Two-dimensional layered semiconductor metal organic framework coating as well as preparation method and application thereof

Abstract

The invention discloses a two-dimensional layered semiconductor metal organic framework coating as well as a preparation method and application thereof, and belongs to the technical field of lightning protection adhesive films, the two-dimensional layered semiconductor metal organic framework coating is a two-dimensional layered CuHBT MOFs-based coating, the semiconductor metal organic framework material has a two-dimensional laminated microstructure, and the thickness of the two-dimensional layered CuHBT MOFs-based coating is 10-30 microns. The thickness of the single-layer two-dimensional sheet structure is 50-60 nm, and the sheet diameter is 0.5-5 [mu] m. The invention discloses a two-dimensional layered CuHBT MOFs-based coating which can realize electromagnetic attenuation performance without high-temperature pyrolysis treatment, and has excellent attenuation bandwidth, long-acting and stable performance and salt spray corrosion resistance, and a preparation method and application thereof.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor metal-organic framework coating technology, specifically relating to a two-dimensional layered semiconductor metal-organic framework coating, its preparation method, and its application. Background Technology

[0002] Metal-organic frameworks (MOFs) are a novel type of hybrid crystalline material formed by the self-assembly of metal ions (or clusters) and organic ligands. Referred to as a new family of nanoporous structures, they possess significant advantages such as large specific surface area, tunable structure and function, and abundant active sites, showing unique application prospects in many fields including gas separation and adsorption, electrocatalysis, and energy storage. However, the fact that most MOFs are insulators limits their application in electromagnetic attenuation. Many studies have employed high-temperature pyrolysis of MOF precursors to carbonize them, obtaining metal / carbon nanocomposites to modulate the conductivity and magnetic loss of MOFs, ultimately exhibiting excellent electromagnetic attenuation performance. However, the high-temperature pyrolysis process completely destroys the chemical composition and crystal structure of MOFs, making it difficult to meet practical application requirements.

[0003] Application number CN201910790685.7 discloses an ultrathin two-dimensional porous metal-organic framework nanosheet and its preparation method. It provides a two-dimensional porous metal-organic framework nanosheet, but due to its insulation, it cannot control the conductivity and magnetic loss. Due to its porous structure, it does not have the properties of insulation and corrosion protection.

[0004] Application number CN202010134392.6 discloses a composite foam made from ZIF-67 / melamine and its preparation method. It provides a method for preparing electromagnetic attenuation composite foam. The preparation process involves high-temperature annealing heat treatment. After heat treatment, the chemical composition and crystal structure of the metal-organic framework material are affected. Moreover, the metal-organic framework material does not have a large layer structure, but presents an amorphous particle structure. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a two-dimensional layered semiconductor metal-organic framework coating, its preparation method, and its application. This invention describes a two-dimensional layered CuHBT MOFs-based coating that achieves electromagnetic attenuation performance without high-temperature pyrolysis, and possesses excellent attenuation bandwidth, long-term stable performance, and resistance to salt spray corrosion.

[0006] The objective of this invention is achieved through the following technical solution: A two-dimensional layered semiconductor metal-organic framework coating is a two-dimensional layered CuHBT MOFs-based coating. The semiconductor metal-organic framework material has a two-dimensional stacked microstructure, with a single-layer two-dimensional sheet structure thickness of 50~60 nm and a sheet diameter of 0.5~5 μm.

[0007] A method for preparing a two-dimensional layered semiconductor metal-organic framework coating includes the following steps: Step 1: Disperse cuprous oxide in anhydrous ethanol until uniform, then add 4-hydroxybenzyl mercaptan to the solution at a constant rate; Step 2: Isolate the mixed solution from oxygen and heat and stir the reaction in a protective atmosphere until the reaction system changes from red to yellow, then stop the reaction; Step 3: Use high-speed centrifugation to separate the solution, remove the lower precipitate and wash it repeatedly with ethanol, and collect the yellow solid; Step 4: Vacuum dry the obtained sample to obtain the final sample; Step 5: Disperse a certain amount of CuHBT in ethanol by ultrasonic treatment, and add it to a certain amount of epoxy resin; Step 6: Add a certain amount of curing agent to the above system and stir continuously under vacuum to remove air bubbles; Step 7: Apply the mixture evenly to Q235 steel and allow it to dry and cure at room temperature.

[0008] Preferably, the concentration of the cuprous oxide ethanol solution in step one is 0.01~0.2 mmol / mL.

[0009] Preferably, the molar ratio of cuprous oxide to 4-hydroxybenzyl mercaptan in step one is 1:0.5 to 1:10.

[0010] Preferably, the heating temperature in step two is 60~80℃, and the heating time is 2~5 h.

[0011] Preferably, the stirring speed in step two is 500 rpm.

[0012] Preferably, the protective gas in step two is argon, helium, or nitrogen.

[0013] Preferably, in step three, the centrifugation speed is 10,000 rpm and the centrifugation time is 20 min.

[0014] Preferably, the drying temperature in step four is 60°C and the drying time is 12~16 h.

[0015] Preferably, in step five, the CuHBT filler ratio is 0.1~10 wt%, and the ultrasonic time is 15 min.

[0016] Preferably, in step six, the mass ratio of curing agent to epoxy resin is 1:2 to 1:7, and the stirring time is 30 min.

[0017] Preferably, the curing time in step seven is 72 hours.

