A method for preparing high-entropy spinel oxide materials using microwave hydrothermal technology and its products and applications

Abstract

The present invention discloses a method for preparing a high-entropy spinel oxide material using microwave hydrothermal treatment, as well as its products and applications. The method belongs to the fields of materials science and chemical engineering technology. The method comprises the following steps: dissolving six metal sources, namely iron, cobalt, nickel, chromium, zinc, and copper, in water in an equimolar ratio of the metal ions, stirring uniformly to obtain a mixed solution; adding a precipitant to the mixed solution, and then sequentially performing microwave hydrothermal treatment, cooling, washing, centrifugation, drying, and calcining to obtain a high-entropy spinel oxide material (FeCoNiCrZnCu)3O4. Specifically, the present invention synthesizes a high-entropy spinel material with excellent water electrolysis catalytic performance by high-entropy design of the spinel oxide. On the one hand, the raw materials for synthesizing the material are relatively inexpensive transition metal nitrates, which are widely available and low in cost. On the other hand, the microwave hydrothermal method can efficiently synthesize the high-entropy spinel material under mild reaction conditions, making it environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials science and chemical engineering, and in particular relates to a method for preparing a high-entropy spinel oxide material by utilizing microwave hydrothermal technology, and a product and application thereof. Background Art

[0002] High-entropy oxides (HEOs), an innovative new material, were first proposed in 2015 by a team of scientists including Rost, Maria, and Curtarolo, who published groundbreaking research results. Due to their unique multi-principal component nature and disordered arrangement among the principal components, these materials readily form a variety of solid solution structures, such as rock salt, calcium fluoride, spinel, and perovskite, resulting in exceptional performance. HEOs exhibit significant application potential, particularly in energy storage and magnetic materials. HEOs can be prepared using diverse methods, including solid-phase methods, thermal decomposition, co-precipitation, hydrothermal synthesis, and liquid-phase combustion synthesis. Each of these methods offers distinct advantages, providing a wealth of options for material research and application. Compared to traditional oxides, HEOs possess numerous significant advantages, including abundant active sites, tunable surface area, stable crystal structures, and unique geometric compatibility and electronic structure properties. These properties have made them increasingly important in materials science. HEO spinel oxides, in particular, demonstrate exceptional performance in energy storage and magnetic materials, making them ideal oxide materials and attracting considerable attention from both research and industry.

[0003] However, due to its complex crystal structure and multi-component characteristics, the preparation of high-entropy spinel oxide materials still faces some challenges and problems, mainly including the following aspects:

[0004] 1. High-entropy spinel oxide materials are multi-component alloys composed of multiple metal elements. Achieving uniform distribution of these components and forming a stable crystal structure is a challenge.

[0005] 2. The traditional hydrothermal method has complex operating steps, long reaction time, and the morphology and particle size distribution of the prepared product are uncontrollable;

[0006] 3. Due to the multi-component nature of high-entropy spinel oxide materials, their performance is often affected by the content of each component, and different synthesis conditions will also affect their performance, so the preparation process needs to be finely controlled;

[0007] 4. The traditional hydrothermal method for preparing high-entropy spinel oxide materials will produce a large amount of waste liquid and waste gas, causing certain pollution to the environment.

[0008] Therefore, there is an urgent need to provide a method that is simple and easy to use and can accurately control the morphology and particle size distribution of high-entropy spinel oxide materials. Summary of the Invention

[0009] In response to the above technical problems, the present invention proposes a method for preparing high-entropy spinel oxide material (FeCoNiCrZnCu)3O4 using microwave hydrothermal technology, as well as its products and applications.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] One of the technical solutions of the present invention:

[0012] A method for preparing a high-entropy spinel oxide material using microwave hydrothermal treatment comprises the following steps:

[0013] Dissolve six metal sources, namely iron, cobalt, nickel, chromium, zinc and copper, in water in equal moles of metal ions and stir evenly to obtain a mixed solution;

[0014] A precipitant is added to the mixed solution, and then microwave hydrothermal treatment, cooling, washing, centrifugation, drying and calcination are carried out in sequence to obtain a high entropy spinel oxide material (FeCoNiCrZnCu)3O4.

