NH4V4O10 nanosheet microcluster, and preparation method and application thereof

Abstract

This invention relates to the field of nanomaterial preparation technology, and in particular to an NH4V4O 10 Nanosheet clusters, their preparation methods, and applications are prepared via a hydrothermal reaction between ammonium metavanadate and organic acids, resulting in NH4V4O. 10 Nanosheet clusters, by changing the amount of NH4VO3, can achieve NH4V4O 10 The morphology and size of nanosheet clusters can be controlled. No structure-directing agent needs to be added to the reaction system to achieve NH4V4O 10 The method effectively controls the microstructure, is simple and easy to control, produces pure products, is low in cost, and is easy to promote. It can be extended to the deposition of ammonium vanadate nanosheets and clusters on carbon substrates. The ammonium vanadate nanosheets and clusters and related composite materials prepared by this invention are expected to be applied in the desalination of dyeing and printing wastewater, seawater desalination, and capacitor deionization.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial preparation technology, and in particular to an NH4V4O 10 Nanosheet clusters, their preparation methods, and applications. Background Technology

[0002] Dyeing and printing wastewater contains a wide variety of organic matter and has a complex salt composition, making it difficult for traditional desalination technologies to achieve ideal desalination results. Capacitive deionization (CDI) is an emerging water treatment process with advantages such as low energy consumption, environmental friendliness, simple equipment, and convenient operation, and it holds promise for achieving efficient desalination of dyeing and printing wastewater. Based on the ion storage mechanism of CDI, the electrode material is crucial to the desalination effect. Carbon-based electrodes are limited by their electroadsorption characteristics and low porosity, resulting in typically low desalination capacities. Therefore, Faraday electrode materials (such as manganese oxides, vanadium oxides, transition metal sulfides, MXene, Prussian blue, and their analogues) have gradually attracted widespread attention.

[0003] NH4V4O 10 Ammonium vanadate, as a typical layered vanadium oxide, possesses multiple mixed valence states and an open layered structure; NH4 intercalated between the VO layers... + As a "pillar" ion, it not only prevents structural changes during ion insertion / deintercalation, but also expands the interlayer distance of VO, promoting rapid ion migration; simultaneously, NH4 + The NH4V4O hydrogen bond network formed between the vanadium and VO layers is beneficial to improving the cycling stability of the electrode material; in addition, compared with other metal (zinc, potassium, sodium, etc.) vanadium oxides, NH4V4O 10 With its low molecular weight, NH4V4O can provide a high specific capacity; in addition, my country has the world's largest vanadium reserves, making its vanadium resources relatively abundant and its usage costs relatively low; these advantages make NH4V4O 10 It shows great application potential in the field of capacitive deionization.

[0004] Currently, in most literature, NH4V4O 10 It is generally prepared by a hydrothermal reaction between ammonium metavanadate (NH4VO3) and oxalic acid (H2C2O4). Although this method is simple, the obtained NH4V4O 10The morphology and size are difficult to control; on the other hand, CN116514165 A discloses a structure-directing agent-induced ammonium vanadate nanoribbon cathode material, its preparation method, and its application. The preparation method includes: under magnetic stirring, weighing ammonium metavanadate and adding it to a beaker containing deionized water and stirring to dissolve, forming a milky white solution; adding organic acid powder to the milky white solution under magnetic stirring and stirring to dissolve, forming a yellow solution; adding structure-directing agent powder to the yellow solution under magnetic stirring and stirring to dissolve, forming a homogeneous solution; pouring the homogeneous solution into a polytetrafluoroethylene mold, placing it in a reaction vessel, and then placing it in an oven to react, obtaining a primary product; washing the primary product multiple times with deionized water and ethanol, and then drying it in an oven to obtain the ammonium vanadate nanoribbon cathode material. This method adds a structure-directing agent to the reaction system, which can achieve NH4V4O 10 Effective control of microstructure is possible, but this will significantly increase the synthesis cost. Therefore, it is necessary to develop a simple, controllable, and efficient method for preparing NH4V4O. 10 The approach remains extremely challenging. Summary of the Invention

[0005] To address the shortcomings of the existing technology, an NH4V4O is provided. 10 Nanosheet clusters, their preparation methods, and applications: NH4V4O can be achieved without the addition of structure-directing agents in the reaction system. 10 This method effectively controls microscopic morphology and size, is simple to implement, easy to control, produces pure products, is low in cost, and is easy to promote.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is an NH4V4O 10 Nanosheet clusters are prepared by a hydrothermal reaction between ammonium metavanadate and organic acids, resulting in NH4V4O. 10 Nanosheet clusters, by changing the amount of NH4VO3, can achieve NH4V4O 10 Control of the morphology and size of nanosheet clusters.