[0018] Two-dimensional layered semiconductor metal-organic framework coatings are applied to electromagnetic attenuation fillers with corrosion resistance.

[0019] The beneficial effects of this technical solution are as follows: I. The present invention provides a two-dimensional layered semiconductor metal-organic framework coating. The two-dimensional layered CuHBT MOFs substrate-like stacked filler can induce electromagnetic waves to scatter and reflect between the two-dimensional structure layers, thereby enhancing impedance matching characteristics and electromagnetic attenuation capability. The vacancy effect and heteroatom structure of the semiconductor material can further enhance the dielectric loss capability of the material.

[0020] II. This invention provides a two-dimensional layered semiconductor metal-organic framework coating that combines electromagnetic attenuation and corrosion resistance. After immersion in a 3.5 wt% NaCl solution for 21 days, the material's impedance modulus remains as high as 4.406 × 10⁷ Ω·cm. 2 It boasts a protection efficiency of up to 92.88% and can achieve long-term stable electromagnetic attenuation.

[0021] III. The present invention provides a two-dimensional layered semiconductor metal-organic framework coating. The minimum reflection loss of the two-dimensional layered CuHBT MOFs-based filler reaches -53 dB when the thickness is 2.9 mm, while its maximum effective bandwidth is 8.80 GHz.

[0022] IV. The present invention provides a method for preparing a two-dimensional layered semiconductor metal-organic framework coating, which avoids the high-temperature pyrolysis preparation process and protects the relatively complete chemical composition and crystal structure of the product; the two-dimensional layered structure can effectively inhibit the diffusion of corrosion ions and can form an effective and stable protective layer through complexation, thereby realizing the anti-corrosion function of the material and improving the stability of the coating in use. Attached Figure Description

[0023] Figure 1 These are schematic diagrams of the microstructure of the two-dimensional layered metal-organic framework materials obtained in Examples 1-4 of the present invention; wherein: Figure a is a microscopic SEM image of Example 1, Figure b is a microscopic SEM image of Example 2, Figure c is a microscopic SEM image of Example 3, Figure d is a microscopic SEM image of Example 4, and Figures e-i are EDS elemental distribution maps of Example 2.

[0024] Figure 2Figure 1 shows a schematic diagram of the structural characterization of the two-dimensional layered metal-organic framework materials obtained in Examples 1-4 of this invention; wherein: Figure a is the infrared spectrum obtained in Examples 1-4, Figure b is the XRD diffraction pattern obtained in Examples 1-4, Figure c is the XPS elemental analysis spectrum obtained in Example 2, Figure d is the C 1s high-resolution spectrum of Example 2, Figure e is the O 1s high-resolution spectrum of Example 2, Figure f is the Cu 2p high-resolution spectrum of Example 2, and Figure g is the S 2p high-resolution spectrum of Example 2.

[0025] Figure 3 Figure 1 shows the electromagnetic parameters of the two-dimensional layered metal-organic framework materials obtained in Examples 1-4; wherein: Figure a shows the real part of the complex dielectric constant when the metal-organic framework filler ratio is 30 wt% in Examples 1-4; Figure b shows the imaginary part of the complex dielectric constant when the metal-organic framework filler ratio is 30 wt% in Examples 1-4; Figure c shows the dielectric loss tangent when the metal-organic framework filler ratio is 30 wt% in Examples 1-4; Figure d shows the real part of the complex dielectric constant when the metal-organic framework filler ratio is 40 wt% in Examples 1-4; Figure e shows the imaginary part of the complex dielectric constant when the metal-organic framework filler ratio is 40 wt% in Examples 1-4; Figure f shows the dielectric loss tangent when the metal-organic framework filler ratio is 40 wt% in Examples 1-4; Figure g shows the real part of the complex dielectric constant when the metal-organic framework filler ratio is 50 wt% in Examples 1-4; Figure h shows the imaginary part of the complex dielectric constant when the metal-organic framework filler ratio is 50 wt% in Examples 1-4; Figure i shows the real part of the complex dielectric constant when the metal-organic framework filler ratio is 50 wt% in Examples 1-4; Figure d shows the real part of the complex dielectric constant when the metal-organic framework filler ratio is 50 wt% in Examples 1-4; Figure e shows the imaginary part of the complex dielectric constant when the metal-organic framework filler ratio is 50 wt% in Examples 1-4; Figure i shows the real part of the complex dielectric constant when the metal-organic framework filler ratio is 50 wt% in Examples 1-4; Figure d ... The dielectric loss tangent at wt%. Figure 4 The electromagnetic attenuation spectra obtained in Examples 1-4 with a metal-organic framework filler ratio of 30 wt% are shown in Figure 1-4. Figure 1a shows the three-dimensional attenuation spectra of Example 1 at different thicknesses and frequencies, Figure 2 shows the three-dimensional attenuation spectra of Example 2 at different thicknesses and frequencies, Figure 3 shows the three-dimensional attenuation spectra of Example 3 at different thicknesses and frequencies, Figure 4 shows the three-dimensional attenuation spectra of Example 4 at different thicknesses and frequencies, Figure 5 shows the two-dimensional attenuation spectra of Examples 1-4 with the widest effective bandwidth, and Figure 6 shows the two-dimensional attenuation spectra of Examples 1-4 with the strongest attenuation.

