Simple high-throughput preparation method of spinel type nano high-entropy oxide

Abstract

The invention discloses a simple high-throughput preparation method of spinel type nano high-entropy oxide, which comprises the following steps: 1) dissolving ferric nitrate, cobalt acetate, nickel acetate and at least two other different metal salts in a solvent to form a feed liquid A; 2) dissolving a precipitant in the same solvent as the solvent in the step 1) to form feed liquid B; 3) starting the supergravity reactor; 4) simultaneously introducing the feed liquid A and the feed liquid B into a supergravity reactor through a peristaltic pump to carry out a coprecipitation reaction, and obtaining a high-entropy oxide precursor solution after the reaction; 5) centrifuging and washing the high-entropy oxide precursor solution, and dispersing the high-entropy oxide precursor solution in water to obtain a clean precursor solution; 6) introducing the clean precursor solution into a hydrothermal kettle for hydrothermal reaction, and obtaining a nano high-entropy oxide solution after the reaction; and 7) carrying out alcohol washing on the nano high-entropy oxide solution, and drying to obtain the nano high-entropy oxide. The prepared oxide is high in quality, the particle size is 10-100 nm, and the oxide still has good dispersity under the condition that a modifier is not added.

Description

Technical Field

[0001] This invention belongs to the field of high-entropy oxide material preparation technology, and in particular relates to a simple and high-throughput preparation method for spinel-type nano high-entropy oxides. Background Technology

[0002] High-entropy oxides typically refer to oxide materials with a single-crystal structure composed of five or more metal cations in equimolar or near-equimolar amounts. Unlike traditional low-entropy materials, driven by high configurational entropy, multiple different metal elements and oxygen anions can be completely stabilized within a single crystal lattice or sublattice. This endows high-entropy oxides with unique core effects, including the high-entropy effect, lattice distortion effect, slow diffusion effect, and "cocktail" effect. Furthermore, the complex microstructure of high-entropy oxides allows for a rich variety of crystal structures, such as rock salt, spinel, fluorite, perovskite, and pyrochlore structures. Among these, spinel-type high-entropy oxides, with their abundant redox centers and oxygen vacancies on octahedral sites, exhibit high activity and stability in various catalytic fields, making them highly valuable for research.

[0003] Currently, research on high-entropy oxides mainly focuses on the nanoscale, where the unique size effect of nanomaterials brings additional advantages and performance improvements. As a promising emerging thermal barrier material, nano-high-entropy oxides, with their strong structural heterogeneity, can significantly improve phonon scattering, thereby reducing thermal conductivity and enhancing thermal stability. In the fields of catalysis and energy, spinel-type nano-high-entropy oxide materials can enhance interface and defect polarization, provide larger surface areas and abundant active sites, improve electron transport capabilities, and modulate band structure, demonstrating great potential. Therefore, exploring simple and high-throughput synthesis strategies for spinel-type nano-high-entropy oxides is of great significance.

[0004] Existing literature has reported numerous preparation processes for spinel-type high-entropy nano-oxides, including co-precipitation, sol-gel methods, ball milling, and carbothermal shock methods. However, due to the complex elemental composition and stringent preparation conditions, these methods still suffer from limitations such as difficulty in reducing material size, poor dispersibility, low versatility, and slow reaction times. For example, in Chinese patent application CN112340787A, entitled "Single-phase spinel-type high-entropy oxide and its preparation method and application," a high-entropy oxide powder with a unidirectional spinel structure is obtained by chelating five metal nitrates and glycine into a viscous dry gel, followed by calcination. While this method is simple to operate, the chelation time is long, requiring 2-4 hours, which limits production efficiency. Furthermore, the resulting spinel-type high-entropy oxide particles are large and lack regular morphology.

[0005] For example, Chinese patent application CN110364717A discloses "a spinel-type high-entropy oxide electrode material and its preparation method." This method involves thoroughly mixing different types of metal oxides using a ball mill, followed by high-temperature calcination to obtain various spinel-type high-entropy oxides such as (FeCoNiCrMn)O as electrode materials. The drawback of this method is that the resulting spinel-type high-entropy oxide particles have a large particle size and a wide size distribution (100-500 nm), which affects performance.

[0006] For example, Chinese patent application CN116870924A discloses "A method for preparing a spinel-structured high-entropy oxide nanofiber-based photocatalyst." In this method, sol-gel electrospinning technology combined with a gradient calcination process is used to synthesize (NiCuMnCoZnFe)3O4 high-entropy oxide nanofibers with a spinel structure. The nanoribbon structure provides a high active area, but the complex process significantly impacts production efficiency.

