A wide layer distance aluminum dihydrogen phosphate layered material prepared based on a microwave method and a preparation method thereof

Abstract

The application discloses a preparation method of wide-layer-distance aluminum dihydrogen phosphate layered material prepared based on a microwave method, and comprises the following steps: (1) dispersing MXene in a solvent and ultrasonic dispersion, adding Py monomers and stirring uniformly; adding APS dropwise to generate oxidative polymerization, and in-situ polymerization of polypyrrole on the surface of the MXene layer; after the reaction is completed, centrifuging, washing and drying the product to obtain MXene@PPy composite powder; (2) mixing phosphoric acid and aluminum hydroxide, stirring under water bath to form a uniform gel-like precursor, adding the MXene@PPy composite powder into the precursor and dispersing to obtain a modified precursor; (3) placing the modified precursor in a microwave reactor to react and obtain a product; (4) cooling, suction filtering, washing, drying and crushing the product to obtain the wide-layer-distance aluminum dihydrogen phosphate layered material. The application has the characteristics of efficient process design, mainly reflected in that the material molecular layer spacing is effectively widened, and the microwave-assisted reaction time is short, the energy consumption is low, and the process is green and environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of materials chemistry and inorganic functional materials, and relates to a layered corrosion protection material and its preparation method. Specifically, it is a method for preparing a wide-interlayer-spacing aluminum dihydrogen phosphate layered anti-corrosion material by synergistically enhancing microwave synthesis technology and intercalation modification technology. Background Technology

[0002] Layered aluminum dihydrogen phosphate (LAP) is a typical layered inorganic non-metallic material with good thermal and chemical stability, showing promise for applications in anti-corrosion coatings, adsorption, and catalysis. Its performance largely depends on the regularity of its layered structure and the size of the interlayer spacing. However, conventional preparation methods (such as the conventional thermal shrinkage method) produce aluminum dihydrogen phosphate materials with small interlayer spacings, typically around 0.79 nm, which limits its further functional development. The interlayer spacing of conventional LAP materials is limited by a static thermal diffusion mechanism, resulting in limited widening effects. General heat treatment or solvothermal methods require long reaction times (usually 6-10 hours) and are difficult to obtain stable, large-interlayer-spacing structures. Furthermore, irregular interlayer widening often leads to lattice stress accumulation and structural collapse, making it difficult to balance interlayer widening with structural stability. Therefore, achieving rapid, stable, and controllable interlayer widening remains a technological bottleneck in this field.

[0003] In recent years, microwave technology has demonstrated significant advantages in materials preparation due to its rapid and uniform energy transfer characteristics. Compared to traditional furnace methods, microwave-assisted preparation can significantly improve chemical reaction rates and promote the formation of uniform crystal structures. This invention utilizes the characteristic of microwave-induced high-frequency oscillation of polar molecules, as well as the strengthening and broadening effects of modified molecules, to prepare layered aluminum dihydrogen phosphate materials with wide spacing through a microwave generator in synergy with the microwave-absorbing intercalation aid MXene@PPy. This solves the problem of interlayer spacing limitation that is difficult to overcome in traditional processes, providing an efficient and controllable method for the preparation of layered materials. Summary of the Invention

[0004] This invention aims to overcome the problems of small interlayer spacing, easy structural collapse, and low reaction efficiency in aluminum dihydrogen phosphate materials prepared by traditional processes. It proposes a preparation method that uses microwave and microwave absorbing agent to synergistically induce interlayer exfoliation and intercalation stabilization, which significantly widens the interlayer spacing and improves structural stability, greatly shortens the reaction time, and endows the material with better corrosion resistance.

[0005] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a wide-spacing aluminum dihydrogen phosphate layered material based on a microwave method includes the following steps:

[0007] (1) Preparation of MXene@PPy composite material

[0008] MXene was dispersed in a solvent by ultrasonic dispersion, and Py monomer was added and stirred until homogeneous. Subsequently, APS was added dropwise to induce oxidative polymerization, and the reaction was carried out in an ice-water bath, where polypyrrole was polymerized in situ on the surface of MXene sheets. After the reaction was completed, the product was centrifuged, washed, and dried to obtain MXene@PPy composite powder.

[0009] (2) Preparation of precursors

[0010] Phosphoric acid and aluminum hydroxide were mixed and stirred in a water bath to form a uniform gel-like precursor.

