Preparation method of high-entropy phosphide nanotube

Abstract

The invention discloses a preparation method of a high-entropy phosphide nanotube, which successfully prepares a nanotube phosphide with a high-entropy structure by adopting a hydrogen bond organic framework (HOF)-metal organic framework (MOF) template conversion method. In the preparation process of the material, a core-shell structure (HOF (MOF)) is firstly formed, the core gradually disappears through a diffusion mechanism, and finally, the material is converted into a hollow nanotube structure which is uniform and controllable in size. According to the hollow structure, the specific surface area is remarkably increased, more active sites are provided, the transmission path of reactant molecules is optimized, and the electro-catalytic performance is greatly improved. Besides, the overall tubular morphology of the material is uniform, the size is controllable, and compared with a traditional granular material, the specific surface area is remarkably increased, so that more reaction sites are exposed in the external environment, and the catalytic efficiency and the reaction rate of the material in an electro-catalytic reaction are greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of high entropy derivatives, and in particular to a method for preparing high entropy phosphide nanotubes. Background Art

[0002] With the increase in global population and rapid economic development, greenhouse gases such as carbon dioxide produced by the consumption of large amounts of mineral fuels have led to increasingly serious energy pressures and environmental problems. Countries around the world have reduced greenhouse gas emissions through global agreements, and my country has therefore proposed the goals and requirements of carbon peak and carbon neutrality. In order to achieve the goals and requirements of carbon peak and carbon neutrality, it has become a trend to seek to develop environmentally friendly and renewable energy utilization methods. One of the more effective energy utilization methods is to convert greenhouse gases generated by the excess electricity in the use of green energy into fuels such as formic acid and methanol, which are then reused and released through electrochemical devices such as fuel cells. Suitable catalysts can effectively increase the electrochemical reaction rate in the process of converting electrical energy and chemical energy, thereby improving energy storage efficiency.

[0003] Among the many known materials, high entropy alloys are composed of multiple alloy components, with the structural characteristics of site disorder and lattice order. They can be formulated according to the characteristics of multiple components during the design process, and play a synergistic role in multiple mechanisms. They have been widely used in the design of electrocatalysts. The advantages of high entropy alloy electrocatalysts are becoming more and more obvious as people's understanding of them deepens. For example, based on the research of high entropy alloys, high entropy derivatives have developed rapidly. High entropy derivatives are usually combined with a non-metallic element in addition to metal elements, such as high entropy phosphides. The synergistic effect between phosphorus and multiple metal elements can regulate the electronic state of the active site, thereby further regulating the electronic structure and morphology of the synthetic material. However, most of the current methods for synthesizing high entropy phosphides have certain limitations. First, the morphology is relatively simple, most of them are granular, and the size is difficult to continuously control. Secondly, the sodium hypophosphite used in the phosphating process will release toxic phosphine gas at high temperatures. In addition, the nanoscale synthesis of high entropy derivatives is still a challenge. Therefore, it is urgent to develop simple and environmentally friendly new methods to construct high entropy phosphides with novel microstructures.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a method for preparing high entropy phosphide nanotubes, thereby solving the problems raised in the above-mentioned background technology.

[0006] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0007] A method for preparing high entropy phosphide nanotubes comprises the following steps:

[0008] S1: adding trimesic acid, melamine, phosphoric acid and boric acid into an organic solvent according to a molar ratio and performing ultrasonication to form a hydrogen-bonded organic framework nanowire precursor, and then placing the obtained precursor in a high-temperature and high-pressure hydrothermal reactor for the first hydrothermal reaction. After the first hydrothermal reaction is completed, a HOF nanowire template is obtained;

[0009] S2: The obtained HOF nanowire template is mixed with a nickel source, a cobalt source, an iron source, a zinc source and an auxiliary metal element, and after the HOF nanowire template is evenly mixed with the nickel source, the cobalt source, the iron source, the zinc source and the auxiliary metal element, a secondary hydrothermal reaction is performed to form a hydrogen-bonded organic framework@metal-organic framework nanowire template with a core-shell structure, and then, the HOF@MOF nanowire template is converted into a metal-organic framework nanotube template through a diffusion mechanism;

[0010] S3: centrifuging the secondary hydrothermal reaction product, washing with anhydrous ethanol and drying the product after the centrifugation, and obtaining a dry product after the drying;

[0011] S4: placing the dried product in a muffle furnace for calcination, and finally obtaining high entropy phosphide nanotubes NiCoFeZnXBP (X=Mn, Cu) after calcination.

