Energy-containing polynitrogen framework derived silver-doped porous thin film as well as preparation method and application of energy-containing polynitrogen framework derived silver-doped porous thin film

Abstract

The invention discloses an energetic polytriazole framework derived silver-doped porous film and a preparation method and application thereof.The preparation method comprises the steps that firstly, a triazole framework is ground and then heated, subjected to heat preservation and cooled in the nitrogen atmosphere, and a carbonized triazole framework is obtained; carrying out ultrasonic treatment on a matrix material and the carbonized triazole framework, stirring, and uniformly mixing; and after silver salt is added for dark treatment, silver ions are reduced into nano-silver particles through illumination, stirring is carried out while illumination is carried out, reduction is evenly distributed, a silver-doped porous material solution is obtained, vacuum-assisted filtering is carried out, and drying is carried out to obtain the energetic polynitrogen framework derived silver-doped porous film. According to the invention, the triazole framework is combined with the bacterial cellulose, so that the prepared porous cellulose film has the advantages of large specific surface area, rich pore structure, adjustable structure and the like, and also has the advantage of good mechanical property, the synergistic effect of the nano-silver particles and the porous structure of the material is realized, and the shielding performance of the material can reach-60dB or above.

Description

Technical Field

[0001] The invention relates to the technical field of electromagnetic wave shielding materials, and in particular to an energetic polynitrogen azole framework-derived silver-doped porous film, and a preparation method and application thereof. Background Art

[0002] The rapid innovation of the electronics industry has intensified the development of magnetic radiation in the surrounding environment, thus bringing about serious information security issues and even posing a huge threat to human health. EMI shielding is an important and effective technology to limit the destructive electromagnetic radiation of EMI. The conductive shell of the original EMI shielding device is named Faraday cage, which is a conductive shell with zero electric field inside. According to this principle, metal materials including stainless steel, copper, aluminum and silver are made into shielding cabinets, foil plates, conductive coatings and fabrics. However, this material is always limited by high defect density, easy corrosion and high cost. Carbon-based materials including carbon black, graphene and carbon nanotubes have the characteristics of low density, chemical resistance and excellent electrical properties. They have good conductivity and are therefore often filled into polymers to make lightweight and flexible conductive polymer composites. According to the shielding principle of electromagnetic wave shielding materials, the impedance of conductive materials and free space is not matched, and part of the incident electromagnetic waves are reflected on the surface of the material. The higher the conductivity of the material, the lower the impedance matching degree with free space, and the greater the power of the reflected and attenuated electromagnetic waves, so high conductivity is an important factor in electromagnetic wave shielding materials.

[0003] Porous solid materials with nanoscale porosity have extremely high specific surface areas and have long been used for applications in adsorption, separation, exchange, and heterogeneous catalysis. In this family, metal-organic frameworks (MOFs) have attracted attention due to their large specific surface area, variable pore size, and the ability to control the chemical properties of organic ligands to achieve specific and selective binding. While developing new MOFs and characterizing their properties, people have been working hard to create mesoscopic superstructures of MOFs to enhance the performance of MOFs and increase their processability in different applications. The main method of introducing new functions is to conjugate MOFs nano- or microcrystals to other materials, especially to introduce MOFs into polymer fibers, which can take advantage of highly developed technological capabilities to produce composite materials with excellent performance and broad application prospects. The patent with publication number CN117604720A combines triazole framework materials with electrospinning technology to prepare nanofiber film materials with shielding performance of more than -50dB, and the shielding mechanism is mainly absorption. It uses electrospinning to form nanofibers and then performs heat treatment. This treatment method is mainly to make polyacrylonitrile fibers undergo stable fiberization at a certain temperature and improve the density of the material fibers. However, the fiber material prepared in this way is easily damaged because there is no polymer protection on the outer layer, and its tensile strength is poor. Summary of the invention

[0004] The purpose of the present invention is to provide an energetic nitrogen azole framework derived silver doped porous film;

[0005] Another object of the present invention is to provide a method for preparing an energetic nitrogen azole framework-derived silver-doped porous film;

[0006] The invention also provides an application of an energetic polynitrogen azole framework-derived silver-doped porous film in electromagnetic shielding.