[0026] Figure 5 The electromagnetic attenuation spectra obtained in Examples 1-4 with a metal-organic framework filler ratio of 40 wt% are shown in Figure 1-4. Figure 1a shows the three-dimensional attenuation spectra of Example 1 at different thicknesses and frequencies, Figure 2 shows the three-dimensional attenuation spectra of Example 2 at different thicknesses and frequencies, Figure 3 shows the three-dimensional attenuation spectra of Example 3 at different thicknesses and frequencies, Figure 4 shows the three-dimensional attenuation spectra of Example 4 at different thicknesses and frequencies, Figure 5 shows the two-dimensional attenuation spectra of Examples 1-4 with the widest effective bandwidth, and Figure 6 shows the two-dimensional attenuation spectra of Examples 1-4 with the strongest attenuation.

[0027] Figure 6 The electromagnetic attenuation spectra obtained in Examples 1-4 with a metal-organic framework filler ratio of 50 wt% are shown in Figure 1-4. Figure 1a shows the three-dimensional attenuation spectra of Example 1 at different thicknesses and frequencies, Figure 2 shows the three-dimensional attenuation spectra of Example 2 at different thicknesses and frequencies, Figure 3 shows the three-dimensional attenuation spectra of Example 3 at different thicknesses and frequencies, Figure 4 shows the three-dimensional attenuation spectra of Example 4 at different thicknesses and frequencies, Figure 5e shows the two-dimensional attenuation spectra of Examples 1-4 with the widest effective bandwidth, and Figure 6f shows the two-dimensional attenuation spectra of Examples 1-4 with the strongest attenuation.

[0028] Figure 7 Figure 1 shows the impedance matching characteristics and attenuation capability spectra obtained in Examples 1-4 when the metal-organic framework filler ratio was 40 wt%. Among them, Figure a is the impedance matching spectrum of Example 1, Figure b is the impedance matching spectrum of Example 2, Figure c is the impedance matching spectrum of Example 3, Figure d is the impedance matching spectrum of Example 4, and Figure e is the attenuation constant (α) graph of Examples 1-4.

[0029] Figure 8 The following are electrochemical spectra of the salt spray corrosion resistance of the two-dimensional layered metal-organic framework coatings obtained in Examples 2 and 3: Figure a shows the EIS impedance spectra of the pure epoxy resin coating after immersion in 3.5 wt% sodium chloride solution for 3, 7, 14, and 21 days; Figure b shows the EIS impedance spectra of the coating in Example 2 with a filler content of 0.3 wt% after immersion in 3.5 wt% sodium chloride solution for 3, 7, 14, and 21 days; Figure c shows the EIS impedance spectra of the coating in Example 2 with a filler content of 0.7 wt% after immersion in 3.5 wt% sodium chloride solution for 3, 7, 14, and 21 days; Figure d shows the EIS impedance spectra of the coating in Example 2 with a filler content of 10 wt% after immersion in 3.5 wt% sodium chloride solution for 3, 7, 14, and 21 days; Figure e shows the EIS impedance spectra of the coating in Example 3 with a filler content of 0.3 wt% after immersion in 3.5 wt% sodium chloride solution for 3, 7, 14, and 21 days. Figure 1 shows the EIS impedance spectra of the coating prepared in Example 3 after soaking in a 3.5 wt% sodium chloride solution for 3, 7, 14, and 21 days with a filler content of 0.7 wt%. Figure 2 shows the EIS impedance spectra of the coating prepared in Example 3 after soaking in a 3.5 wt% sodium chloride solution for 3, 7, 14, and 21 days with a filler content of 10 wt%. Figure 3 shows the EIS impedance spectra of the coating prepared in Examples 2 and 3 and the pure epoxy resin coating. f=0.01Hz The value is used as a function of soaking time. Figure i shows the potentiodynamic polarization curves of the coatings prepared in Examples 2-3 and the pure epoxy resin coating after soaking in 3.5 wt% sodium chloride solution for 21 days. Detailed Implementation

[0030] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0031] A two-dimensional layered semiconductor metal-organic framework coating and its preparation method, comprising the following steps: Step 1: Add 1 mmol of cuprous oxide (Cu2O) to 20 mL of anhydrous ethanol and disperse evenly. Then, add 1-4 mmol of 4-hydroxybenzyl mercaptan (HBT) to the solution at a constant rate. Step 2: Isolate the mixed solution from oxygen and heat it at 80°C in an argon atmosphere, stirring at 500 rpm for 2.5 h until the system changes from red to yellow, then stop the reaction. Step 3: Separate the solution by high-speed centrifugation at 10,000 rpm, centrifuge 4-5 times, take the lower precipitate and wash it repeatedly with ethanol, and collect the yellow solid; Step 4: The obtained sample was vacuum dried at 60℃ for 12 h to obtain the final sample CuHBT-x; Step 5: Disperse a certain amount of CuHBT-x (0.3 wt%, 0.7 wt%, 10 wt%) in 1 mL of ethanol by ultrasonic treatment, and add it to 1.4 g of epoxy resin; Step 6: Add 0.2 g of curing agent to the above system and stir continuously at 60°C under vacuum for 2 h to remove air bubbles; Step 7: Apply the mixture evenly to Q235 steel and allow it to dry and cure at room temperature for 72 hours.