[0015] Beneficial effects: The present invention uses microwave hydrothermal technology to prepare high-entropy spinel oxide materials, cleverly utilizing microwave energy to supplement the temperature deficiencies of traditional hydrothermal methods, thereby greatly improving the efficiency of practical applications. That is, microwave hydrothermal technology, with its higher heating efficiency and uniformity, can quickly reach high-temperature and high-pressure reaction conditions, significantly accelerating the reaction rate. At the same time, this technology can also more accurately control the morphology and particle size distribution of the product during the synthesis process, providing a powerful means for preparing high-quality functional materials. Among them, the present application selects six metal ions, namely iron, cobalt, nickel, chromium, zinc and copper, and prepares oxide materials in an equimolar ratio in order to precisely control the morphology, composition and oxidation state of the material by substitution of uniformly distributed metal ions in the crystal lattice, thereby obtaining a multi-component oxide with optimized structure and performance. The equimolar ratio of these metal ions can ensure the formation of a stable spinel or similar structure, provide abundant active sites, enhance electron transport performance, and enhance the overall catalytic activity, electrochemical performance and stability of the material through the synergistic effect between metal ions, so that it exhibits excellent performance in related applications.

[0016] Preferably, the metal source is a hydrated metal nitrate.

[0017] Preferably, the six metal sources of iron, cobalt, nickel, chromium, zinc and copper are: Fe(NO3)3·9H2O, Co(NO3)2·6H2O, Ni(NO3)2·6H2O, Cr(NO3)2·9H2O, Zn(NO3)2·6H2O, Cu(NO3)2·3H2O respectively.

[0018] Preferably, in the mixed solution, the concentration of each metal ion is 0.01-0.06 mol / L.

[0019] Preferably, the precipitant comprises one or two of disodium edetate, ammonium fluoride, glucose, ammonia water or urea.

[0020] Preferably, the molar ratio of the precipitant to the total metal ions in the mixed solution is (3-6):1.

[0021] Preferably, the parameter conditions in the microwave hydrothermal process are:

[0022] The rated output power of the microwave is 400W, the microwave operating frequency is 2450MHz, the microwave hydrothermal temperature is 100-160℃, and the holding time is 0.5-6h.

[0023] Preferably, the washing process comprises the following specific steps:

[0024] The precipitate obtained by cooling was washed three times with ethanol and deionized water in sequence.

[0025] Preferably, the parameter conditions during the centrifugation process are:

[0026] Centrifuge at 8000 rpm for 3 min.

[0027] Preferably, the drying process is: drying at 60° C. for 10 hours.

[0028] Preferably, the calcination process is:

[0029] The temperature was raised to 300-900°C at a heating rate of 2-10°C / min, and then kept at this temperature for 0.5-5h.

[0030] The second technical solution of the present invention:

[0031] A high-entropy spinel oxide material is prepared by the above method.

[0032] Preferably, the high entropy spinel oxide material has the morphology of round nanoparticles, a porosity of 0.074 to 0.253 cc / g, a particle size of 3.062 to 3.414 nm, and a specific surface area of ​​27.017 to 168.271 m 2 / g.

[0033] The third technical solution of the present invention:

[0034] Application of the above-mentioned high-entropy spinel oxide material in the field of catalytic water electrolysis.

[0035] Compared with the prior art, the present invention has the following advantages and technical effects:

[0036] 1. The present invention uses metal nitrate as raw material, which is low in cost, easy to handle and has a wide range of sources;

[0037] 2. The present invention utilizes microwave hydrothermal method to precisely prepare raw materials in a liquid environment, ensuring uniform distribution of metal elements and accurately matching the product with the predetermined stoichiometric ratio. This method not only has mild reaction conditions, energy-saving and high efficiency, and cost-effectiveness, but also the entire synthesis process is green and environmentally friendly.

[0038] 3. The high-entropy spinel oxide material prepared by the method of the present invention exhibits excellent catalytic activity, stability and corrosion resistance in electrocatalysis, effectively improving the efficiency and life of the electrocatalytic reaction.