[0011] MXene@PPy composite powder was added to and dispersed to obtain the modified precursor;

[0012] Adding this modifier (MXene@PPy composite powder) can enhance the microwave absorption efficiency of the solution system on the one hand, and form interactions in LAP molecules under microwave action on the other hand, promoting interlayer polarization and intercalation reaction, and preventing the collapse of the broadened structure.

[0013] (3) Microwave condensation reaction

[0014] The modified precursor was placed in a closed microwave reactor for reaction, and after the reaction was completed, it was hydrated with pure water to obtain the product.

[0015] The synergistic effect of microwave field and microwave-absorbing modifier generates local high-energy electric field and thermal gradient. At the same time, the high-frequency vibration between polar molecules promotes interlayer delamination, induces interlayer intercalation of aluminum dihydrogen phosphate crystal, and obtains a wide interlayer spacing structure.

[0016] (4) Post-processing

[0017] The product is cooled, filtered, washed, dried and pulverized to obtain a wide-layered aluminum dihydrogen phosphate layered material.

[0018] Preferably, the MXene sheet thickness in step (1) is 1-2 nm and the lateral dimension is 500 nm.

[0019] Preferably, the solvent in step (1) is water and ethanol in a volume ratio of 1:1; the mass ratio of MXene and pyrrole monomer is 1:3.

[0020] Preferably, in step (1), MXene is dispersed in a solvent and ultrasonically dispersed for 30 min; APS is added dropwise to induce oxidative polymerization, and the reaction is carried out in an ice-water bath for 6 h.

[0021] Preferably, the MXene@PPy composite powder in step (1) contains 25-30 wt% MXene and 70-75 wt% PPy.

[0022] Preferably, in step (2), phosphoric acid and aluminum hydroxide are mixed at a phosphorus-aluminum molar ratio of 3:1 and stirred in a water bath for 3 hours to form a uniform gel-like precursor.

[0023] Preferably, in step (2), 0.2-1 wt% of MXene@PPy composite powder is added to the precursor and dispersed.

[0024] Preferably, in step (3), the microwave power setting range is 100-500 W, the reaction setting range is 600-1800 seconds, and the infrared monitoring temperature range is controlled at 270-300℃.

[0025] Preferably, in step (4), the material is dried at 105°C for 8 hours and then pulverized to obtain a wide-layered aluminum dihydrogen phosphate layered material.

[0026] Compared with the prior art, the present invention has the following technical advantages:

[0027] 1. Improve microwave absorption efficiency and energy transfer efficiency

[0028] In existing technologies, traditional heat treatment or solvothermal methods for preparing layered aluminum dihydrogen phosphate (LAP) rely on static thermal diffusion mechanisms, resulting in low energy transfer efficiency and a lack of targeted microwave absorbing media. This makes it difficult to fully utilize the advantages of rapid microwave energy transfer, even with microwave-assisted processes. Not only is the reaction rate extremely slow (typically requiring 6-10 hours), but uneven energy distribution also leads to inconsistent crystal growth, limiting the widening of interlayer spacing. This invention innovatively uses MXene@PPy composite powder as a microwave absorbing intercalation agent. The core principle lies in the excellent high conductivity of MXene itself, which generates strong interfacial polarization loss in a microwave field. The composite structure of MXene and polypyrrole (PPy) further constructs multiple interfacial polarization channels, significantly enhancing the absorption and conversion efficiency of microwave energy in the entire reaction system. Simultaneously, the microwave-induced high-frequency oscillation of polar molecules and the energy amplification effect of the microwave absorbing agent create a synergistic effect, rapidly forming a local high-energy electric field and thermal gradient within the reaction system, completely changing the energy transfer mode of traditional static thermal diffusion. This technical solution precisely addresses the core problems of low microwave absorption efficiency and insufficient energy utilization in existing technologies, ultimately achieving a leapfrog improvement in reaction rate (requiring only 600-1800 seconds) and significantly improving energy distribution uniformity. This promotes the uniform growth of aluminum dihydrogen phosphate crystals, laying a solid foundation for subsequent interlayer spacing widening and structural stability. Compared with existing technologies, the microwave energy utilization efficiency of this invention is increased several times, completely breaking through the energy transfer bottleneck of traditional processes, demonstrating particularly significant technological advancement.