[0012] Optionally, the solvent in step S1 is methanol, and the molar ratio of trimesic acid, melamine, phosphoric acid and boric acid in step S1 is 2:3:3:3.

[0013] Optionally, in step S1, the ultrasonic time is 120 minutes, the ultrasonic power is 900 watts, the reaction temperature of the first hydrothermal reaction is 150° C., and the reaction time is 12 hours.

[0014] Optionally, the nickel source, cobalt source, iron source and zinc source in step S2 are nickel acetate, cobalt acetate, ferrous chloride and zinc acetate respectively, and the auxiliary metal element is one of manganese acetate or copper acetate.

[0015] Optionally, in step S2, the molar ratio of the nickel source, the cobalt source, the iron source, the zinc source and the auxiliary metal elements thereof is 5:1:1:1:1.

[0016] Optionally, in step S2, the stirring time is 30 minutes, the stirring speed is 300 rpm, the secondary hydrothermal reaction temperature is 150° C., the reaction time is 12 hours, the centrifugation time is 3 minutes, the rotation speed is 8000 rpm, and the drying time is 24 hours.

[0017] Optionally, the calcination temperature in step S4 is 500° C., the time is 2 hours, and the heating rate is 5° C. / min.

[0018] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art. Of course, any product implementing the present invention does not necessarily need to achieve all the advantages described below at the same time:

[0019] 1. By adopting the hydrogen-bonded organic framework (HOF)-metal organic framework (MOF) template conversion method, this method successfully prepared nanotube phosphides with high entropy structure. During the preparation process, the material first forms a core-shell structure (HOF@MOF). Through the diffusion mechanism, the core gradually disappears and is finally transformed into a uniform and size-controlled hollow nanotube structure. The hollow structure significantly increases the specific surface area, provides more active sites, and optimizes the transmission path of the reactant molecules, greatly improving the electrocatalytic performance. In addition, the overall tubular morphology of the material is uniform and size-controlled. Compared with traditional granular materials, the specific surface area is significantly increased, so that more reaction sites are exposed to the external environment, thereby greatly improving its catalytic efficiency and reaction rate in electrocatalytic reactions.

[0020] 2. This method achieves stable conversion of the organic framework through hydrothermal reaction, avoiding the production of toxic phosphine gas caused by the use of sodium hypophosphite in the traditional phosphating process. The whole process is green and environmentally friendly, meeting the current requirements of clean production. This method is not only safe and environmentally friendly, but also simplifies the operation process and reduces the special requirements for equipment, so it has good process versatility. The preparation method also has high production operability, is suitable for large-scale production under industrial conditions, and provides reliable process support to meet large-scale application needs.

[0021] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings described below are only some embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0023] Figure 1 ac are scanning electron microscope images of the high entropy nanotube phosphide NiCoFeZnMnBP obtained in Example 1 of the present invention at different magnifications;

[0024] Figure 2 a is a transmission electron microscope low-power image of the high entropy nanotube phosphide NiCoFeZnMnBP obtained in Example 1 of the present invention;

[0025] Figure 2 b is a transmission electron microscope high-resolution image of the high entropy nanotube phosphide NiCoFeZnMnBP obtained in Example 1 of the present invention;

[0026] Figure 2c is a transmission electron microscope diffraction pattern of the high entropy nanotube phosphide NiCoFeZnMnBP obtained in Example 1 of the present invention;

[0027] Figure 2 d is a transmission electron microscope element distribution diagram of the high entropy nanotube phosphide NiCoFeZnMnBP obtained in Example 1 of the present invention.