[0007] In order to address the existing shortcomings and accelerate the large-scale preparation and industrial application of spinel-type high-entropy nano-oxides, it is urgent to develop a simple and high-throughput preparation method for spinel-type high-entropy nano-oxides with good versatility. Summary of the Invention

[0008] The first technical problem this invention aims to solve is to provide a simple and high-throughput method for preparing spinel-type high-entropy nano-oxides. This method utilizes a hypergravity device to enhance the co-precipitation reaction, which not only shortens the reaction time and improves production efficiency, facilitating large-scale production, but also yields high-quality spinel-type high-entropy nano-oxides with a narrow particle size distribution (10-100 nm) and good dispersibility even without the addition of modifiers. Furthermore, this invention has excellent versatility, applicable to the preparation of spinel-type high-entropy nano-oxides of different elements, thus expanding its application prospects in various fields.

[0009] To solve the first technical problem mentioned above, the present invention adopts the following technical solution:

[0010] A simple, high-throughput preparation method for spinel-type nano-high-entropy oxides includes the following steps:

[0011] 1) Dissolve ferric nitrate, cobalt acetate, nickel acetate and at least two other different types of metal salts in a solvent to form solution A;

[0012] 2) Dissolve the precipitant in the same solvent as in step 1) to form solution B;

[0013] 3) Activate the hypergravity reactor;

[0014] 4) Feed solution A and feed solution B are simultaneously fed into the high gravity reactor by a peristaltic pump to carry out a co-precipitation reaction, and a high-entropy oxide precursor solution is obtained after the reaction.

[0015] 5) Centrifuge and wash the high-entropy oxide precursor solution with water, then disperse it in water to obtain a clean precursor solution;

[0016] 6) A clean precursor solution is introduced into a hydrothermal reactor for hydrothermal reaction, and a nano high-entropy oxide solution is obtained after the reaction.

[0017] 7) Wash the nano high-entropy oxide solution with alcohol and dry it to obtain nano high-entropy oxide.

[0018] Preferably, in step 1), the other different types of metal salts include magnesium acetate, chromium acetate, manganese acetate, copper acetate, and zinc acetate; preferably, the solvent is selected from water, methanol, ethanol, ethylene glycol, and N,N-dimethylformamide; preferably, the concentration of the metal salt precursor in the feed solution A is preferably 0.05-0.2 mol / L.

[0019] Preferably, in step 2), the precipitant is selected from one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water.

[0020] Preferably, in step 2), the concentration of the precipitant in the feed solution B is 0.1-0.6 mol / L, and the concentration ratio of the precipitant to the metal salt is 2-3:1.

[0021] Preferably, in step 3), the hypergravity reactor is selected from a hypergravity rotating packed bed reactor, a baffled hypergravity rotating bed reactor, a stator-rotor hypergravity rotating bed reactor, a spiral channel hypergravity rotating reactor, or a rotating disc hypergravity rotating bed reactor; preferably, the rotor speed of the hypergravity reactor is 250-1500 rpm.

[0022] Preferably, in step 4), the feed rate of liquid A is 100-300 mL / min; the feed rate of liquid B is 100-300 mL / min; and the ratio of the feed rates of liquid A and liquid B is 1:0.5-1.5.

[0023] Preferably, in step 5), the centrifugation speed is 8000-10000 rpm; the centrifugation time is 3-8 min; and the number of water washes is 2-5.

[0024] Preferably, in step 6), the solid content of the precursor solution is 2-6 wt%; the temperature of the hydrothermal reaction is 180-240℃; and the time of the hydrothermal reaction is 8-24 h.

[0025] Preferably, in step 7), the detergent for the alcohol wash is selected from one of methanol, ethanol, isopropanol, and glycerol; the number of alcohol washes is 1-3.

[0026] Preferably, in step 7), the drying temperature is 60-100℃; the drying time is 6-12h.

[0027] Any range described in this invention includes the endpoint, any value between the endpoints, and any subrange consisting of the endpoint or any value between the endpoints.

[0028] Unless otherwise specified, all raw materials used in this invention can be obtained commercially, and the equipment used in this invention can be conventional equipment in the relevant field or refer to existing technology in the relevant field.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1) The process of this invention is simple, easy to operate, highly repeatable, and easy to scale up; the precipitation reaction is completed instantaneously in the supergravity reactor, resulting in high production efficiency and suitability for large-scale production.