[0007] The technical solution adopted to achieve the purpose of the present invention is:

[0008] A method for preparing an energetic polynitrogen azole framework-derived silver-doped porous film comprises the following steps:

[0009] Step 1, grinding the triazole framework, heating and heat preservation under protective gas, and obtaining a carbonized triazole framework after cooling;

[0010] Step 2, dispersing the matrix material in a solvent, and uniformly mixing it with the carbonized triazole framework obtained in step 1 to obtain a mixed solution;

[0011] Step 3, uniformly dispersing the silver salt in the mixed solution obtained in step 2, and after light protection, irradiating the solution with light to reduce the silver ions to nanosilver particles, thereby obtaining a silver-doped porous material solution;

[0012] Step 4, subjecting the silver-doped porous material solution obtained in step 3 to vacuum-assisted filtration, and drying to obtain an energetic polynitrogen azole framework-derived silver-doped porous film.

[0013] In the above technical scheme, the preparation method of the triazole framework in step 1 is:

[0014] Weigh ZnCl 2 Dissolve in a mixture solvent of ethanol, water, ammonium hydroxide and N,N-dimethylformamide, add 1H-1,2,3-triazole dropwise to the mixture, stir at room temperature, filter and dry to obtain a white powder triazole framework.

[0015] In the above technical solution, the heating temperature of the triazole framework in step 1 is 800-1000° C., and the insulation time is 1-3 hours.

[0016] In the above technical solution, in step 2, the matrix material is bacterial cellulose, polyamide, polyvinyl alcohol or polyethylene terephthalate, and the mass ratio of the matrix material to the carbonized triazole framework is 0.8-1.5.

[0017] In the above technical solution, the concentration of the bacterial cellulose dispersion is 5-9 mg / mL.

[0018] In the above technical solution, the silver salt in step 3 is selected from any one of silver nitrate, silver acetate, silver chlorate and silver perchlorate.

[0019] In the above technical solution, the concentration of the silver salt is 50-500 mM.

[0020] In the above technical solution, the illumination condition in step 3 is ultraviolet illumination or xenon lamp illumination, the illumination time is not less than 1 hour, and the stirring time is not less than 1 hour.

[0021] Another aspect of the present invention also includes an energetic polynitrogen azole framework-derived silver-doped porous film obtained by the preparation method.

[0022] Another aspect of the present invention also includes the use of the energetic polynitrogen azole framework-derived silver-doped porous film in electromagnetic shielding.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention adopts vacuum-assisted filtration technology to make the interior of the film material have a densely stacked porous structure, providing more paths for multiple reflections of electromagnetic waves.

[0025] 2. Different from the shielding mechanism based on absorption in publication number CN117604720A, although its shielding performance can reach above -50dB, it may be due to the nanofiber structure brought by the electrostatic spinning process, which is conducive to multiple reflections of electromagnetic waves inside the material. The present invention uses MOFs as a precursor, reduces silver nanoparticles by simple ultraviolet light, and only loads silver during the illumination process. After carbonization, the nanosilver particles are relatively evenly distributed on the triazole framework. The prepared energetic polyazole framework-derived silver-doped porous film has the advantages of rich pore structure, large specific surface area, and adjustable structure. At the same time, combined with vacuum-assisted filtration technology, the silver nanoparticles are better combined with the porous structure, which enhances the conductivity of the material. The prepared energetic polyazole framework-derived silver-doped porous film has a shielding performance of above -60dB.

[0026] 3. In the present invention, the heat treatment stage of the triazole framework at 800-1000°C is performed after the triazole framework is prepared and before it is mixed with bacterial cellulose. The heat treatment is performed fully with the bacterial cellulose. The purpose of the heat treatment in advance is to retain the mechanical properties brought by the bacterial cellulose. At the same time, a vacuum-assisted filtration process is used to improve the bonding strength between the bacterial celluloses, so that the obtained energetic polyazole framework-derived silver-doped porous film has a high porosity and strong tensile strength and deformation resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a flow chart of the silver-doped porous film derived from the energetic polynitrogen azole framework.

[0028] Figure 2 The XRD diagrams are of the energetic polynitrogen azole framework-derived silver-doped porous films BMA-1000, BMA-900, BMA-800 and comparative example BC of the present invention.

[0029] Figure 3 This is a SEM picture of the silver-doped porous film derived from the energetic polynitrogen azole framework of the present invention.

[0030] Figure 4 It is a graph showing the electromagnetic wave shielding performance of the energetic polynitrogen azole framework-derived silver-doped porous films BMA-1000, BMA-900, BMA-800 and the comparative example BC of the present invention.