[0028] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0029] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0030] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0031] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0032] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present application description and examples are exemplary only.

[0033] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0034] See also Figure 1-2 As shown, in this embodiment, a method for preparing high entropy phosphide nanotubes is provided, comprising the following steps:

[0035] S1: adding trimesic acid, melamine, phosphoric acid and boric acid into an organic solvent according to a molar ratio and performing ultrasonication to form a hydrogen-bonded organic framework nanowire precursor, and then placing the obtained precursor in a high-temperature and high-pressure hydrothermal reactor for the first hydrothermal reaction. After the first hydrothermal reaction is completed, a HOF nanowire template is obtained;

[0036] S2: mixing and stirring the obtained HOF nanowire template with a nickel source, a cobalt source, an iron source, a zinc source and an auxiliary metal element, and after the HOF nanowire template is evenly stirred with the nickel source, the cobalt source, the iron source, the zinc source and the auxiliary metal element, a secondary hydrothermal reaction is performed to form a hydrogen-bonded organic framework@metal-organic framework (HOF@MOF) nanowire template with a core-shell structure, and then, through a diffusion mechanism, the HOF@MOF nanowire template is converted into a metal-organic framework nanotube template;

[0037] S3: centrifuging the secondary hydrothermal reaction product, washing with anhydrous ethanol and drying the product after the centrifugation, and obtaining a dry product after the drying;

[0038] S4: placing the dried product in a muffle furnace for calcination, and finally obtaining high entropy phosphide nanotubes NiCoFeZnXBP (X=Mn, Cu) after calcination.

[0039] In this embodiment, the solvent in step S1 is methanol, and the molar ratio of trimesic acid, melamine, phosphoric acid and boric acid in step S1 is 2:3:3:3.

[0040] In this embodiment, the ultrasonic time in step S1 is 120 minutes, the ultrasonic power is 900 watts, the reaction temperature of the first hydrothermal reaction is 150° C., and the reaction time is 12 hours.

[0041] In this embodiment, the nickel source, cobalt source, iron source and zinc source in step S2 are nickel acetate, cobalt acetate, ferrous chloride and zinc acetate respectively, and the auxiliary metal element is one of manganese acetate or copper acetate.

[0042] In this embodiment, the molar ratio of the nickel source, the cobalt source, the iron source, the zinc source and the auxiliary metal elements in step S2 is 5:1:1:1:1.

[0043] In this embodiment, the stirring time in step S2 is 30 minutes, the stirring speed is 300 rpm, the secondary hydrothermal reaction temperature is 150° C., the reaction time is 12 hours, the centrifugal time is 3 minutes, the rotation speed is 8000 rpm, and the drying time is 24 hours.

[0044] In this embodiment, the calcination temperature in step S4 is 500° C., the calcination time is 2 hours, and the heating rate is 5° C. / min.

[0045] The present invention will now be further described in detail with reference to embodiments.

[0046] It should be noted that all raw materials in the examples of the present invention were obtained through commercial sources.

[0047] Example 1: A preparation method for synthesizing NiCoFeZnMnBP by a hydrogen bond organic framework-metal organic framework template conversion method is provided, comprising the following steps:

[0048] (1): Trimellitic acid, melamine, phosphoric acid and boric acid are added to an organic solvent in a molar ratio of 2:3:3:3 and ultrasonicated. Trimellitic acid and melamine form a uniform hydrogen-bonded organic framework nanowire precursor through hydrogen bonding in the organic solvent, while phosphoric acid and boric acid are adsorbed on the surface of the hydrogen-bonded organic framework nanowire precursor through hydrogen bonding; the hydrogen-bonded organic framework nanowire precursor is transferred to a high-temperature and high-pressure hydrothermal reactor for hydrothermal reaction to obtain a hydrogen-bonded organic framework nanowire template; the organic solvent is methanol and the volume is 35 mL. The ultrasonic time is 120 minutes and the ultrasonic power is 900 watts. The hydrothermal reaction temperature is 150°C and the reaction time is 12 hours.

