CN113800563B

CN113800563B - NbO microsphere and hydrothermal synthesis method and application thereof

Info

Publication number: CN113800563B
Application number: CN202111247443.7A
Authority: CN
Inventors: 原长洲; 武东旭; 程超; 秦理; 侯林瑞
Original assignee: University of Jinan
Current assignee: University of Jinan
Priority date: 2021-10-26
Filing date: 2021-10-26
Publication date: 2022-07-08
Anticipated expiration: 2041-10-26
Also published as: CN113800563A

Abstract

The invention belongs to the technical field of preparation of niobium monoxide, and discloses NbO microspheres and a hydrothermal synthesis method and application thereof. The synthesis method comprises the following steps: (1) adding niobium-based MXene material serving as a niobium source into an aqueous solution of hydrogen peroxide and lithium hydroxide, and uniformly mixing to obtain a precursor solution. (2) And carrying out hydrothermal reaction on the precursor solution, separating a solid product in the reaction solution after the hydrothermal reaction is finished, washing and drying to obtain the catalyst. The synthesis method can obtain the NbO microspheres only by one step of hydrothermal reaction, can synthesize the NbO at the low temperature of 160-200 ℃, has mild condition and simple process, obviously reduces energy loss in production and preparation, is safer and more environment-friendly, and is convenient for realizing large-scale production. The size of the NbO microspheres prepared by the method is adjustable, the morphology is controllable, the NbO microspheres with different morphology sizes can be prepared according to actual needs, and a new way is provided for preparing the NbO.

Description

NbO microsphere and hydrothermal synthesis method and application thereof

Technical Field

The invention belongs to the technical field of preparation of niobium monoxide, and particularly relates to NbO microspheres and a hydrothermal synthesis method and application thereof.

Background

The information in this background section is disclosed to enhance understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms part of the prior art already known to a person of ordinary skill in the art.

Niobium monoxide (NbO) has a conductivity close to that of metals, which has attracted much interest to researchers. Niobium monoxide has excellent electrical conductivity, corrosion resistance, high strength at high temperature, and the like, and thus is widely used in high-tech industrial fields such as electronics, precision instruments, electro-acoustic optical devices, hard alloys, and the like. For example, in the electrolytic oxidation of an anode produced from the above-mentioned material, an oxide film having excellent dielectric properties can be formed on the surface of the anode similarly to a valve metal such as aluminum, tantalum, or niobium. These characteristics lay a foundation for the low valence niobium oxides to become the anode material of electrolytic capacitors. Inspired by the good use of niobium monoxide in capacitor research, the recommendation group of university of south and middle schools proposed NbO as an electrode materialThe research aims to provide a novel lithium ion negative electrode material to solve the defects of low capacity, poor safety performance and the like of the conventional carbon negative electrode material. The theoretical capacity of NbO is 492mAh g according to theoretical calculation^-1Larger than the graphite cathode material which is commercially used at present. Experimental results show that the NbO material can be used as a negative electrode material for a lithium ion battery and has the advantages of large lithium intercalation capacity, good rate capability, good cycle stability and the like. The portable electronic power supply is suitable for small electronic power supply equipment, is convenient to carry and has wide commercial application prospect.

Currently, the main methods for preparing NbO include high temperature solid phase methods and carbon reduction methods. However, these methods require extremely high temperature (mostly above 1000 ℃), which not only consumes huge energy, but also brings safety hazard to material production and preparation. In addition, the NbO prepared by the method has the problems of irregular particle shape, serious accumulation and the like, and further research and application of the NbO are severely limited.

Disclosure of Invention

Aiming at the problems, the invention provides NbO microspheres and a hydrothermal synthesis method and application thereof.

The method has simple and mild synthesis conditions, the prepared NbO microspheres have uniform and regular shapes, the size and the morphology of the NbO microspheres can be conveniently controlled by regulating and controlling the synthesis conditions, and the problem of material accumulation is effectively solved. In order to achieve the purpose, the invention discloses the following technical scheme:

in a first aspect of the present invention, there is provided an NbO microsphere which is a smooth-surfaced spherical body or a microsphere having a textured surface or a polymeric microsphere formed by polymerizing a plurality of microspheres together.

