Metal monatomic wave-absorbing agent based on layered coordination derivation as well as preparation method and application of metal monatomic wave-absorbing agent

Abstract

The invention provides a metal monatomic wave-absorbing agent based on layered coordination derivation. The unique atomic confinement structure of the metal monatomic wave-absorbing agent has excellent electromagnetic wave absorbing performance. The monatomic wave-absorbing material is constructed by adopting an interlayer coordination confinement strategy for the first time. According to the technical scheme, an interlayer metal atom confinement structure is constructed through slow oxidative polymerization and coordination synergistic effect. Due to high stability, metal atoms are not easy to agglomerate during high-temperature pyrolysis and exist in the form of stable monatomic sites. Therefore, metal monatomic modification can significantly improve the electromagnetic wave absorption performance of the material, and the minimum reflection loss can reach-63.69 dB.

Description

Technical Field

[0001] The present invention belongs to the field of electromagnetic wave absorbing materials, and particularly relates to a metal single-atom absorbent derived from layered coordination and a preparation method thereof. Background Art

[0002] With the rapid development of high-frequency communication technology, the problem of electromagnetic wave pollution in the human living environment has become increasingly serious. To address this challenge, the development of functional materials with high-efficiency electromagnetic wave absorption performance has become a current research hotspot.

[0003] In recent years, metal-atom-confined nanostructures have attracted much attention due to their unique structural features. Such materials have extremely high surface free energy and an atomic utilization rate close to 100%, showing broad application prospects in the field of electromagnetic wave absorption. It should be noted that the "atoms" in metal-atom-confined nanostructures do not refer to elementary atoms in the zero-valent state, but usually exist in the form of cations and are combined with the carrier material through chemical bonds.

[0004] Research has shown that when isolated single atoms are confined in a nanoscale space, their physicochemical properties and interactions are significantly affected by the confined space (X. Fan et al., ACS Catal. 2024, 14 , 12991–13014). However, due to the extremely small atomic scale, it is quite technically difficult to achieve the confinement and stabilization of single atoms only by relying on rigid space isolation (such as the van der Waals gap in layered two-dimensional materials, nanotube channels, or porous sites, etc.). Therefore, the synergistic effect of combining the carrier-metal interaction (including coordination bonds or ionic bonds) between the functional groups on the carrier material and the guest metal atoms with space confinement is considered an effective strategy for stabilizing single atoms. Currently, most single-atom-confined materials adopt the method of anchoring metal atoms in the plane lattice of the carrier material (X. Zhang et al., J. Am. Chem. Soc. 2021, 143 , 20657–20669). However, this in-plane atomic configuration has the following technical defects: an increase in the coordination number of metal atoms leads to an increase in the electron loss rate, a decrease in the exposed area of metal atoms results in a decrease in atomic utilization rate, a weakening of the polarization ability, and a large loss of conductivity, etc. (J. Zhang et al., Applied Catalysis B: Environment and Energy 2024, 358 , 124393). Therefore, by selecting a suitable carrier material and designing and constructing a single-atom absorbing material with excellent atomic configuration and electronic structure is the key technical issue to solve the contradiction between the isolated and dispersed characteristics of single atoms and the high-quality activity ratio.

[0005] In the prior art, a Chinese invention patent with the application number 202211043318.9 discloses a conductive polymer / metal single-atom nanocomposite material, its preparation method and application. The technical solution mainly includes the following steps: First, a conductive polymer is prepared by chemical polymerization method. Subsequently, the conductive polymer and a metal precursor salt are mixed and stirred by an impregnation method. After centrifugal washing and freeze-drying treatment, the metal precursor salt is adsorbed and anchored on the conductive polymer. Finally, the metal precursor salt is reduced to metal single atoms by a hydrogen-argon reduction method, thereby obtaining the conductive polymer / metal single-atom nanocomposite material. Its disadvantages are that the exposed area of metal atoms decreases, resulting in a decrease in atomic utilization rate, a weakening of polarization ability, and a large loss of conductivity. Summary of the Invention