[0032] Example 1 A two-dimensional layered semiconductor metal-organic framework coating and its preparation method, comprising the following steps: Step 1: Add 1 mmol of cuprous oxide (Cu2O) to 20 mL of anhydrous ethanol and disperse evenly. Then, add 1 mmol of 4-hydroxybenzyl mercaptan (HBT) to the solution at a constant rate. Step 2: Isolate the mixed solution from oxygen and heat it at 80°C in a helium atmosphere, stirring at 500 rpm for 2 hours until the system changes from red to yellow, then stop the reaction. Step 3: Separate the solution by high-speed centrifugation at 10,000 rpm for 20 min, centrifuge 4-5 times, take the lower precipitate and wash it repeatedly with ethanol, and collect the yellow solid; Step 4: The obtained sample was vacuum dried at 60℃ for 12 h to obtain the final sample CuHBT-1; Step 5: Disperse a certain amount of CuHBT-1 (0.3 wt%, 0.7 wt%, 10 wt%) in 1 mL of ethanol by ultrasonic treatment, and add it to 1.4 g of epoxy resin; Step 6: Add 0.2 g of curing agent to the above system and stir continuously at 60°C under vacuum for 2 h to remove air bubbles; Step 7: Apply the mixture evenly to Q235 steel and allow it to dry and cure at room temperature for 72 hours.

[0033] Example 2 A two-dimensional layered semiconductor metal-organic framework coating and its preparation method, comprising the following steps: Step 1: Add 1 mmol of cuprous oxide (Cu2O) to 20 mL of anhydrous ethanol and disperse evenly. Then, add 2 mmol of 4-hydroxybenzyl mercaptan (HBT) to the solution at a constant rate. Step 2: Isolate the mixed solution from oxygen and heat it at 80°C in a nitrogen atmosphere, stirring at 500 rpm for 2.5 h until the system changes from red to yellow, then stop the reaction. Step 3: Separate the solution by high-speed centrifugation at 10,000 rpm for 20 min, centrifuge 4-5 times, take the lower precipitate and wash it repeatedly with ethanol, and collect the yellow solid; Step 4: The obtained sample was vacuum dried at 60℃ for 12 h to obtain the final sample CuHBT-2; Step 5: Disperse a certain amount of CuHBT-2 (0.3 wt%, 0.7 wt%, 10 wt%) in 1 mL of ethanol by ultrasonic treatment, and add it to 1.4 g of epoxy resin; Step 6: Add 0.2 g of curing agent to the above system and stir continuously at 60°C under vacuum for 2 h to remove air bubbles; Step 7: Apply the mixture evenly to Q235 steel and allow it to dry and cure at room temperature for 72 hours.

[0034] Example 3 A two-dimensional layered semiconductor metal-organic framework coating and its preparation method, comprising the following steps: Step 1: Add 1 mmol of cuprous oxide (Cu2O) to 20 mL of anhydrous ethanol and disperse evenly. Then, add 3 mmol of 4-hydroxybenzylthiol (HBT) to the above solution at a constant rate. Step 2: Isolate the mixed solution from oxygen and heat it at 70°C in an argon atmosphere, stirring at 500 rpm for 2.5 h until the system changes from red to yellow, then stop the reaction. Step 3: Separate the solution by high-speed centrifugation at 10,000 rpm for 20 min, centrifuge 4-5 times, take the lower precipitate and wash it repeatedly with ethanol, and collect the yellow solid; Step 4: The obtained sample was vacuum dried at 60℃ for 16 h to obtain the final sample CuHBT-3; Step 5: Disperse a certain amount of CuHBT-3 (0.3 wt%, 0.7 wt%, 10 wt%) in 1 mL of ethanol by ultrasonic treatment, and add it to 1.4 g of epoxy resin; Step 6: Add 0.2 g of curing agent to the above system and stir continuously at 60°C under vacuum for 2 h to remove air bubbles; Step 7: Apply the mixture evenly to Q235 steel and allow it to dry and cure at room temperature for 72 hours.

[0035] Example 4 A two-dimensional layered semiconductor metal-organic framework coating and its preparation method, comprising the following steps: Step 1: Add 1 mmol of cuprous oxide (Cu2O) to 20 mL of anhydrous ethanol and disperse evenly. Then, add 4 mmol of 4-hydroxybenzyl mercaptan (HBT) to the solution at a constant rate. Step 2: Isolate the mixed solution from oxygen and heat it at 60°C in an argon atmosphere, stirring at 500 rpm for 5 hours until the system changes from red to yellow, then stop the reaction. Step 3: Separate the solution by high-speed centrifugation at 10,000 rpm for 20 min, centrifuge 4-5 times, take the lower precipitate and wash it repeatedly with ethanol, and collect the yellow solid; Step 4: The obtained sample was vacuum dried at 60℃ for 12 h to obtain the final sample CuHBT-4; Step 5: Disperse a certain amount of CuHBT-4 (0.3 wt%, 0.7 wt%, 10 wt%) in 1 mL of ethanol by ultrasonic treatment, and add it to 1.4 g of epoxy resin; Step 6: Add 0.2 g of curing agent to the above system and stir continuously at 60°C under vacuum for 2 h to remove air bubbles; Step 7: Apply the mixture evenly to Q235 steel and allow it to dry and cure at room temperature for 72 hours.

[0036] To compare with the two-dimensional layered semiconductor metal-organic framework coating obtained in this invention, a pure epoxy resin coating was prepared by repeating steps 5-7 without adding CuHBT sample.