[0007] The above-mentioned NH4V4O 10 Nanosheet clusters, which are monoclinic crystalline phase NH4V4O 10 The morphology is flower-like nanosheet clusters, NH4V4O 10 The size of the nanosheet clusters increases with increasing amount of ammonium metavanadate, NH4V4O 10 The nanosheet clusters became more compact with increasing amounts of ammonium metavanadate.

[0008] The above-mentioned NH4V4O 10 Nanosheet clusters containing NH4V4O 10 The nanosheets are strip-shaped, approximately 3.7 μm in length, with an aspect ratio of approximately 30:1, and are interwoven with each other in a random orientation.

[0009] The above-mentioned NH4V4O 10 Nanosheet clusters with an average diameter of approximately 7.5 μm-12 μm.

[0010] The above-mentioned NH4V4O 10 The method for preparing nanosheet clusters includes the following steps:

[0011] (1) Dissolve a certain mass of ammonium metavanadate powder in an appropriate amount of deionized water under water bath heating, cool to room temperature, add a certain mass of organic acid, stir evenly, and obtain a mixed reaction solution.

[0012] (2) Transfer the reaction solution obtained in step (1) to a high-pressure hydrothermal reactor for hydrothermal reaction;

[0013] (3) After the solution from the hydrothermal reaction in step (2) is cooled, centrifuged to obtain a solid powder, washed several times with deionized water, and dried, NH4V4O can be obtained. 10 Nanosheets and microclusters.

[0014] The above-mentioned NH4V4O 10 The method for preparing nanosheet clusters, wherein in the mixed reaction solution of step (1), the concentration of ammonium metavanadate is 4-12 g / L, and the organic acid is citric acid with a concentration of 3-22 g / L.

[0015] The above-mentioned NH4V4O 10 The preparation method of nanosheet microclusters, wherein the hydrothermal reaction temperature in step (2) is 120-180℃ and the reaction time is 2-24h.

[0016] The above-mentioned NH4V4O 10 The method for preparing nanosheet clusters, in step (3), the solution cooling time after hydrothermal reaction is 3-6h, the centrifuge speed is 7000-10000rpm, the centrifugation time is 10-15min, the solution is washed with deionized water 3-6 times, the drying temperature is 50-70℃, and the drying time is 8-24h.

[0017] NH4V4O 10 Applications of nanosheets and microclusters, NH4V4O 10 Nanosheets or microclusters of NH4V4O 10 Nanosheet clusters deposited on carbon substrates can be applied to desalination of dyeing and printing wastewater, seawater desalination, and capacitor deionization.

[0018] This invention provides an NH4V4O 10The beneficial effects of the nanosheet clusters, their preparation method, and their applications are as follows: by controlling the amount of reaction raw materials, the microstructure and size of ammonium vanadate can be controlled without the addition of structure-directing agents; the preparation method described in this invention is simple, easy to control, low in cost, and easy to promote, and can be extended to the deposition of ammonium vanadate nanosheet clusters on carbon substrates; the ammonium vanadate nanosheet clusters and related composite materials prepared by this invention are expected to be applied in the desalination of dyeing and printing wastewater, seawater desalination, and capacitor deionization.

[0019] (1) In this invention, when the molar ratio of ammonium metavanadate to citric acid is less than 1:2, ammonium metavanadate product will not be obtained; when the amount of ammonium metavanadate is small (the molar ratio of ammonium metavanadate to citric acid is close to 1:1), the pH value of the reaction solution is low (pH≈3.5), and at this time, small-sized sheet-like structures are easily formed.

[0020] (2) In this invention, increasing the amount of ammonium metavanadate slightly increases the pH value of the reaction solution, and the resulting products are mostly banded structures. The larger the amount of ammonium metavanadate, the larger the size of the product.

[0021] (3) The pH value of the reaction solution in this invention has a great influence on the morphology of the product. HCl, H2SO4 and NaOH can be used to adjust the acidity and alkalinity of the solution. When the pH value of the reaction solution is greater than 4.1, the corresponding product can hardly be obtained.

[0022] (4) The citric acid used in this invention is an organic weak acid with certain reducing properties, and it is abundant, safe and non-toxic. On the one hand, as an acidity regulator, it can promote the dissolution of the reaction raw material ammonium metavanadate. On the other hand, as a reducing agent, it can reduce ammonium metavanadate to ammonium vanadate. In addition, the chelating effect of citric acid is conducive to the formation of ammonium vanadate nanosheets and microclusters. Attached Figure Description

[0023] Figure 1 NH4V4O prepared in Example 2 10 Scanning electron microscope images;

[0024] Figure 2 NH4V4O prepared in Example 3 10 Scanning electron microscope images;

[0025] Figure 3 NH4V4O prepared in Example 2 10 Transmission electron microscope images;

[0026] Figure 4 NH4V4O prepared in Example 2 10 High-resolution transmission electron microscope images;