[0031] 2) Without adding a modifier, the spinel-type high-entropy nano-oxide synthesized by this invention has a small particle size (10-100nm), a narrow particle size distribution, and good dispersibility.

[0032] 3) The present invention has strong versatility and a wide range of element selection. It can be used to prepare spinel-type nano-high-entropy oxides with different elements, and has application potential in multiple fields such as catalysis and electrochemical energy storage materials. Attached Figure Description

[0033] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0034] Figure 1 A schematic diagram of a hypergravity reactor used in the present invention is shown;

[0035] Figure 2 This shows a transmission electron microscope (TEM) image of the spinel-type nano-high-entropy oxide (FeCoNiMnCu)3O4 obtained in Example 1 of the present invention;

[0036] Figure 3 The XRD pattern of spinel-type nano high-entropy oxide (FeCoNiMnCu)3O4 obtained in Example 1 of the present invention is shown.

[0037] Figure 4 The XRD pattern of spinel-type nano high-entropy oxide (FeCoNiMnZn)3O4 obtained in Example 2 of the present invention is shown.

[0038] Figure 5 This shows a transmission electron microscope (TEM) image of spinel-type nano-high-entropy oxide (FeCoNiMnZn)3O4 obtained in Example 2 of the present invention;

[0039] Figure 6 This shows a transmission electron microscope (TEM) image of the spinel-type nano-high-entropy oxide (FeCoNiCrMn)3O4 obtained in Example 3 of the present invention;

[0040] Figure 7 The XRD pattern of spinel-type nano high-entropy oxide (FeCoNiCrMn)3O4 obtained in Example 3 of the present invention is shown.

[0041] Figure 8 This shows a transmission electron microscope (TEM) image of the spinel-type nano-high-entropy oxide (FeCoNiCrMnZn)3O4 obtained in Example 4 of the present invention.

[0042] Figure 9 The XRD pattern of spinel-type nano high-entropy oxide (FeCoNiCrMnZn)3O4 obtained in Example 4 of the present invention is shown.

[0043] Figure 10 The image shown is a transmission electron microscope (TEM) image of spinel-type nano-high-entropy oxide (FeCoNiMnCu)3O4 obtained in Comparative Example 2 of this invention. Detailed Implementation

[0044] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0045] As one aspect of the present invention, a simple and high-throughput preparation method for spinel-type high-entropy nano-oxides is provided, comprising the following steps:

[0046] 1) Dissolve ferric nitrate, cobalt acetate, nickel acetate and at least two other different types of metal salts in a solvent to form solution A;

[0047] 2) Dissolve the precipitant in the same solvent as in step 1) to form solution B;

[0048] 3) Activate the hypergravity reactor;

[0049] 4) Feed solution A and feed solution B are simultaneously fed into the high gravity reactor by a peristaltic pump to carry out a co-precipitation reaction, and a high-entropy oxide precursor solution is obtained after the reaction.

[0050] 5) Centrifuge and wash the high-entropy oxide precursor solution with water, then disperse it in water to obtain a clean precursor solution;

[0051] 6) A clean precursor solution is introduced into a hydrothermal reactor for hydrothermal reaction, and a nano high-entropy oxide solution is obtained after the reaction.

[0052] 7) Wash the nano high-entropy oxide solution with alcohol and dry it to obtain nano high-entropy oxide.

[0053] Preferably, in step 1), the other different types of metal salts include magnesium acetate, chromium acetate, manganese acetate, copper acetate, and zinc acetate; preferably, the solvent is selected from water, methanol, ethanol, ethylene glycol, and N,N-dimethylformamide; preferably, the concentration of the metal salt precursor in the feed solution A is preferably 0.05-0.2 mol / L.

