Transition metal phosphide nanowire bundles, preparation method thereof and applications

Abstract

The present invention discloses a transition metal phosphide nanowire bundle, a preparation method thereof and an application. Among them, the preparation method includes the following steps: S1, dissolving a transition metal salt in an organic solvent, heating to 100-150 °C, after constant temperature reaction, cooling to room temperature, centrifuging, washing and drying to obtain a precursor with a nanowire bundle morphology; S2, mixing the precursor with a phosphorus source, heating to 200-300 °C, and cooling to room temperature after reaction to obtain a transition metal phosphide nanowire bundle. Applying the technical solution of the present invention, a method for preparing a transition metal phosphide nanowire bundle material based on low-temperature calcination of a precursor, the method is simple to operate, the raw materials used are cheap and easy to obtain, the cost is low, the safety is high, and no surfactant and template are required during the synthesis process, which is green and environmentally friendly. The prepared transition metal phosphide nanowire bundle material has a one-dimensional linear morphology, and the surface of the nanowire bundle is clean and easy to be surface-modified.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and in particular, to a transition metal phosphide nanowire bundle, a preparation method thereof, and an application thereof. Background Art

[0002] The negative electrode materials of ion batteries are mainly carbon materials such as graphite, and their specific capacity is relatively low, which limits the further development and application of lithium ion batteries. Therefore, it is particularly important to develop a negative electrode material for high-performance lithium ion batteries.

[0003] Transition metal phosphides have shown excellent properties in magnetism, catalysis, energy storage, etc. Researchers have developed a variety of synthesis routes to prepare phosphides and study their potential properties. However, most of these methods are relatively complex, require multiple steps, the reaction reagents are toxic, expensive, explosive, etc., and usually require a very high reaction temperature. The route of low-temperature calcination of precursors has the advantages of mildness, low energy consumption, no danger, environmental friendliness, and good crystallinity of the obtained products. There are various forms of copper phosphides (Cu 3 P, CuP 2 , Cu 2 P 7 ), but only Cu 3 P can exist stably in air and has been widely used as a welding material in industry and a reinforcing agent for high-speed steel composite materials. Recent studies have shown that cuprous phosphide has good cycle stability as a negative electrode material for lithium ion batteries, which is one of the important topics in the research of transition metal phosphide negative electrode materials.

[0004] At present, researchers have synthesized various morphologies including nanotubes, hollow spheres, nanowire bundles, hexagonal nanoparticles, etc. (C. Wei; Y. Huang, Chem. Eng. J. 317, (2017), 873 - 881, D. Liu; Q. Lu, Nanoscale 7, (2015), 15122 - 15126). At present, there are few reports on the synthesis of Cu 3 P nanowire bundles. Fan, M. (Chen, Y.; Xie, Y., (2016), Adv. Funct. Mater., 26:5019 - 5027.) prepared Cu 3 P nanowire bundles by a two-step method, in which a precursor was grown on a copper foil and then in-situ phosphated.

[0005] The synthesis of copper phosphide is more complex than other phosphides. Some methods also require special instruments, resulting in cumbersome processes, high costs, and poor repeatability. Therefore, it is of great significance to design a new process with low temperature, non-toxicity, simple operation, and low cost. Summary of the Invention

[0006] The present invention aims to provide a transition metal phosphide nanowire bundle, a preparation method thereof and an application, so as to solve the technical problem of complex process in the preparation of nanowire bundle materials in the prior art.

[0007] To achieve the above object, according to one aspect of the present invention, a preparation method of a transition metal phosphide nanowire bundle is provided. The preparation method includes the following steps: S1, dissolving a transition metal salt in an organic solvent, heating to 100-150 °C, carrying out a constant temperature reaction, then cooling to room temperature, centrifuging, washing and drying to obtain a precursor with a nanowire bundle morphology; S2, mixing the precursor with a phosphorus source, heating to 200-300 °C, carrying out a reaction and then cooling to room temperature to obtain a transition metal phosphide nanowire bundle.