Further, the particle size of the NbO microspheres is between 1 and 5 mu m. The size of the NbO microspheres can be conveniently controlled by regulating and controlling the synthesis conditions, and the NbO microspheres can present various appearance appearances.

In a second aspect of the present invention, there is provided a hydrothermal synthesis method of NbO microspheres, comprising the steps of:

(1) adding niobium-based MXene material serving as a niobium source into an aqueous solution of hydrogen peroxide and lithium hydroxide, and uniformly mixing to obtain a precursor solution.

(2) And carrying out hydrothermal reaction on the precursor solution, separating a solid product in the reaction solution after the hydrothermal reaction is finished, washing and drying to obtain the catalyst.

Further, in the step (1), the molecular formula of the niobium source is Nb₂CT_xWherein T represents a surface group, typically comprising: one or more of-OH, -O, -F, -Cl and the like.

Further, in the step (1), the concentration of the niobium source in the precursor solution is preferably controlled to be 0.01 to 0.02 mol/L.

Further, in the step (1), the amount of the hydrogen peroxide in the precursor solution is preferably kept within a range of 0.01 to 1 mol/L. In this step, hydrogen peroxide first adds Nb₂CT_xCarbon in (1) is oxidized to Nb₂CT_xThe niobium atoms on the surface are exposed in preparation for the hydrothermal reaction.

Further, in the step (1), the concentration of lithium hydroxide in the precursor solution is preferably controlled to be 1.5-4 mol/L. In this step, the higher concentration of lithium hydroxide makes the solution strongly basic, constituting the reaction environment together with the previously added hydrogen peroxide solution.

Further, in the step (2), the temperature of the solvothermal reaction is preferably controlled to be 160-200 ℃, and the reaction time is preferably controlled to be 12-24 hours. In the step, under the synergistic action of hydrogen peroxide and lithium hydroxide, niobium atoms exposed in a reaction environment are directly oxidized into niobium monoxide, and the NbO crystal grains generated firstly are used as crystal nuclei for growing, so that NbO microspheres with different shapes and sizes are gradually generated. In addition, the lithium ions play a structural induction role in the crystal growth process, so that NbO finally forms a microsphere structure.

Further, in the step (2), solid products in the reaction liquid are separated through filtration, centrifugation and other modes, then the solid products are sequentially washed by ethanol and deionized water, and then the solid products are dried for 10-24 hours at the temperature of 50-80 ℃ to obtain the precursor.

In a third aspect of the invention, the NbO microspheres are used in energy storage materials, precision instruments, electro-acoustic optical devices, hard alloys, and the like.

Compared with the prior art, the invention has the following beneficial effects:

(1) as described above, the preparation of NbO by the high-temperature solid phase method and the carbon reduction method requires extremely high temperature, which not only consumes huge energy, but also brings potential safety hazard to the production and preparation of materials. Most of the current NbO preparation methods are Nb reduction₂O₅Mainly, Nb₂O₅The melting point is high, and the reduction needs extremely high temperature, so that the energy consumption of the current NbO preparation is serious, and the appearance is not good. The method can synthesize the NbO at a low temperature of 160-200 ℃, so that the energy loss in production and preparation is remarkably reduced, and the method is safer and more environment-friendly. In addition, since Nb₂CT_xWith a microstructure with an accordion-like morphology, the atoms are connected by metallic and covalent bonds, wherein the niobium atom can be regarded as having a valence of 0 and is therefore Nb₂CT_xWhen the niobium source is used for preparing the NbO microspheres, the NbO can be obtained in one step only by controlling the oxidation conditions and the environment, and the morphology can be adjusted. In addition, the invention also provides the use of NbCl₅The experimental scheme for preparing NbO for the niobium source is shown in the specification, but the prepared product has nonuniform size, the morphology and the size are difficult to further regulate and control, and the Nb source is used for preparing the NbO₂CT_xThe niobium source for preparing the NbO microspheres has the advantages.