[0054] The hypergravity reactor used in this invention is an existing one, such as the published Chinese patent application (publication number: CN2221437A, invention title "Rotating bed hypergravity field device for enhancing transfer reaction"); Figure 1 This is a schematic diagram of a conventional hypergravity reactor used in this invention. The specific implementation of the hypergravity reactor is as follows: The hypergravity reactor device is turned on, and the rotation speed is adjusted to bring the rotor speed inside the hypergravity reactor device to a preset value; liquid A is introduced into the feed inlet 1 of the hypergravity reactor through a peristaltic pump; liquid B is introduced into the feed inlet 2 of the hypergravity reactor through a peristaltic pump; the rotor packing 3 inside the hypergravity reactor is driven by a motor 4 to generate high-speed rotation, thereby obtaining a hypergravity environment; liquids A and B are sprayed onto the inner edge of the rotor packing of the hypergravity reactor through a liquid distributor on the feed pipe, where they collide with the packing. The material enters the packing material through collision; after being divided, broken, and torn by the wire mesh packing, liquid A and liquid B inside the packing material generate a large number of rapidly renewed liquid surfaces, which greatly enhances the mass transfer process between molecules, shortens the nucleus growth time after the reactants react, precipitate, and crystallize, and thus effectively controls the particle size and morphology of the nucleated particles; the solution after the reaction flows out from the liquid phase outlet 5 at the bottom of the supergravity reactor, and the precursor solution flowing out of the outlet is collected, centrifuged, washed, and dispersed in water to obtain a clean nano high-entropy oxide precursor solution.

[0055] According to certain embodiments of the present invention, in step 2), the precipitant is selected from one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water.

[0056] According to some embodiments of the present invention, in step 2), the concentration of the precipitant in the feed solution B is 0.1-0.6 mol / L, and the concentration ratio of the precipitant to the metal salt is 2-3:1.

[0057] According to certain embodiments of the present invention, in step 3), the hypergravity reactor is selected from a hypergravity rotating packed bed reactor, a baffled hypergravity rotating bed reactor, a stator-rotor hypergravity rotating bed reactor, a spiral channel hypergravity rotating reactor, or a rotating disc hypergravity rotating bed reactor; preferably, the rotor speed of the hypergravity reactor is 250-1500 rpm.

[0058] According to some embodiments of the present invention, in step 4), the feed rate of liquid A is 100-300 mL / min; the feed rate of liquid B is 100-300 mL / min; and the ratio of the feed rates of liquid A and liquid B is 1:0.5-1.5.

[0059] According to certain embodiments of the present invention, in step 5), the centrifugation speed is 8000-10000 rpm; the centrifugation time is 3-8 min; and the number of water washes is 2-5.

[0060] According to certain embodiments of the present invention, in step 6), the solid content of the precursor solution is 2-6 wt%; the temperature of the hydrothermal reaction is 180-240°C; and the time of the hydrothermal reaction is 8-24 h.

[0061] According to certain embodiments of the present invention, in step 7), the detergent for the alcohol wash is selected from one of methanol, ethanol, isopropanol, and glycerol; the number of alcohol washes is 1-3.

[0062] According to certain embodiments of the present invention, in step 7), the drying temperature is 60-100°C; the drying time is 6-12 hours.

[0063] Example 1

[0064] A method for preparing spinel-type nano-high-entropy oxide (FeCoNiMnCu)3O4 includes the following steps:

[0065] (1) Take equimolar amounts of ferric nitrate, cobalt acetate, nickel acetate, manganese acetate and copper acetate and dissolve them in water to prepare a 0.1 mol / L metal salt solution, which is used as feed solution A;

[0066] (2) Prepare a 0.2 mol / L sodium hydroxide aqueous solution as feed solution B;

[0067] (3) Start the high gravity rotating packed bed reactor and set the rotor speed to 800 rpm;

[0068] (4) Feed A and feed B are simultaneously fed into the high gravity rotating packed bed reactor by a peristaltic pump. The feed rate of feed A is 165 mL / min and the feed rate of feed B is 200 mL / min. The precursor solution obtained after the reaction.

[0069] (5) The (FeCoNiMnCu)3O4 precursor solution was centrifuged and washed with water 5 times, each centrifugation speed was 10000 rpm and the duration was 5 min; then the wet solid after centrifugation was dispersed in water to form a homogeneous solution with a solid content of 5 wt%.

[0070] (6) Place the clean precursor solution into a hydrothermal reactor and react it hydrothermally at 230°C for 12 hours;

[0071] (7) After the hydrothermal reactor has cooled down, open it and pour out the nano (FeCoNiMnCu)3O4 solution in the reactor. Wash it three times with ethanol by centrifugation, then dry it at 70℃ for 8 hours and grind it into powder to obtain spinel-type nano high-entropy oxide (FeCoNiMnCu)3O4.

