Preparation method of nanometer hexagonal flaky high-entropy Fe-Co-Ni-Mn-based hydroxide

Abstract

The application relates to a preparation method of nanometer hexagonal flaky high-entropy Fe-Co-Ni-Mn-based hydroxide, and belongs to the technical field of high-entropy hydroxide preparation. Magnesium salt or copper salt, iron salt, cobalt salt, nickel salt and manganese salt are dissolved in deionized water to obtain a mixed solution A; the mixed solution A is placed in an ice water bath, and under ultrasonic conditions, a urea solution is uniformly and steadily added into the mixed solution A to form hexagonal high-entropy hydroxide crystal nuclei, thereby obtaining a suspension A; the pH value of the suspension A is adjusted to 8.5-10 by using an alkaline solution, thereby obtaining a suspension B; the suspension B is sealed, then oxygen is introduced into the suspension B, and stirring reaction is carried out at 65-80 DEG C for 5-8 h; the suspension B is sequentially washed by using deionized water and ethanol, and is dried, thereby obtaining nanometer hexagonal flaky high-entropy Fe-Co-Ni-Mn-based hydroxide. According to the unique structure of the ammonium ion, small-size hexagonal high-entropy hydroxide crystal nuclei are formed in the mixed solution in advance, and then the crystal nuclei are steadily grown under alkaline and aerobic conditions.

Description

Technical Field

[0001] This invention relates to a method for preparing nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-based hydroxides, belonging to the field of high-entropy hydroxide preparation technology. Background Technology

[0002] With the rapid development of new electronic devices and communication tools, electromagnetic pollution has become an increasingly serious problem. Based on structural design theory and electromagnetic loss principle, materials with large specific surface area and uniform heterojunctions have become ideal microwave absorbing materials due to their ability to induce strong interfacial polarization behavior. Layered hydroxides have stood out among materials such as nanowires, graphene, and metal-organic frameworks.

[0003] However, due to the significant differences in the solubility of various ions, different hydroxides precipitate at different pH ranges, making it impossible to guarantee the simultaneous nucleation and growth of each metal hydroxide. Common electrochemical deposition, hydrothermal methods, or the addition of various nucleating agents, reducing agents, and surfactants can only prepare binary or ternary lamellar hydroxides. But according to the high entropy effect, high composition implies high structural entropy, high stability, high active sites, and multiple mixing band gaps. Therefore, preparing multi-component (high entropy) lamellar hydroxides through simple methods is crucial for the field of microwave absorbing materials. Summary of the Invention

[0004] To address the issue that existing sheet hydroxides are limited to the preparation of low-component materials due to differences in ion solubility and pH range of precipitates, this invention proposes a method for preparing nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-based hydroxides. This method involves slowly adding an alkaline solution of a specific concentration to a mixed metal salt solution to pre-form small-sized high-entropy hydroxide nuclei, which then grow into hexagonal shapes based on the unique structure of ammonium ions during an alkaline aerobic hydrothermal process.

[0005] A method for preparing nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-based hydroxides, the specific steps of which are as follows:

[0006] (1) Dissolve iron salt, cobalt salt, nickel salt, manganese salt and M salt in deionized water and sonicate at 10-20℃ for 20-30 min to obtain mixed solution A; wherein M salt is magnesium salt or copper salt;

[0007] (2) Place the mixed solution A in an ice-water bath and add urea solution dropwise to the mixed solution A at a uniform rate under ultrasonic conditions to form hexagonal high-entropy hydroxide crystal nuclei, and obtain suspension A;

[0008] (3) Adjust the pH of suspension A to 8.5-10 using an alkaline solution to obtain suspension B;

[0009] (4) Seal the suspension B, then introduce oxygen into the suspension B and stir the reaction at 65-80℃ for 5-8 hours. Wash with deionized water and ethanol in sequence, and dry to obtain nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn based hydroxide.