(2) The NbO prepared by the high-temperature solid phase method and the carbon reduction method has irregular particle shape and serious accumulation. This is because of the high temperature reduction of Nb₂O₅During the reaction, the reaction environment temperature is extremely high and the reducing agent can release a large amount of heat in the reaction process, so that the ordered lattice structure of the product particles is destroyed. Agglomeration is easy to occur. And because the synthesis conditions of the two methods are difficult to control, the size and the morphology of the prepared NbO cannot be regulated, and further research and application of the NbO are severely limited. The preparation method can prepare the NbO microspheres with different shapes and sizes by adjusting the temperature and the using amount of the oxidant (hydrogen peroxide). For exampleIn the invention, the NbO microspheres with a plurality of morphologies are obtained by regulating and controlling the synthesis conditions, thereby providing a foundation for researching the electrochemical properties of the NbO microspheres with different appearance morphologies and the influence of the NbO microspheres on the battery performance.

(3) The synthesis method can obtain the NbO microspheres only by one step of hydrothermal reaction, has mild conditions and simple process, and is convenient for realizing large-scale production. The NbO microspheres prepared by the method have adjustable size and controllable morphology, and can be prepared into NbO microspheres with different morphology and size according to actual needs, thereby providing a new approach for preparing NbO.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:

FIG. 1 shows a multilayer niobium-based MXene (m-Nb) prepared in the first example₂CT_x) XRD spectrum (a) and SEM image (b) of (a).

Fig. 2 is an XRD pattern (a) and SEM image (b) of the NbO smooth microspheres prepared in the second example.

Fig. 3 is an XRD pattern (a) and SEM image (b) of NbO polymeric microspheres prepared in the third example.

Fig. 4 is an XRD pattern (a) and an SEM image (b) of the NbO patterned microspheres prepared in the fifth fourth example.

Fig. 5 is an XRD pattern (a) and SEM image (b) of the first comparative prepared NbO pellet.

DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out according to conventional conditions or according to conditions recommended by the manufacturers.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The reagents or starting materials used in the present invention can be purchased from conventional sources, and unless otherwise specified, the reagents or starting materials used in the present invention can be used in a conventional manner in the art or in accordance with the product specifications. In addition, any methods and materials similar or equivalent to those described herein can be used in the methods of the present invention. The preferred methods and materials described in this invention are exemplary only. The invention will now be further described with reference to the drawings and specific examples in the specification.

First embodiment

Multilayer niobium-based MXene (m-Nb)₂CT_x) The preparation method of the material comprises the following steps:

(1) 10mL of deionized water was mixed with 30mL of 12M HCl, magnetically stirred for 30min to form a homogeneous hydrochloric acid solution, to which 3g of lithium fluoride (LiF) and 2g of Nb were added₂And completely dissolving AlC by magnetic stirring for 30min to obtain a mixed solution.

(2) Putting the mixed solution obtained in the step (1) into a Taylor reaction kettle, and carrying out hydrothermal reaction for 48 hours at 180 ℃ so as to facilitate Nb₂And etching the AlC.

(3) And (3) centrifuging the etched mixed solution obtained in the step (2), and adding the separated solid product into deionized water for repeated cleaning until the pH value of the supernatant reaches more than 6. And (3) pouring out the supernatant, taking the lower layer to precipitate and dry to obtain the multilayer niobium-based MXene: m-Nb₂CT_xAnd then standby.

Further, the m-Nb₂CT_xThe commercially available product can also be used as it is.

Second embodiment

A hydrothermal synthesis method of NbO microspheres comprises the following steps:

(1) 0.15 mol of LiOH is added into 100mL of deionized water, and the mixture is magnetically stirred until the LiOH is completely dissolved, so that a 1.5M aqueous solution of the LiOH is obtained.

(2) 0.0004mol of m-Nb prepared in the first example is taken₂CT_xAnd 0.04mL of a 30% by mass hydrogen peroxide solution was added to 36mL of the 1.5M Li prepared in step (1)Preparing a solution with the total volume of 40mL in an OH aqueous solution, and stirring for 1h by using a magnetic stirrer to ensure that the m-Nb is dissolved in the solution₂CT_xAnd completely dissolving to obtain a precursor solution.

(3) And (3) placing the precursor solution obtained in the step (2) in a Taylor reaction kettle for solvothermal reaction at 160 ℃ for 24 hours, and after the solvothermal reaction is finished, placing the obtained reaction solution in a centrifuge for centrifugal separation to obtain a solid product.