[0006] In order to make up for the defects of the prior art, the present invention provides a metal single-atom absorbent derived from layered coordination, and the technical solution is as follows: A metal single-atom absorbent derived from layered coordination, and its preparation method includes the following steps: Step 1, adding a thiophene compound to a metal salt dispersion liquid at a rate of 1-5 ml / min and mixing evenly to obtain a polymerization raw material liquid; Step 2, in a nitrogen or inert gas atmosphere, heating and stirring the polymerization raw material liquid obtained in Step 1, and pyrolyzing to obtain a metal single-atom absorbent derived from layered coordination; The metal salt is selected from copper salts, iron salts, silver salts; the thiophene compound is selected from one of thiophene, 3-methylthiophene, 3,4-ethylenedioxythiophene, dithiophene or benzothiophene.

[0007] Preferably, the metal salt dispersion liquid in Step 1 is obtained by dispersing a metal salt in an organic solvent; the organic solvent is selected from ethanol, methanol, isopropanol.

[0008] Preferably, the metal salt is selected from copper salts; the thiophene compound is selected from 3,4-ethylenedioxythiophene; the copper salt is based on Cu 2+ calculated, the molar ratio of the copper salt to 3,4-ethylenedioxythiophene is 1:(0.5-2); Or, the metal salt is selected from iron salts; the thiophene compound is selected from 3,4-ethylenedioxythiophene; the iron salt is based on Fe 3+ calculated, the molar ratio of the copper salt to 3,4-ethylenedioxythiophene is 1:(0.5-2); Or, the metal salt is selected from silver salts; the thiophene compound is selected from 3,4-ethylenedioxythiophene; the silver salt is based on Ag + calculated, the molar ratio of the copper salt to 3,4-ethylenedioxythiophene is 1:(0.5-2).

[0009] Preferably, the copper salt is selected from copper nitrate, copper chloride, copper sulfate, and copper acetate; the iron salt is selected from ferric chloride and iron p-toluenesulfonate; and the silver salt is selected from silver chloride.

[0010] Preferably, in step 2, the heating and stirring is to place the polymerization raw material liquid in a stirrer at 80-120 °C and heat for 70-80 h.

[0011] Preferably, in step 2, the pyrolysis is to heat the treated polymerization raw material liquid to 400-600 °C at a rate of 5-10 °C / min and hold for 2-6 h.

[0012] Preferably, the preparation method includes the following steps: Disperse the copper salt in absolute ethanol; disperse the 3,4-ethylenedioxythiophene monomer into the metal salt dispersion at a rate of 1-2 ml / min, and fully dissolve to obtain the polymerization raw material liquid.

[0013] Place the polymerization raw material liquid in a nitrogen atmosphere, heat at 80-120 °C for 70-80 h; then place it in an argon atmosphere and heat to 400-600 °C at a rate of 5-10 °C / min, and hold for 2-6 h.

[0014] A metal single-atom absorber based on layered coordination derivative prepared according to the technical solution of the present invention is applied to the field of electromagnetic wave absorption.

[0015] Beneficial effects The present invention provides a metal single-atom absorber based on layered coordination derivative, and its unique atomic confinement structure has excellent electromagnetic wave absorption performance.

[0016] The present invention first adopts the interlayer coordination confinement strategy to construct a single-atom absorbing material, and the technical solution is to construct an interlayer metal atom confinement structure through slow oxidative polymerization and coordination synergy. Due to the high stability of the coordination effect, metal atoms are not easily agglomerated during high-temperature pyrolysis and exist in the form of stable single-atom sites. Therefore, the modification of metal single atoms can significantly improve the electromagnetic wave absorption performance of the material, and the minimum reflection loss can reach -63.69 dB.