[0049] (2): Add nickel source, cobalt source, iron source and auxiliary metal element to the hydrogen-bonded organic framework nanowire template and stir thoroughly before performing a secondary hydrothermal reaction. During the reaction, the nickel source, cobalt source, iron source, zinc source and auxiliary metal element as well as phosphoric acid and boric acid form a nanowire template with a core-shell structure (hydrogen-bonded organic framework @ metal organic framework) through coordination bonds with the trimesic acid in the hydrogen-bonded organic framework nanowire template. Under the action of the diffusion mechanism, the hydrogen-bonded organic framework @ metal organic framework nanowire template is transformed into a metal organic framework nanotube template; the metal organic framework nanotube template obtained after the secondary hydrothermal reaction is centrifuged and washed, and the solid obtained after washing is dried; the nickel source is 1 mmol nickel acetate, the cobalt source is 0.2 mmol cobalt acetate, the iron source is 0.2 mmol ferrous chloride, the zinc source is 0.2 mmol zinc acetate, and the auxiliary metal element is 0.2 mmol manganese acetate or 0.2 mmol copper acetate. The stirring time is 30 minutes and the stirring speed is 300. The secondary hydrothermal reaction temperature is 150°C and the reaction time is 12 hours. The centrifugation time is 3 minutes, the speed is 8000 rpm, the detergent is anhydrous ethanol, and the drying time is 24 hours.

[0050] (3) The solid obtained after drying is placed in a muffle furnace for calcination to obtain high entropy nanotube phosphide NiCoFeZnMnBP. The calcination temperature is 500°C, the time is 2 hours, and the rate is 5°C / min.

[0051] Figure 1(a) shows the microscopic details of the high entropy nanotube phosphide. At this magnification, it can be clearly observed that the surface of the nanotube has obvious roughness and presents a granular fine structure. These particles are evenly distributed on the surface of the nanotube, forming a special microstructure, increasing the specific surface area of ​​the material, thereby improving the surface activity of the material.

[0052] This granular feature not only increases the surface roughness of the nanotubes, but also may provide more attachment sites for reactant molecules, which helps to increase the reaction rate in electrochemical and catalytic reactions. This porous, granular surface structure can effectively promote the contact between reactants and active sites, increase the effective area of ​​the reaction, and therefore may show higher activity in catalytic reactions. In addition, this surface feature can also provide more evacuation channels for reaction products, which is beneficial to improve the stability of the material during long-term reactions and prevent phenomena such as reactant accumulation or catalyst poisoning.

[0053] Figure 1 (b) shows the overall morphology and arrangement of high entropy nanotube phosphide. At this magnification, it can be clearly observed that the nanotubes present a uniform long strip structure, and their length and diameter do not vary much between different nanotubes, reflecting a high degree of structural consistency. This uniform long strip morphology is extremely important in nanomaterials. It not only improves the stability of the material in the electrochemical reaction, but also lays the foundation for the controllability of the material performance.

[0054] In addition, the surface of the nanotubes has obvious granular features. This granular surface structure increases the roughness of the nanotubes and increases the active sites on the surface, thereby providing more reaction sites for potential catalytic reactions. This structural characteristic can significantly improve the efficiency of the material in electrocatalytic reactions, because more active sites mean more opportunities for electron or ion exchange. In addition, the granular features of the surface may also form tiny pore structures, which further increase the specific surface area of ​​the material and help improve the specific capacity of the material in electrochemical applications.

