An ultrathin hexagonal aluminum hydroxide nanosheet and a preparation method thereof

Abstract

This invention belongs to the field of inorganic nanomaterials technology, specifically disclosing an ultrathin hexagonal aluminum hydroxide nanosheet and its preparation method. The invention employs a hydrothermal synthesis method. The precursor solution is prepared as follows: aluminum powder, aluminum shavings, or aluminum ash are used as the aluminum source; an aqueous solution of ethanol is used as the solvent; and bromine, iodine, or hydrogen peroxide is used as the oxidant. Mixing and stirring: A certain mass of aluminum powder, aluminum shavings, or aluminum ash is mixed into the aqueous solution of ethanol and stirred continuously until a stable suspension is formed. Then, the oxidant is added, and stirring is continued at 50-90 °C until the suspension turns completely milky white and the Tyndall effect is observed, indicating the synthesis is complete. This combination of temperature and time is crucial for forming a complete hexagonal and ultrathin structure. Cooling and collection: After the reaction, the mixture is naturally cooled to room temperature, and the product is obtained by centrifugation and washing (several times with water and ethanol). Drying: The product is dried at a specific temperature (e.g., 60 °C) to obtain ultrathin hexagonal aluminum hydroxide nanosheets with a complete hexagonal morphology.

Description

[0001] This application claims priority to application number 2025116933115, filed on November 18, 2025, entitled "An ultrathin hexagonal aluminum hydroxide nanosheet and its preparation method", the original receiving agency of which is in China. Technical Field

[0002] This invention belongs to the field of inorganic nanomaterials technology, and specifically discloses an ultrathin hexagonal aluminum hydroxide nanosheet and its preparation method. Background Technology

[0003] Aluminum hydroxide nanomaterials, as an important inorganic chemical raw material, have shown broad application prospects in various fields such as coatings, flame retardants, adsorption, new energy batteries, catalyst supports, and composite materials due to their low toxicity, cost advantages, and unique nano-effects. Their performance is primarily dependent on microstructural parameters such as morphology, size, and crystallinity. For example, regular sheet-like or fibrous morphologies are beneficial for increasing specific surface area and surface activity, thereby enhancing their application effects in adsorption and catalysis; nanoscale thickness can induce quantum confinement effects, improving electron transport efficiency; and high crystallinity is directly related to the material's thermal stability and chemical durability. Therefore, achieving precise control of morphology, size, and crystallinity is key to improving their overall performance and meeting the demands of high-end applications.

[0004] Currently, the preparation of aluminum hydroxide nanomaterials mainly relies on precipitation, sol-gel, template, hydrothermal / solvothermal, and mechanical exfoliation methods. While each method has its own characteristics, they all have significant limitations. Precipitation is simple and low-cost, but the product is prone to agglomeration, has low crystallinity, and is difficult to control in terms of morphology. The sol-gel method can achieve good dispersibility, but the process is complex, the product is prone to solvent residue, and the yield is low. Template methods can control morphology, but template removal is cumbersome, easily introduces impurities, and increases costs. Mechanical exfoliation is energy-intensive, inefficient, and prone to introducing structural defects. A common problem with these methods is the difficulty in simultaneously achieving high purity, high crystallinity, and uniform morphology. Especially in the preparation of ultrathin hexagonal nanosheets, defects such as uneven thickness (typically greater than 50 nm), wide size distribution, poor crystallinity, and easy stacking and agglomeration are common, severely restricting the full realization of material properties.