[0031] Figure 5 It is a diagram of the electromagnetic wave shielding mechanism of the energetic polynitrogen azole framework-derived silver-doped porous films BMA-1000, BMA-900, BMA-800 and the comparative example BC of the present invention.

[0032] Figure 6 It is a comparison chart of the mechanical properties of the energetic polynitrogen azole framework-derived silver-doped porous film BMA-1000 of the present invention and the comparative example BC. DETAILED DESCRIPTION

[0033] The method for preparing a vacuum-assisted filtration energetic polyazole framework-derived silver-doped porous film provided by the present invention reduces silver nanoparticles by simple ultraviolet light irradiation, only loads silver during the irradiation process, and the nanosilver particles are relatively evenly distributed on the triazole framework after carbonization. By incorporating silver nanoparticles, the conductivity of the material is improved, and combined with the vacuum-assisted filtration process, the silver nanoparticles are closely combined with the porous structure of MOFs. The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] Example 1

[0035] Reference Figure 1 , a method for preparing an energetic polynitrogen azole framework-derived porous film, the specific steps are as follows:

[0036] Step 1, weigh 5g ZnCl 2 Dissolved in a mixture solvent of 50 mL ethanol, 75 mL water, 20 mL of 25% to 28% ammonium hydroxide and 50 mL N, N-dimethylformamide, 6.26 mL 1H-1,2,3-triazole was added dropwise to the mixture, stirred at room temperature for 24 h, the white product was filtered out, washed with ethanol, and dried at 80 ° C for 8 h to obtain a triazole framework;

[0037] Step 2, grinding the triazole framework obtained in step 1 into fine powder, placing the triazole framework powder in a porcelain boat, placing it in a programmable temperature-controlled tube furnace under a nitrogen atmosphere, heating it to 1000° C. at a heating rate of 5° C. / min, keeping it warm for 2 hours, and cooling it to room temperature to obtain a carbonized triazole framework;

[0038] Step 3, adding 30.6 mL of bacterial cellulose dispersion with a mass fraction of 0.8% into 35 mL of deionized water, heating to 50° C. and ultrasonicating for 30 min, and then stirring for 4 h, taking 0.3 g of the carbonized triazole framework, ultrasonicating and stirring, and mixing and stirring for 24 h;

[0039] Step 4, adding 300 mM silver nitrate to the solution obtained in step 3, wrapping the beaker with tin foil to avoid light, irradiating with ultraviolet light for 1 hour on a magnetic stirrer to reduce the silver ions to nanosilver particles, and stirring at room temperature while irradiating with light to uniformly reduce and distribute the nanosilver particles to obtain a silver-doped porous cellulose solution;

[0040] Step 5, vacuum-assisted filtration and drying of the solution obtained in step 4 to obtain an energetic polynitrogen azole framework-derived porous film with good mechanical properties, recorded as BMA-1000;

[0041] Step 6, testing the electromagnetic wave shielding performance of the energetic polynitrogen azole framework-derived porous film.

[0042] Example 2

[0043] A method for preparing an energetic polynitrogen azole framework-derived porous film comprises the following steps:

[0044] Step 1, weigh 5g ZnCl 2 Dissolved in a mixture solvent of 50 mL ethanol, 75 mL water, 20 mL of 25% to 28% ammonium hydroxide and 50 mL N, N-dimethylformamide, 6.26 mL 1H-1,2,3-triazole was added dropwise to the mixture, stirred at room temperature for 24 h, the white product was filtered out, washed with ethanol, and dried at 80 ° C for 8 h to obtain a triazole framework;

[0045] Step 2, grinding the triazole framework obtained in step 1 into fine powder, placing the triazole framework powder in a porcelain boat, placing it in a programmable temperature-controlled tube furnace under a nitrogen atmosphere, heating it to 900° C. at a heating rate of 5° C. / min, keeping it warm for 2 hours, and cooling it to room temperature to obtain a carbonized triazole framework;

[0046] Step 3, add 30.6 mL of 0.8% polyvinyl alcohol to 35 mL of deionized water, heat to 50°C, perform ultrasonication for 30 min, and then stir for 4 h, take 0.3 g of the carbonized triazole framework, perform ultrasonication and stirring, mix and stir for 24 h, and stir evenly;

[0047] Step 4, adding 200 mM silver acetate to the solution obtained in step 3, wrapping the beaker with tin foil to avoid light, irradiating with ultraviolet light for 1 hour on a magnetic stirrer to reduce the silver ions to nanosilver particles, and stirring at room temperature while irradiating with light to uniformly reduce and distribute the nanosilver particles to obtain a silver-doped porous material solution;

[0048] Step 5, vacuum-assisted filtration is performed on the solution obtained in step 4 to obtain an energetic polynitrogen azole framework-derived porous film with good mechanical properties, which is recorded as BMA-900;

[0049] Step 6, testing the electromagnetic wave shielding performance of the energetic polynitrogen azole framework-derived porous film.