[0039] The microwave hydrothermal method for preparing high-entropy oxides (HEOs) disclosed in this invention, through comparison with existing patented technologies, reveals its innovative reaction principle. This method utilizes the unique synergistic effect of microwave hydrothermal technology to effectively overcome the difficulties of existing technologies, such as high reaction temperature, high energy consumption, uneven element distribution, and the bias towards uniform solid solution of complex components. This invention achieves the rapid synthesis of highly uniform and crystalline HEOs at relatively low temperatures, significantly improving the material's catalytic performance and electrochemical activity while also unexpectedly enhancing its thermal stability and durability. These remarkable technical results exceed the expectations of traditional preparation methods and fully demonstrate the non-obviousness and innovative nature of this invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings:

[0041] Figure 1 The SEM and XRD patterns of the high entropy spinel oxide prepared at different calcination temperatures in the present invention;

[0042] Among them, (a)-(f) are SEM images, (a) 0°C (Comparative Example 1), (b) 400°C (Example 3), (c) 500°C (Example 4), (d) 600°C (Example 5), (e) 700°C (Example 6), (f) 900°C (Example 7), and (g) are XRD patterns;

[0043] Figure 2 The SEM and XRD patterns of the high-entropy spinel oxide prepared under different hydrothermal conditions at 500°C in Example 4 of the present invention; (a) microwave hydrothermal, (b) conventional hydrothermal, and (c) XRD pattern;

[0044] Figure 3For Examples 1, 2, and 7 of the present invention, at 900° C., (a)-(c) SEM images of precipitants at 1:4, 1:5, and 1:6, respectively, and (d) XRD patterns of precipitants at 1:4, 1:5, and 1:6, respectively;

[0045] Figure 4 These are the LSV diagrams of high-entropy spinel oxides prepared under different hydrothermal conditions; among them, (a) is the LSV diagram at different heat treatment temperatures (Examples 3-7); (b) is the LSV diagram of conventional-microwave comparison at 500°C; (c) is the LSV diagram at different precipitant contents (different precipitant contents correspond to Examples 1, 2 and 7, respectively).

[0046] Figure 5 Graphs showing the stability of hydrogen evolution (right) and oxygen evolution (left) at 500° C. and 1:6 in Example 4 of the present invention. DETAILED DESCRIPTION

[0047] 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 rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0048] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0049] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice 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 any conflict with any incorporated document, the contents of this specification shall prevail.

[0050] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0051] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0052] The present invention discloses a method for preparing a high entropy spinel oxide material (FeCoNiCrZnCu)3O4 by a microwave hydrothermal method, comprising the following steps:

[0053] Ferric nitrate, cobalt nitrate, nickel nitrate, chromium nitrate, zinc nitrate, and copper nitrate are respectively dissolved in deionized water and thoroughly stirred to obtain a mixed solution of metal salts; urea is introduced into the mixed solution as a precipitant, and then the solution is transferred to a microwave synthesizer for a hydrothermal reaction (synthesis conditions of the microwave synthesizer: microwave rated output power of 400W; microwave operating frequency: 2450MHz). After the reaction is completed, the solution is cooled to room temperature to form a precipitate, which is washed three times with ethanol and deionized water in sequence, centrifuged at 8000rpm for 3min, and then dried at 60°C for 10h. The powder is annealed in air at 300-900°C for 0.5-5h to obtain a high-entropy spinel oxide material.

[0054] In some preferred embodiments, the concentration of each metal nitrate in the mixed solution of six metal nitrate salts is 0.01-0.06 mol / L to ensure the normal progress of the hydrothermal reaction.

[0055] In some preferred embodiments, the precipitant is urea, and the molar ratio of the precipitant to the total metal ions in the metal nitrate is (3-6):1. The addition of the precipitant serves to adjust the solution pH and provide a uniform precipitation environment, encouraging the metal ions to form uniform, fine precipitate particles. The amount of precipitant added significantly affects the sample morphology. While an appropriate amount can form uniform, fine particles, an excessive amount may cause the precipitate to agglomerate or form irregular, large particles, while an insufficient amount may result in incomplete precipitation or uneven particle size. Therefore, precise control of the precipitant addition is key to achieving ideal sample morphology.

