Preparation method of acetylene carbon black / tungsten trioxide composite heterostructure thin film for electrodynamic regulation and control of electromagnetic waves

Abstract

The invention discloses a preparation method of an acetylene carbon black / tungsten trioxide composite heterostructure film for electromagnetic wave electrodynamic regulation and control, and relates to the field of electrodynamic regulation and control of electromagnetic interference shielding effectiveness. Preparing an acetylene carbon black / tungsten trioxide composite heterostructure material through a hydrothermal method; and mixing with a polyvinylidene fluoride (PVDF) binder solution, and preparing the acetylene carbon black / tungsten trioxide composite heterostructure film through a film coating method. Cationes are embedded into / separated from tungsten trioxide, so that the tungsten trioxide can be converted among monoclinic phase, orthorhombic phase and cubic phase, the electronic structure of the tungsten trioxide is further modulated, the reflection efficiency is improved, the constructed heterostructure provides a large number of interfaces capable of inducing interface polarization, and the absorption efficiency is improved. And the two synergistically improve the modulation amplitude of the dynamic electromagnetic interference shielding effectiveness.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic interference shielding effectiveness controlled by electric drive, specifically to a self-supporting acetylene black / tungsten trioxide composite heterostructure thin film and its preparation method. Background Technology

[0002] With the advancement of the communication era, the proliferation of miniaturized and precision-driven electronic devices has led to a dramatic increase in electromagnetic pollution. The dynamic operation of contemporary intelligent electronic devices demands complex electromagnetic environments that can change in real time. Therefore, developing lightweight, thin-film, dynamically tunable electromagnetic interference shielding materials with real-time adaptive protection capabilities is crucial. Tungsten trioxide can achieve dynamic and reversible tuning of its crystal phase and conductivity through electrochemically driven hydrogen ion insertion / extraction, thereby modulating reflection efficiency. Constructing heterojunctions with high carrier mobility conductor acetylene black significantly enhances carrier insertion and transport dynamics during the initial electroactivation phase. Furthermore, the thin-film material designed through a composite strategy provides numerous internal interfaces, which induce reversible reconstruction of interface electronic states, forming interface polarization and thus improving absorption efficiency. This synergistic mechanism sets a new paradigm for intelligent electromagnetic interference shielding thin-film materials with broad spectral adaptability and excellent modulation range. Summary of the Invention

[0003] Therefore, the present invention aims to provide an acetylene black / tungsten trioxide composite heterostructure thin film for electromagnetic wave electro-induced dynamic control. This material is constructed by combining tungsten trioxide, which has electrically tunable conductivity, with acetylene black, a conductor with high carrier mobility, to create a heterostructure shielding thin film. This material exhibits excellent dynamic shielding performance for dynamically controlling electromagnetic interference shielding effectiveness.

[0004] This invention discloses a method for preparing an acetylene black / tungsten trioxide composite heterostructure thin film for electromagnetic wave electro-induced dynamic control, comprising the following steps:

[0005] S1. Preparation of acetylene black / tungsten trioxide composite heterostructure material by hydrothermal method;

[0006] S2. Prepare a polyvinylidene fluoride (PVDF) binder solution and prepare an acetylene black / tungsten trioxide composite heterostructure film by coating method.

[0007] Furthermore, the preparation of the acetylene black / tungsten trioxide composite heterostructure material in step S1 includes the following steps:

[0008] a. After preparing a transparent solution from sodium tungstate and deionized water, add hydrochloric acid solution and stir until homogeneous. Then add oxalic acid and stir until a transparent and clear solution is obtained. Finally, add acetylene black powder and stir to obtain a uniform dispersion.

[0009] b. The dispersion was placed in a polytetrafluoroethylene liner and hydrothermally grown at 180°C for 10 h. After stirring, it was centrifuged at 8000 r / min for 5 min and dried at 60°C to obtain an acetylene black / tungsten trioxide composite heterostructure material.