[0017] Now, a better solution is used to further illustrate the effect of the present invention. An interlayer coordination-derived Cu atom confinement structure is constructed through slow oxidative polymerization and coordination synergy, and a special combination of thiophene-based organic monomer compound-metal salt - 3,4-ethylenedioxythiophene monomer-Cu is selected. 2+For the combination, due to the poor solubility of 3,4-ethylenedioxythiophene monomers and the weak oxidizing property of the divalent copper ions added to the system, by adjusting the mixing rate of the reactants, the oxidative polymerization reaction of thiophene-based organic monomers occurs slowly. During this process, the coordination of metal ions with the S atoms in the thiophene ring is achieved, and finally, an ordered and highly stable layered structure is obtained through coordination confinement. Description of the Drawings

[0018] Figure 1 This is the transmission electron microscope image and element distribution map of the layered coordination-derived Cu atom-confined highly efficient microwave absorber prepared in Test Comparative Example 3 of the present invention; Figure 2 This is the conductivity of the layered coordination-derived Cu atom-confined highly efficient microwave absorber prepared in Test Comparative Examples 1 - 5 of the present invention; Figure 3 This is the conduction loss and polarization loss of the layered coordination-derived Cu atom-confined highly efficient microwave absorber prepared in Test Comparative Examples 1 - 5 of the present invention; Figure 4 This is the microwave absorption performance graph of Cu@PEDOT-1-500 prepared in Test Comparative Example 1 of the present invention; Figure 5 This is the microwave absorption performance graph of Cu@PEDOT-2-500 prepared in Test Comparative Example 2 of the present invention; Figure 6 This is the microwave absorption performance graph of Cu@PEDOT-3-500 prepared in Test Comparative Example 3 of the present invention; Figure 7 This is the microwave absorption performance graph of Cu@PEDOT-3-400 prepared in Test Comparative Example 4 of the present invention; Figure 8 This is the microwave absorption performance graph of Cu@PEDOT-3-600 prepared in Test Comparative Example 5 of the present invention; Figure 9 This is the microwave absorption performance graph of PC-S prepared in Test Comparative Example 6 of the present invention. Detailed Description of the Preferred Embodiments

[0019] To describe in detail the technical content, structural features, achieved objectives, and effects of the technical solution, the following provides a detailed description in conjunction with specific embodiments and accompanying drawings.

[0020] In the embodiments, the designed metal salt raw materials come from their common hydrates, which only serve to clarify the raw materials and do not constitute a limitation to the technical solution.

[0021] Example 1 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from copper chloride dihydrate, and the addition amount is 0.32 g; Step 2: Gradually add 200 μl of 3,4-ethylenedioxythiophene monomer dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h; then place it under an argon atmosphere and heat it to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the final product.

[0022] Example 2 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from copper sulfate pentahydrate, and the addition amount is 0.48 g; Step 2: Gradually add 200 μl of 3,4-ethylenedioxythiophene monomer dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h; then place it under an argon atmosphere and heat it to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the final product.

[0023] Example 3 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from copper nitrate trihydrate, and the addition amount is 0.46 g; Step 2: Gradually add 200 μl of 3,4-ethylenedioxythiophene monomer dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h; then place it under an argon atmosphere and heat it to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the final product.

[0024] Example 4 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from copper acetate monohydrate, and the addition amount is 0.38 g; Step 2: Gradually add 200 μl of 3,4-ethylenedioxythiophene monomer dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h; then place it under an argon atmosphere, and increase the temperature to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the final product.

[0025] Example 5 Step 1: Disperse the metal salt in 5 ml of absolute ethanol, and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from ferric chloride hexahydrate, and the addition amount is 0.51 g; Step 2: Gradually add 200 μl of 3,4-ethylenedioxythiophene monomer dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h; then place it under an argon atmosphere, and increase the temperature to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the final product.

[0026] Example 6 Step 1: Disperse the metal salt in 5 ml of absolute ethanol, and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from iron(II) acetate hexahydrate, and the addition amount is 1.29 g; Step 2: Gradually add 200 μl of 3,4-ethylenedioxythiophene monomer dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h; then place it under an argon atmosphere, and increase the temperature to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the final product.