[0056] Unless otherwise specified, the "room temperature" in the present invention refers to 20-30°C.

[0057] The raw materials used in the present invention are all purchased from the market.

[0058] The technical solution of the present invention is further illustrated by the following examples.

[0059] Example 1

[0060] A method for preparing a high entropy spinel oxide material (FeCoNiCrZnCu)3O4 using microwave hydrothermal method, the specific steps are as follows:

[0061] 1. Weigh according to the raw material ratio and set aside

[0062] Weigh Fe(NO3)3·9H2O (0.001 mol), Co(NO3)2·6H2O (0.001 mol), Ni(NO3)2·6H2O (0.001 mol), Cr(NO3)2·9H2O (0.001 mol), Zn(NO3)2·6H2O (0.001 mol), and Cu(NO3)2·3H2O (0.001 mol). The molar ratio of urea to the total metal ions is 4:1.

[0063] 2. Dissolve the six nitrates mentioned above in 100 mL of water and stir evenly. After the six metal elements are completely mixed, continue to add urea to the solution to obtain a mixed solution;

[0064] 3. The mixed solution was transferred to a microwave synthesizer (microwave rated output power: 400 W; microwave operating frequency: 2450 MHz; hydrothermal temperature: 100°C; synthesis time: 2 h) for reaction. After the reaction was completed, the microwave reactor was cooled to room temperature and the liquid was removed under reduced pressure. The liquid was then centrifuged to precipitate solid matter. The precipitate was washed three times with ethanol and deionized water, sequentially, and centrifuged at 8000 rpm for 3 min.

[0065] 4. The powder was then dried at 60°C for 10 hours and annealed in air at 900°C for 2 hours to obtain a high-entropy spinel oxide material. Throughout the calcination process, the heating rate was controlled at 10°C / min, and the temperature was lowered as the furnace cooled.

[0066] Figure 1 The SEM and XRD patterns of the high entropy spinel oxide prepared at different calcination temperatures in the present invention;

[0067] Among them, (a)-(f) are SEM images, (a) 0℃ (Comparative Example 1), (b) 400℃ (Example 3), (c) 500℃ (Example 4), (d) 600℃ (Example 5), (e) 700℃ (Example 6), (f) 900℃ (Example 7), and (g) are XRD images; it can be seen from the XRD image that the main peak positions of the five spinels are 18.453°, 30.357°, 35.760°, 37.408°, 43.466°, 53.938°, 57.503°, and 63.156°, respectively, belonging to the (111), (220), (311), (222), (400), (422), (511), and (440) crystal planes; it can be seen from the SEM image that the calcination temperature affects the porosity and nanodiameter of the sample. Too low a temperature may result in incomplete decomposition of the raw materials, forming an amorphous or partially crystalline structure. Excessively high temperatures may lead to over-sintering of the sample, resulting in a reduced diameter. This may also cause the spinel structure to deteriorate or undergo phase transitions, compromising its performance. Therefore, controlling the calcination temperature is a critical step in preparing spinel nanoparticles.

[0068] Figure 2 The SEM and XRD patterns of the high entropy spinel oxide prepared under different hydrothermal conditions at 500°C in Example 4 of the present invention; (a) microwave hydrothermal, (b) conventional hydrothermal (the difference from Example 4 is that microwave hydrothermal is replaced by conventional hydrothermal), (c) is the XRD pattern; Figure 2 As can be seen from (a), the microwave hydrothermal method formed small-sized round nanoparticles with regular morphology, large porosity, and no agglomeration. Figure 2 As can be seen from (b), the grain size obtained by conventional hydrothermal method is larger, the pore structure is less, and there are more agglomeration phenomena and crystal defects; Figure 2 (c) The XRD patterns under different hydrothermal conditions show that the high-entropy spinel prepared by microwave hydrothermal method usually shows sharper and more symmetrical diffraction peaks in the XRD spectrum, indicating that the crystal structure is more complete and ordered, while the spinel prepared by conventional hydrothermal method may show broader and less symmetrical diffraction peaks, reflecting that its crystal structure is less ordered.