[0027] Figure 5 NH4V4O prepared in Example 210 Element distribution diagram;

[0028] Figure 6 NH4V4O prepared in Examples 2 and 3 10 X-ray diffraction pattern of the powder. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0030] Example 1:

[0031] First, 240 mg of NH4VO3 was added to 60 mL of deionized water and heated and stirred in a 50 °C water bath for 30 min until dissolved, yielding a pale yellow transparent solution. After cooling to room temperature, 442.5 mg of citric acid was added, and stirring continued for 1 h, yielding an orange solution. This solution was then transferred to a 100 mL polytetrafluoroethylene (PTFE) high-pressure reactor and hydrothermally reacted at 180 °C for 3 h, followed by natural cooling for approximately 4 h. Finally, the precipitate at the bottom of the hydrothermal reactor was collected, centrifuged at 10,000 rpm, and washed with water for 10 min each time, repeated four times. The product was then dried in a 60 °C oven for 12 h to obtain NH4V4O. 10 powder.

[0032] Example 2:

[0033] First, 480 mg of NH4VO3 was added to 60 mL of deionized water and heated and stirred in a 50°C water bath for 30 min until dissolved, yielding a pale yellow transparent solution. After cooling to room temperature, 442.5 mg of citric acid was added, and stirring continued for 1 h, resulting in an orange solution. This solution was then transferred to a 100 mL polytetrafluoroethylene (PTFE) high-pressure reactor and hydrothermally reacted at 180°C for 3 h, followed by natural cooling for approximately 4 h. Finally, the precipitate at the bottom of the hydrothermal reactor was collected, centrifuged at 8000 rpm, and washed with water for 15 min each time, repeated three times. The product was then dried in a 60°C oven for 12 h to obtain NH4V4O. 10 Nanosheet clusters, sample labeled NVO-1.

[0034] Example 3:

[0035] First, 720 mg of NH4VO3 was added to 60 mL of deionized water and heated and stirred in a 50 °C water bath for 30 min until dissolved, yielding a pale yellow transparent solution. After cooling to room temperature, 442.5 mg of citric acid was added, and stirring continued for 1 h, yielding an orange solution. This solution was then transferred to a 100 mL polytetrafluoroethylene high-pressure reactor and hydrothermally reacted at 180 °C for 3 h, followed by natural cooling for approximately 4 h. Finally, the precipitate at the bottom of the hydrothermal reactor was collected, centrifuged at 8000 rpm, and washed with water for 15 min each time, repeated three times. The product was then dried in a 60 °C oven for 12 h to obtain NH4V4O. 10 Nanosheet clusters, sample labeled NVO-2.

[0036] Implementation effect

[0037] Figure 1 It can be seen that the sample consists of flower-like microclusters composed of nanosheets, with an average diameter of about 7.5 μm.

[0038] Figure 2 By comparison Figure 1 It was found that increasing the amount of NH4VO3 reduced the NH4V4O 10 The size of the nanosheet clusters increased to 12 μm, and the flower-like clusters became more compact.

[0039] Figure 3 The nanosheets were shown to be strip-shaped (approximately 3.7 μm in length and approximately 30:1 in aspect ratio), interwoven, and randomly oriented.

[0040] Figure 4 The image shows lattice fringes with a spacing of 0.19 nm corresponding to the monoclinic phase NH4V4O. 10 (PDF#31_0075) Crystal facets.

[0041] Figure 5 The N, V, and O elements are shown to be uniformly distributed in the banded NH4V4O 10 In nanosheets.

[0042] Figure 6 The NH4V4O prepared in Examples 2 and 3 10 X-ray diffraction (XRD) patterns of the powders, both of which are related to the monoclinic phase NH4V4O 10 This corresponds to the standard PDF card (PDF#31-0075). Furthermore, comparison of XRD patterns shows that increasing the amount of NH4VO3 can increase the amount of NH4V4O. 10 The size of nanocrystals.

[0043] The characterization results described above all prove that NH4V4O 10The successful preparation of nanosheet clusters, and the fact that this invention can achieve NH4V4O by changing the amount of NH4VO3. 10 Control of the morphology and size of nanosheet clusters.

[0044] Example 4:

[0045] The above-mentioned NH4V4O 10 The method for preparing nanosheet clusters includes the following steps:

[0046] (1) A certain mass of ammonium metavanadate powder is dissolved in an appropriate amount of deionized water under water bath heating. After cooling to room temperature, a certain mass of organic acid is added and stirred evenly to obtain a mixed reaction solution. In the mixed reaction solution, the concentration of ammonium metavanadate is 4 g / L and the organic acid is citric acid with a concentration of 3 g / L.

[0047] (2) Transfer the reaction solution obtained in step (1) to a high-pressure hydrothermal reactor for hydrothermal reaction; the hydrothermal reaction temperature is 180℃ and the reaction time is 2h.