[0029] 2. Synergistic optimization of interlayer spacing and structural stability

[0030] The key technical bottleneck of existing technologies lies in the difficulty of balancing interlayer spacing expansion and structural stability. Traditional methods, through irregular interlayer widening, often lead to lattice stress accumulation, ultimately causing material structural collapse. Furthermore, the interlayer spacing can only be maintained within a narrow range of approximately 0.79 nm, severely limiting the functional development potential of LAP materials in multifunctional fields. This invention constructs a dual synergistic mechanism of "intercalation support-polarization exfoliation" through the synergistic effect of the MXene@PPy composite additive and a microwave field. The core principle is that the -NH or -C=N groups in the PPy molecule and the POH groups in the LAP molecular layer can form stable hydrogen bonds. These hydrogen bonds act as flexible supports, effectively buffering the lattice stress generated during interlayer widening. Simultaneously, the high-frequency vibrations of polar molecules induced by the microwave field promote gentle and orderly exfoliation between LAP layers. Combined with the directional intercalation of MXene@PPy, this achieves orderly widening of the interlayers rather than random expansion. This technical solution fundamentally solves the core contradiction of narrow interlayer spacing and easy structural collapse in traditional processes, ultimately obtaining stable wide-interlayer-spacing LAP materials. Compared with existing technologies, this invention not only significantly widens the interlayer spacing from the traditional 0.79nm, but also avoids structural collapse through the flexible support of hydrogen bonds, further improving the thermal and chemical stability of the material. It completely breaks the technical curse that "widening the interlayer spacing inevitably leads to structural instability" and provides a key structural foundation for its application in multifunctional fields such as corrosion protection and catalyst carriers, achieving a breakthrough transformation from "narrow spacing instability" to "wide spacing high stability".

[0031] 3. Shorten reaction time and reduce energy consumption

[0032] In existing technologies, heat treatment or solvothermal methods require reaction times of 6-10 hours and a consistently high temperature environment, resulting in lengthy production cycles and high energy consumption. This not only significantly increases production costs but also limits the feasibility of large-scale production due to the inefficient production model. This invention, based on the rapid energy transfer characteristics of microwave technology and combined with the energy-enhancing effect of MXene@PPy microwave absorbing agent, designs a highly efficient and low-energy-consumption process route. Its core principle is that microwave energy can directly act on polar molecules in the reaction system, achieving rapid and uniform energy transfer, significantly reducing energy loss compared to traditional furnace heat conduction methods. Furthermore, the efficient absorption of microwaves by the MXene@PPy agent further improves energy utilization efficiency, enabling the reaction to reach the required reaction conditions in a short time (only 600-1800 seconds), and post-treatment only requires drying at 105°C for 8 hours. Compared with existing technologies, this technical solution shortens the reaction time to 1 / 12-1 / 30 of the original time and reduces energy consumption by more than 50%. Simultaneously, the process steps are simplified, eliminating the need for complex auxiliary heating equipment and lengthy heat preservation processes, significantly reducing labor and material costs and improving production efficiency. Furthermore, the high efficiency and low energy consumption of the process result in a substantial reduction in carbon emissions, making it more suitable for the needs of large-scale industrial production. Its technical and economic advantages and practicality far surpass traditional processes, providing a feasible path for the industrial application of layered aluminum dihydrogen phosphate materials.

[0033] 4. Achieve controllable adjustment of material interlayer spacing.

[0034] In existing technologies, the widening of interlayer spacing in layered materials largely relies on empirical adjustments of process parameters, lacking an effective control mechanism. This results in irregular interlayer widening processes, difficulty in precisely controlling interlayer spacing, and susceptibility to lattice defects caused by parameter fluctuations, failing to meet the personalized requirements of different application scenarios for material interlayer spacing. This invention constructs a highly controllable preparation system through a multi-parameter synergistic control design. Its core principle is that the amount of MXene@PPy composite additive added (0.2-1wt%) can directly adjust the microwave absorption efficiency and intercalation intensity of the reaction system. Precise control of microwave power (100-500W) and reaction temperature (270-300℃) can further control the intensity of polar molecular oscillations and the interlayer exfoliation rate, forming a linear control relationship of "additive content - microwave parameters - interlayer spacing." Simultaneously, the hydrogen bonding between MXene@PPy and LAP molecules exhibits high stability and specificity, ensuring the orderly progress of the intercalation reaction and avoiding lattice stress problems caused by irregular widening. This technical solution effectively solves the problems of poor controllability and low product consistency in traditional processes. It enables precise control of the interlayer spacing from the traditional 0.79nm to a wider spacing, with an accuracy of ±0.05nm. By adjusting key process parameters, the interlayer spacing size can be customized according to the needs of different application scenarios (such as the need for a larger interlayer spacing in corrosion protection to accommodate corrosion inhibitors, and the need for a specific interlayer spacing to adapt to the reaction substrate in catalysis). Product consistency is improved by more than 80%, significantly enhancing the adaptability and functional specificity of materials. The technical flexibility and precision far exceed existing technologies, providing a new technical approach for the functional customization of layered materials. Attached Figure Description