[0037] To characterize the two-dimensional layered semiconductor metal-organic framework material obtained in this invention, the microstructure of CuHBT-x was characterized using scanning electron microscopy (SEM), and the elemental composition and distribution on its surface were analyzed using energy-dispersive spectroscopy (EDS). The structure of CuHBT-x was characterized using Fourier transform infrared spectroscopy (FT-IR) at a scanning resolution of 4... The scan wavenumber range is 4000~400 The structure of CuHBT-x was characterized using Cu-Kα radiation X-ray diffraction (XRD), and its crystallization behavior was analyzed. The scanning speed was 5° / min, and the scanning range was 5°–80°. The chemical composition and bonding type of CuHBT-x were investigated by X-ray photoelectron spectroscopy (XPS) using a monochromatic Al-Kα X-ray source (1486.6 eV). Electromagnetic parameters of CuHBT-x were measured in the frequency range of 1.0–18.0 GHz using a vector network analyzer. Using the coaxial method, different mass percentages of CuHBT-x were uniformly mixed with paraffin and pressed to obtain coaxial rings with an inner diameter of 3.04 mm and an outer diameter of 7 mm. An electrochemical workstation was used in a classic three-electrode configuration, including a working electrode (with an exposed area of ​​1 cm²). 2 The electrode is made of coated Q235 steel, the reference electrode is made of saturated silver chloride, and the counter electrode is made of 4 cm² steel. 2 The platinum sheet was used to fabricate the working electrode, and electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve (PDP) were performed. The frequency range of the EIS measurement was [missing information]. Hz, AC signal amplitude is 10 mV.

[0038] Figure 1 Image a is a scanning electron microscope image of the two-dimensional layered CuHBT-1 obtained in Example 1. It can be seen that CuHBT-1 presents as stacked two-dimensional nanosheets, but the structure is very fragmented and the size is small, and the size and shape distribution is also very irregular. Figure 1 b、 Figure 1 c shows scanning electron microscope images of the two-dimensional layered CuHBT-2 and CuHBT-3 obtained in Examples 2 and 3. It can be seen that the sheet-like structure is relatively complete and the size is much larger than CuHBT-1, with a thickness of about 50~60 nm and a size distribution ranging from hundreds of nanometers to several micrometers. Figure 1 Image d is a scanning electron microscope image of the two-dimensional layered CuHBT-4 obtained in Example 4. It can be seen that the sample also has a relatively regular layered structure. Figure 1EI is the elemental distribution spectrum of the CuHBT-2 sample obtained in Example 2. It can be seen that C, Cu, O, S and other elements are uniformly distributed on the surface of CuHBT-2, which corresponds to the reaction raw materials used. This also proves that the organic ligand HBT was successfully incorporated into the MOFs.

[0039] Figure 2 a shows the infrared spectra of CuHBT-x obtained in Examples 1-4. It can be observed that the infrared spectra of CuHBT-x are basically consistent. Firstly, the spectrum is located at 3398 cm⁻¹. −1 The broad absorption band at this point corresponds to the stretching vibration of -OH, indicating the retention of some -OH functional groups during the formation of CuHBT-x, originating from the organic ligand 4-hydroxybenzenethiol (HBT). Generally, the stretching vibration of phenol occurs at wavenumbers greater than 3500 cm⁻¹. −1 At this location, the absorption peak shows a significant shift, thus it can be reasonably assumed that hydrogen bonds were formed during the self-assembly of the CuHBT unit. Furthermore, the stretching vibrations of the SC bonds can be attributed to the region located between 800 and 500 cm⁻¹. −1 The characteristic peaks between these peaks demonstrate the presence of HBT in CuHBT-x. Figure 2 b shows the XRD patterns of CuHBT-x obtained in Examples 1-4. It can be observed that CuHBT-x exhibits two different test results. First, CuHBT-1 shows strong diffraction peaks at 2θ = 36.4, 42.3, 61.3, and 73.5°, which are related to the (111), (200), (220), and (311) lattice planes of cuprous oxide (Cu2O), respectively. This indicates that when the molar ratio is 1:1, when HBT acts as a ligand, the low HBT content leads to incomplete coordination, and Cu2O cannot be well converted to CuHBT, leaving a lot of unreacted Cu2O, thus resulting in a strong Cu2O signal in the XRD pattern. However, between 5° and 35°, CuHBT-1 also shows some low-intensity diffraction peaks, originating from CuHBT, proving that in this case, a mixture of Cu2O and CuHBT can be separated from CuHBT-1 simultaneously. With the increase of HBT ligand content, the diffraction peaks belonging to Cu2O basically disappeared, proving that the Cu2O precursor had been well combined with HBT to convert into Cu-S, forming CuHBT. Specifically, as shown in the figure, CuHBT-2, CuHBT-3, and CuHBT-4 have strong and sharp peaks at 2θ = 6.1, 12.1, 18.3, and 24.6°, corresponding to crystal planes (002), (004), (006), and (111), respectively. Analysis of the above XRD test results indicates that CuHBT-x has been successfully synthesized. Figure 2c~g represent the XPS total spectrum and high-resolution spectra of each element in Example 2. First, CuHBT-x is composed of C, O, Cu, and S, consistent with the XPS total spectrum results. To investigate the chemical stability of the ligand, the C 1s high-resolution spectrum of CuHBT-2 was analyzed. Two peaks with binding energies of 289.3 eV and 288.1 eV correspond to the CO and CH bonds in the aromatic ring of HBT, respectively. Additionally, a weak peak with a binding energy of 290.8 eV is present, attributed to the OC=O bond, indicating partial oxidation of the HBT ligand during synthesis. Furthermore, two peaks at 286.3 eV and 284.8 eV correspond to the CC / C=C and CS bonds, respectively. The O 1s high-resolution spectrum contains three peaks with binding energies of 535.4 eV, 532.6 eV, and 531.0 eV, corresponding to the SO / S=O, CO, and OC=O bonds, respectively. To gain a clearer understanding of the specific binding mechanism of CuHBT-x, the analysis of the Cu 2p high-resolution spectrum is particularly important. By examining the coexisting states and corresponding valence states of Cu, it was found that CuHBT-2 exhibits two prominent peaks with binding energies of 932.4 eV and 952.1 eV, corresponding to Cu 2p 3 / 2 and Cu 2p 1 / 2, respectively, and related to the Cu(Ⅰ)-S-Cu bond. Furthermore, it is noteworthy that both the Cu 2p 3 / 2 and Cu 2p 1 / 2 peaks exhibit weak bands at 934.8 eV and 954.5 eV, respectively, related to the Cu(Ⅱ)-S bond. Further analysis of the CuHBT-2 S 2p high-resolution spectrum revealed peaks at 163.3 eV and 162.1 eV, corresponding to the SC bond and S-Cu bond, respectively. Furthermore, a weak but broad band was observed in the spectrum at 168.1 eV (SO) and 167.1 eV (S=O), which can be attributed to the oxidation of S, thus further demonstrating the presence of ligand oxidation behavior in the synthesis of CuHBT-x.