[0027] Example 7 Step 1: Disperse the metal salt in 5 ml of absolute ethanol, and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from silver chloride, and the addition amount is 0.27 g; Step 2: Gradually add 200 μl of 3,4-ethylenedioxythiophene monomer dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h; then place it under an argon atmosphere and heat it to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the final product.

[0028] Example 8 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from copper chloride dihydrate, and the addition amount is 0.43 g; Step 2: Gradually add 200 μl of thiophene dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h; then place it under an argon atmosphere and heat it to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the final product.

[0029] Example 9 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from copper nitrate trihydrate, and the addition amount is 0.6 g; Step 2: Gradually add 200 μl of thiophene dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h; then place it under an argon atmosphere and heat it to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the final product.

[0030] Example 10 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from ferric chloride hexahydrate, and the addition amount is 0.67 g; Step 2: Gradually add 200 μl of thiophene dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 20 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 1 ml / min; Step 3: Transfer the polymerization raw material liquid obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 120 °C and stir for 70 h; then place it under an argon atmosphere and heat it to 600 °C at a heating rate of 10 °C / min for pyrolysis for 6 h to obtain the final product.

[0031] Example 11 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from silver chloride and the addition amount is 0.36 g; Step 2: Slowly add 200 μl of thiophene dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 15 min to fully dissolve it to obtain a polymerization raw material liquid; the dropping rate is 2 ml / min; Step 3: Transfer the polymerization raw material liquid obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 90 °C and stir for 72 h; then place it under an argon atmosphere and heat it to 600 °C at a heating rate of 8 °C / min for pyrolysis for 3 h to obtain the final product.

[0032] Example 12 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from silver chloride and the addition amount is 0.36 g; Step 2: Slowly add 200 μl of thiophene dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 11 min to fully dissolve it to obtain a polymerization raw material liquid; the dropping rate is 3 ml / min; Step 3: Transfer the polymerization raw material liquid obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 110 °C and stir for 75 h; then place it under an argon atmosphere and heat it to 450 °C at a heating rate of 6 °C / min for pyrolysis for 5 h to obtain the final product.

[0033] Example 13 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from copper sulfate pentahydrate and the addition amount is 0.52 g; Step 2: Slowly add 200 μl of trimethylthiophene dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 15 min to fully dissolve it to obtain a polymerization raw material liquid; the dropping rate is 3 ml / min; Step 3: Transfer the polymerization raw material liquid obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 110 °C and stir for 78 h; then place it under an argon atmosphere and heat it to 450 °C at a heating rate of 8 °C / min for pyrolysis for 5 h to obtain the final product.

[0034] Example 14 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant. The metal salt is selected from copper acetate monohydrate, and the addition amount is 0.41 g. Step 2: Gradually add 200 μl of trimethylthiophene dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 18 min to fully dissolve it to obtain a polymerization raw material solution. The rate of the dropwise addition is 4 ml / min. Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 90 °C and stir for 75 h; then place it under an argon atmosphere and heat it to 580 °C at a heating rate of 7 °C / min for pyrolysis for 3 h to obtain the final product.

[0035] Example 15 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant. The metal salt is selected from iron(III) acetate hexahydrate, and the addition amount is 1.41 g. Step 2: Gradually add 200 μl of trimethylthiophene dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 15 min to fully dissolve it to obtain a polymerization raw material solution. The rate of the dropwise addition is 1.5 ml / min. Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 110 °C and stir for 72 h; then place it under an argon atmosphere and heat it to 550 °C at a heating rate of 9 °C / min for pyrolysis for 6 h to obtain the final product.

[0036] Example 16 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant. The metal salt is selected from iron(III) acetate hexahydrate, and the addition amount is 1.41 g. Step 2: Gradually add 200 μl of trimethylthiophene dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 16 min to fully dissolve it to obtain a polymerization raw material solution. The rate of the dropwise addition is 3.5 ml / min. Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 95 °C and stir for 75 h; then place it under an argon atmosphere and heat it to 550 °C at a heating rate of 7 °C / min for pyrolysis for 2 h to obtain the final product.