[0069] Figure 4The LSV diagrams of high entropy spinel oxides prepared under different hydrothermal conditions; wherein, (a) is the LSV diagram at different heat treatment temperatures (Examples 3-7); (b) is the LSV diagram of conventional-microwave (Example 4) comparison at 500°C; (c) is the LSV diagram under different precipitant contents (corresponding to Example 1, Example 2 and Example 7). In order to reveal the effect of high entropy spinel oxides under different hydrothermal conditions on the electrocatalytic activity of the material, the present invention uses a standard three-electrode to measure the HER performance of (FeCoNiCrZnCu)3O4. The HER catalytic activity of HEO / NF electrode was analyzed in 1M KOH solution. As Figure 4 As shown in (b), it was found that the sample prepared under microwave hydrothermal conditions had a -2 At 138 mV, the HER performance of the samples prepared under microwave hydrothermal conditions is significantly better than that under conventional hydrothermal conditions (161 mV).

[0070] Example 2

[0071] A method for preparing a high entropy spinel oxide material (FeCoNiCrZnCu)3O4 using microwave hydrothermal method, the specific steps are as follows:

[0072] 1. Weigh according to the raw material ratio and set aside;

[0073] Fe(NO3)3·9H2O (0.002 mol), Co(NO3)2·6H2O (0.002 mol), Ni(NO3)2·6H2O (0.002 mol), Cr(NO3)2·9H2O (0.002 mol), Zn(NO3)2·6H2O (0.002 mol), and Cu(NO3)2·3H2O (0.002 mol) were weighed as raw materials, and the ratio of urea to metal ions was (5:1);

[0074] 2. Dissolve the six nitrates mentioned above in 100 mL of water and stir thoroughly. Once the six metal elements are completely mixed, continue adding urea to the solution.

[0075] 3. Subsequently, the mixed solution was transferred to a microwave synthesizer (microwave rated output power: 400 W; microwave operating frequency: 2450 MHz; hydrothermal temperature: 100°C; synthesis time: 2 h). After the reaction was completed, the microwave reactor was cooled to room temperature, and the liquid was removed under reduced pressure. The liquid was then centrifuged to precipitate solid matter. The precipitate was washed three times with ethanol and deionized water, followed by centrifugation at 8000 rpm for 3 min.

[0076] 4. The powder was then dried at 60°C for 10 hours and annealed in air at 900°C for 2 hours to obtain a high-entropy spinel oxide material. Throughout the calcination process, the heating rate was controlled at 10°C / min, and the temperature was lowered as the furnace cooled.

[0077] like Figure 3 The XRD pattern of 1:5 is that the ratio of metal ion to urea content in Example 2 is 1:5 at 900°C. From the XRD pattern, it can be seen that the main peak positions of the five spinels are at 18.453°, 30.357°, 35.760°, 37.408°, 43.466°, 53.938°, 57.503°, and 63.156°, which belong to the (111), (220), (311), (222), (400), (422), (511), and (440) crystal planes respectively. Figure 3 As can be seen from the SEM in (b), under this condition, grains with diverse morphologies were successfully synthesized. These grains are arranged tightly and orderly and are evenly distributed throughout the structure, showing good crystal growth characteristics. Figure 4 The FCNCZC-5:1 in (a) is the LSV curve of the sample at 900℃.

[0078] Example 3

[0079] A method for preparing a high entropy spinel oxide material (FeCoNiCrZnCu)3O4 using microwave hydrothermal method, the specific steps are as follows:

[0080] 1. Weigh according to the raw material ratio and set aside;

[0081] Fe(NO3)3·9H2O (0.002 mol), Co(NO3)2·6H2O (0.002 mol), Ni(NO3)2·6H2O (0.002 mol), Cr(NO3)2·9H2O (0.002 mol), Zn(NO3)2·6H2O (0.002 mol), and Cu(NO3)2·3H2O (0.002 mol) were weighed as raw materials, and the ratio of urea to metal ions was (6:1);

[0082] 2. Dissolve the six nitrates mentioned above in 100 mL of water and stir evenly. After the six metal elements are completely mixed, continue to add urea to the solution;

[0083] 3. Subsequently, the mixed solution was transferred to a microwave synthesizer (microwave rated output power: 400 W; microwave operating frequency: 2450 MHz; hydrothermal temperature: 100°C; synthesis time: 1 h). After the reaction was completed, the microwave reactor was cooled to room temperature, and the liquid was removed under reduced pressure. The liquid was then centrifuged to precipitate solid matter. The precipitate was washed three times with ethanol and deionized water, sequentially, and centrifuged at 8000 rpm for 3 min.