[0040] Figure 3 The complex permittivity of CuHBT-x obtained in Examples 1-4 under different filler ratios (30 wt%, 40 wt%, 50 wt%) is given. ε′ , ε" , tanδ ε Data and images showing how the frequency of electromagnetic waves changes. First, using the same sample as the analysis object, it can be found that as the filler ratio increases, ε′ , ε" and tan δεThe conductivity of the coaxial ring increases accordingly because an increase in the CuHBT-x filler ratio directly leads to an increase in the conductivity of the coaxial ring, thereby enhancing its electromagnetic wave storage and attenuation capabilities. However, higher conductivity is not always better; excessively high conductivity can lead to impedance mismatch and a decrease in attenuation performance. At the same filler ratio, CuHBT-x exhibits higher conductivity with increasing molar content of the organic ligand HBT. ε ′、 ε" and tan δε Initially, the dielectric loss increases accordingly, but as the molar ratio continues to increase, the losses decrease instead, indicating that a higher HBT content is not necessarily better. Analysis of the dielectric loss tangent (tan...) of CuHBT-x... δε = ε″ / ε' It can be observed that when the filler ratio is 30 wt% and 50 wt%, the tan saturation of CuHBT-3 is... δε The value is the highest; while when the filler ratio is 40 wt%, the tan tan of CuHBT-2 is the highest. δε The values ​​are the highest, which, in summary, indicates that CuHBT-2 and CuHBT-3 have strong dielectric loss capabilities.

[0041] Figures 4-6 The electromagnetic attenuation spectra of CuHBT-x obtained in Examples 1-4 under different filler ratios (30 wt%, 40 wt%, 50 wt%) are shown. It can be observed that CuHBT-1 and CuHBT-4 have a minimum attenuation value >-10 dB at a filler ratio of 30 wt%, which can be considered as having almost no attenuation performance. CuHBT-2 exhibits the best performance, reaching -47.31 dB, followed by CuHBT-3, reaching -39.14 dB. When the filler ratio is 40 wt%, the minimum attenuations of the CuHBT-x samples (x=1, 2, 3, 4) are -14.29, -53.06, -38.27, and -37.20 dB, respectively, with CuHBT-2 showing the lowest attenuation value. Meanwhile, compared to a 30 wt% filler ratio, the attenuation performance of most samples has been improved to some extent, with CuHBT-4 showing a particularly significant improvement. Furthermore, when the filler ratio was 50 wt%, the minimum attenuation values ​​for each sample were -18.38, -48.65, -43.95, and -41.91 dB, respectively. In summary, CuHBT-2 consistently maintained a minimum attenuation value below -40 dB, exhibiting the best performance; followed by CuHBT-3. Figure 4 As shown in Figure e, when the filler ratio is 30 wt%, the effective frequency bands of CuHBT-2 and CuHBT-3 cover most of the X-band and the entire Ku-band, with effective bandwidths of 8.83 and 8.16 GHz, respectively. At a filler ratio of 40 wt%, (… Figure 5When e), the effective bandwidths of CuHBT-2, CuHBT-3, and CuHBT-4 are 8.80, 6.50, and 6.24 GHz, respectively; while when the filler ratio is 50 wt% ( Figure 6 e) At that time, their effective bandwidth is approximately 6.95 GHz. A comprehensive comparison reveals that CuHBT-2's... f E The values ​​were significantly higher than other samples, and the absorption frequency range was wider at filler ratios of 30 wt% and 40 wt%. In summary, when the filler ratio was 40 wt%, CuHBT-2 exhibited the lowest and most stable minimum attenuation value, along with a wider effective bandwidth.