[0037] Example 17 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant. The metal salt is selected from copper(II) chloride dihydrate, and the addition amount is 0.51 g. Step 2: Slowly add 200 μl of dithiophene drop by drop into the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 18 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 4.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 105 °C and stir for 80 h; then place it under an argon atmosphere and heat it at a heating rate of 8 °C / min to 580 °C for pyrolysis for 4 h to obtain the final product.

[0038] Example 18 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from copper nitrate trihydrate, and the addition amount is 0.72 g; Step 2: Slowly add 200 μl of dithiophene drop by drop into the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 15 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 2.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 110 °C and stir for 75 h; then place it under an argon atmosphere and heat it at a heating rate of 6 °C / min to 480 °C for pyrolysis for 4 h to obtain the final product.

[0039] Example 19 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from ferric chloride hexahydrate, and the addition amount is 0.8 g; Step 2: Slowly add 200 μl of dithiophene drop by drop into the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 15 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 110 °C and stir for 72 h; then place it under an argon atmosphere and heat it at a heating rate of 5 °C / min to 550 °C for pyrolysis for 3 h to obtain the final product.

[0040] Example 20 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from silver chloride, and the addition amount is 0.43 g; Step 2: Slowly add 200 μl of dithiophene drop by drop into the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 3.5 ml / min; Step 3: Transfer the polymerization raw material liquid obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 120 °C and stir for 76 h; then place it under an argon atmosphere and heat it to 550 °C at a heating rate of 8 °C / min for pyrolysis for 4 h to obtain the final product.

[0041] Example 21 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from copper sulfate pentahydrate, and the addition amount is 0.43 g; Step 2: Slowly add 200 μl of benzothiophene dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material liquid; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material liquid obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h; then place it under an argon atmosphere and heat it to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the final product.

[0042] Example 22 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from copper acetate monohydrate, and the addition amount is 0.34 g; Step 2: Slowly add 200 μl of benzothiophene dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material liquid; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material liquid obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h; then place it under an argon atmosphere and heat it to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the final product.

[0043] Example 23 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from iron(III) acetate hexahydrate, and the addition amount is 1.16 g; Step 2: Slowly add 200 μl of benzothiophene dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material liquid; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material liquid obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h; then place it under an argon atmosphere and heat it to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the final product.

[0044] Test Comparative Example 1 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant. The metal salt is selected from copper chloride dihydrate, and the addition amount is 0.225 g. Step 2: Gradually add 200 μl of 3,4-ethylenedioxythiophene monomer dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution. The rate of the dropwise addition is 1.5 ml / min. Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen atmosphere, heat it to 100 °C and stir for 72 h to obtain a polymer Cu@PEDOT-1. Then, place it under an argon atmosphere and heat it at a heating rate of 5 °C / min to 500 °C and pyrolyze for 4 h to obtain a layered coordination-derived Cu atom-confined highly efficient microwave absorber Cu@PEDOT-1-500.

[0045] Test Comparative Example 2 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant. The metal salt is selected from copper chloride dihydrate, and the addition amount is 0.48 g. Step 2: Gradually add 200 μl of 3,4-ethylenedioxythiophene monomer dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution. The rate of the dropwise addition is 1.5 ml / min. Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen atmosphere, heat it to 100 °C and stir for 72 h to obtain a polymer Cu@PEDOT-2. Then, place it under an argon atmosphere and heat it at a heating rate of 5 °C / min to 500 °C and pyrolyze for 4 h to obtain a layered coordination-derived Cu atom-confined highly efficient microwave absorber Cu@PEDOT-2-500.

[0046] Test Comparative Example 3 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant. The metal salt is selected from copper chloride dihydrate, and the addition amount is 0.63 g. Step 2: Gradually add 200 μl of 3,4-ethylenedioxythiophene monomer dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution. The rate of the dropwise addition is 1.5 ml / min. Step 3: Transfer the aggregated raw material liquid obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h to obtain the polymer Cu@PEDOT-3; then place it under an argon atmosphere and heat it to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the layered coordination-derived Cu atom-confined highly efficient microwave absorber Cu@PEDOT-3-500.