[0010] Further, in step a, after preparing a transparent solution by mixing 1.6 g of sodium tungstate with 20-40 mL of deionized water, 3 mL of hydrochloric acid solution is added and stirred evenly, followed by the addition of 1.8 g of oxalic acid and stirring until a transparent and clear solution is obtained; finally, acetylene black powder is added and stirred to obtain a uniform dispersion; theoretically, the mass ratio of sodium tungstate to added acetylene black is (2.5-8.5):1, for example 2.9:1, 4.3, 5.7:1, 7.1:1, 8.5:1, preferably 5.7:1.

[0011] Furthermore, the preparation of the acetylene black / tungsten trioxide composite heterostructure film in step S2 includes the following steps:

[0012] a. Prepare a PVDF binder by adding 0.2 g of polyvinylidene fluoride (PVDF) powder to 3-4 mL, preferably 3.35 mL, of N-methylpyrrolidone (NMP) solution;

[0013] b. Add acetylene black / tungsten trioxide composite heterostructure material to PVDF adhesive and stir for 4 h, then coat the film. After coating, dry at 35℃ for 12 h to obtain acetylene black / tungsten trioxide composite heterostructure film.

[0014] Furthermore, the mass ratio of the acetylene black / tungsten trioxide composite heterostructure material added in step b to PVDF is 1.5~3.5:1 (preferably 2.5:1).

[0015] The coating was applied with a wet film thickness of approximately 1 mm, and the film thickness after drying was 80.16 μm.

[0016] The acetylene black / tungsten trioxide composite heterostructure film obtained in this invention is used for electro-dynamically controlled electromagnetic interference (EMI) shielding. The process is carried out in an acidic electrolyte; reversible adjustment is performed between 0 and -0.3 V (vs. Ag / AgCl). The EMI shielding effectiveness gradually increases from 0 V to -0.3 V, for example, from 13 dB to 24 dB, while gradually decreasing from 24 dB to 13 dB as the voltage increases from -0.3 V to 0 V. Furthermore, the conductivity is reversibly adjustable between 0 and -0.3 V (vs. Ag / AgCl), with the conductivity gradually increasing from 0 V to -0.3 V and gradually decreasing as the voltage increases from -0.3 V to 0 V.

[0017] The beneficial effects of this invention are: This invention discloses a method for preparing and applying an acetylene black / tungsten trioxide composite heterostructure thin film for electromagnetic wave electro-induced dynamic control. Tungsten trioxide, which has electrically driven cation insertion / extraction modulation conductivity characteristics, is combined with acetylene black, a conductor with high carrier mobility, to construct a heterostructure thin film, namely an acetylene black / tungsten trioxide composite heterostructure thin film (AB / H). x WO3). The insertion / extraction of cations within tungsten trioxide allows it to transition between monoclinic, orthorhombic, and cubic phases, further modulating its electronic structure and improving reflection efficiency. The constructed heterostructure provides numerous interfaces that can induce interfacial polarization, enhancing absorption efficiency. Both work synergistically to improve the modulation amplitude of dynamic electromagnetic interference shielding effectiveness. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0019] Figure 1 AB / H prepared in Example 3 of this invention x X-ray diffraction pattern of WO3.

[0020] Figure 2 AB / H prepared in Example 3 of this invention x Scanning electron microscope images of WO3 in (a) plane and (b) cross section.

[0021] Figure 3 AB / H prepared in Example 3 of this invention x WO3 electromagnetic interference shielding overall effectiveness diagram as voltage varies.

[0022] Figure 4 AB / H prepared in Example 3 of this invention x Electromagnetic interference shielding reflection effectiveness (SE) of WO3 R ), absorption efficiency (SE) A Total Effectiveness (SE) T )picture.

[0023] Figure 5 AB / H prepared in Example 3 of this invention x X-ray diffraction pattern of WO3 as a function of voltage.

