (a water suspension containing 15 g of NH4HCO3) was slowly added dropwise. After the addition was completed, the reaction was continued for 30 min, the reaction solution was filtered, and the product was repeatedly washed with a saturated NH4HCO3 solution until no Cl was detected. - , purple crystals, namely vanadyl (IV) ammonium carbonate, were obtained;

[0031] Preparation of S2 and M phase vanadium dioxide:

[0032] The purple crystals, namely vanadium (IV) ammonium carbonate, were placed in a tube furnace and heat treated at 500°C for 1 hour in a N2 protective atmosphere to obtain a blue-black M-phase VO2 powder named 1.0-VO2. The XRD, SEM and TEM spectra are shown in Figure 1 and Figure 2 .

[0033] Example 2

[0034] A method for preparing M-phase vanadium dioxide comprises the following steps:

[0035] S1. Preparation of Vanadyl (IV) Basic Ammonium Carbonate:

[0036] 5.46 g of V2O5 was added to a three-necked flask containing 15 mL of deionized water and stirred until completely dispersed; 2.18 g of N2H4·HCl and 9.6 ml of HCl were slowly and alternately added to the above dispersion in a CO2 atmosphere. After the solution changed from yellow to blue, NH4HCO3 was slowly added dropwise. After the addition was completed, the reaction was continued for 30 min. The reaction solution was filtered and the product was repeatedly washed with a saturated NH4HCO3 solution until no Cl was detected. - , purple crystals, namely vanadyl (IV) ammonium carbonate, were obtained;

[0037] Preparation of S2 and M phase vanadium dioxide:

[0038] The purple crystals, namely vanadium (IV) ammonium carbonate, were placed in a tubular furnace and heat treated at 500°C for 1 hour in a N2 protective atmosphere to obtain a blue-black M-phase VO2 powder, named 0.5-VO2.

[0039] Example 3

[0040] A method for preparing M-phase vanadium dioxide comprises the following steps:

[0041] S1. Preparation of Vanadyl (IV) Basic Ammonium Carbonate:

[0042] 5.46 g of V2O5 was added to a three-necked flask containing 15 mL of deionized water and stirred until completely dispersed; 1.68 g of N2H4·HCl and 9.6 ml of HCl were slowly and alternately added to the above dispersion in a CO2 atmosphere. After the solution changed from yellow to blue, NH4HCO3 was slowly added dropwise. After the addition was completed, the reaction was continued for 30 min. The reaction solution was filtered and the product was repeatedly washed with a saturated NH4HCO3 solution until no Cl was detected. - , purple crystals, namely vanadyl (IV) ammonium carbonate, were obtained;

[0043] Preparation of S2 and M phase vanadium dioxide:

[0044] The purple crystals, namely vanadium (IV) ammonium carbonate, were placed in a tube furnace and heat treated at 500°C for 1 hour in a N2 protective atmosphere to obtain a blue-black M-phase VO2 powder named 0-VO2. The XRD, SEM and TEM spectra are shown in Figure 1 and Figure 2 .

[0045] Depend on Figure 1 The results show that the diffraction peaks of the M-phase vanadium dioxide (VO2(M)) prepared in Examples 1-3 of the present invention correspond to the XRD standard card of VO2(M), indicating that the present invention successfully prepared M-phase vanadium dioxide.

[0046] Depend on Figure 2 The results show that the M-phase VO2 prepared by the present invention has a uniform morphology and a monoclinic crystal structure.

[0047] The M-phase vanadium dioxide prepared in Example 1 was grafted onto Ti3C2T x VO2@Ti3C2T is obtained on the surface of MXene materials x MXene materials were then tested for UV-visible-infrared spectral absorption performance. The results are shown in Figure 3 .

[0048] Depend on Figure 3 The results show that the M-phase vanadium dioxide prepared by the present invention has a high optical absorption rate, especially at a high temperature. x MXene materials can regulate the transmittance of visible light to near-infrared wavelengths to achieve controllable photothermal conversion, so they have broad application prospects in photothermal fields such as solar panels.

[0049] The present invention is not limited to the above-mentioned specific implementation modes. Various changes made by ordinary technicians in this field based on the above-mentioned concepts without creative work are all within the protection scope of the present invention.

Claims

1. A method for preparing M-phase vanadium dioxide, characterized in that: The following steps are involved: S1. Preparation of Vanadyl (IV) Basic Ammonium Carbonate: S11, dispersing V2O5 in deionized water to obtain an aqueous dispersion of V2O5; S12, adding N2H4·HCl and HCl to the aqueous dispersion of V2O5, stirring until the solution changes from yellow to blue, adding the aqueous suspension of NH4HCO3 while maintaining the CO2 atmosphere, continuing to stir the reaction, purifying, and obtaining vanadyl (IV) basic ammonium carbonate; Preparation of S2 and M phase vanadium dioxide: Vanadyl (IV) ammonium carbonate hydroxide is placed in a protective gas atmosphere for high temperature heat treatment to obtain M phase vanadium dioxide.

2. The method for preparing M-phase vanadium dioxide according to claim 1, characterized in that: In step S1, the molar ratio of V2O5 to N2H4·HCl is 1:1-2.

3. The method for preparing M-phase vanadium dioxide according to claim 1, characterized in that: In step S1, the stirring reaction time is 25 to 40 minutes.

4. The method for preparing M-phase vanadium dioxide according to claim 1, characterized in that: In step S12, the purification includes filtering and washing the reaction product.

5. The method for preparing M-phase vanadium dioxide according to claim 4, characterized in that: The washing treatment is to use saturated NH4HCO3 solution to wash repeatedly until no Cl is detected - .

6. The method for preparing M-phase vanadium dioxide according to claim 1, characterized in that: In step S2, the high temperature heat treatment temperature is 500-800°C, and the heat treatment time is 1-3 hours.

7. The method for preparing M-phase vanadium dioxide according to claim 1, characterized in that: The protective gas is N2 or Ar.

8. M-phase vanadium dioxide obtained by the preparation method according to any one of claims 1 to 7.

Images