[0050] Example 3

[0051] A method for preparing an energetic polynitrogen azole framework-derived porous film comprises the following steps:

[0052] Step 1, weigh 5g ZnCl 2 Dissolved in a mixture solvent of 50 mL ethanol, 75 mL water, 20 mL of 25% to 28% ammonium hydroxide and 50 mL N, N-dimethylformamide, 6.26 mL 1H-1,2,3-triazole was added dropwise to the mixture, stirred at room temperature for 24 h, the white product was filtered out, washed with ethanol, and dried at 80 ° C for 8 h to obtain a triazole framework;

[0053] Step 2, grinding the triazole framework obtained in step 1 into fine powder, placing the triazole framework powder in a porcelain boat, placing it in a programmable temperature-controlled tube furnace under a nitrogen atmosphere, heating it to 800° C. at a heating rate of 5° C. / min, keeping it warm for 2 hours, and cooling it to room temperature to obtain a carbonized triazole framework;

[0054] Step 3, add 30.6 mL of 0.8% polyamide to 35 mL of deionized water, heat to 50° C., perform ultrasonication for 30 min, and then stir for 4 h, take 0.3 g of the carbonized triazole framework, perform ultrasonication and stirring, mix and stir for 24 h, and stir evenly;

[0055] Step 4, adding 100 mM silver chlorate to the solution obtained in step 3, wrapping the beaker with tin foil to avoid light, irradiating with ultraviolet light for 1 hour on a magnetic stirrer to reduce the silver ions to nanosilver particles, and stirring at room temperature while irradiating with light to uniformly reduce and distribute the nanosilver particles to obtain a silver-doped porous material solution;

[0056] Step 5, vacuum-assisted filtration is performed on the solution obtained in step 4 to obtain an energetic polynitrogen azole framework-derived porous film with good mechanical properties, which is recorded as BMA-800;

[0057] Step 6, testing the electromagnetic wave shielding performance of the energetic polynitrogen azole framework-derived porous film.

[0058] Example 4

[0059] A method for preparing an energetic polynitrogen azole framework-derived porous film comprises the following steps:

[0060] Step 1, weigh 5g ZnCl 2 Dissolved in a mixture solvent of 50 mL ethanol, 75 mL water, 20 mL of 25% to 28% ammonium hydroxide and 50 mL N, N-dimethylformamide, 6.26 mL 1H-1,2,3-triazole was added dropwise to the mixture, stirred at room temperature for 24 h, the white product was filtered out, washed with ethanol, and dried at 80 ° C for 8 h to obtain a triazole framework;

[0061] Step 2, grinding the triazole framework obtained in step 1 into fine powder, placing the triazole framework powder in a porcelain boat, placing it in a programmable temperature-controlled tube furnace under a nitrogen atmosphere, heating it to 1000° C. at a heating rate of 5° C. / min, keeping it warm for 2 hours, and cooling it to room temperature to obtain a carbonized triazole framework;

[0062] Step 3, add 21.875 mL of 0.8% polyethylene terephthalate to 35 mL of deionized water, heat to 50° C., perform ultrasonication for 30 min, and then stir for 4 h, take 0.3 g of the carbonized triazole framework, perform ultrasonication and stirring, mix and stir for 24 h, and stir evenly;

[0063] Step 4, adding 300 mM silver perchlorate to the solution obtained in step 3, wrapping the beaker with tin foil to protect from light, irradiating with ultraviolet light for 2 hours on a magnetic stirrer to reduce the silver ions to nanosilver particles, and stirring at room temperature while irradiating with light to uniformly reduce and distribute the nanosilver particles to obtain a silver-doped porous material solution;

[0064] Step 5, vacuum-assisted filtration is performed on the solution obtained in step 4 to obtain an energetic polynitrogen azole framework-derived porous film having good mechanical properties;

[0065] Step 6, testing the electromagnetic wave shielding performance of the energetic polynitrogen azole framework-derived porous film.