[0024] Figure 6 AB / H prepared in Example 3 of this invention x Conductivity of WO3 as a function of voltage. Detailed Implementation

[0025] This embodiment presents an acetylene black / tungsten trioxide composite heterostructure thin film for electromagnetic wave electro-induced dynamic control. The material is a heterostructure formed by combining tungsten trioxide, which has electrically driven cation insertion / extraction modulation conductivity characteristics, with acetylene black, a conductor with high carrier mobility. + Insertion drives tungsten trioxide from the initial monoclinic phase (m-WO3) to the tetragonal phase (tH). x WO3) then to cubic phase (CH) x The controllable transformation of WO3 triggers a dynamic response in the valence electrons and work function of the material, leading to a reversible increase in carrier density and achieving tunable reflection shielding efficiency. + The insertion and phase transition of tungsten trioxide induce a large number of dipoles in AB / H x A strong polarization region is formed at the WO3 interface, which significantly modulates the absorption and shielding efficiency.

[0026] This embodiment describes a method for preparing an acetylene black / tungsten trioxide composite heterostructure thin film for electromagnetic wave electro-induced dynamic control, comprising the following steps:

[0027] S1. Steps for preparing acetylene black / tungsten trioxide composite heterostructure materials by hydrothermal method;

[0028] S2. Prepare a polyvinylidene fluoride (PVDF) binder solution and prepare an acetylene black / tungsten trioxide composite heterostructure film by coating method.

[0029] In this embodiment, step S1, the preparation of the acetylene black / tungsten trioxide composite heterostructure material includes the following steps:

[0030] a. Prepare a transparent solution by mixing 1.6 g sodium tungstate and 30 mL deionized water, add 3 mL hydrochloric acid solution and stir until homogeneous, then add 1.8 g oxalic acid and stir until a transparent and clear solution is obtained, and finally add acetylene black powder and stir to obtain a uniform dispersion.

[0031] b. The dispersion was placed in a polytetrafluoroethylene liner and hydrothermally grown at 180 °C for 10 h. After stirring, it was centrifuged at 8000 r / min for 5 min and dried at 60 °C to obtain an acetylene black / tungsten trioxide composite heterostructure material.

[0032] In this embodiment, the mass ratio of sodium tungstate to added acetylene black in step a is 2.9, 4.3, 5.7, 7.1, 8.5:1 (preferably 5.7:1).

[0033] In this embodiment, step S2, the preparation of the acetylene black / tungsten trioxide composite heterostructure film includes the following steps:

[0034] a. Prepare PVDF binder by adding 0.2 g of polyvinylidene fluoride (PVDF) powder to 3.35 mL of N-methylpyrrolidone (NMP) solution.

[0035] b. Add acetylene black / tungsten trioxide composite heterostructure material to PVDF adhesive and stir for 4 h. The coating thickness is 1 mm. After coating, dry at 35 ℃ for 12 h to obtain acetylene black / tungsten trioxide composite heterostructure film.

[0036] In this embodiment, the mass ratio of the acetylene black / tungsten trioxide composite heterostructure material added in step b to the mass of PVDF is 1.5~3.5:1 (preferably 2.5:1), and the film thickness of the dried film material is 80.16 μm.

[0037] The shielding material prepared in the above embodiments has the following advantages compared with the prior art:

[0038] (1) The synthesized material can dynamically regulate the electromagnetic interference shielding effectiveness during the process of electrically driven hydrogen ion insertion / extraction.

[0039] (2) The acetylene black / tungsten trioxide composite heterostructure thin film material exhibits excellent total shielding effectiveness modulation amplitude and thickness-normalized total shielding effectiveness modulation amplitude. It can achieve dynamic modulation of shielding effectiveness from 13.6 dB to 24.0 dB within a voltage range of 0 to -0.3 V, with an amplitude of 10.4 dB. The thickness-normalized shielding modulation amplitude reaches 130 dB mm. -1 .