[0084] 4. The powder was then dried at 60°C for 10 hours and annealed in air at 400°C for 2 hours to obtain a high-entropy spinel oxide material. Throughout the calcination process, the heating rate was controlled at 10°C / min, and the temperature was lowered as the furnace cooled.

[0085] like Figure 1 The XRD pattern at 400°C in (g) shows that the ratio of metal ions to urea content in Example 3 at 400°C is 1:6. From the XRD pattern, it can be seen that the main peak positions of the five spinels are at 18.453°, 30.357°, 35.760°, 37.408°, 43.466°, 53.938°, 57.503°, and 63.156°, which belong to the (111), (220), (311), (222), (400), (422), (511), and (440) crystal planes, respectively. Figure 1 As can be seen from the SEM in (b), the sample synthesized under this condition has some holes. Figure 4 FCNCZC-400℃ in (a) is the LSV curve of the sample at 400℃.

[0086] Example 4

[0087] A method for preparing a high entropy spinel oxide material (FeCoNiCrZnCu)3O4 using microwave hydrothermal method, the specific steps are as follows:

[0088] 1. Weigh according to the raw material ratio and set aside;

[0089] Fe(NO3)3·9H2O (0.003 mol), Co(NO3)2·6H2O (0.003 mol), Ni(NO3)2·6H2O (0.003 mol), Cr(NO3)2·9H2O (0.003 mol), Zn(NO3)2·6H2O (0.003 mol), and Cu(NO3)2·3H2O (0.003 mol) were weighed as raw materials, and the ratio of urea to metal ions was (6:1);

[0090] 2. Dissolve the six nitrates mentioned above in 100 mL of water and stir thoroughly. Once the six metal elements are completely mixed, continue adding urea to the solution.

[0091] 3. Subsequently, the mixed solution was transferred to a microwave synthesizer (microwave rated output power: 400 W; microwave operating frequency: 2450 MHz; hydrothermal temperature: 100°C; synthesis time: 1 hour). After the reaction was completed, the microwave reactor was cooled to room temperature and the liquid was removed under reduced pressure. The liquid was then centrifuged to precipitate the solid material. The resulting precipitate was washed three times with ethanol and deionized water, sequentially, and centrifuged at 8000 rpm for 3 minutes.

[0092] 4. The powder was then dried at 60°C for 10 hours and annealed in air at 500°C for 2 hours to obtain a high-entropy spinel oxide material. During the entire calcination process, the heating rate was controlled at 10°C / min, and the temperature was lowered as the furnace cooled.

[0093] like Figure 1 The XRD pattern at 500°C in (g) shows that the ratio of metal ions to urea content in Example 4 at 500°C is 1:6. From the XRD pattern, it can be seen that the main peak positions of the five spinels are at 18.453°, 30.357°, 35.760°, 37.408°, 43.466°, 53.938°, 57.503°, and 63.156°, which belong to the (111), (220), (311), (222), (400), (422), (511), and (440) crystal planes, respectively. Figure 1 As can be seen from the SEM in (c), the sample synthesized under this condition has some holes. Figure 4 FCNCZC-500℃ in (a) is the LSV curve of the sample at 500℃.

[0094] Example 5

[0095] A method for preparing a high entropy spinel oxide material (FeCoNiCrZnCu)3O4 using microwave hydrothermal method, the specific steps are as follows:

[0096] 1. Weigh according to the raw material ratio and set aside;

[0097] Fe(NO3)3·9H2O (0.004 mol), Co(NO3)2·6H2O (0.004 mol), Ni(NO3)2·6H2O (0.004 mol), Cr(NO3)2·9H2O (0.004 mol), Zn(NO3)2·6H2O (0.004 mol), and Cu(NO3)2·3H2O (0.004 mol) were weighed as raw materials, and the ratio of urea to metal ions was (6:1);

[0098] 2. Dissolve the six nitrates mentioned above in 100 mL of water and stir thoroughly. Once the six metal elements are completely mixed, continue adding urea to the solution.