[0066] Example 5

[0067] A method for preparing an energetic polynitrogen azole framework-derived porous film comprises the following steps:

[0068] Step 1, weigh 5g ZnCl 2 Dissolved in a mixture solvent of 50 mL ethanol, 75 mL water, 20 mL of 25% to 28% ammonium hydroxide and 50 mL N, N-dimethylformamide, 6.26 mL 1H-1,2,3-triazole was added dropwise to the mixture, stirred at room temperature for 24 h, the white product was filtered out, washed with ethanol, and dried at 80 ° C for 8 h to obtain a triazole framework;

[0069] Step 2, grinding the triazole framework obtained in step 1 into fine powder, placing the triazole framework powder in a porcelain boat, placing it in a programmable temperature-controlled tube furnace under a nitrogen atmosphere, heating it to 1000° C. at a heating rate of 5° C. / min, keeping it warm for 2 hours, and cooling it to room temperature to obtain a carbonized triazole framework;

[0070] Step 3, adding 21.875 mL of bacterial cellulose with a mass fraction of 0.8% to 35 mL of deionized water, heating to 50° C. and ultrasonicating for 30 min, and then stirring for 4 h, taking 0.3 g of the carbonized triazole framework, ultrasonicating and stirring, and mixing and stirring for 24 h to achieve uniform mixing;

[0071] Step 4, adding 300 mM silver perchlorate to the solution obtained in step 3, wrapping the beaker with tin foil to protect from light, irradiating with ultraviolet light for 1 hour on a magnetic stirrer to reduce the silver ions to nanosilver particles, and stirring at room temperature while irradiating with light to uniformly reduce and distribute the nanosilver particles to obtain a silver-doped porous cellulose solution;

[0072] The solution obtained in step 4 is subjected to vacuum-assisted filtration to obtain an energetic polyazole framework-derived porous film having good mechanical properties;

[0073] Step 6, testing the electromagnetic wave shielding performance of the energetic polynitrogen azole framework-derived porous film.

[0074] Comparative Example 1

[0075] 21.875 mL of bacterial cellulose with a mass fraction of 0.8% was added to 35 mL of deionized water, heated to 50°C and ultrasonicated for 30 min, then stirred for 4 h, and the resulting solution was vacuum-assisted filtered to obtain an unmodified cellulose film, recorded as BC.

[0076] Figure 1 It is a flow chart of the preparation method of the vacuum-assisted filtration energetic polynitrogen azole framework-derived silver-doped porous film of the present invention. The energetic polynitrogen azole framework-derived silver-doped porous film can be obtained through five steps.

[0077] Figure 2It is the XRD diagram of the energetic polyazole framework-derived silver-doped porous films BMA-1000, BMA-900, BMA-800 and comparative example BC of the present invention. It can be seen that after the silver nanoparticles are reduced by ultraviolet light, a peak corresponding to the silver nanoparticle standard card appears, indicating that silver is successfully loaded on the bacterial cellulose and triazole pores.

[0078] Figure 3 This is a scanning electron microscope (SEM) image of the vacuum-assisted energetic polynitrogen azole framework-derived silver-doped porous electromagnetic wave shielding material of the present invention; it can be seen that the material has a rich porous structure, and the doping of nanosilver particles does not block the pores of the material, providing more effective paths for multiple reflections of electromagnetic waves inside the material.

[0079] Figure 4 This is the electromagnetic wave shielding performance diagram of the energetic polyazole framework-derived silver-doped porous film BMA-1000, BMA-900, BMA-800 and the comparative example BC of the present invention. It can be seen that the film without silver nanoparticles and triazole framework has no obvious shielding performance, while the shielding performance of the cellulose film doped with silver nanoparticles and triazole framework can reach -60-80dB at most, and as the concentration of silver salt increases, the silver nanoparticles incorporated into the flexible porous cellulose film increase, and the shielding performance of the porous cellulose film increases. It can be seen that the successful incorporation of silver nanoparticles greatly improves the electromagnetic wave shielding performance of the flexible porous fiber electromagnetic shielding film, reflecting the superiority of the material.