[0048] (3) After the hydrothermal reaction in step (2) is cooled, the solution is centrifuged for 3 hours to obtain a solid powder. The centrifuge speed is 7000 rpm and the centrifugation time is 10 minutes. After washing with deionized water 3 times and drying, NH4V4O can be obtained. 10 Nanosheet clusters. Drying temperature: 50℃, drying time: 8h.

[0049] Example 5:

[0050] The above-mentioned NH4V4O 10 The method for preparing nanosheet clusters includes the following steps:

[0051] (1) A certain mass of ammonium metavanadate powder is dissolved in an appropriate amount of deionized water under water bath heating, cooled to room temperature, and then a certain mass of organic acid is added and stirred evenly to obtain a mixed reaction solution; in the mixed reaction solution, the concentration of ammonium metavanadate is 8 g / L, and the organic acid is citric acid with a concentration of 10 g / L.

[0052] (2) Transfer the reaction solution obtained in step (1) to a high-pressure hydrothermal reactor for hydrothermal reaction; the hydrothermal reaction temperature is 140℃ and the reaction time is 9h.

[0053] (3) After the hydrothermal reaction in step (2) is cooled, the solution is centrifuged for 4 hours to obtain a solid powder. The centrifuge speed is 8000 rpm and the centrifugation time is 13 minutes. After washing with deionized water 4 times and drying, NH4V4O can be obtained. 10Nanosheet clusters. Drying temperature: 60℃, drying time: 13h.

[0054] Example 6:

[0055] The above-mentioned NH4V4O 10 The method for preparing nanosheet clusters includes the following steps:

[0056] (1) A certain mass of ammonium metavanadate powder is dissolved in an appropriate amount of deionized water under water bath heating. After cooling to room temperature, a certain mass of organic acid is added and stirred evenly to obtain a mixed reaction solution. In the mixed reaction solution, the concentration of ammonium metavanadate is 12 g / L and the organic acid is citric acid with a concentration of 22 g / L.

[0057] (2) Transfer the reaction solution obtained in step (1) to a high-pressure hydrothermal reactor for hydrothermal reaction; the hydrothermal reaction temperature is 120℃ and the reaction time is 24h.

[0058] (3) After the hydrothermal reaction in step (2) is cooled, the solution is centrifuged for 6 hours to obtain a solid powder. The centrifuge speed is 10,000 rpm and the centrifugation time is 15 minutes. After washing with deionized water 6 times and drying, NH4V4O can be obtained. 10 Nanosheet clusters. Drying temperature: 70℃, drying time: 24h.

[0059] Example 7

[0060] NH4V4O 10 The application of nanosheet clusters can be extended to the deposition of ammonium vanadate nanosheet clusters on carbon substrates, including carbon fiber cloth, carbon nanofibers, and graphene. The ammonium vanadate nanosheet clusters and related composite materials prepared by this invention can be applied to desalination of dyeing and printing wastewater, seawater desalination, and capacitive deionization.

[0061] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A type of NH4V4O 10 Nanosheet microclusters, characterized by: NH4V4O 10 NH4V4O 10 NH4V4O 10 NH4V4O 10 NH4V4O 10 NH4V4O 10 NH4V4O A kind of NH4V4O 10 The method for preparing nanosheet clusters includes the following steps: (1) Dissolve a certain mass of ammonium metavanadate powder in an appropriate amount of deionized water under water bath heating, cool to room temperature, add a certain mass of organic acid, stir evenly, and obtain a mixed reaction solution. (2) Transfer the reaction solution obtained in step (1) to a high-pressure hydrothermal reactor for hydrothermal reaction; (3) After the solution from the hydrothermal reaction in step (2) is cooled, centrifuge to obtain a solid powder, wash it several times with deionized water, and dry it to obtain NH4V4O. 10 Nanosheets and microclusters; In the mixed reaction solution of step (1), the concentration of ammonium metavanadate is 4-12 g / L, and the organic acid is citric acid with a concentration of 3-22 g / L.

2. The NH4V4O according to claim 1 10 Nanosheets and microclusters, characterized by, The hydrothermal reaction temperature in step (2) is 120-180℃, and the reaction time is 2-24h.

3. The NH4V4O according to claim 2 10 Nanosheets and microclusters, characterized by, In step (3), the solution cooling time after hydrothermal reaction is 3-6 hours, the centrifuge speed is 7000-10000 rpm, the centrifugation time is 10-15 minutes, the solution is washed with deionized water 3-6 times, the drying temperature is 50-70℃, and the drying time is 8-24 hours.

4. The NH4V4O according to claim 1 10 The application of nanosheets and microclusters is characterized by, NH4V4O 10 Nanosheets or microclusters of NH4V4O 10 Nanosheet clusters deposited on carbon substrates can be applied to desalination of dyeing and printing wastewater or seawater desalination.

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