[0099] 3. Subsequently, the mixed solution was transferred to a microwave synthesizer (microwave rated output power: 400 W; microwave operating frequency: 2450 MHz; hydrothermal temperature: 160°C; synthesis time: 1 hour). After the reaction was completed, the microwave reactor was cooled to room temperature and the liquid was removed under reduced pressure. Next, the liquid was centrifuged to precipitate the solid material. The resulting precipitate was washed three times with ethanol and deionized water, followed by centrifugation at 8000 rpm for 3 minutes.

[0100] 4. The powder was then dried at 60°C for 10 hours and annealed in air at 600°C for 2 hours to obtain a high-entropy spinel oxide material. During the entire calcination process, the heating rate was controlled at 10°C / min, and the temperature was lowered as the furnace cooled.

[0101] like Figure 1 The XRD pattern at 600°C in (g) shows that the ratio of metal ions to urea content in Example 5 at 600°C is 1:6. From the XRD pattern, it can be seen that the main peak positions of the five spinels are at 18.453°, 30.357°, 35.760°, 37.408°, 43.466°, 53.938°, 57.503°, and 63.156°, which belong to the (111), (220), (311), (222), (400), (422), (511), and (440) crystal planes, respectively. Figure 1 As can be seen from the SEM of (d), the sample synthesized under this condition has some holes. Figure 4 FCNCZC-600℃ in (a) is the LSV curve of the sample at 600℃.

[0102] Example 6

[0103] A method for preparing a high entropy spinel oxide material (FeCoNiCrZnCu)3O4 using microwave hydrothermal method, the specific steps are as follows:

[0104] 1. Weigh according to the raw material ratio and set aside;

[0105] Fe(NO3)3·9H2O (0.005 mol), Co(NO3)2·6H2O (0.005 mol), Ni(NO3)2·6H2O (0.005 mol), Cr(NO3)2·9H2O (0.005 mol), Zn(NO3)2·6H2O (0.005 mol), and Cu(NO3)2·3H2O (0.005 mol) were weighed as raw materials, and the ratio of urea to metal ions was (6:1);

[0106] 2. Dissolve the six nitrates mentioned above in 100 mL of water and stir thoroughly. Once the six metal elements are completely mixed, continue adding urea to the solution.

[0107] 3. Subsequently, the mixed solution was transferred to a microwave synthesizer (microwave rated output power: 400 W; microwave operating frequency: 2450 MHz; hydrothermal temperature: 100°C; synthesis time: 1 hour). After the reaction was completed, the microwave reactor was cooled to room temperature and the liquid was removed under reduced pressure. Next, the liquid was centrifuged to precipitate the solid material. The resulting precipitate was washed three times with ethanol and deionized water, sequentially, and centrifuged at 8000 rpm for 3 minutes.

[0108] 4. The powder was then dried at 60°C for 10 hours and annealed in air at 700°C for 1 hour to obtain a high-entropy spinel oxide material. During the entire calcination process, the heating rate was controlled at 10°C / min, and the temperature was lowered as the furnace cooled.

[0109] like Figure 1 The XRD pattern at 700°C in (g) shows that the ratio of metal ions to urea content in Example 6 at 700°C is 1:6. From the XRD pattern, it can be seen that the main peak positions of the five spinels are at 18.453°, 30.357°, 35.760°, 37.408°, 43.466°, 53.938°, 57.503°, and 63.156°, which belong to the (111), (220), (311), (222), (400), (422), (511), and (440) crystal planes, respectively. Figure 1 As can be seen from the SEM in (e), the sample synthesized under this condition has some holes. Figure 4 FCNCZC-700℃ in (a) is the LSV curve of the sample at 700℃.