[0040] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0041] Example 1:

[0042] Step 1: Acetylene black / tungsten trioxide composite heterostructure material:

[0043] a. Prepare a transparent solution by mixing 1.6 g sodium tungstate and 30 mL deionized water, add 3 mL hydrochloric acid solution and stir until homogeneous, add 1.8 g oxalic acid and stir until a transparent and clear solution is obtained, then add 0.56 g acetylene black powder and stir to obtain a uniform dispersion.

[0044] b. The dispersion was placed in a polytetrafluoroethylene liner and hydrothermally grown at 180 °C for 10 h. After stirring, it was centrifuged at 8000 r / min for 5 min and dried at 60 °C to obtain an acetylene black / tungsten trioxide composite heterostructure material.

[0045] Step 2: Acetylene black / tungsten trioxide composite heterostructure film:

[0046] a. Prepare PVDF binder by adding 0.2 g of polyvinylidene fluoride (PVDF) powder to 3.35 mL of N-methylpyrrolidone (NMP) solution.

[0047] b. Add 0.3 g of tungsten trioxide and acetylene black composite heterostructure material to 3.35 mL of PVDF adhesive and stir for 4 h. After coating, dry at 35 ℃ for 12 h to obtain acetylene black / tungsten trioxide composite heterostructure film.

[0048] Example 2:

[0049] Step 1: Acetylene black / tungsten trioxide composite heterostructure material:

[0050] a. Prepare a transparent solution by mixing 1.6 g sodium tungstate and 30 mL deionized water, add 3 mL hydrochloric acid solution and stir until homogeneous, add 1.8 g oxalic acid and stir until a transparent and clear solution is obtained, then add 0.37 g acetylene black powder and stir to obtain a uniform dispersion.

[0051] b. The dispersion was placed in a polytetrafluoroethylene liner and hydrothermally grown at 180 °C for 10 h. After stirring, it was centrifuged at 8000 r / min for 5 min and dried at 60 °C to obtain an acetylene black / tungsten trioxide composite heterostructure material.

[0052] Step 2: Acetylene black / tungsten trioxide composite heterostructure film:

[0053] a. Prepare PVDF binder by adding 0.2 g of polyvinylidene fluoride (PVDF) powder to 3.35 mL of N-methylpyrrolidone (NMP) solution.

[0054] b. Add 0.4 g of tungsten trioxide and acetylene black composite heterostructure material to 3.35 mL of PVDF adhesive and stir for 4 h. After coating, dry at 35 ℃ for 12 h to obtain acetylene black / tungsten trioxide composite heterostructure film.

[0055] Example 3 (Optimal):

[0056] Step 1: Acetylene black / tungsten trioxide composite heterostructure material:

[0057] a. Prepare a transparent solution by mixing 1.6 g sodium tungstate and 30 mL deionized water, add 3 mL hydrochloric acid solution and stir until homogeneous, add 1.8 g oxalic acid and stir until a transparent and clear solution is obtained, then add 0.28 g acetylene black powder and stir to obtain a uniform dispersion.

[0058] b. The dispersion was placed in a polytetrafluoroethylene liner and hydrothermally grown at 180 °C for 10 h. After stirring, it was centrifuged at 8000 r / min for 5 min and dried at 60 °C to obtain an acetylene black / tungsten trioxide composite heterostructure material.

[0059] Step 2: Acetylene black / tungsten trioxide composite heterostructure film:

[0060] a. Prepare PVDF binder by adding 0.2 g of polyvinylidene fluoride (PVDF) powder to 3.35 mL of N-methylpyrrolidone (NMP) solution.

[0061] b. Add 0.5 g of tungsten trioxide and acetylene black composite heterostructure material to 3.35 mL of PVDF adhesive and stir for 4 h. After coating, dry at 35 ℃ for 12 h to obtain acetylene black / tungsten trioxide composite heterostructure film.