[0055] Figure 1 (c) further shows the macroscopic distribution and overall arrangement of high entropy nanotube phosphide. In the figure, the nanotube structure shows the characteristics of relatively orderly arrangement, and the individual nanotubes are appropriately spaced, forming a uniformly distributed structural network. In addition, the sizes of these nanotubes are relatively consistent, with little variation in length and diameter. This uniformity is very important in structural design and contributes to the stability and consistency of material properties. The mutual stacking and cross-arrangement between nanotubes form a mesh structure with porous characteristics, which can significantly increase the specific surface area of ​​the material.

[0056] The increase in specific surface area exposes more active sites on the surface, thereby improving the activity of the material in applications such as electrocatalysis and energy storage. In addition, this network structure is also conducive to the formation of transport channels for molecules or ions, which can improve the diffusion efficiency of reactants and the transport efficiency of products in catalytic reactions or electrochemical processes.

[0057] Figure 2 The overall morphology of the nanotubes can be observed in (a), showing the length and structural characteristics of the nanotubes. It can be seen in the figure that the nanotubes are evenly distributed and the tubular structure is clear, indicating the morphological integrity of the material.

[0058] Figure 2 (b) shows the fine crystal structure of the high entropy nanotube. The lattice fringes of the nanotube can be observed, indicating that the material has a high degree of crystallinity. This high-resolution image can show the crystal structure characteristics of the nanomaterial and provide intuitive evidence for the lattice parameters and defect information of the material.

[0059] Figure 2 (c) reveals the crystal structure and phase composition of the material. The presence of clear annular or spot-like diffraction rings in the electron diffraction pattern indicates that the material is a polycrystalline structure. This information is important for confirming the crystal phase and crystal orientation of the material.

[0060] Figure 2 (d) shows the distribution of different elements in the nanotubes. Each color in the figure represents an element, such as nickel, cobalt, iron, zinc, manganese and phosphorus. The uniform distribution of different elements indicates that the metal elements are uniformly doped and distributed during the preparation process, indicating the uniformity of the material composition, which is important for the stability and consistency of catalytic and electrochemical performance.

[0061] Example 2: A preparation method for synthesizing NiCoFeZnCuBP by a hydrogen bond organic framework-metal organic framework template conversion method is provided, and the method specifically comprises the following steps:

[0062] (1) Trimellitic acid, melamine, phosphoric acid and boric acid are added to an organic solvent in a molar ratio of 2:3:3:3 and ultrasonicated. Trimellitic acid and melamine form a uniform hydrogen-bonded organic framework nanowire precursor in the organic solvent through hydrogen bonding, while phosphoric acid and boric acid are adsorbed on the surface of the hydrogen-bonded organic framework nanowire precursor through hydrogen bonding; the hydrogen-bonded organic framework nanowire precursor is transferred into a high-temperature and high-pressure hydrothermal reactor for hydrothermal reaction to obtain a hydrogen-bonded organic framework nanowire template; the organic solvent is methanol and the volume is 35 mL. The ultrasonic time is 120 minutes and the ultrasonic power is 900 watts. The hydrothermal reaction temperature is 150°C and the reaction time is 12 hours.

[0063] (2) Adding nickel source, cobalt source, iron source and auxiliary metal element to the hydrogen-bonded organic framework nanowire template and stirring them thoroughly, a secondary hydrothermal reaction is performed. During the reaction, the nickel source, cobalt source, iron source and auxiliary metal element as well as phosphoric acid, boric acid and trimesic acid in the hydrogen-bonded organic framework nanowire template form a nanowire template with a core-shell structure (hydrogen-bonded organic framework @ metal organic framework) through coordination bonds. Under the action of the diffusion mechanism, the hydrogen-bonded organic framework @ metal organic framework nanowire template is transformed into a metal organic framework nanotube template; the metal organic framework nanotube template obtained after the secondary hydrothermal reaction is centrifuged and washed, and the solid obtained after washing is dried; the nickel source is 1mmol nickel acetate, the cobalt source is 0.2mmol cobalt acetate, the iron source is 0.2mmol ferrous chloride, the zinc source is 0.2mmol zinc acetate, and the auxiliary metal element is 0.2mmol manganese acetate or 0.2mmol copper acetate. The stirring time is 30 minutes and the stirring speed is 300. The secondary hydrothermal reaction temperature is 150℃ and the reaction time is 12 hours. The centrifugation time is 3 minutes, the speed is 8000 rpm, the detergent is anhydrous ethanol, and the drying time is 24 hours.