[0047] Test and comparison Example 4 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from copper chloride dihydrate, and the addition amount is 0.63 g; Step 2: Dropwise add 200 μl of 3,4-ethylenedioxythiophene monomer into the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain an aggregated raw material liquid; the dropping rate is 1.5 ml / min; Step 3: Transfer the aggregated raw material liquid obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h to obtain the polymer Cu@PEDOT-3; then place it under an argon atmosphere and heat it to 400 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the layered coordination-derived Cu atom-confined highly efficient microwave absorber Cu@PEDOT-3-400.

[0048] Test and comparison Example 5 Step 1: Disperse the metal salt in 5 ml of absolute ethanol and ultrasonically disperse it evenly to obtain a metal salt dispersant; the metal salt is selected from copper chloride dihydrate, and the addition amount is 0.63 g; Step 2: Dropwise add 200 μl of 3,4-ethylenedioxythiophene monomer into the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain an aggregated raw material liquid; the dropping rate is 1.5 ml / min; Step 3: Transfer the aggregated raw material liquid obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h to obtain the polymer Cu@PEDOT-3; then place it under an argon atmosphere and heat it to 600 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain the layered coordination-derived Cu atom-confined highly efficient microwave absorber Cu@PEDOT-3-600.

[0049] Test and comparison Example 6 Step 1: Add 0.81 g of FeCl3, 1.14 g of Fe(Tos)3 and 200 μl of EDOT monomer to 5 mL of absolute ethanol, and ultrasonically disperse them evenly; Step 2: Gradually add 200 μl of 3,4-ethylenedioxythiophene monomer dropwise to the metal salt dispersant obtained in Step 1 above, and continue ultrasonic treatment for 10 min to fully dissolve it to obtain a polymerization raw material solution; the rate of the dropwise addition is 1.5 ml / min; Step 3: Transfer the polymerization raw material solution obtained in Step 2 to a closed device filled with a nitrogen environment, heat it to 100 °C and stir for 72 h to obtain a polymer PEDOT; then place it under an argon atmosphere, and heat it to 500 °C at a heating rate of 5 °C / min for pyrolysis for 4 h to obtain a layered coordination-derived Cu atom-confined highly efficient microwave absorber PC-S.

[0050] Test Example 1 Use TEM (FEI Tecnai F20) and STEM-EDS (Hitachi Regulus8100) to detect the morphological changes of the single-atom modified carbon composite microwave absorber prepared in Test Comparative Example 3: Figure 1 The transmission electron microscope image and elemental distribution map of Cu@PEDOT-3-500 prepared in Test Comparative Example 3 are shown. It can be observed from the HAADF-STEM image and the corresponding energy dispersive spectrum STEM-EDS image that the Cu, S, and C elements are evenly distributed in Cu@PEDOT-3-500, indicating that the interlayer Cu atom-confined structure is successfully constructed through the coordination and synergistic effect of slow oxidative polymerization. Due to the high stability of this structure, the metal atoms are not easily agglomerated during high-temperature pyrolysis and exist in the form of stable single-atom sites.