[0005] Existing literature further reveals the shortcomings of current synthetic techniques. For example, while top-to-bottom exfoliation can yield thin sheets, the process involves organic solvents and ultrasonic treatment, which can easily lead to sheet damage and low yield, making it difficult to achieve both ultrathin thickness and high crystallinity. Sep. Purif. Technol. , 2025, 354, 129180. The biotemplate method can achieve crystallinity control, but the products are mostly spherical particles, unable to form the desired plate-like structure, and the introduction of the template reduces process repeatability ( Nanomaterials,2020, 10, 150). The sol-gel combined template method can prepare nanosheet clusters, but the morphology is irregular and cannot form a complete hexagonal structure (CN104961146A). Although the one-pot method can control the morphology, the product has low crystallinity, wide size distribution, and is prone to aggregation ( ). J. Ceram. Soc. Jpn. , 2013, 121, 141). Furthermore, while a green synthesis method for Mg / Al layered double hydroxides has achieved ultrathin sheets (2-5 nm), this method relies on specific metal ratios and cannot be directly applied to the controllable preparation of pure-phase, highly crystalline hexagonal aluminum hydroxide nanosheets. Mater. Lett. , 2024, 137123).

[0006] In summary, existing technologies generally face the challenge of achieving precise and coordinated control over morphology (especially complete hexagons), thickness (ultra-thin characteristics, such as less than 5 nm), and crystallinity. The main root cause lies in the difficulty of finely controlling nucleation and growth kinetics in traditional synthesis routes. Therefore, developing a method for preparing aluminum hydroxide nanosheets that can simultaneously achieve regular morphology, ultra-thin thickness, and high crystallinity is of great significance for promoting the application of this material in high-performance fields and is also an urgent need for technological development in this field. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the present invention aims to provide a method for preparing ultrathin hexagonal aluminum hydroxide nanosheets. This hydrothermal preparation method is simple to operate, low in cost, mild under mild conditions, has good repeatability and is suitable for large-scale production. The aluminum hydroxide nanosheets obtained have a complete hexagonal morphology and ultrathin characteristics.

[0008] To achieve the above objectives, the present invention employs the following technical solution: a method for preparing ultrathin hexagonal aluminum hydroxide nanosheets, comprising the following steps: S1. Preparation of precursor solution: aluminum powder, aluminum shavings or aluminum ash are used as aluminum source, aqueous solution of ethanol is used as solvent, and at least one of bromine, iodine or hydrogen peroxide is used as oxidant. S2. Mixing and stirring: Add the aluminum powder, aluminum chips or aluminum ash to the aqueous solution of the ethanol and stir to form a suspension. Then add the oxidant and continue stirring at a temperature of 50~90°C until the reaction system becomes a milky white suspension and the Tyndall effect appears, to obtain a reaction product containing ultrathin hexagonal aluminum hydroxide nanosheets. S3. Post-processing: The reaction product obtained in step S2 is cooled and then centrifuged, washed and dried in sequence to obtain the ultrathin hexagonal aluminum hydroxide nanosheet powder.

[0009] As a further improvement to the above-mentioned method for preparing ultrathin hexagonal aluminum hydroxide nanosheets: Preferably, in step S1, the aluminum powder is industrial-grade aluminum powder or uncoated high-purity aluminum powder with a purity greater than 99%; the aluminum shavings are small fragments or powders generated during the machining process of aluminum or aluminum alloys, wherein the aluminum content is not less than 80%; the aluminum ash is solid waste generated during the aluminum industry production process, originating from slag floating on the surface of molten aluminum in the smelting process of electrolytic aluminum, cast aluminum, or recycled aluminum, and has an aluminum content of 15-80%.

[0010] Preferably, in step S1, the oxidant is an ethanol solution of iodine, and the mass concentration of iodine is 1% to 10%.

[0011] Preferably, in step S1, the oxidant is an ethanol solution of bromine, and the mass concentration of bromine is 1% to 10%.

[0012] Preferably, in step S1, the oxidant is hydrogen peroxide or a combination of iodine and hydrogen peroxide.

[0013] Preferably, in step S1, the mass concentration of ethanol in the aqueous solution of ethanol is 5% to 10%.

[0014] Preferably, in step S2, the reaction temperature is 80±1°C, and the reaction time continues until the aluminum powder is completely consumed.

[0015] Preferably, in step S3, the washing process involves multiple centrifugal washes using water, ethanol, or a mixture of both.

[0016] Preferably, in step S3, the drying temperature is 40~150°C.