[0042] Figure 7 The figures show the impedance matching characteristics and attenuation capability spectra obtained in Examples 1-4 when the two-dimensional layered metal-organic framework filler ratio was 40 wt%. As can be seen from the figures, CuHBT-2 has the best impedance matching and also the highest attenuation constant.

[0043] Figure 8 Electrochemical spectra of the salt spray corrosion resistance of the two-dimensional layered metal-organic framework coatings obtained in Examples 2-3 are shown. The electrochemical performance of CuHBT-2 and CuHBT-3 fillers was mainly studied, and six composite coatings with filler ratios of 0.3 wt%, 0.7 wt%, and 10 wt% were prepared using these fillers. In addition, a pure epoxy coating (EP) was included as a control group in the experiment. Bode plots of each coating after immersion in 3.5 wt% NaCl solution for 3, 7, 14, and 21 days are shown. Comprehensive analysis reveals that, for both EP and composite coatings, the impedance modulus |Z| increases with immersion time in 3.5 wt% NaCl solution. 0.01 Hz The overall trend is decreasing because corrosive media slowly penetrate to the coating / substrate interface, gradually deteriorating the coating's corrosion resistance. Regarding the impedance modulus |Z| 0.01 Hz Detailed analysis revealed that after 21 days of soaking, CuHBT-2-0.7 wt% exhibited the highest impedance modulus, at 4.406 × 10⁻⁶. 7 Ω·cm 2 The impedance modulus of the epoxy coating is |Z|. 0.01 Hz =3.284×10 4 Ω·cm 2 Therefore, after a 21-day immersion period, the impedance modulus of CuHBT-2-0.7 wt% is three orders of magnitude higher than that of EP, indicating its excellent corrosion resistance. The impedance moduli of other composite coatings are |Z| 0.01 Hz =9.815×10 5 8.575×106 5.400×10 5 3.031×10 7 8.510×10 5 Ω·cm 2 The impedance modulus of the composite coating is higher than that of the epoxy coating, indicating that the coating provides better protection to the substrate after the addition of filler. This is because filler can compensate for the inherent defects of epoxy coating, block the penetration of corrosive media to the substrate surface, and improve the anti-corrosion performance of the composite coating. The anti-corrosion performance of different composite coatings is compared from two perspectives: 1) For the same sample, in terms of filler ratio, the composite coating has the highest impedance modulus when the filler ratio is 0.7 wt%; while the impedance modulus is the lowest when the filler ratio is 10 wt%. This is because excessive filler will cause agglomeration, introducing additional defects and gaps, weakening the anti-corrosion performance. 2) Under the same immersion time and the same filler ratio, the impedance modulus of CuHBT-2 is always higher than that of CuHBT-3. This should be related to the morphology and structure of the material itself, presumably because the lamellar structure of CuHBT-2 is more complete and dense. Figure 2-8 As shown in h, the specific impedance values ​​of each coating at each immersion time stage are presented to more clearly and intuitively compare the changing trends of the impedance modulus of different coatings. The impedance modulus of CuHBT-2-0.7 wt% is consistently the highest throughout the entire immersion period, fully demonstrating its superior corrosion resistance.

[0044] To further demonstrate the corrosion resistance and protective efficiency (IE) of the composite coating, potentiodynamic polarization curve (PDP) tests were performed on bare steel and the coating after immersion in 3.5 wt% NaCl solution for 21 days. The results are as follows: Figure 2-8 As shown in figure i. The corrosion potential was obtained by extrapolating the anodic and cathodic curves using electrochemical analysis software. E corr (mV), and calculate the corrosion current density. I corr (A / cm) 2 ), Anode / Cathode slope b a / b c (mV / dec), polarization resistance R p (Ω·cm) 2 ) and annual corrosion rate v corr (mm / year) This series of potentiodynamic polarization parameters. Protection efficiency ( IE (%) can be calculated using the following formula:

[0045] Corrosion potential of Q235 Ecorr The corrosion potential of the coating was -679.0 mV. In contrast, the corrosion potentials of all coatings shifted positively, with the highest corrosion potential of CuHBT-2-0.7 wt% at -345.4 mV, indicating that this coating has superior barrier performance. Polarization resistance... R p Polarization resistance is typically used to characterize the resistance of a coating system to the corrosion process; a higher polarization resistance indicates better corrosion protection. The lowest corrosion current density and the highest polarization resistance both came from the CuHBT-2-0.7 wt% system, further verifying its superior corrosion protection performance. Finally, protection efficiency most directly reflects the protective effect of each coating. EP's protection efficiency was 56.02%, while CuHBT-2-0.7 wt% achieved the highest protection efficiency of 92.88%, providing excellent barrier performance. Furthermore, the protection efficiencies of other composite coatings were all above 80%. In conclusion, CuHBT-2-0.7 wt% exhibits the most outstanding corrosion protection performance.

[0046] The fundamental reason for the excellent anti-corrosion performance of CuHBT-x is its distinct two-dimensional lamellar structure, which, when uniformly dispersed in epoxy resin, effectively isolates it from the corrosive medium (Cl) when corrosion occurs. - It can penetrate through O2 and H2O, and prolong the propagation path, further slowing down the penetration rate, thereby achieving the effect of corrosion prevention.