[0062] Example 4:

[0063] Step 1: Acetylene black / tungsten trioxide composite heterostructure material:

[0064] a. Prepare a transparent solution by mixing 1.6 g sodium tungstate and 30 mL deionized water, add 3 mL hydrochloric acid solution and stir until homogeneous, add 1.8 g oxalic acid and stir until a transparent and clear solution is obtained, then add 0.22 g acetylene black powder and stir to obtain a uniform dispersion.

[0065] b. The dispersion was placed in a polytetrafluoroethylene liner and hydrothermally grown at 180 °C for 10 h. After stirring, it was centrifuged at 8000 r / min for 5 min and dried at 60 °C to obtain an acetylene black / tungsten trioxide composite heterostructure material.

[0066] Step 2: Acetylene black / tungsten trioxide composite heterostructure film:

[0067] a. Prepare PVDF binder by adding 0.2 g of polyvinylidene fluoride (PVDF) powder to 3.35 mL of N-methylpyrrolidone (NMP) solution.

[0068] b. Add 0.6 g of tungsten trioxide and acetylene black composite heterostructure material to 3.35 mL of PVDF adhesive and stir for 4 h. After coating, dry at 35 ℃ for 12 h to obtain acetylene black / tungsten trioxide composite heterostructure film.

[0069] Example 5:

[0070] Step 1: Acetylene black / tungsten trioxide composite heterostructure material:

[0071] a. Prepare a transparent solution by mixing 1.6 g sodium tungstate and 30 mL deionized water, add 3 mL hydrochloric acid solution and stir until homogeneous, add 1.8 g oxalic acid and stir until a transparent and clear solution is obtained, then add 0.19 g acetylene black powder and stir to obtain a uniform dispersion.

[0072] b. The dispersion was placed in a polytetrafluoroethylene liner and hydrothermally grown at 180 °C for 10 h. After stirring, it was centrifuged at 8000 r / min for 5 min and dried at 60 °C to obtain an acetylene black / tungsten trioxide composite heterostructure material.

[0073] Step 2: Acetylene black / tungsten trioxide composite heterostructure film:

[0074] a. Prepare PVDF binder by adding 0.2 g of polyvinylidene fluoride (PVDF) powder to 3.35 mL of N-methylpyrrolidone (NMP) solution.

[0075] b. Add 0.7 g of tungsten trioxide and acetylene black composite heterostructure material to 3.35 mL of PVDF adhesive and stir for 4 h. After coating, dry at 35 ℃ for 12 h to obtain acetylene black / tungsten trioxide composite heterostructure film.

[0076] Comparative Example 1:

[0077] Step 1, tungsten trioxide material:

[0078] a. Prepare a transparent solution by mixing 1.6 g of sodium tungstate and 30 mL of deionized water, then add 3 mL of hydrochloric acid solution and stir until homogeneous. Finally, add 1.8 g of oxalic acid and stir until a clear and transparent solution is obtained.

[0079] b. The clarified solution was placed in a polytetrafluoroethylene liner and hydrothermally grown at 180 °C for 10 h. After stirring, it was centrifuged at 8000 r / min for 5 min and dried at 60 °C to obtain tungsten trioxide material.

[0080] Step 2, tungsten trioxide thin film:

[0081] a. Prepare PVDF binder by adding 0.2 g of polyvinylidene fluoride (PVDF) powder to 3.35 mL of N-methylpyrrolidone (NMP) solution.

[0082] b. Add 2 g of tungsten trioxide material to 3.35 mL of PVDF adhesive and stir for 4 h. After coating, dry at 35 ℃ for 12 h to obtain a tungsten trioxide film.

[0083] Comparative Example 2:

[0084] The first step involves adding 0.2 g of polyvinylidene fluoride (PVDF) powder to 3.35 mL of N-methylpyrrolidone (NMP) solution to prepare PVDF binder.

[0085] The second step involves adding 0.1 g of acetylene black material to 3.35 mL of PVDF adhesive and stirring for 4 h. After coating, the mixture is dried at 35 ℃ for 12 h to obtain an acetylene black film.