[0017] The second objective of this invention is to provide an ultrathin hexagonal aluminum hydroxide nanosheet prepared by the above-mentioned method, wherein the nanosheet has a complete hexagonal morphology, with a side length between 50 nm and 1000 nm and a thickness between 1 nm and 50 nm.

[0018] The advantages of this invention compared to the prior art are as follows: This application addresses the common technical challenge of existing preparation methods in synergistically controlling morphology, thickness, and crystallinity, and provides a method for preparing aluminum hydroxide nanosheets that combine regular morphology, ultrathin properties, and high crystallinity: This invention overcomes the challenge of simultaneously achieving both regular morphology and ultrathin thickness: existing techniques (such as sol-gel and one-pot methods) often produce products that are irregularly sheet-like or spherical, with thicknesses typically exceeding 50 nm. This application, through optimization of the reaction system and temperature conditions, achieves for the first time the simultaneous and precise control of complete, regular hexagonal morphology and ultrathin thicknesses in the 1–2 nm range, as well as thicknesses in the 20–50 nm range. This solves the defects of existing methods, such as uneven product morphology, excessive thickness, and difficulty in controllability.

[0019] This invention achieves a balance between high crystallinity and ultrathin structure: Existing methods such as exfoliation and precipitation often sacrifice crystallinity to obtain thin sheets, resulting in poor crystallinity and numerous structural defects in the products. This application promotes perfect crystal growth under mild conditions, and the XRD patterns of the obtained nanosheets are completely consistent with the standard cards, exhibiting high crystallinity. Thus, while ensuring an ultrathin structure, it significantly improves the thermal stability and chemical durability of the material.

[0020] This invention provides a simple, green, and efficient solution: Compared to existing technologies that rely on complex templates, harsh hydrothermal conditions, or energy-intensive mechanical stripping, this application uses only aluminum powder, aluminum shavings, or aluminum-containing aluminum ash (primary or secondary aluminum ash from electrolytic aluminum, or aluminum ash from aluminum processing or recycled aluminum smelting) as the aluminum source, and uses ethanol aqueous solution and common oxidants as raw materials. The reaction can be completed under normal pressure and medium temperature (50~90°C). This method is simple, has mild conditions, good repeatability, low cost, and is environmentally friendly. It is also easy to scale up for production, fundamentally overcoming the problems of complex processes, easy introduction of impurities, high cost, or difficulty in scaling up existing technologies.

[0021] In summary, this application successfully solves the technical bottlenecks in the prior art, such as irregular morphology, large thickness, low crystallinity, and complex preparation process of aluminum hydroxide nanosheets, and provides a practical and advantageous preparation method for obtaining high-performance aluminum hydroxide nanomaterials. Attached Figure Description

[0022] Figure 1 This is a transmission electron microscope (TEM) image of the ultrathin hexagonal aluminum hydroxide nanosheets prepared in Example 1 of this invention.

[0023] Figure 2 This is a transmission electron microscope (TEM) image of the ultrathin hexagonal aluminum hydroxide nanosheets prepared in Example 1 of this invention.

[0024] Figure 3 This is a selected area electron diffraction (TEM) image of the ultrathin hexagonal aluminum hydroxide nanosheets prepared in Example 1 of this invention.

[0025] Figure 4 This is the X-ray diffraction (XRD) pattern of the ultrathin hexagonal aluminum hydroxide nanosheets prepared in Example 1 of this invention.

[0026] Figure 5 This is a transmission electron microscope (TEM) image of the aluminum hydroxide nanosheets prepared in Comparative Example 1 of this invention.

[0027] Figure 6 Transmission electron microscope (TEM) image of aluminum hydroxide nanosheets prepared in Comparative Example 2 of this invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] Example 1

[0030] This embodiment provides a method for preparing ultrathin hexagonal aluminum hydroxide nanosheets, specifically following the steps described in the technical solution: S1. Preparation of precursor solution Aluminum source: Uncoated aluminum powder with a purity >99% is used.