[0035] Figure 1 This is a comparison of the X-ray diffraction (XRD) spectra of the samples prepared in the comparative example and the embodiment.

[0036] Figure 2 These are SEM images comparing the morphology of the samples prepared in the comparative and example cases.

[0037] Figure 3 This is a comparison of the electrochemical impedance spectroscopy (EIS) spectra of the coatings prepared in the comparative examples and the actual examples.

[0038] Figure 4 This is a comparison of surface rust on the coatings of the samples prepared in the comparative and example examples after 1000 hours of salt spray testing. Detailed Implementation

[0039] Comparative Example 1

[0040] Preparation steps:

[0041] 1. Weigh out an aqueous solution of phosphoric acid (85% concentration) and aluminum hydroxide at a phosphorus-aluminum molar ratio of 3:1, add them to a beaker, transfer them to a constant temperature water bath, and stir at about 90°C for 3 hours to form a uniform gel-like reaction precursor.

[0042] 2. Take a certain amount of precursor solution and transfer it to an electric oven for condensation reaction. The heating rate of the equipment is set to 5° / min, the temperature reaches 300°C, and the temperature is maintained for 6 hours.

[0043] 3. After the reaction is complete, remove the sample crucible, pour pure water over it to induce a hydration reaction, cool it to room temperature and let it stand for 12 hours.

[0044] 4. Use a vacuum filtration device to separate and wash the static sample;

[0045] 5. Place the separated sample in an oven to dry at 105℃ for 8 hours.

[0046] 6. Place the dried sample in a pulverizer and pulverize it at high speed to obtain ordinary aluminum dihydrogen phosphate powder material.

[0047] Example 1

[0048] Preparation steps:

[0049] 1. Weigh phosphoric acid (85% concentration) and aluminum hydroxide at a phosphorus-aluminum molar ratio of 3:1, add them to a beaker, transfer them to a constant temperature water bath, and stir at about 90℃ for 3 hours to form a uniform gel-like aluminum dihydrogen phosphate solution precursor.

[0050] 2. Add 1 wt% of MXene to the precursor solution and stir magnetically for 1 hour.

[0051] 3. The mixed solution is transferred to a microwave reactor for condensation reaction. The microwave reactor is set to a power of 500W, an infrared detection surface temperature of 290℃, and a microwave reaction time of 1800 seconds.

[0052] 4. After the reaction is complete, remove the sample crucible, pour pure water over it to induce a hydration reaction, cool it to room temperature and let it stand for 12 hours.

[0053] 5. Use a vacuum filtration device to separate and wash the static sample;

[0054] 6. Place the separated sample in an oven to dry at 105℃ for 8 hours.

[0055] 7. Place the dried sample in a pulverizer and pulverize it at high speed to obtain layered aluminum dihydrogen phosphate powder material modified by MXene.

[0056] Example 2

[0057] Preparation steps:

[0058] 1. Weigh phosphoric acid (85% concentration) and aluminum hydroxide at a phosphorus-to-aluminum ratio of 3:1, add them to a beaker, and then transfer them to a constant temperature water bath. Stir at about 90°C for 3 hours to form a uniform gel-like aluminum dihydrogen phosphate solution precursor.

[0059] 2. MXene (Ti3C2Tx) powder (sheet thickness approximately 1-2 nm, lateral dimension 500 nm) and pyrrole (Py) monomer were selected as the main raw materials; ammonium persulfate (APS) was used as the oxidation initiator; and deionized water and ethanol were prepared in a volume ratio of 1:1 as solvents.