(4) And (3) repeatedly washing the solid product with deionized water for several times in sequence, and then drying in an oven at 50 ℃ for 10 hours to obtain the NbO microspheres.

Third embodiment

(1) and adding 0.3 mol of LiOH into 100mL of deionized water, and magnetically stirring until the LiOH is completely dissolved to obtain a 3M LiOH aqueous solution.

(2) 0.0008mol of m-Nb prepared in the first example is taken₂CT_xAnd 4mL of a 30% hydrogen peroxide solution by mass fraction, adding the hydrogen peroxide solution into 36mL of the 3M LiOH aqueous solution prepared in the step (1) to prepare a solution with a total volume of 40mL, and stirring for 1h by using a magnetic stirrer to enable M-Nb to be in a mixed solution state₂CT_xAnd completely dissolving to obtain a precursor solution.

(3) And (3) placing the precursor solution obtained in the step (2) in a Taylor reaction kettle for solvothermal reaction at the temperature of 200 ℃ for 16h, and placing the obtained reaction solution in a centrifuge for centrifugal separation to obtain a solid product.

(4) And (3) repeatedly washing the solid product with deionized water for several times in sequence, and then drying in an oven at 70 ℃ for 24 hours to obtain the NbO microspheres.

Fourth embodiment

(1) 0.4 mol of LiOH is added into 100mL of deionized water, and the mixture is magnetically stirred until the LiOH is completely dissolved to obtain a 4M aqueous solution of LiOH.

(2) Get0.0006mol of m-Nb prepared in the first example₂CT_xAnd 2 mL of a 30% hydrogen peroxide solution by mass fraction, adding the hydrogen peroxide solution into 36mL of the 4M LiOH aqueous solution prepared in the step (1) to prepare a solution with a total volume of 40mL, and stirring for 1h by using a magnetic stirrer to enable M-Nb to be in a mixed solution state₂CT_xAnd completely dissolving to obtain a precursor solution.

(3) And (3) placing the precursor solution obtained in the step (2) in a Taylor reaction kettle for solvothermal reaction at the temperature of 180 ℃ for 12 hours, and placing the obtained reaction solution in a centrifuge for centrifugal separation to obtain a solid product after the reaction is finished.

(4) And (3) repeatedly washing the solid product with deionized water for several times in sequence, and then drying in an oven at 80 ℃ for 16h to obtain the NbO microspheres.

Fifth embodiment

(1) adding 0.2 mol of LiOH into 100mL of deionized water, and magnetically stirring until the LiOH is completely dissolved to obtain a 2M LiOH aqueous solution.

(2) 0.0004mol of m-Nb prepared in the first example is taken₂CT_xAnd 0.04mL of a 30% hydrogen peroxide solution by mass fraction, adding the hydrogen peroxide solution into 36mL of the 2M LiOH aqueous solution prepared in the step (1) to prepare a solution with a total volume of 40mL, and stirring for 1h by using a magnetic stirrer to ensure that the M-Nb is added₂CT_xAnd completely dissolving to obtain a precursor solution.

(3) And (3) placing the precursor solution obtained in the step (2) in a Taylor reaction kettle for solvothermal reaction at the temperature of 170 ℃ for 20 hours, and placing the obtained reaction solution in a centrifuge for centrifugal separation to obtain a solid product.

Sixth embodiment

(2) 0.0004mol of m-Nb prepared in the first example is taken₂CT_xAnd 0.04mL of a 30% by mass hydrogen peroxide solution, adding the solution to 36mL of the 3M LiOH aqueous solution prepared in the step (1) to prepare a solution with a total volume of 40mL, and stirring for 1h by using a magnetic stirrer to ensure that M-Nb is added₂CT_xAnd completely dissolving to obtain a precursor solution.

(3) And (3) placing the precursor solution obtained in the step (2) in a Taylor reaction kettle for solvothermal reaction at the temperature of 190 ℃ for 15h, and placing the obtained reaction solution in a centrifuge for centrifugal separation to obtain a solid product.