[0031] Solvent: Prepare 500 ml of an aqueous solution of ethanol as the solvent, with a mass concentration of 5%.

[0032] Oxidizing agent: An ethanol solution of iodine is prepared as the oxidizing agent. Specifically, 5.0 g of iodine crystals are dissolved in 50 mL of ethanol to obtain 50 mL of iodine solution.

[0033] S2, Mixing and Stirring

[0034] 20.0 g of the aluminum powder was added to 500 mL of deionized water and stirred for 1 hour to form a stable suspension. Then, 50 mL of iodine solution was added to the suspension. The reaction system was placed in a temperature-controlled heating mantle and heated to 80±1°C, where it was continuously stirred to carry out the reaction.

[0035] The reaction lasted for about two weeks until the aluminum powder reacted completely. The reaction system turned into a milky white suspension and exhibited a significant Tyndall effect when stirred, indicating that a reaction product containing ultrathin hexagonal aluminum hydroxide nanosheets was generated.

[0036] S3, Post-processing

[0037] After the reaction was complete, the resulting suspension was allowed to cool naturally to room temperature. The cooled suspension was then centrifuged to collect the precipitate. The precipitate was washed four times with 95% ethanol solution (each wash volume was the same as the original precipitate volume) to remove impurities.

[0038] The washed product was placed in a drying oven and dried at 90°C for 24 hours to finally obtain white ultrathin hexagonal aluminum hydroxide Al(OH)3 nanosheet powder.

[0039] Characterization showed that the obtained nanosheets were complete hexagons with a side length of about 500 nm and a thickness of about 2 nm. The XRD pattern was consistent with the standard card, and the yield was 86-87%.

[0040] Transmission electron microscopy (TEM) images of the ultrathin hexagonal aluminum hydroxide nanosheets prepared above are shown below. Figure 1 , 2 As shown, the aluminum hydroxide nanosheets of this invention exhibit high dispersibility and possess a complete, regular hexagonal sheet structure. The average side length of the aluminum hydroxide nanosheets ranges from 400 to 600 nm. The thickness of the aluminum hydroxide nanosheets ranges from 1 to 20 nm.

[0041] Figure 3 These are selected area electron diffraction (TEM) images of the ultrathin hexagonal aluminum hydroxide nanosheets prepared above. Figure 4 The image shows the X-ray diffraction (XRD) pattern of the ultrathin hexagonal aluminum hydroxide nanosheets prepared above. Figure 3 and Figure 4 The spectral data confirm that the aluminum hydroxide nanosheets of this invention are crystalline and have an α-phase gibbsite crystal structure (JCPDS # No. 76-1782).

[0042] Example 2

[0043] This embodiment provides a method for preparing ultrathin hexagonal aluminum hydroxide nanosheets, specifically following the steps described in the technical solution: S1. Preparation of precursor solution Aluminum source: Uncoated aluminum powder with a purity >99% is used.

[0044] Solvent: Prepare 750 ml of an aqueous solution of ethanol as the solvent, with a mass concentration of 7%.

[0045] Oxidizing agent: Prepare an ethanol solution of bromine as the oxidizing agent. Specifically, dissolve 0.5 mL of bromine in 50 mL of ethanol to obtain a 50 mL bromine solution.

[0046] S2, Mixing and Stirring

[0047] 20.0 g of the aluminum powder was added to 750 mL of deionized water and stirred for 1 hour to form a stable suspension. Then, 50 mL of the bromine solution was added to the suspension. The reaction system was placed in a temperature-controlled heating mantle and heated to 70 ± 1°C, where it was continuously stirred to carry out the reaction.

[0048] The reaction continued for at least two weeks until the reaction system turned into a milky white suspension and exhibited a significant Tyndall effect when stirred, indicating the formation of a reaction product containing ultrathin hexagonal aluminum hydroxide nanosheets.