[0064] (3) The solid obtained after drying is placed in a muffle furnace for calcination to obtain high entropy nanotube phosphide NiCoFeZnCuBP. The calcination temperature is 500°C, the time is 2 hours, and the rate is 5°C / min.

[0065] The present invention is not limited to the above-mentioned embodiments. Anyone should be aware that any structural changes made under the enlightenment of the present invention, and any technical solutions that are the same or similar to the present invention, fall within the protection scope of the present invention. The technology, shape, and structural parts not described in detail in the present invention are all well-known technologies.

Claims

1. A method for preparing high entropy phosphide nanotubes, characterized in that: The following steps are involved: S1: adding trimesic acid, melamine, phosphoric acid and boric acid into an organic solvent according to a molar ratio and performing ultrasonication to form a hydrogen-bonded organic framework nanowire precursor, and then placing the obtained precursor in a high-temperature and high-pressure hydrothermal reactor for the first hydrothermal reaction. After the first hydrothermal reaction is completed, a HOF nanowire template is obtained; S2: The obtained HOF nanowire template is mixed with a nickel source, a cobalt source, an iron source, a zinc source and an auxiliary metal element, and after the HOF nanowire template is evenly mixed with the nickel source, the cobalt source, the iron source, the zinc source and the auxiliary metal element, a secondary hydrothermal reaction is performed to form a hydrogen-bonded organic framework@metal-organic framework nanowire template with a core-shell structure, and then, the HOF@MOF nanowire template is converted into a metal-organic framework nanotube template through a diffusion mechanism; S3: centrifuging the secondary hydrothermal reaction product, washing with anhydrous ethanol and drying the product after the centrifugation, and obtaining a dry product after the drying; S4: placing the dried product in a muffle furnace for calcination, and finally obtaining high entropy phosphide nanotubes NiCoFeZnXBP (X=Mn, Cu) after calcination.

2. The method for preparing high entropy phosphide nanotubes according to claim 1, characterized in that: The solvent in step S1 is methanol, and the molar ratio of trimesic acid, melamine, phosphoric acid and boric acid in step S1 is 2:3:3:

3.

3. The method for preparing high entropy phosphide nanotubes according to claim 1, characterized in that: In step S1, the ultrasonic time is 100-120 minutes, the ultrasonic power is 850-900 watts, the reaction temperature of the first hydrothermal reaction is 140-150° C., and the reaction time is 10-12 hours.

4. The method for preparing high entropy phosphide nanotubes according to claim 1, characterized in that: The nickel source, cobalt source, iron source and zinc source in step S2 are nickel acetate, cobalt acetate, ferrous chloride and zinc acetate respectively, and the auxiliary metal element is one of manganese acetate or copper acetate.

5. The method for preparing high entropy phosphide nanotubes according to claim 1, characterized in that: In step S2, the molar ratio of the nickel source, the cobalt source, the iron source, the zinc source and the auxiliary metal elements is 5:1:1:1:

1.

6. The method for preparing high entropy phosphide nanotubes according to claim 1, characterized in that: In step S2, the stirring time is 20-30 minutes, the stirring speed is 300 rpm, the secondary hydrothermal reaction temperature is 100-150° C., the reaction time is 10-12 hours, the centrifugation time is 1-3 minutes, the rotation speed is 7000-8000 rpm, and the drying time is 24 hours.

7. The method for preparing high entropy phosphide nanotubes according to claim 1, characterized in that: The calcination temperature in step S4 is 400-500°C, the time is 2 hours, and the heating rate is 5°C / min.

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