[0051] Test Example 2 Perform performance tests on the layered coordination-derived Cu atom-confined highly efficient microwave absorbers prepared in Test Comparative Examples 1-5, and test their conductivity (RTS-8), the real part of the electromagnetic parameters ( ε’ ), and the imaginary part ( ε” ): Figure 2 The conductivity diagrams of the layered coordination-derived Cu atom-confined highly efficient microwave absorbers prepared in Test Comparative Examples 1-5 of the present invention and PC-S in Test Comparative Example 6 are shown. Figure 2It can be observed that the conductivities of Cu@PEDOT-1-500, Cu@PEDOT-2-500, Cu@PEDOT-3-500, Cu@PEDOT-3-400, Cu@PEDOT-3-600 and PC-S are 0.115 S / m, 0.169 S / m, 0.134 S / m, 0.080 S / m, 0.063 S / m and 0.107 S / m respectively. As the amount of copper increases, the conductivity of the material gradually increases, while the conductivity shows a trend of increasing first and then decreasing with the change of pyrolysis temperature. This is because under the influence of high temperature, the confined copper ions are more likely to escape and form nanoparticles or clusters, resulting in a decrease in conductivity. Further, from Figure 3 It can be found that the enhanced electromagnetic wave absorption ability of the wave-absorbing material modified by layer-by-layer coordination-derived Cu atom confinement mainly comes from enhanced polarization loss rather than conduction loss.

[0052] Test Example 3 Perform performance tests on the layer-by-layer coordination-derived Cu atom-confined high-efficiency wave-absorbing agents prepared in Test Comparative Examples 1-5 and PC-S prepared in Test Comparative Example 6, and test the electromagnetic parameters: Use a network analyzer (VNA, N5245A, Agilent, USA) to measure the electromagnetic parameters of the layer-by-layer coordination-derived Cu atom-confined high-efficiency wave-absorbing materials prepared in Test Comparative Examples 1-5 and PC-S in Test Comparative Example 6 in the frequency band of 2-18 GHz respectively.

[0053] The mass ratios of the layer-by-layer coordination-derived Cu atom-confined high-efficiency wave-absorbing materials (Cu@PEDOT-1-500, Cu@PEDOT-2-500, Cu@PEDOT-3-500, Cu@PEDOT-3-400 and Cu@PEDOT-3-500) prepared in Test Comparative Examples 1-5 and PC-S in Test Comparative Example 6 to paraffin are both 6:4. All specimens are pressed into a standard annulus ( : 3.04 mm, : 7.00 mm) by the same mold to maintain the certainty of the geometric shape. The thickness of all annuli is kept at 2.3 mm. The Agilent PNA software automatically outputs the relevant electromagnetic parameters according to the Nicolson and Ross and Weir algorithm.

[0054] Figures 4 - 6The electromagnetic wave absorption properties of the materials prepared in Test Comparative Examples 1-3 and Test Comparative Example 6 are shown. The minimum reflection losses of Cu@PEDOT-1-500, Cu@PEDOT-2-500, and Cu@PEDOT-3-500 are -34.26 dB, -34.85 dB, and -63.69 dB respectively, and the maximum effective absorption bandwidths are 2.68, 3.52, and 3.36 GHz respectively. The results show that compared with the minimum reflection loss (-7.31 dB) of PC-S and the frequency band without absorption below -10 dB, the layered coordination-derived Cu atom confinement modification has completely changed the electromagnetic wave absorption ability of the PEDOT material, changing it from low absorption to high absorption.

[0055] Regarding the variation of the electromagnetic wave absorption performance of Cu@PEDOT with the pyrolysis temperature, it is shown in Figures 6 - 8 , it can be observed that the minimum reflection losses of Cu@PEDOT-3-500, Cu@PEDOT-3-400, and Cu@PEDOT-3-600 are -63.69 dB, -11.26 dB, and -8.9 dB respectively, and the maximum effective absorption bandwidths of Cu@PEDOT-3-500 and Cu@PEDOT-3-400 are 3.36 and 1.76 GHz respectively.

[0056] Among the layered coordination-derived Cu atom confinement high-efficiency electromagnetic wave absorption materials of the Cu@PEDOT series, the material corresponding to Test Comparative Example 3 shows the strongest electromagnetic wave absorption performance. Therefore, the metal single atoms modified between the PEDOT layers can significantly improve the electromagnetic wave absorption performance of the material. In addition, through the unique method shown in the present invention - slow oxidative polymerization and coordination synergy, a unique interlayer Cu atom confinement structure can be constructed.