[0049] S3, Post-processing

[0050] After the reaction was complete, the resulting suspension was allowed to cool naturally to room temperature. The cooled suspension was then centrifuged to collect the precipitate. The precipitate was washed four times with 95% ethanol solution by centrifugation to remove impurities. The washed product was placed in a drying oven and dried at 90°C for 24 hours to obtain white, ultrathin hexagonal aluminum hydroxide Al(OH)3 nanosheet powder.

[0051] Characterization revealed that the obtained nanosheets were complete hexagons with a side length of approximately 450 nm and a thickness of approximately 2 nm. The XRD pattern was consistent with the standard card, and the yield reached 72-74%.

[0052] Example 3

[0053] This embodiment provides a method for preparing ultrathin hexagonal aluminum hydroxide nanosheets, specifically following the steps described in the technical solution: S1. Preparation of precursor solution Aluminum source: Uncoated aluminum powder with a purity >99% is used.

[0054] Solvent: Prepare 500 ml of an aqueous solution of ethanol as the solvent, with a mass concentration of 10%.

[0055] Oxidizing agent: A combination of iodine and hydrogen peroxide is used as the oxidizing agent. The iodine solution is prepared by dissolving 5.0 g of iodine crystals in 50 mL of 95% ethanol solution; separately, 10 mL of hydrogen peroxide (H2O2) is prepared.

[0056] S2, Mixing and Stirring

[0057] 40.0 g of the aluminum powder was added to 500 mL of deionized water and stirred for 1 hour to form a stable suspension. Then, 50 mL of the iodine solution and 10 mL of hydrogen peroxide were added sequentially to the suspension. The reaction system was placed in a temperature-controlled heating mantle and heated to 50 ± 1°C, where stirring was continued continuously to carry out the reaction.

[0058] The reaction lasted for about 100 hours until the aluminum powder reacted completely. The reaction system turned into a milky white suspension and exhibited a significant Tyndall effect when stirred, indicating that a reaction product containing ultrathin hexagonal aluminum hydroxide nanosheets was generated.

[0059] S3, Post-processing

[0060] After the reaction was complete, the resulting suspension was allowed to cool naturally to room temperature. The cooled suspension was then centrifuged to collect the precipitate. The precipitate was washed four times with 95% ethanol solution (each wash volume was the same as the original precipitate volume) to remove impurities.

[0061] The washed product was placed in a drying oven and dried at 90°C for 24 hours to finally obtain white ultrathin hexagonal aluminum hydroxide Al(OH)3 nanosheet powder.

[0062] Characterization revealed that the obtained nanosheets were complete hexagons with a side length of approximately 250 nm and a thickness of approximately 1 nm. The XRD pattern was consistent with the standard card, and the yield reached 76-78%.

[0063] Example 4

[0064] This embodiment provides a method for preparing ultrathin hexagonal aluminum hydroxide nanosheets, specifically following the steps described in the technical solution: S1. Preparation of precursor solution Aluminum source: Uncoated aluminum powder with a purity >99% is used.

[0065] Solvent: Prepare 500 ml of an aqueous solution of ethanol as the solvent, with a mass concentration of 7%.

[0066] Oxidizing agent: Hydrogen peroxide (H2O2) is used as the oxidizing agent. In this example, 20 mL of hydrogen peroxide is used.

[0067] S2, Mixing and Stirring

[0068] 20.0 g of the aluminum powder was added to 500 mL of deionized water and stirred for 1 hour to form a stable suspension. Then, 20 mL of the hydrogen peroxide was added to the suspension. The reaction system was placed in a temperature-controlled heating mantle and heated to 50 ± 1°C, where it was continuously stirred to carry out the reaction.

[0069] The reaction continued for at least two weeks until the reaction system turned into a milky white suspension and exhibited a significant Tyndall effect when stirred, indicating the formation of a reaction product containing ultrathin hexagonal aluminum hydroxide nanosheets.

[0070] S3, Post-processing

[0071] After the reaction was complete, the resulting suspension was allowed to cool naturally to room temperature. The cooled suspension was then centrifuged to collect the precipitate. The precipitate was washed four times with 95% ethanol solution (each wash volume was the same as the original precipitate volume) to remove impurities.