[0086] The thin film materials prepared in Example 3 and Comparative Examples 1-2 were subjected to X-ray scanning, as detailed in the figures below. Figure 1 As shown. By Figure 1 It can be seen that all samples have sharp and obvious characteristic peaks belonging to tungsten trioxide. Due to the low crystallinity of acetylene black, it was not clearly shown in the sample of Example 3.

[0087] The AB / H prepared in Example 3 x Scanning electron microscopy images of WO3 thin film materials are shown in the attached image. Figure 2 As shown. By Figure 2 It can be observed that tungsten trioxide nanosheets and acetylene carbon black nanoparticles were successfully combined. Figure 2 b shows that the thickness (d) of the acetylene black / tungsten trioxide composite heterostructure thin film material is 80.16 μm.

[0088] test:

[0089] 1. The thin film material prepared in Example 3 was subjected to an electro-induced dynamic electromagnetic interference shielding effectiveness test. The specific steps are as follows:

[0090] Step 1: Cut the thin film material prepared in Example 3 into 1.5 × 3.5 cm pieces. 2 Size, and used as working electrode.

[0091] The second step is to use AB / H x A WO3 thin film was used as the working electrode, an Ag / AgCl electrode as the reference electrode, and a Pt sheet as the counter electrode. 0.5 M H2SO4 was used as the electrolyte. The AB / H2SO4 electrode was subjected to electrolysis in a three-electrode electrolytic cell. x Apply a 0 to -0.3 V (vs. Ag / AgCl) cyclic voltage to WO3.

[0092] The third step is to measure the AB / H ratio when different voltages are applied during the electrochemical process. x Overall electromagnetic interference shielding effectiveness (SE) of WO3 thin film T X-ray scans and conductivity data are shown in the attached image. Figures 3-6 .

[0093] The AB / H prepared in Example 3 x The overall shielding effectiveness (SE) of WO3 thin film samples under electrically driven dynamic electromagnetic interference in the X-band (8.2-12.4 GHz) was measured. T For details, please see the test. Figure 3 As shown. By Figure 3 As can be seen from a, during the process of the voltage dropping from 0 V to -0.3 V, H + Embedded into the WO3 lattice, the electromagnetic interference shielding effectiveness is enhanced. Figure 3 As can be seen from b, during the process of voltage increasing from -0.3 V to 0 V, H + Withdrawal weakens electromagnetic interference shielding effectiveness, based on AB / H x WO3 thin film materials exhibit reversible potential-dependent modulation of electromagnetic interference shielding effectiveness in the X-band.

[0094] The AB / H prepared in Example 3 x Total electromagnetic interference shielding effectiveness (SE) of WO3 thin film samples under different voltage driving at 8.2 GHz frequency. T ), reflectivity (SE) R Absorption efficiency (SE) A For specific numerical values, please refer to [the relevant documentation / reference]. Figure 4 As shown, SE R and SE A The sum of the values ​​is SE T .Depend on Figure 4 It can be seen that in AB / H x During the reversible potential modulation process from 0 V to -0.3 V, the SE of WO3 thin film material... R It changed from 3.7 dB to 6.0 dB and then back to 3.8 dB, SE A It changed from 9.9 dB to 18.0 dB and then back to 9.7 dB, SE T The modulation amplitude changed from 13.6 dB to 24.0 dB and then back to 13.5 dB, with a total shielding effectiveness modulation amplitude of 10.4 dB (ΔSE). T = 10.4 dB), thickness-normalized shielding modulation amplitude (ΔSE) T / d) reaches 130 dB mm -1 Absorption efficiency is the main contributing factor to the overall shielding effectiveness.