[0057] The present invention provides a layered coordination-derived Cu atom confinement high-efficiency electromagnetic wave absorption material and a preparation method thereof. There are many methods and ways to specifically implement this technical solution. The above description is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented by existing technologies.

[0058] It should be noted that although the above embodiments have been described in this article, this does not limit the patent protection scope of the present invention. Therefore, based on the innovative concept of the present invention, the changes and modifications made to the embodiments described in this article, or the equivalent structural or equivalent process transformations made using the content of the specification and drawings of the present invention, directly or indirectly applying the above technical solutions to other related technical fields, are all included in the patent protection scope of the present invention.

Claims

1. A preparation method of a metal single-atom absorbing agent based on layered coordination derivation, characterized in that, The preparation method comprises the following steps: Step 1: Add the thiophene compound to the metal salt dispersion liquid at a rate of 1-5 ml / min and mix evenly to obtain a polymerization raw material liquid; Step 2: In a nitrogen or inert gas atmosphere, subject the polymerization raw material liquid obtained in Step 1 to heating and stirring and pyrolysis to obtain a metal single-atom wave absorber derived from layered coordination; The metal salt is selected from copper salts, iron salts, and silver salts; the thiophene compound is selected from one of thiophene, 3-methylthiophene, 3,4-ethylenedioxythiophene, dithiophene, or benzothiophene.

2. The preparation method according to claim 1, characterized in that, The metal salt dispersion liquid in Step 1 is obtained by dispersing the metal salt in an organic solvent; the organic solvent is selected from ethanol, methanol, and isopropanol.

3. The preparation method according to claim 1, characterized in that, The metal salt is selected from copper salts; the thiophene compound is selected from 3,4-ethylenedioxythiophene; the copper salt is in terms of Cu 2+ The molar ratio of the copper salt to 3,4-ethylenedioxythiophene is 1:(0.5-2); Alternatively, the metal salt is selected from iron salts; the thiophene compound is selected from 3,4-ethylenedioxythiophene; based on Fe 3+ calculated, the molar ratio of the copper salt to 3,4-ethylenedioxythiophene is 1:(0.5~2); Alternatively, the metal salt is selected from silver salts; the thiophene compound is selected from 3,4-ethylenedioxythiophene; the silver salt is in terms of Ag + The molar ratio of the copper salt to 3,4-ethylenedioxythiophene is 1:(0.5 to 2).

4. The preparation method according to claim 1, characterized in that, The copper salt is selected from copper nitrate, copper chloride, copper sulfate, and copper acetate; the iron salt is selected from ferric chloride and iron p-toluenesulfonate; the silver salt is selected from silver chloride.

5. The preparation method according to claim 1, characterized in that, The heating and stirring in Step 2 means placing the polymerization raw material liquid in a stirrer and heating it at 80-120 °C for 70-80 h.

6. The preparation method according to claim 1, characterized in that, The pyrolysis in Step 2 means heating the heat-treated polymerization raw material liquid to 400-600 °C at a rate of 5-10 °C / min and performing a constant-temperature treatment for 2-6 h.

7. The preparation method according to claim 1, characterized in that, The said preparation method comprises the following steps: Disperse the copper salt in absolute ethanol; disperse the 3,4-ethylenedioxythiophene monomer into the metal salt dispersion liquid at a rate of 1-2 ml / min, and after complete dissolution, obtain a polymerization raw material liquid.

8. Place the polymerization raw material liquid in a nitrogen atmosphere, heat it at 80-120 °C for 70-80 h; then place it in an argon atmosphere and heat it to 400-600 °C at a rate of 5-10 °C / min, and perform a constant-temperature treatment for 2-6 h.

9. A metal single-atom absorbent derived from layered coordination, characterized in that, It is prepared by using the preparation method according to any one of claims 1-7.

10. Application of the metal single-atom absorbing agent based on layered coordination derivative prepared by the preparation method according to any one of claims 1 to 7, characterized in that, Apply the metal single-atom wave absorber derived from layered coordination to the field of electromagnetic wave absorption.

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