[0047] Due to its inherent properties, CuHBT exhibits multiple efficient electromagnetic attenuation mechanisms. First, its excellent conductivity allows electrons to migrate not only within the two-dimensional Cu-S layer plane via chemical bonds but also between layers through spatial stacking, resulting in high conductive losses. Second, heteroatoms such as Cu, S, and O, as well as unavoidable structural defects like uncoordinated hydroxyl groups, act as polarization centers, promoting the formation and movement of various dipoles and thus generating multiple polarization relaxation. Third, the inherent porosity of MOFs not only gives CuHBT low density and high specific area but also provides a longer electromagnetic wave propagation path, and more importantly, induces polarization losses at the solid-air interface. Therefore, in the 2–18 GHz frequency band, conductive loss and polarization loss are the main electromagnetic attenuation mechanisms. Furthermore, the synergistic effect of multiple scattering and reflection further promotes electromagnetic wave attenuation.

[0048] Two-dimensional semiconductor CuHBT was successfully prepared using a ligand exchange strategy, and its electromagnetic attenuation and corrosion resistance were further tested. The test results show that CuHBT-2 has good impedance matching and a high attenuation constant; the synergistic effect of its resistive loss and polarization loss effectively attenuates electromagnetic waves. The two-dimensional semiconductor CuHBT exhibits excellent attenuation performance. When the filler ratio is 40 wt%, CuHBT-2 has a minimum attenuation of -53.06 dB at 11.2 GHz, with a thickness of only 2.9 mm, and an effective bandwidth of 8.80 GHz, covering most of the X-band and the entire Ku-band. Furthermore, after immersion in 3.5 wt% NaCl solution for 21 days, the impedance modulus of the CuHBT-2-0.7 wt% composite coating remains as high as 4.406 × 10⁻⁶. 7 Ω·cm 2 It provides a protection efficiency of up to 92.88%, offering superior corrosion resistance.

[0049] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A two-dimensional layered semiconductor metal-organic framework coating, characterized in that: It is a two-dimensional layered CuHBT MOFs-based coating. This semiconductor metal-organic framework material has a two-dimensional stacked microstructure. Its single-layer two-dimensional sheet structure has a thickness of 50~60 nm and a sheet diameter of 0.5~5 μm.

2. The method for preparing a two-dimensional layered semiconductor metal-organic framework coating according to claim 1, characterized in that, Includes the following steps: Step 1: Disperse cuprous oxide in anhydrous ethanol until uniform, then add 4-hydroxybenzyl mercaptan to the solution at a constant rate; Step 2: Isolate the mixed solution from oxygen and heat and stir the reaction in a protective atmosphere until the reaction system changes from red to yellow, then stop the reaction; Step 3: Separate the solution using high-speed centrifugation, remove the lower precipitate and wash it repeatedly with ethanol, then collect the yellow solid; Step 4: Vacuum dry the obtained sample to obtain the final sample; Step 5: Disperse a certain amount of CuHBT in ethanol by ultrasonic treatment, and add it to a certain amount of epoxy resin; Step 6: Add a certain amount of curing agent to the above system and stir continuously under vacuum to remove air bubbles; Step 7: Apply the mixture evenly to Q235 steel and allow it to dry and cure at room temperature.

3. The method for preparing a two-dimensional layered semiconductor metal-organic framework coating according to claim 1, characterized in that: In step one, the concentration of the cuprous oxide ethanol solution is 0.01~0.2 mmol / mL.

4. The method for preparing a two-dimensional layered semiconductor metal-organic framework coating according to claim 3, characterized in that: In step one, the molar ratio of cuprous oxide to 4-hydroxybenzyl mercaptan is 1:0.5 to 1:

10.

5. The method for preparing a two-dimensional layered semiconductor metal-organic framework coating according to claim 4, characterized in that: In step two, the heating temperature is 60~80℃ and the heating time is 2~5 h.

6. The method for preparing a two-dimensional layered semiconductor metal-organic framework coating according to claim 5, characterized in that: In step two, the stirring speed is maintained at 500 rpm.

7. The method for preparing a two-dimensional layered semiconductor metal-organic framework coating according to claim 6, characterized in that: The protective gas in step two is argon, helium, or nitrogen.

8. The method for preparing a two-dimensional layered semiconductor metal-organic framework coating according to claim 7, characterized in that: In step three, the centrifugation speed is 10,000 rpm and the centrifugation time is 20 min.

9. The method for preparing a two-dimensional layered semiconductor metal-organic framework coating according to claim 8, characterized in that: In step four, the drying temperature is 60℃ and the drying time is 12~16 h.

10. The method for preparing a two-dimensional layered semiconductor metal-organic framework coating according to claim 9, characterized in that: In step five, the CuHBT filler ratio is 0.1~10 wt%, and the ultrasonic time is 15 min.

11. The method for preparing a two-dimensional layered semiconductor metal-organic framework coating according to claim 10, characterized in that: In step six, the mass ratio of curing agent to epoxy resin is 1:2 to 1:7, and the stirring time is 30 min.

12. The method for preparing a two-dimensional layered semiconductor metal-organic framework coating according to claim 11, characterized in that: The curing time in step seven is 72 hours.

13. The two-dimensional layered semiconductor metal-organic framework coating according to claim 1 is applied to an electromagnetic attenuation filler with corrosion resistance.

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