[0008] Further, the transition metal phosphide in the transition metal phosphide nanowire bundle is one or more of cobalt phosphide, molybdenum phosphide, nickel phosphide and cuprous phosphide.

[0009] Further, the transition metal phosphide in the transition metal phosphide nanowire bundle is cuprous phosphide.

[0010] Further, when the transition metal phosphide in the transition metal phosphide nanowire bundle is cuprous phosphide, the transition metal salt is a copper salt, and the copper salt is copper sulfate, copper acetate, copper nitrate or copper chloride; preferably, the amount of substance of the copper salt is 1-5 mmol.

[0011] Further, the organic solvent is a combination of any two or at least two of N,N-dimethylformamide, ethylene glycol, ethanol, dimethyl sulfoxide and isopropanol.

[0012] Further, the constant temperature reaction time in S1 is 2-8 hours; the reaction temperature in S2 is 2-8 hours; preferably, the reaction temperature in S2 is 200-270 °C.

[0013] Further, the phosphorus source is one or more selected from the group consisting of diammonium hydrogen phosphate, sodium phosphate, sodium hypophosphite and phosphine.

[0014] Further, the mass ratio of the precursor to the phosphorus source is 1:8-1:20.

[0015] According to another aspect of the present invention, a transition metal phosphide nanowire bundle is provided. The transition metal phosphide nanowire bundle is prepared by any one of the above preparation methods.

[0016] According to still another aspect of the present invention, an application of a transition metal phosphide nanowire bundle as a negative electrode material, a catalyst, an optical material, a sensing material of a lithium ion battery is provided.

[0017] Applying the technical solution of the present invention, a method for preparing transition metal phosphide nanowire bundle materials based on low-temperature calcination of precursors. This method is simple to operate, uses inexpensive and easily available raw materials, has low costs, high safety, and does not require the use of any surfactants and templates during the synthesis process, being green and environmentally friendly. The prepared transition metal phosphide nanowire bundle materials have a one-dimensional linear morphology, and the surfaces of the nanowire bundles are clean, making it easy to perform surface modification. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0019] Figure 1 Shows the X-ray diffraction pattern of the Cu 3 P nanowire bundle material prepared in Example 1; and

[0020] Figure 2 Shows the scanning electron microscope image of the Cu 3 P nanowire bundle material prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0022] According to a typical embodiment of the present invention, a method for preparing transition metal phosphide nanowire bundles is provided. The preparation method includes the following steps: S1, dissolving a transition metal salt in an organic solvent, heating to 100 - 150 °C, carrying out a constant-temperature reaction, then cooling to room temperature, centrifuging, washing, and drying to obtain a precursor with a nanowire bundle morphology; S2, mixing the precursor with a phosphorus source, heating to 200 - 300 °C, reacting, and then cooling to room temperature to obtain transition metal phosphide nanowire bundles.

[0023] Applying the technical solution of the present invention, a method for preparing transition metal phosphide nanowire bundle materials based on low-temperature calcination of precursors. This method is simple to operate, uses inexpensive and easily available raw materials, has low costs, high safety, and does not require the use of any surfactants and templates during the synthesis process, being green and environmentally friendly.

[0024] In the present invention, the transition metal phosphide in the transition metal phosphide nanowire bundle can be one or more of cobalt phosphide, molybdenum phosphide, nickel phosphide, and cuprous phosphide, typically single-metal phosphides and bimetal phosphides. Importantly, in the present invention, the transition metal phosphide in the transition metal phosphide nanowire bundle is cuprous phosphide. When the transition metal phosphide in the transition metal phosphide nanowire bundle is cuprous phosphide, the transition metal salt is a copper salt, and the copper salt is copper sulfate, copper acetate, copper nitrate, or copper chloride; preferably, the amount of the copper salt is 1 to 5 mmol.