[0072] Figure 2 The image shows a transmission electron microscope (TEM) image of spinel-type nano-high-entropy oxide (FeCoNiMnCu)3O4 produced in Example 1. As can be seen from the image, the obtained nano-(FeCoNiMnCu)3O4 has a small average particle size (16.1 nm), a narrow particle size distribution, and good dispersibility.

[0073] Figure 3 The image shows the XRD pattern of the spinel-type nano high-entropy oxide (FeCoNiMnCu)3O4 product in Example 1. As can be seen from the image, the obtained nano (FeCoNiMnCu)3O4 exhibits a single-phase spinel structure.

[0074] Example 2

[0075] A method for preparing spinel-type nano-high-entropy oxide (FeCoNiMnZn)3O4 includes the following steps:

[0076] (1) Take equimolar amounts of ferric nitrate, cobalt acetate, nickel acetate, manganese acetate and zinc acetate and dissolve them in water to prepare a 0.1 mol / L metal salt solution, which is used as feed solution A;

[0077] (2) Prepare a 0.25 mol / L sodium hydroxide aqueous solution as feed solution B;

[0078] (3) Start the baffled rotating bed reactor and set the rotor speed to 1000 rpm;

[0079] (4) Feed A and feed B are simultaneously fed into the hypergravity reactor by a peristaltic pump. The feed rate of feed A is 150 mL / min and the feed rate of feed B is 105 mL / min. After the reaction, a precursor solution is obtained.

[0080] (5) The (FeCoNiMnZn)3O4 precursor solution was centrifuged and washed with water 5 times, each centrifugation speed was 10000 rpm and the duration was 5 min; then the wet solid after centrifugation was dispersed in water to form a homogeneous solution with a solid content of 6 wt%.

[0081] (6) Place the clean precursor solution into a hydrothermal reactor and hydrothermally react at 210°C for 10 h;

[0082] (7) After the hydrothermal reactor has cooled down, open it and pour out the nano (FeCoNiMnZn)3O4 solution in the reactor. Wash it three times with ethanol by centrifugation, then dry it at 70℃ for 8 hours and grind it into powder to obtain spinel-type nano high-entropy oxide (FeCoNiMnZn)3O4.

[0083] Figure 4 The image shows a transmission electron microscope (TEM) image of spinel-type nano-high-entropy oxide (FeCoNiMnZn)3O4 produced in Example 2. As can be seen from the image, the obtained nano-(FeCoNiMnZn)3O4 has a small average particle size (14.7 nm), a narrow particle size distribution, and good dispersibility.

[0084] Figure 5 The image shows the XRD pattern of spinel-type nano high-entropy oxide (FeCoNiMnZn)3O4 in Example 2. As can be seen from the image, the obtained nano (FeCoNiMnZn)3O4 exhibits a single-phase spinel structure.

[0085] Example 3

[0086] A method for preparing spinel-type nano-high-entropy oxide (FeCoNiCrMn)3O4 includes the following steps:

[0087] (1) Take equimolar amounts of ferric nitrate, cobalt acetate, nickel acetate, chromium acetate, and manganese acetate and dissolve them in water to prepare a 0.15 mol / L metal salt solution, which is used as feed solution A;

[0088] (2) Prepare a 0.5 mol / L sodium hydroxide aqueous solution as feed solution B;

[0089] (3) Start the high gravity rotating packed bed reactor and set the rotor speed to 1000 rpm;

[0090] (4) Feed A and feed B are simultaneously fed into the high gravity rotating packed bed reactor by a peristaltic pump. The feed rate of feed A is 180 mL / min and the feed rate of feed B is 150 mL / min. After the reaction, a precursor solution is obtained.

[0091] (5) The (FeCoNiCrMn)3O4 precursor solution was centrifuged and washed with water three times, each time at a speed of 8000 rpm for 5 min; then the wet solid after centrifugation was dispersed in water to form a homogeneous solution with a solid content of 6 wt%.

[0092] (6) Place the clean precursor solution into a hydrothermal reactor and react it hydrothermally at 180°C for 8 hours;

[0093] (7) After the hydrothermal reactor has cooled down, open it and pour out the nano (FeCoNiCrMn)3O4 solution in the reactor. Wash it three times with ethanol by centrifugation, then dry it at 70℃ for 8 hours and grind it into powder to obtain spinel-type nano high-entropy oxide (FeCoNiCrMn)3O4.