First comparative example

(1) 0.4 mol of LiOH is added into 100mL of deionized water, and the mixture is magnetically stirred until the LiOH is completely dissolved, so that 4M LiOH aqueous solution is obtained.

(2) Taking 0.0008mol of NbCl₅And 0.1 mL of a 30% by mass hydrogen peroxide solution, adding the hydrogen peroxide solution to 36mL of the 4M LiOH aqueous solution prepared in the step (1) to prepare a solution with a total volume of 40mL, and stirring the solution for 1 hour by using a magnetic stirrer to ensure that NbCl is added₅And completely dissolving to obtain a precursor solution.

(3) And (3) placing the precursor solution obtained in the step (2) in a Taylor reaction kettle for solvothermal reaction at the temperature of 160 ℃ for 12 hours, and placing the obtained reaction solution in a centrifuge for centrifugal separation to obtain a solid product after the reaction is finished.

Structural characterization and analysis:

the final products prepared in the examples were subjected to XRD testing and observed under a scanning electron microscope, with the following results:

FIG. 1 shows a multilayer Nb-based MXene (Nb) prepared in accordance with the first example₂CT_x) XRD pattern (a) and SEM image (b), from which it can be seen that: the multilayer niobium-based MXene is successfully prepared and has an accordion structure unique to MXene.

Fig. 2 is an XRD pattern (a) and SEM image (b) of the NbO smooth microspheres prepared in the second example, from which it can be seen that: compared with a standard pdf card, the NbO preparation is proved to be successful, and the surface of the prepared NbO microsphere is smooth.

Fig. 3 is an XRD pattern (a) and SEM image (b) of NbO polymeric microspheres prepared in the third example, from which it can be seen that: in contrast to standard pdf cards, the successful preparation of NbO was demonstrated and the prepared NbO microspheres exhibited multiple microspheres polymerized together to form new polymeric microspheres.

Fig. 4 is an XRD pattern (a) and SEM image (b) of NbO patterned microspheres prepared in the fourth example, from which it can be seen that: compared with a standard pdf card, the preparation of NbO can be proved to be successful, and the surface of the prepared NbO microspheres has irregular patterns.

Fig. 5 is an XRD pattern (a) and SEM image (b) of a first comparative prepared NbO pellet, from which it can be seen that: compared with a standard pdf card, the NbO is successfully prepared, but as can be seen from an SEM image, a large number of small particles are attached to the surface of the prepared NbO microsphere, and the size difference between the two particles is very large, so that the heterogeneity of the material is reflected. This also confirms the direct use of NbCl₅As a niobium source, the prepared material is uneven, the size and the shape are difficult to regulate, and the further research and the subsequent practical production application are not facilitated. Meanwhile, the advantage of utilizing MXene as a niobium source is also reflected from the other aspect.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The hydrothermal synthesis method of NbO microspheres is characterized by comprising the following steps:

(1) adding a niobium-based MXene material serving as a niobium source into an aqueous solution of hydrogen peroxide and lithium hydroxide, and uniformly mixing to obtain a precursor solution;

(2) carrying out hydrothermal reaction on the precursor solution, separating a solid product in a reaction solution after the hydrothermal reaction is finished, and washing and drying the solid product to obtain the catalyst;

in the step (1), the molecular formula of the niobium source is Nb₂CT_xWherein T represents a surface group comprising: at least one of-OH, -O, -F, -Cl;

in the step (1), the concentration of a niobium source in the precursor solution is controlled to be 0.01-0.02 mol/L;

in the step (1), the concentration of hydrogen peroxide in the precursor solution is 0.01-1 mol/L;

in the step (1), the concentration of lithium hydroxide in the precursor solution is 1.5-4 mol/L;

in the step (2), the temperature of the hydrothermal reaction is 160-200 ℃, and the reaction time is 12-24 h.

2. The hydrothermal synthesis method of NbO microspheres as claimed in claim 1, wherein in the step (2), solid products in the reaction solution are separated by filtration and centrifugation, and then are sequentially washed by ethanol and deionized water, and then dried at 50-80 ℃ for 10-24 h.

3. The use of NbO microspheres prepared by the synthesis method of claim 1 or 2 in precision instruments, electro-acoustic optical devices or cemented carbides.