[0110] Example 7

[0111] A method for preparing a high entropy spinel oxide material (FeCoNiCrZnCu)3O4 using microwave hydrothermal method, the specific steps are as follows:

[0112] 1. Weigh according to the raw material ratio and set aside;

[0113] Fe(NO3)3·9H2O (0.005 mol), Co(NO3)2·6H2O (0.005 mol), Ni(NO3)2·6H2O (0.005 mol), Cr(NO3)2·9H2O (0.005 mol), Zn(NO3)2·6H2O (0.005 mol), and Cu(NO3)2·3H2O (0.005 mol) were weighed as raw materials, and the ratio of urea to metal ions was (6:1);

[0114] 2. Dissolve the six nitrates mentioned above in 100 mL of water and stir thoroughly. Once the six metal elements are completely mixed, continue adding urea to the solution.

[0115] 3. Subsequently, the mixed solution was transferred to a microwave synthesizer (microwave rated output power: 400 W; microwave operating frequency: 2450 MHz; hydrothermal temperature: 100°C; synthesis time: 1 hour). After the reaction was completed, the microwave reactor was cooled to room temperature and the liquid was removed under reduced pressure. Next, the liquid was centrifuged to precipitate the solid material. The resulting precipitate was washed three times with ethanol and deionized water, sequentially, and centrifuged at 8000 rpm for 3 minutes.

[0116] 4. The powder was then dried at 60°C for 10 hours and annealed in air at 900°C for 1 hour to obtain a high-entropy spinel oxide material. During the entire calcination process, the heating rate was controlled at 10°C / min, and the temperature was lowered as the furnace cooled.

[0117] like Figure 1 The XRD pattern at 900°C in (g) shows that the ratio of metal ions to urea content in Example 7 at 900°C is 1:6. From the XRD pattern, it can be seen that the main peak positions of the five spinels are at 18.453°, 30.357°, 35.760°, 37.408°, 43.466°, 53.938°, 57.503°, and 63.156°, which belong to the (111), (220), (311), (222), (400), (422), (511), and (440) crystal planes, respectively. Figure 1 As can be seen from the SEM of (f), the sample synthesized under this condition has some holes. Figure 4 FCNCZC-900℃ in (a) is the LSV curve of the sample at 900℃.

[0118] Comparative Example 1

[0119] The difference from Example 3 is that the annealing temperature in step 4 is 0°C.

[0120] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for preparing high entropy spinel oxide materials using microwave hydrothermal method, characterized in that: The following steps are involved: Dissolve six metal sources, namely iron, cobalt, nickel, chromium, zinc and copper, in water in equal moles of metal ions and stir evenly to obtain a mixed solution; A precipitant is added to the mixed solution, and then microwave hydrothermal treatment, cooling, washing, centrifugation, drying and calcination are carried out in sequence to obtain a high entropy spinel oxide material (FeCoNiCrZnCu)3O4; The parameter conditions in the microwave hydrothermal process are: The microwave rated output power is 400W, the microwave operating frequency is 2450MHz, the microwave hydrothermal temperature is 100-160℃, and the holding time is 0.5-6h; The calcination process is: Heat to 300-900°C at a heating rate of 2-10°C / min, and then keep at this temperature for 0.5-5h.

2. The method for preparing high entropy spinel oxide materials using microwave hydrothermal method according to claim 1, characterized in that: The metal source is metal nitrate.

3. The method for preparing high entropy spinel oxide materials using microwave hydrothermal method according to claim 2, characterized in that: In the mixed solution, the concentration of each metal ion is 0.01-0.06 mol / L.

4. The method for preparing a high entropy spinel oxide material using microwave hydrothermal method according to claim 1, characterized in that: The precipitant comprises one or two of disodium edetate, ammonium fluoride, glucose, ammonia water or urea.

5. The method for preparing high entropy spinel oxide materials using microwave hydrothermal method according to claim 4, characterized in that: The molar ratio of the precipitant to the total metal ions in the mixed solution is (3-6):

1.

6. The method for preparing high entropy spinel oxide materials using microwave hydrothermal method according to claim 1, characterized in that: The drying process is: drying at 60° C. for 10 hours.

7. A high entropy spinel oxide material, characterized in that: The method is prepared by any one of claims 1 to 6.

8. Use of the high-entropy spinel oxide material according to claim 7 in the field of catalytic water electrolysis.

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