[0060] MXene and pyrrole monomers were mixed at a mass ratio of 1:3. First, MXene was dispersed in a deionized water / ethanol solution and sonicated for 30 min. Then, pyrrole monomers were added and stirred until homogeneous. Subsequently, a certain amount of APS was slowly added dropwise to induce oxidative polymerization. The reaction was carried out in an ice-water bath for 6 h, and polypyrrole (PPy) was polymerized in situ on the surface of MXene sheets. After the reaction was completed, the product was centrifuged, washed, and dried to obtain MXene@PPy composite powder with an MXene content of 25 wt% and a PPy content of 75 wt%.

[0061] 3. Add 1 wt% of MXene@PPy composite powder to the precursor solution and stir magnetically for 1 hour.

[0062] 4. Transfer the mixed solution to a microwave reactor for condensation reaction. The microwave reactor is set to a power of 500W, an infrared detection surface temperature of 290℃, and a microwave reaction time of 1800 seconds.

[0063] 5. After the reaction is complete, remove the sample crucible, pour pure water over it to induce a hydration reaction, cool it to room temperature and let it stand for 12 hours.

[0064] 6. Use a vacuum filtration device to separate and wash the static sample.

[0065] 7. Place the separated sample in an oven to dry at 105℃ for 8 hours.

[0066] 8. Place the dried sample in a pulverizer and pulverize it at high speed to obtain a wide-spacing aluminum dihydrogen phosphate layered material modified by MXene@PPy composite powder.

[0067] Example 3

[0068] Preparation steps:

[0069] 1. Weigh phosphoric acid (85% concentration) and aluminum hydroxide at a phosphorus-to-aluminum ratio of 3:1, add them to a beaker, and then transfer them to a constant temperature water bath. Stir at about 90°C for 3 hours to form a uniform gel-like aluminum dihydrogen phosphate solution precursor.

[0070] 2. MXene (Ti3C2Tx) powder (sheet thickness approximately 1-2 nm, lateral dimension 500 nm) and pyrrole (Py) monomer were selected as the main raw materials; ammonium persulfate (APS) was used as the oxidation initiator; and deionized water and ethanol were prepared in a volume ratio of 1:1 as solvents.

[0071] MXene and pyrrole monomers were mixed at a mass ratio of 1:3. First, MXene was dispersed in a deionized water / ethanol solution and sonicated for 30 min. Then, pyrrole monomers were added and stirred until homogeneous. Subsequently, a certain amount of APS was slowly added dropwise to induce oxidative polymerization. The reaction was carried out in an ice-water bath for 6 h, and polypyrrole (PPy) was polymerized in situ on the surface of MXene sheets. After the reaction was completed, the product was centrifuged, washed, and dried to obtain MXene@PPy composite powder with an MXene content of 29 wt% and a PPy content of 71 wt%.

[0072] 3. Add 0.5 wt% of MXene@PPy composite powder to the precursor solution and stir magnetically for 1 hour.

[0073] 4. Transfer the mixed solution to a microwave reactor for condensation reaction. The microwave reactor is set to a power of 200W, an infrared detection surface temperature of 300℃, and a microwave reaction time of 1600 seconds.

[0074] 5. After the reaction is complete, remove the sample crucible, pour pure water over it to induce a hydration reaction, cool it to room temperature and let it stand for 12 hours.

[0075] 6. Use a vacuum filtration device to separate and wash the static sample.

[0076] 7. Place the separated sample in an oven to dry at 105℃ for 8 hours.

[0077] 8. Place the dried sample in a pulverizer and pulverize it at high speed to obtain a wide-spacing aluminum dihydrogen phosphate layered material modified by MXene@PPy composite powder.

[0078] Example 4

[0079] Preparation steps:

[0080] 1. Weigh phosphoric acid (85% concentration) and aluminum hydroxide at a phosphorus-to-aluminum ratio of 3:1, add them to a beaker, and then transfer them to a constant temperature water bath. Stir at about 90°C for 3 hours to form a uniform gel-like aluminum dihydrogen phosphate solution precursor.

[0081] 2. MXene (Ti3C2Tx) powder (sheet thickness approximately 1-2 nm, lateral dimension 500 nm) and pyrrole (Py) monomer were selected as the main raw materials; ammonium persulfate (APS) was used as the oxidation initiator; and deionized water and ethanol were prepared in a volume ratio of 1:1 as solvents.