[0010] In step (1), the iron salt is ferric chloride or ferric nitrate, the cobalt salt is cobalt chloride or cobalt nitrate, the nickel salt is nickel chloride or nickel nitrate, the manganese salt is manganese chloride or manganese nitrate, the magnesium salt is magnesium chloride or magnesium nitrate, and the copper salt is copper chloride or copper nitrate.

[0011] In step (1), the molar ratio of iron salt, cobalt salt, nickel salt, manganese salt and M salt in mixed solution A is 1:1:1:1:0.5 to 1.5; the total molar concentration of metal ions in mixed solution A is 0.1 to 0.3 mol / L.

[0012] In step (2), the concentration of the urea solution is 0.10-0.15 mol / L, the urea solution drop rate is 30-50 μL / s, and the volume ratio of the urea solution to the mixed solution A is 0.3-0.6:1.

[0013] The alkaline solution in step (3) is a sodium hydroxide solution and / or a potassium hydroxide solution, with a concentration of 8 to 12 mol / L.

[0014] In step (4), the oxygen introduction rate is 10-30 mL / min, and the stirring rate is 500-1000 r / min.

[0015] The beneficial effects of this invention are:

[0016] (1) The present invention involves slowly dripping a urea solution into a mixed metal salt solution and then sonicating it in an ice-water bath to pre-form small-sized hexagonal high-entropy hydroxide crystal nuclei.

[0017] (2) This invention, under alkaline aerobic conditions, is based on the ammonium ions (NH2) contained in urea. - The unique structure of the crystal nucleus stably controls its growth morphology to be hexagonal;

[0018] (3) The present invention can adjust the elemental ratio and size of the nano-hexagonal sheet-like high-entropy hydroxide obtained by changing the concentration of each metal salt, pH and drop acceleration rate, thereby adjusting its microwave absorption capacity. Attached Figure Description

[0019] Figure 1 SEM image of nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Mg hydroxide from Example 1;

[0020] Figure 2EDS image of nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Mg hydroxide from Example 1;

[0021] Figure 3 This is a SEM image of the nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Cu hydroxide from Example 2.

[0022] Figure 4 EDS image of nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Cu hydroxide from Example 2;

[0023] Figure 5 This is a SEM image of the nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Cu hydroxide from Example 3;

[0024] Figure 6 EDS image of nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Cu hydroxide from Example 3. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0026] Example 1: A method for preparing nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Mg hydroxide, the specific steps of which are as follows:

[0027] (1) Dissolve ferric chloride, cobalt chloride, nickel chloride, manganese chloride and magnesium chloride in deionized water and sonicate at 15℃ for 20 min to obtain mixed solution A; wherein the molar ratio of ferric chloride, cobalt chloride, nickel chloride, manganese chloride and magnesium chloride is 1:1:1:1:1, and the total molar concentration of metal ions in mixed solution A is 0.1 mol / L;

[0028] (2) Place the mixed solution A in an ice-water bath and, under ultrasonic conditions, add a urea solution with a concentration of 0.15 mol / L at a rate of 30 μL / s to the mixed solution A to form hexagonal high-entropy hydroxide crystal nuclei, thereby obtaining suspension A; wherein the volume ratio of urea solution to mixed solution A is 0.5:1.

[0029] (3) Adjust the pH of suspension A to 8.5 using a 10 mol / L sodium hydroxide solution to obtain suspension B;

[0030] (4) Seal the suspension B, then introduce oxygen into the suspension B at a rate of 15 mL / min and stir at 70 °C for 7 h (stirring rate of 500 r / min). Wash with deionized water and ethanol in sequence, and dry to obtain nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Mg hydroxide.

[0031] The SEM and EDS images of the nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Mg hydroxide prepared in this embodiment are shown in the figures below. Figure 1 and 2 The Fe-Co-Ni-Mn-Mg hydroxide has an average width of 225 nm and a thickness of 14 nm, exhibiting a hexagonal shape. Surface scan results show that there are five elements: Fe, Co, Ni, Mn, and Mg, and each element has a continuous and uniform distribution, indicating the successful preparation of nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Mg hydroxide.