[0072] The washed product was placed in a drying oven and dried at 60°C for 24 hours to finally obtain white ultrathin hexagonal aluminum hydroxide Al(OH)3 nanosheet powder.

[0073] Characterization revealed that the obtained nanosheets were complete hexagons with a side length of approximately 250 nm and a thickness of approximately 1 nm. The XRD pattern was consistent with the standard card, and the yield reached 86-87%.

[0074] Example 5

[0075] This embodiment provides a method for preparing ultrathin hexagonal aluminum hydroxide nanosheets. The specific steps are the same as in Example 1, except that aluminum shavings are used as the aluminum source. The aluminum shavings are small fragments or powders produced by machining aluminum or aluminum alloys. The mass content of each main component is as follows: aluminum 82%, magnesium 14%, manganese 3%, copper 0.4%, and other metals and impurities.

[0076] Characterization revealed that the obtained nanosheets were complete hexagons (and Figure 1 , Figure 2 (Similar), with a side length of about 200~800 nm and a thickness of about 5~20 nm, the XRD pattern is consistent with the standard card, and the yield reaches 85%.

[0077] Example 6

[0078] This embodiment provides a method for preparing ultrathin hexagonal aluminum hydroxide nanosheets. The specific steps are the same as in Example 1, except that aluminum ash containing aluminum is used as the aluminum source. The aluminum ash is a solid waste generated during the aluminum industry production process, which comes from the slag floating on the surface of the aluminum melt in the smelting process of electrolytic aluminum, cast aluminum, or recycled aluminum. The mass content of each main component is as follows: aluminum 61%, aluminum oxide 22%, aluminum nitride 6%, salts (such as NaCl, KCl, etc.) 1%.

[0079] Characterization revealed that the obtained nanosheets were complete hexagons (and Figure 1 , Figure 2 (Similar), with a side length of about 500~800 nm and a thickness of about 50 nm, the XRD pattern is consistent with the standard card, and the yield reaches 45%.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing aluminum hydroxide, for comparison with the technical solution of this invention. The specific steps are as follows: S1. Preparation of precursor solution Aluminum source: Uncoated aluminum powder with a purity >99% is used.

[0082] Solvent: An aqueous solution of ethanol was prepared as the solvent. Specifically, 500 mL of deionized water was used in this comparative example.

[0083] Oxidizing agent: An ethanol solution of iodine is prepared as the oxidizing agent. Specifically, 5.0 g of iodine crystals are dissolved in 50 mL of 95% ethanol solution to obtain 50 mL of iodine solution.

[0084] S2, Mixing and Stirring

[0085] 25.0 g of the aluminum powder was added to 500 mL of deionized water and stirred for 1 hour to form a stable suspension. Subsequently, 50 mL of the iodine solution was added to the suspension.

[0086] The reaction system was placed in a temperature-controlled heating mantle and heated to 50±1°C. The mixture was stirred continuously at this temperature to carry out the reaction. The reaction was stopped after 20 hours.

[0087] S3, Post-processing

[0088] After the reaction was completed, the resulting suspension was centrifuged to collect the precipitate. The precipitate was then washed four times with 95% ethanol solution by centrifugation (each wash volume was the same as the original precipitate volume).

[0089] The washed product was placed in a drying oven and dried at 90°C for 24 hours to obtain a powder.

[0090] Characterization results showed that the aluminum hydroxide nanosheets prepared above were as follows: Figure 5 As shown in the results, the aluminum powder in the obtained powder was not completely oxidized, and pure-phase, crystalline aluminum hydroxide nanosheets could not be successfully obtained.

[0091] Comparative Example 2

[0092] This comparative example provides another method for preparing aluminum hydroxide, for comparison with the technical solution of this invention. The specific steps are as follows: S1. Preparation of precursor solution Aluminum source: Uncoated aluminum powder with a purity >99% is used.

[0093] Solvent: An aqueous solution of ethanol was prepared as the solvent. Specifically, 500 mL of deionized water was used in this comparative example.