[0094] Figure 6 The image shows a transmission electron microscope (TEM) image of spinel-type nano-high-entropy oxide (FeCoNiCrMn)3O4 produced in Example 3. As can be seen from the image, the obtained nano-(FeCoNiCrMn)3O4 has a small average particle size (38.6 nm) and good dispersibility.

[0095] Figure 7 The image shows the XRD pattern of the spinel-type nano high-entropy oxide (FeCoNiCrMn)3O4 product in Example 3. As can be seen from the image, the obtained nano (FeCoNiCrMn)3O4 exhibits a single-phase spinel structure.

[0096] Example 4

[0097] A method for preparing spinel-type nano-high-entropy oxide (FeCoNiCrMnZn)3O4 includes the following steps:

[0098] (1) Take equimolar amounts of ferric nitrate, cobalt acetate, nickel acetate, chromium acetate, manganese acetate and zinc acetate and dissolve them in water to prepare a 0.2 mol / L metal salt solution, which is used as feed solution A;

[0099] (2) Prepare a 0.5 mol / L sodium hydroxide aqueous solution as feed solution B;

[0100] (3) Start the spiral channel high gravity rotating reactor and set the rotor speed to 1200 rpm;

[0101] (4) Feed A and feed B are simultaneously fed into the spiral channel high gravity rotating reactor by a peristaltic pump. The feed rate of feed A is 150 mL / min and the feed rate of feed B is 200 mL / min. After the reaction, a precursor solution is obtained.

[0102] (5) The (FeCoNiCrMnZn)3O4 precursor solution was centrifuged and washed with water 3 times, each centrifugation speed was 10000 rpm and the duration was 5 min; then the wet solid after centrifugation was dispersed in water to form a homogeneous solution with a solid content of 4 wt%.

[0103] (6) Place the clean precursor solution into a hydrothermal reactor and react it hydrothermally at 220°C for 12 hours;

[0104] (7) After the hydrothermal reactor has cooled down, open it and pour out the nano (FeCoNiCrMnZn)3O4 solution in the reactor. Wash it three times with ethanol by centrifugation, then dry it at 70℃ for 8 hours and grind it into powder to obtain nano spinel-type high entropy oxide (FeCoNiCrMnZn)3O4.

[0105] Figure 8 The image shows a transmission electron microscope (TEM) image of spinel-type nano-high-entropy oxide (FeCoNiCrMnZn)3O4 produced in Example 4. As can be seen from the image, the obtained nano-(FeCoNiCrMnZn)3O4 has a small average particle size (19.3 nm), a narrow particle size distribution, and good dispersibility.

[0106] Figure 9 The image shows the XRD pattern of spinel-type nano high-entropy oxide (FeCoNiCrMnZn)3O4 in Example 4. As can be seen from the image, the obtained nano (FeCoNiCrMnZn)3O4 exhibits a single-phase spinel structure.

[0107] Comparative Example 1

[0108] Nano-high entropy oxide (FeCoNiMnCu)3O4 was prepared using the steps described in Example 1, except that the concentration ratio of precipitant to metal salt in step 2) is outside the given range of 2:1-3:1.

[0109] Tests revealed that when the concentration of the precipitant is too low, it is impossible to completely precipitate all metal ions, which will lead to element segregation and ultimately prevent the preparation of the corresponding spinel-type high-entropy oxide. When the concentration of the precipitant is too high, it exacerbates the difference in precipitation rate among the metal elements, which will lead to uneven element distribution, causing local phase segregation and affecting the quality of the spinel-type high-entropy oxide.

[0110] Comparative Example 2

[0111] Nano-high entropy oxide (FeCoNiMnCu)3O4 was prepared using the steps described in Example 1, except that a supergravity reactor was not used in step 3), and the reaction was carried out directly in a beaker with stirring.

[0112] Testing revealed that the lack of a hypergravity process enhancer resulted in the inability to produce spinel-type high-entropy nano-oxides with narrow particle size distribution and good dispersibility.

[0113] Figure 10 The image shows a transmission electron microscope (TEM) image of the nano high-entropy oxide (FeCoNiMnCu)3O4 product in Comparative Example 2. As can be seen from the image, the obtained nano (FeCoNiMnCu)3O4 particles have large differences in size and are severely agglomerated.

[0114] Comparative Example 3

[0115] Nano-high entropy oxide (FeCoNiMnCu)3O4 was prepared using the steps described in Example 1, except that the ratio of the feed rates of liquid A and liquid B in step 4) is outside the given range of 1:0.5-1:1.5.