[0032] In this embodiment, the maximum reflection loss of the nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Mg hydroxide is -31.6 dB and the maximum effective absorption bandwidth is 3.1 GHz.

[0033] Example 2: A method for preparing a nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Cu hydroxide, the specific steps of which are as follows:

[0034] (1) Dissolve ferric chloride, cobalt chloride, nickel chloride, manganese chloride and copper chloride in deionized water and sonicate at 20℃ for 30 min to obtain mixed solution A; wherein the molar ratio of ferric chloride, cobalt chloride, nickel chloride, manganese chloride and copper chloride is 1:1:1:1:1, and the total molar concentration of metal ions in mixed solution A is 0.25 mol / L;

[0035] (2) Place the mixed solution A in an ice-water bath and, under ultrasonic conditions, add a urea solution with a concentration of 0.15 mol / L to the mixed solution A at a rate of 40 μL / s to form hexagonal high-entropy hydroxide crystal nuclei, thereby obtaining suspension A; wherein the volume ratio of urea solution to mixed solution A is 0.6:1.

[0036] (3) Adjust the pH of suspension A to 10 using a mixed alkaline solution of sodium hydroxide and potassium hydroxide to obtain suspension B; wherein the mixed alkaline solution contains OH... - The ion concentration is 12 mol / L, and the molar ratio of sodium ions to potassium ions is 8:2;

[0037] (4) Seal the suspension B, then introduce oxygen into the suspension B at a rate of 20 mL / min and stir at 65 °C for 8 h (stirring rate of 700 r / min). Wash with deionized water and ethanol in sequence, and dry to obtain nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Cu hydroxide.

[0038] The SEM and EDS images of the nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Cu hydroxide prepared in this embodiment are shown in the figures below. Figure 3 and 4 The Fe-Co-Ni-Mn-Cu hydroxide has an average width of 156 nm and a thickness of 15 nm, exhibiting a hexagonal shape. Surface scan results show that there are five elements: Fe, Co, Ni, Mn, and Cu, and each element has a continuous and uniform distribution, indicating the successful preparation of nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Cu hydroxide.

[0039] In this embodiment, the maximum reflection loss of the nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-Cu hydroxide is -29.8 dB and the maximum effective absorption bandwidth is 2.8 GHz.

[0040] Example 3: A method for preparing a nano-hexagonal sheet-like high-entropy (Fe-Co-Ni-Mn)2-Cu hydroxide, the specific steps of which are as follows:

[0041] (1) Iron chloride, cobalt chloride, nickel chloride, manganese chloride and copper chloride were dissolved in deionized water and ultrasonically treated at 10℃ for 30 min to obtain mixed solution A; wherein the molar ratio of iron chloride, cobalt chloride, nickel chloride, manganese chloride and copper chloride was 1:1:1:1:0.5, and the total molar concentration of metal ions in mixed solution A was 0.27 mol / L;

[0042] (2) Place the mixed solution A in an ice-water bath and, under ultrasonic conditions, add a urea solution with a concentration of 0.13 mol / L at a rate of 35 μL / s to the mixed solution A to form hexagonal high-entropy hydroxide crystal nuclei, thereby obtaining suspension A; wherein the volume ratio of urea solution to mixed solution A is 0.3:1.

[0043] (3) Adjust the pH of suspension A to 9 using a potassium hydroxide solution with a concentration of 11 mol / L to obtain suspension B;

[0044] (4) Seal the suspension B, then introduce oxygen into the suspension B at a rate of 20 mL / min and stir at 80 °C for 7 h (stirring rate is 1000 r / min). Wash with deionized water and ethanol in sequence, and dry to obtain nano-hexagonal sheet-like high entropy (Fe-Co-Ni-Mn)2-Cu hydroxide.