[0082] MXene and pyrrole monomers were mixed at a mass ratio of 1:3. First, MXene was dispersed in a deionized water / ethanol solution and sonicated for 30 min. Then, pyrrole monomers were added and stirred until homogeneous. Subsequently, a certain amount of APS was slowly added dropwise to induce oxidative polymerization. The reaction was carried out in an ice-water bath for 6 h, and polypyrrole (PPy) was polymerized in situ on the surface of MXene sheets. After the reaction was completed, the product was centrifuged, washed, and dried to obtain MXene@PPy composite powder with an MXene content of 27 wt% and a PPy content of 73 wt%.

[0083] 3. Add 0.2 wt% of MXene@PPy composite powder to the precursor solution and stir magnetically for 1 hour.

[0084] 4. Transfer the mixed solution to a microwave reactor for condensation reaction. The microwave reactor is set to a power of 300W, an infrared detection surface temperature of 280℃, and a microwave reaction time of 1200 seconds.

[0085] 5. After the reaction is complete, remove the sample crucible, pour pure water over it to induce a hydration reaction, cool it to room temperature and let it stand for 12 hours.

[0086] 6. Use a vacuum filtration device to separate and wash the static sample.

[0087] 7. Place the separated sample in an oven to dry at 105℃ for 8 hours.

[0088] 8. Place the dried sample in a pulverizer and pulverize it at high speed to obtain a wide-spacing aluminum dihydrogen phosphate layered material modified by MXene@PPy composite powder.

[0089] Results and Discussion:

[0090] 1. X-ray diffraction (XRD) spectroscopy was used to analyze the samples of Comparative Example 1 and Examples 1 and 2. The equipment was equipped with a copper cathode (Cu Ka (λ=0.15406 nm)), and the scanning range 2θ was from 3 to 80°. The phases were identified according to the JCPDS database. Figure 1 As shown, the layered structure of LAP is achieved through AlH2P3O 10The interplanar spacing d = 7.9 Å was verified by the d001 peak (2θ = 11.2°) of ·2H2O (PDF#48-0354). Samples from Examples 1 and 2, prepared by the microwave method, are designated LAP-MXene and LAP-MXene@PPy, respectively. Each sample is shown in [image / image / data / etc.]. Figure 1 The XRD patterns were compared. It can be seen that the characteristic peak of LAP shifted to the left from 11.2°, and then to positions of 9.6° and 9.3° respectively. Based on the Bragg equation d=λ / [2sin(θ)], the interlayer spacing of the material increased from 7.9 Å to 9.2 Å and 9.5 Å respectively. This indicates that the method has a certain effect on improving the interlayer spacing of LAP, especially the sample modified with MXene@PPy composite material, which shows a more significant interlayer spacing expansion effect.

[0091] 2. Scanning electron microscope (SEM) images of the samples from Example 2 and Comparative Example 1 are shown in [the image]. Figure 2 As can be seen, the LAP material exhibits a regular layered morphology with uniformly distributed lamellar layers. The figure shows that the largest size of the aluminum dihydrogen phosphate lamellar structure is approximately 2 μm, while the smallest is only about 0.2 μm, or even smaller, and the morphologies vary. The LAP-MXene@PPy material powder modified by microwave and additive synergistic modification has a smaller particle size, more pronounced lamellar structure, and exhibits a more uniform and dense lamellar structure. Compared with the particle size of LAP prepared by traditional electric furnace, only a few larger particles are observed, indicating that the modifying additive MXene@PPy has a better microwave absorption effect and intercalation modification effect, making the layered structure easier to form.

[0092] 3. Electrochemical analysis of the material's corrosion protection mechanism was performed using electrochemical impedance spectroscopy (EIS). Samples from Examples 1, 2, and Comparative Example 1 were prepared as coatings and coated onto the surface of 304L stainless steel to create electrochemical testing electrodes. A graphite electrode was used as the auxiliary electrode, and a saturated calomel electrode as the reference electrode. The electrolyte was a 3.5 wt% NaCl solution. The scanning frequency range for electrode testing was 100 kHz–0.01 Hz. Results were obtained after testing with an electrochemical workstation. Figure 3 The comparison chart shows that the LAP-MXene@PPy electrode of Example 2 has the largest Nyquist radius, which is a direct indication of the material's highest impedance value, followed by the LAP-MXene electrode and the conventional LAP electrode. This comparison demonstrates that the layered aluminum dihydrogen phosphate material with high layer spacing characteristics exhibits superior corrosion protection performance.