[0116] Testing revealed that the large difference in the feed rates of the two materials prevented normal convection mixing, resulting in the inability to produce spinel-type high-entropy nano-oxides with narrow particle size distribution and good dispersibility.

[0117] Comparative Example 4

[0118] Nano-high entropy oxide (FeCoNiMnCu)3O4 was prepared using the steps described in Example 1, except that the temperature of the hydrothermal reaction in step 6) was adjusted to 150°C.

[0119] Testing revealed that the precursor was not completely decomposed due to insufficient hydrothermal temperature, which ultimately prevented the preparation of spinel-type nano-high-entropy oxides.

[0120] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A simple, high-throughput preparation method for spinel-type nano-high-entropy oxides, characterized in that, The following steps are involved: 1) Dissolve ferric nitrate, cobalt acetate, nickel acetate and at least two other different types of metal salts in a solvent to form solution A; 2) Dissolve the precipitant in the same solvent as in step 1) to form solution B; 3) Activate the hypergravity reactor; 4) Feed solution A and feed solution B are simultaneously fed into the high gravity reactor by a peristaltic pump to carry out a co-precipitation reaction, and a high-entropy oxide precursor solution is obtained after the reaction. 5) Centrifuge and wash the high-entropy oxide precursor solution with water, then disperse it in water to obtain a clean precursor solution; 6) A clean precursor solution is introduced into a hydrothermal reactor for hydrothermal reaction, and a nano high-entropy oxide solution is obtained after the reaction. 7) Wash the nano high-entropy oxide solution with alcohol and dry it to obtain nano high-entropy oxide.

2. The simple, high-throughput preparation method of spinel-type high-entropy nano-oxides according to claim 1, characterized in that: In step 1), the other different types of metal salts include magnesium acetate, chromium acetate, manganese acetate, copper acetate, and zinc acetate; preferably, the solvent is selected from water, methanol, ethanol, ethylene glycol, and N,N-dimethylformamide; preferably, the concentration of the metal salt precursor in the feed solution A is preferably 0.05-0.2 mol / L.

3. The simple, high-throughput preparation method for spinel-type high-entropy nano-oxides according to claim 1, characterized in that: In step 2), the precipitant is selected from one or more of sodium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia water.

4. The simple, high-throughput preparation method for spinel-type high-entropy nano-oxides according to claim 1, characterized in that: In step 2), the concentration of the precipitant in the feed solution B is 0.1-0.6 mol / L, and the concentration ratio of the precipitant to the metal salt is 2-3:

1.

5. The simple, high-throughput preparation method of spinel-type high-entropy nano-oxides according to claim 1, characterized in that: In step 3), the hypergravity reactor is selected from a hypergravity rotating packed bed reactor, a baffled hypergravity rotating bed reactor, a stator-rotor hypergravity rotating bed reactor, a spiral channel hypergravity rotating reactor, or a rotating disc hypergravity rotating bed reactor; preferably, the rotor speed of the hypergravity reactor is 250-1500 rpm.

6. The simple, high-throughput preparation method for spinel-type high-entropy nano-oxides according to claim 1, characterized in that: In step 4), the feed rate of liquid A is 100-300 mL / min; the feed rate of liquid B is 100-300 mL / min; and the ratio of the feed rates of liquid A and liquid B is 1:0.5-1.

5.

7. The simple, high-throughput preparation method of spinel-type high-entropy nano-oxides according to claim 1, characterized in that: In step 5), the centrifugation speed is 8000-10000 rpm; the centrifugation time is 3-8 min; and the number of water washes is 2-5.

8. The simple, high-throughput preparation method of spinel-type high-entropy nano-oxides according to claim 1, characterized in that: In step 6), the solid content of the precursor solution is 2-6 wt%; the temperature of the hydrothermal reaction is 180-240℃; and the time of the hydrothermal reaction is 8-24 h.

9. The simple, high-throughput preparation method of spinel-type high-entropy nano-oxides according to claim 1, characterized in that: In step 7), the detergent used for alcohol washing is selected from one of methanol, ethanol, isopropanol, and glycerol; the number of alcohol washing cycles is 1-3.

10. The simple, high-throughput preparation method of spinel-type high-entropy nano-oxides according to claim 1, characterized in that: In step 7), the drying temperature is 60-100℃; the drying time is 6-12h.

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