[0045] The SEM and EDS images of the nano-hexagonal sheet-like high-entropy (Fe-Co-Ni-Mn)2-Cu hydroxide prepared in this embodiment are shown in the figures below. Figure 5 and 6The (Fe-Co-Ni-Mn)2-Cu hydroxide has an average width of 161 nm and a thickness of 14 nm, exhibiting a hexagonal shape. Surface scan results show that there are five elements: Fe, Co, Ni, Mn, and Cu, and each element has a continuous and uniform distribution, indicating the successful preparation of nano-hexagonal sheet-like high-entropy (Fe-Co-Ni-Mn)2-Cu hydroxide.

[0046] The maximum reflection loss and maximum effective absorption bandwidth of this embodiment and embodiments 1-2 are shown in Table 1;

[0047] Table 1 Maximum reflection loss and maximum effective absorption bandwidth of Examples 1-3

[0048] Example Sample Name Maximum reflection loss Maximum effective absorption bandwidth 1 Fe-Co-Ni-Mn-Mg -31.6dB 3.1GHz 2 Fe-Co-Ni-Mn-Cu -29.8 dB 2.8GHz 3 <![CDATA[(Fe-Co-Ni-Mn)2-Cu]]> -40.1 dB 2.8GHz

[0049] In this embodiment, the maximum reflection loss of the nano-hexagonal sheet-like high-entropy (Fe-Co-Ni-Mn)2-Cu hydroxide is -40.1dB and the maximum effective absorption bandwidth is 2.8GHz.

[0050] The specific embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing a nanohexagonal plate-like high-entropy Fe-Co-Ni-Mn-based hydroxide, characterized by, The specific steps are as follows: (1) Dissolve the iron salt, cobalt salt, nickel salt, manganese salt and M salt in deionized water, and ultrasonically treat at a temperature of 10-20 ℃ for 20-30 min to obtain a mixed solution A; wherein the M salt is a magnesium salt or a copper salt; the molar ratio of the iron salt, cobalt salt, nickel salt, manganese salt and M salt in the mixed solution A is 1:1:1:1:0.5-1.5; and the total molar concentration of metal ions in the mixed solution A is 0.1-0.3 mol / L; (2) Place the mixed solution A in an ice water bath, and under ultrasonic conditions, uniformly drop the urea solution into the mixed solution A to form a hexagonal high-entropy hydroxide crystal nucleus, to obtain a suspension A; The concentration of the urea solution is 0.10-0.15 mol / L, the dropping speed of the urea solution is 30-50 μL / s, and the volume ratio of the urea solution to the mixed solution A is 0.3-0.6:1; (3) Adjust the pH value of the suspension A to 8.5-10 by using an alkaline solution, to obtain a suspension B; (4) Seal the suspension B, then pass oxygen into the suspension B and stir at a temperature of 65-80 ℃ for 5-8 h, wash with deionized water and ethanol in sequence, and dry, to obtain a nano hexagonal flake-shaped high-entropy Fe-Co-Ni-Mn-based hydroxide.

2. The method for preparing the nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-based hydroxide according to claim 1, characterized in that: In step (1), the iron salt is ferric chloride or ferric nitrate, the cobalt salt is cobalt chloride or cobalt nitrate, the nickel salt is nickel chloride or nickel nitrate, the manganese salt is manganese chloride or manganese nitrate, the magnesium salt is magnesium chloride or magnesium nitrate, and the copper salt is copper chloride or copper nitrate.

3. The method for preparing the nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-based hydroxide according to claim 1, characterized in that: In step (3), the alkaline solution is a sodium hydroxide solution and / or a potassium hydroxide solution, and the concentration of the alkaline solution is 8-12 mol / L.

4. The method for preparing the nano-hexagonal sheet-like high-entropy Fe-Co-Ni-Mn-based hydroxide according to claim 1, characterized in that: In step (4), the oxygen passing rate is 10-30 mL / min, and the stirring rate is 500-1000 r / min.

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