[0095] The AB / H prepared in Example 3 x X-ray scanning of WO3 thin film samples under different voltage driving conditions is shown in the figure below. Figure 5 As shown. By Figure 5 It can be seen that when the voltage drops from 0 V to -0.3 V, H + Embedded into the WO3 lattice, WO3 transforms from the initial monoclinic phase m-WO3 to the tetragonal phase (tH). x WO3) eventually transforms into the cubic phase (CH3). x WO3). When the voltage rises from -0.3 V to 0 V, H +Upon exiting, the cubic phase reversibly transforms back into the monoclinic phase.

[0096] The AB / H prepared in Example 3 x Conductivity tests were performed on WO3 thin film samples under different voltage driving conditions; see details below. Figure 6 As shown. By Figure 5 It can be seen that during the process of voltage dropping from 0 V to -0.3 V, H + When embedded in the WO3 lattice, the conductivity increases, the voltage rises back to 0 V, and the conductivity decreases.

Claims

1. A method for preparing an acetylene black / tungsten trioxide composite heterostructure thin film, characterized in that, The steps include the following: S1. Steps for preparing acetylene black / tungsten trioxide composite heterostructure materials by hydrothermal method; S2. Prepare a polyvinylidene fluoride (PVDF) binder solution and prepare an acetylene black / tungsten trioxide composite heterostructure film by coating method.

2. The method according to claim 1, characterized in that, The preparation of the acetylene black / tungsten trioxide composite heterostructure material in step S1 includes the following steps: a. After preparing a transparent solution from sodium tungstate and deionized water, add hydrochloric acid solution and stir until homogeneous. Then add oxalic acid and stir until a transparent and clear solution is obtained. Finally, add acetylene black powder and stir to obtain a uniform dispersion. b. The dispersion was placed in a polytetrafluoroethylene liner and hydrothermally grown at 180°C for 10 h. After stirring, it was centrifuged at 8000 r / min for 5 min and dried at 60°C to obtain an acetylene black / tungsten trioxide composite heterostructure material. In step a, after preparing a transparent solution by mixing 1.6 g of sodium tungstate with 20-40 mL of deionized water, add 3 mL of hydrochloric acid solution and stir until homogeneous. Then add 1.8 g of oxalic acid and stir until a transparent and clear solution is obtained. Finally, add acetylene black powder and stir to obtain a uniform dispersion. Theoretically, the mass ratio of sodium tungstate to added acetylene black is (2.5-8.5):1, preferably 5.7:

1.

3. The method according to claim 1, characterized in that, The preparation of the acetylene black / tungsten trioxide composite heterostructure film in step S2 includes the following steps: a. Prepare a PVDF binder by adding 0.2 g of polyvinylidene fluoride (PVDF) powder to 3-4 mL, preferably 3.35 mL, of N-methylpyrrolidone (NMP) solution; b. Add acetylene black / tungsten trioxide composite heterostructure material to PVDF adhesive and stir for 4 h, then coat the film. After coating, dry at 35℃ for 12 h to obtain acetylene black / tungsten trioxide composite heterostructure film.

4. The mass ratio of the acetylene black / tungsten trioxide composite heterostructure material added in step b to PVDF is 1.5~3.5:1 (preferably 2.5:1).

5. The method according to claim 1, characterized in that, The coating was applied with a wet film thickness of 1 mm, and the film thickness of the dried film material was 80.16 μm.

6. The thin film prepared according to any one of claims 1-4.

7. The application of the thin film prepared by the method according to any one of claims 1-4 for electro-dynamically modulated electromagnetic interference shielding.

8. The application according to claim 6 is carried out in an acidic electrolyte.

9. The application according to claim 7, wherein the electromagnetic interference shielding effectiveness is reversibly adjustable between 0 and -0.3 V (vs. Ag / AgCl), and gradually increases from 0 V to -0.3 V, while gradually decreasing as the voltage increases from -0.3 V to 0 V; further, the conductivity is reversibly adjustable between 0 and -0.3 V (vs. Ag / AgCl), gradually increasing from 0 V to -0.3 V, while gradually decreasing as the voltage increases from -0.3 V to 0 V.

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