[0080] Figure 5 This is a diagram of the electromagnetic wave shielding mechanism of the energetic polynitrogen azole framework-derived silver-doped porous film BMA-1000, BMA-900, BMA-800 and comparative example BC of the present invention. It can be seen that the SEA values ​​of BMA-1000, BMA-900 and BMA-800 are much higher than the SER values, indicating that the shielding mechanism of the material is mainly based on absorption, and as the silver salt concentration of the material increases, the silver nanoparticles incorporated into the nanocellulose film increase, the shielding performance of the nanocellulose film increases, and the SEA and SET of BMA-1000, BMA-900 and BMA-800 increase accordingly. This indicates that electromagnetic waves enter the material and are shielded by multiple reflections inside the material.

[0081] Figure 6 This is a comparison chart of the mechanical properties of BMA-1000 of the present invention and the comparative example BC. It can be seen that the deformation performance of the pure bacterial cellulose membrane not doped with the energetic polynitrogen azole framework and nanosilver particles is better, but its tensile strength is very poor and the material is harder. The deformation performance of the fiber membrane doped with the energetic polynitrogen azole framework and nanosilver particles is worse than that of the pure bacterial cellulose membrane, but the tensile strength is better, which can effectively avoid the breakage phenomenon caused by external force.

[0082] By adjusting the process parameters according to the content of the present invention, the energetic polynitrogen azole framework-derived silver-doped porous electromagnetic wave shielding material of the present invention can be prepared, and the performance is basically the same as that of Example 1.

[0083] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing an energetic polynitrogen azole framework-derived silver-doped porous film, characterized in that: The following steps are involved: Step 1, grinding the triazole framework, heating and heat preservation under protective gas, and obtaining a carbonized triazole framework after cooling; Step 2, dispersing the matrix material in a solvent, and uniformly mixing it with the carbonized triazole framework obtained in step 1 to obtain a mixed solution; Step 3, uniformly dispersing the silver salt in the mixed solution obtained in step 2, and after light protection, irradiating the solution with light to reduce the silver ions to nanosilver particles, thereby obtaining a silver-doped porous material solution; Step 4, subjecting the silver-doped porous material solution obtained in step 3 to vacuum-assisted filtration, and drying to obtain an energetic polynitrogen azole framework-derived silver-doped porous film.

2. The method for preparing the energetic polynitrogen azole framework-derived silver-doped porous film according to claim 1, characterized in that: The preparation method of the triazole framework in step 1 is: Weigh ZnCl2 and dissolve it in a mixture solvent of ethanol, water, ammonium hydroxide and N,N-dimethylformamide. Add 1H-1,2,3-triazole dropwise into the mixture, stir at room temperature, filter and dry to obtain a white powder triazole framework.

3. The method for preparing the energetic polynitrogen azole framework-derived silver-doped porous film according to claim 1, characterized in that: The heating temperature of the triazole framework in step 1 is 800-1000° C., and the insulation time is 1-3 hours.

4. The method for preparing the energetic polynitrogen azole framework-derived silver-doped porous film according to claim 1, characterized in that: In step 2, the matrix material is bacterial cellulose, polyamide, polyvinyl alcohol or polyethylene terephthalate, and the mass ratio of the matrix material to the carbonized triazole framework is 0.8-1.

5.

5. The method for preparing the energetic polynitrogen azole framework-derived silver-doped porous film as claimed in claim 4, characterized in that: The concentration of the bacterial cellulose dispersion is 5-9 mg / mL.

6. The method for preparing the energetic polynitrogen azole framework-derived silver-doped porous film according to claim 1, characterized in that: The silver salt in step 3 is selected from any one of silver nitrate, silver acetate, silver chlorate and silver perchlorate.

7. The method for preparing the energetic polynitrogen azole framework-derived silver-doped porous film as claimed in claim 6, characterized in that: The concentration of the silver salt is 50-500 mM.

8. The method for preparing the energetic polynitrogen azole framework-derived silver-doped porous film as claimed in claim 1, characterized in that: In step 3, the illumination condition is ultraviolet light or xenon lamp illumination, the illumination time is not less than 1 hour, and the stirring time is not less than 1 hour.

9. An energetic polynitrogen azole framework-derived silver-doped porous film obtained by the method for preparing an energetic polynitrogen azole framework-derived silver-doped porous film as claimed in any one of claims 1 to 8.

10. Use of the energetic polynitrogen azole framework-derived silver-doped porous film as claimed in claim 9 in electromagnetic shielding.

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