[0025] Preferably, the organic solvent is a combination of any two or at least two of N,N-dimethylformamide, ethylene glycol, ethanol, dimethyl sulfoxide, and isopropanol.

[0026] According to a typical embodiment of the present invention, the constant temperature reaction time in S1 is 2 to 8 hours; the reaction temperature in S2 is 2 to 8 hours to ensure sufficient progress of the reaction; preferably, the reaction temperature in S2 is 200 to 270 °C.

[0027] In one embodiment of the present invention, the phosphorus source is one or more selected from the group consisting of diammonium hydrogen phosphate, sodium phosphate, sodium hypophosphite, and phosphine; preferably, the mass ratio of the precursor to the phosphorus source is 1:8 to 1:20, and a pure phase of cuprous phosphide can be obtained within this mass ratio range. Because, if the mass ratio of the precursor to the phosphorus source is too low, the phosphidation may not be successful, and if the mass ratio of the precursor to the phosphorus source is too high, there may be certain risks during the experiment.

[0028] In a preferred embodiment of the present invention, the preparation method includes:

[0029] 1) Dissolve the copper salt (1 to 5 mmol) in the mixed organic solvent, and stir well to make it uniformly mixed; wherein, the copper salt is one or more of copper sulfate, copper acetate, copper nitrate, and copper chloride; the mixed organic solvent is a combination of any two or at least two of N,N-dimethylformamide, ethylene glycol, ethanol, dimethyl sulfoxide, and isopropanol;

[0030] 2) Put the fully dissolved mixed solution in step 1) into a closed reactor, slowly heat it (heating rate is 3 to 10 °C) to 100 to 150 °C, react at this temperature for 2 to 8 hours, naturally cool to room temperature, centrifuge, wash, and dry to obtain a copper-based precursor with a nanowire bundle morphology;

[0031] 3) Put the precursor obtained in step 1) into a high-temperature reaction device, add the phosphorus source at the same time, heat it to 200 to 300 °C, react for 2 to 8 hours, and then naturally cool to room temperature to obtain Cu 3P nanowire bundles. Among them, the phosphorus source is any one or a combination of at least two of diammonium hydrogen phosphate, sodium phosphate, sodium hypophosphite, and phosphine; the mass ratio of the precursor to the phosphorus source is 1:8 - 1:20.

[0032] According to a typical embodiment of the present invention, a transition metal phosphide nanowire bundle is provided. The transition metal phosphide nanowire bundle is prepared by any of the above preparation methods. The prepared transition metal phosphide nanowire bundle material has a one-dimensional linear morphology, and the surface of the nanowire bundle is clean and easy to perform surface modification.

[0033] According to a typical embodiment of the present invention, the above-mentioned application of the transition metal phosphide nanowire bundle as a negative electrode material, catalyst, optical material, and sensing material for lithium-ion batteries is provided.

[0034] The beneficial effects of the present invention will be further described below in conjunction with the examples.

[0035] Example 1

[0036] 1) Accurately weigh 1 mmol of analytical pure Cu(SO 4 ) 2 5H 2 O and dissolve it in a mixed solution of N,N-dimethylformamide and ethylene glycol, and transfer it to a 250 mL reactor. After magnetic stirring for 25 min, a uniform blue solution is formed, and nitrogen is introduced into it to discharge the air in the reactor, and it is heated to 130 °C and maintained for 2 hours. After the reaction is completed, it is naturally cooled to room temperature, centrifuged and washed, and dried under vacuum conditions at 50 - 80 °C to obtain a precursor with a nanowire bundle morphology.

[0037] 2) Weigh 0.001 g of the precursor obtained in step 1) and put it into a reaction vessel. At the same time, add 0.008 g of sodium hypophosphite, and put them together into a high-temperature reaction device and set the temperature to rise to 200 °C. After reacting for 2 hours, it is naturally cooled to room temperature to obtain Cu 3 P nanowire bundles.