[0094] Oxidizing agent: Hydrogen peroxide (H2O2) was used as the oxidizing agent. Specifically, 50 mL of hydrogen peroxide was used in this comparative example.

[0095] S2, Mixing and Stirring

[0096] 25.0 g of the aluminum powder was added to 500 mL of deionized water and stirred for 1 hour to form a suspension. Then, 50 mL of the hydrogen peroxide was added to the suspension. The reaction system was placed in a temperature-controlled heating mantle and heated to 50 ± 1°C, and the mixture was continuously stirred at this temperature to carry out the reaction. The reaction was stopped after 200 hours.

[0097] S3, Post-processing

[0098] After the reaction was completed, the resulting suspension was centrifuged to collect the precipitate. The precipitate was then washed four times with 95% ethanol solution by centrifugation (each wash volume was the same as the original precipitate volume).

[0099] The washed product was placed in a drying oven and dried at 90°C for 24 hours to obtain a powder.

[0100] Characterization results showed that the aluminum hydroxide nanosheets prepared above were as follows: Figure 6 As shown in the results, the morphology of the product obtained in this comparative example is irregular aluminum hydroxide particles.

[0101] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. A method for preparing ultrathin hexagonal aluminum hydroxide nanosheets, characterized in that, Includes the following steps: S1. Preparation of precursor solution: aluminum powder, aluminum shavings or aluminum ash are used as aluminum source, aqueous solution of ethanol is used as solvent, and at least one of bromine, iodine or hydrogen peroxide is used as oxidant. S2. Mixing and stirring: Add the aluminum powder, aluminum chips or aluminum ash to the aqueous solution of the ethanol and stir to form a suspension. Then add the oxidant and continue stirring at a temperature of 50~90°C until the reaction system becomes a milky white suspension and the Tyndall effect appears, to obtain a reaction product containing ultrathin hexagonal aluminum hydroxide nanosheets. S3. Post-processing: The reaction product obtained in step S2 is cooled and then centrifuged, washed and dried in sequence to obtain the ultrathin hexagonal aluminum hydroxide nanosheet powder.

2. The preparation method according to claim 1, characterized in that, In step S1, the aluminum powder is industrial-grade aluminum powder or uncoated high-purity aluminum powder with a purity greater than 99%; the aluminum shavings are small fragments or powders generated during the machining process of aluminum or aluminum alloys, wherein the aluminum content is not less than 80%; the aluminum ash is solid waste generated during the aluminum industry production process, originating from slag floating on the surface of molten aluminum in the smelting process of electrolytic aluminum, cast aluminum, or recycled aluminum, and has an aluminum content of 15-80%.

3. The preparation method according to claim 1, characterized in that, In step S1, the oxidant is an ethanol solution of iodine, and the mass concentration of iodine is 1% to 10%.

4. The preparation method according to claim 1, characterized in that, In step S1, the oxidant is an ethanol solution of bromine, and the mass concentration of bromine is 1% to 10%.

5. The preparation method according to claim 1, characterized in that, In step S1, the oxidant is hydrogen peroxide or a combination of iodine and hydrogen peroxide.

6. The preparation method according to claim 1, characterized in that, In step S1, the ethanol in the aqueous solution has a mass concentration of 5% to 10%.

7. The preparation method according to claim 1, characterized in that, In step S2, the reaction temperature is 50~90 °C, and the reaction time continues until the aluminum powder is completely consumed.

8. The preparation method according to claim 1, characterized in that, In step S3, the washing process involves multiple centrifugal washes using water, ethanol, or a mixture of both.

9. The preparation method according to claim 1, characterized in that, In step S3, the drying temperature is 60~90°C.

10. The ultrathin hexagonal aluminum hydroxide nanosheets prepared by the method according to any one of claims 1-9, characterized in that, The nanosheets have a complete hexagonal morphology with a side length between 50 nm and 1000 nm and a thickness between 1 nm and 50 nm.

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