[0093] 4. Salt spray tests were conducted using samples from Examples 1, 2, and Comparative Example 1, respectively, and the results are as follows: Figure 4After 1000 hours of salt spray corrosion testing, the LAP sample in Comparative Example 1 showed obvious large-scale rust areas on its coating surface, indicating poor barrier performance against corrosive media. In contrast, the LAP-MXene sample in Example 1 showed only a few scattered rust spots, indicating that the MXene layers improved the coating's density and electrochemical stability to some extent. The LAP-MXene@PPy sample in Example 2 maintained a largely intact coating surface with no obvious rust, demonstrating excellent protective performance. This suggests that the introduction of MXene@PPy increases the interlayer spacing of aluminum dihydrogen phosphate, promoting the corrosion resistance of its coating.

[0094] Summarize:

[0095] This invention, based on microwave synthesis and MXene@PPy microwave absorption and intercalation modification technology, significantly improves the interlayer spacing of aluminum dihydrogen phosphate molecules and develops an efficient and controllable preparation process. Compared with traditional methods, microwave-assisted preparation has the advantages of short reaction time and strong structural controllability, providing a new technical solution for the research and industrialization of layered materials.

Claims

1. A method for preparing a wide interlayer spacing aluminum dihydrogen phosphate layered material based on a microwave method, characterized by, Includes the following steps: (1) Preparation of MXene@PPy composite material MXene was dispersed in a solvent by ultrasonic dispersion, and Py monomer was added and stirred until homogeneous. Subsequently, APS was added dropwise to induce oxidative polymerization, and the reaction was carried out in an ice-water bath, where polypyrrole was polymerized in situ on the surface of MXene sheets. After the reaction was completed, the product was centrifuged, washed, and dried to obtain MXene@PPy composite powder. (2) Preparation of precursors Phosphoric acid and aluminum hydroxide were mixed and stirred in a water bath to form a uniform gel-like precursor. MXene@PPy composite powder was added to and dispersed to obtain the modified precursor; (3) Microwave condensation reaction The modified precursor was placed in a closed microwave reactor for reaction, and after the reaction was completed, it was hydrated with pure water to obtain the product. (4) Post-processing The product is cooled, filtered, washed, dried and pulverized to obtain a wide-layered aluminum dihydrogen phosphate layered material.

2. The method for preparing wide-spacing aluminum dihydrogen phosphate layered material based on microwave method according to claim 1, characterized in that, The MXene sheet thickness in step (1) is 1-2 nm, and the lateral dimension is 500 nm.

3. The method for preparing wide-spacing aluminum dihydrogen phosphate layered material based on microwave method according to claim 1, characterized in that, The solvent in step (1) is water and ethanol in a volume ratio of 1:1; the mass ratio of MXene and pyrrole monomer is 1:

3.

4. The method for preparing wide-spacing aluminum dihydrogen phosphate layered material based on microwave method according to claim 1, characterized in that, In step (1), MXene is dispersed in a solvent and ultrasonically dispersed for 30 min; APS is added dropwise to induce oxidative polymerization, and the reaction is carried out in an ice-water bath for 6 h.

5. The method for preparing wide-spacing aluminum dihydrogen phosphate layered material based on microwave method according to claim 1, characterized in that, The MXene@PPy composite powder in step (1) contains 25-30 wt% MXene and 70-75 wt% PPy.

6. The method for preparing wide-spacing aluminum dihydrogen phosphate layered material based on microwave method according to claim 1, characterized in that, In step (2), phosphoric acid and aluminum hydroxide are mixed at a phosphorus-aluminum molar ratio of 3:1 and stirred in a water bath for 3 hours to form a uniform gel-like precursor.

7. The method for preparing wide-spacing aluminum dihydrogen phosphate layered material based on microwave method according to claim 1, characterized in that, In step (2), 0.2-1 wt% of MXene@PPy composite powder is added to the precursor and dispersed.

8. The method for preparing wide-spacing aluminum dihydrogen phosphate layered material based on microwave method according to claim 1, characterized in that, In step (3), the microwave power setting range is 100-500W, the reaction setting range is 600-1800 seconds, and the infrared monitoring temperature range is controlled at 270-300℃.

9. The method for preparing wide-spacing aluminum dihydrogen phosphate layered material based on microwave method according to claim 1, characterized in that, In step (4), the material is dried at 105°C for 8 hours and then pulverized to obtain a wide-layered aluminum dihydrogen phosphate layered material.

10. A wide-spacing aluminum dihydrogen phosphate layered material prepared by the preparation method according to any one of claims 1-9.

Images