[0038] Figure 1 is the X-ray diffraction (XRD) pattern of the material of Example 1. It can be seen from the figure that the obtained product is pure-phase Cu 3 P, and no other impurities are generated. Figure 2 is the scanning electron microscope (SEM) image of the material of Example 1. It can be seen that the product is a nanowire bundle with a diameter of about 300 nm and a length of 10 - 200 μm and a rough surface.

[0039] Example 2

[0040] Same as Example 1, except that the reaction temperature in step 1) is changed from 130 °C to 150 °C, and the reaction time is changed from 2 hours to 8 hours, with other conditions remaining the same.

[0041] Example 3

[0042] Same as Example 1, except that the reactant Cu(SO 4 ) 2 5H 2 O is changed to Cu(NO 3 ) 2 3H 2 O, with other conditions remaining the same.

[0043] Example 4

[0044] Same as Example 1, except that the mass of sodium hypophosphite in step 2) is changed to 0.02 g, with other conditions remaining the same.

[0045] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0046] (1) No surfactant or template agent is introduced during the synthesis process, which is green and environmentally friendly. The raw materials used are inexpensive and easily available. The synthesis process is simple to operate and has a low cost;

[0047] (2) The present invention uses the precursor low-temperature calcination method to synthesize Cu 3 P nanowire bundles, which only need to be carried out at a relatively low temperature of 200 - 270 °C, and can be extended to the preparation of other metal phosphides, such as cobalt phosphide, molybdenum phosphide, nickel phosphide, and their corresponding bimetallic phosphides;

[0048] (3) The prepared Cu 3 P nanowire bundles have a one-dimensional linear morphology, and the surface of the nanowire bundles is clean, making it easy to perform surface modification;

[0049] (4) The Cu 3 P nanowire bundles prepared by the present invention are not only suitable for use as the anode material of lithium-ion batteries, but can also be applied to other fields such as catalysis, optics, and sensing.

[0050] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of transition metal phosphide nanowire bundles, characterized in that, it comprises the following steps: 1) Dissolve a copper salt in a mixed organic solvent, and stir well to make it evenly mixed; wherein, the copper salt is one or more of copper sulfate, copper acetate, copper nitrate, and copper chloride; the mixed organic solvent is a mixed solution of N,N-dimethylformamide and ethylene glycol; 2) Put the fully dissolved mixed solution in step 1) into a closed reactor, slowly heat it up to 100-150 °C, react for 2-8 hours under this temperature condition, naturally cool to room temperature, centrifuge, wash, and dry to obtain a copper-based precursor with a nanowire bundle morphology; 3) Put the copper-based precursor obtained in step 2) into a high-temperature reaction device, and at the same time add a phosphorus source. Heat up to 200~300 °C, and after reacting for 2~8 hours, naturally cool to room temperature to obtain Cu 3 P nanowire bundles.

2. The preparation method according to claim 1, characterized in that, the transition metal phosphide in the transition metal phosphide nanowire bundles is cuprous phosphide.

3. The preparation method according to claim 2, characterized in that, the amount of substance of the copper salt is 1-5 mmol.

4. The preparation method according to any one of claims 1 to 3, characterized in that, the phosphorus source is one or more selected from the group consisting of diammonium hydrogen phosphate, sodium phosphate, sodium hypophosphite, and phosphine.

5. The preparation method according to any one of claims 1 to 3, characterized in that, the mass ratio of the copper-based precursor to the phosphorus source is 1:8 to 1:

20.

6. A transition metal phosphide nanowire bundle, characterized in that, the transition metal phosphide nanowire bundle is prepared by the preparation method according to any one of claims 1 to 5.

7. Application of the transition metal phosphide nanowire bundle according to claim 6 as a negative electrode material, catalyst, optical material, and sensing material for lithium-ion batteries.

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