Electromagnetic shielding composite material based on plant leaves and preparation method thereof
By sensitizing, activating and electrolessly plating metal layers on plant leaves, an efficient electromagnetic shielding composite material was prepared, which solved the problems of complex processes, high energy consumption and high cost in the prior art, and realized the lightweight material and the sustainable utilization of biomass waste.
Patent Information
- Application Number
- CN202510046077.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-13
- Publication Date
- 2025-04-11
AI Technical Summary
The existing biomass electromagnetic shielding materials have complex processes, high energy consumption and high cost, which violates the original intention of using biomass materials.
Electromagnetic shielding composite materials, including Ni, Ag or Cu metal layers, are prepared by sensitizing, activating and electrolessly plating metal layers using plant leaves as substrates.
It realizes efficient electromagnetic shielding efficiency, reduces metal usage, saves resources, lightens materials, and realizes high value-added sustainable utilization of biomass waste.
Smart Images
Figure CN119800336A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of electromagnetic shielding materials, and specifically relates to an electromagnetic shielding composite material based on plant leaves and a preparation method thereof. Background Art
[0002] With the rapid development of modern information technology, the large-scale application of electromagnetic waves has provided great convenience for people's lives, but also brought serious electromagnetic radiation pollution problems. Electromagnetic radiation pollution may not only cause information leakage and interfere with the normal operation of other electronic equipment, but also has potential hazards to human health and the environment. Therefore, in order to effectively suppress the radiation and interference of electromagnetic waves, it is of great significance to develop electromagnetic shielding materials. With the deepening of research, the types of electromagnetic shielding materials are becoming more and more abundant. On the one hand, metal materials have high shielding effectiveness and are widely used as electromagnetic shielding materials in electronic communication equipment, military facilities, aerospace and other fields. However, traditional metal materials have gradually failed to meet the requirements of high performance and lightweight for electromagnetic wave shielding materials. On the other hand, with the development of human society and the continuous consumption of resources, people have gradually begun to explore the use of cheap, renewable and resource-rich biomass materials to replace or partially replace artificial materials, and effectively treat agricultural waste to make full use of renewable resources. Moreover, researchers have gradually discovered that because biomass materials have unique special structures and surface morphologies, they have certain advantages in reflecting and absorbing electromagnetic waves, so biomass materials have the potential to be used as new electromagnetic shielding materials. Combining the above two aspects, combining a small amount of metal materials with biomass materials is expected to develop new electromagnetic shielding composite materials with high shielding effectiveness, light weight, renewable and energy-saving.
[0003] However, in the prior art, examples of biomass electromagnetic shielding materials, in order to obtain high-performance electromagnetic shielding effects, mostly use high-temperature carbonization methods to convert biomass into biomass-derived carbon and then compound it with a large amount of expensive carbon materials such as graphene, carbon nanotubes or other highly conductive nanomaterials. Not only is the process complicated, but the production and processing energy consumption is high and the cost is high. This goes against the original intention of selecting biomass as a raw material to prepare electromagnetic shielding composite materials. Summary of the invention
[0004] The purpose of the present invention is to provide an electromagnetic shielding composite material based on plant leaves and a preparation method thereof in order to solve the above-mentioned problems.
[0005] The technical solution adopted by the present invention is as follows: an electromagnetic shielding composite material based on plant leaves, the composite material comprising a plant leaf substrate and a metal layer chemically plated on the plant leaf substrate;
[0006] The plant leaf substrate is one or more of tree leaves, shrub leaves and crop leaves;
[0007] The chemically plated metal layer is a Ni metal layer, an Ag metal layer or a Cu metal layer;
[0008] The electromagnetic shielding composite material based on plant leaves acts on the X-band (frequency is 8.2 to 12.4 GHz);
[0009] The total electromagnetic shielding effectiveness of the plant leaf-based electromagnetic shielding composite material is 20-40 dB.
[0010] In a preferred embodiment, the method for preparing the electromagnetic shielding composite material based on plant leaves comprises the following steps:
[0011] S1: Sensitization treatment: wash the plant leaf substrate with deionized water and place it in a 0.01 g / mL SnCl2 solution for 15 minutes for sensitization treatment, and then dry it with filter paper for later use;
[0012] S2: Activation treatment: put the sensitized sample into 0.0001 g / mL PdCl2 solution and ultrasonicate for 15 minutes for activation treatment, and then dry it with filter paper for later use;
[0013] S3: chemical reduction: placing the activated sample in a chemical nickel plating solution, a chemical silver plating solution, or a chemical copper plating solution, and adding 0.05 g / mL sodium hypophosphite (NaH2PO2·H2O) solution dropwise into the solution, the reaction temperature is controlled at 35-45° C., the dropping process is controlled within about 2 hours, and the total reaction time is 2-3 hours;
[0014] S4: After the reaction is completed, the samples are washed and dried, and the prepared samples are collected, stored and packaged, thereby completing the entire preparation process of the electromagnetic shielding composite material based on plant leaves.
[0015] In a preferred embodiment, in step S1, the solvent of the SnCl2 solution is dilute hydrochloric acid with a volume fraction of concentrated hydrochloric acid: water = 5:95.
[0016] In a preferred embodiment, in step S2, the solvent of the PdCl2 solution is dilute hydrochloric acid with a volume fraction of concentrated hydrochloric acid: water = 1:99.
[0017] In a preferred embodiment, in step S3, the chemical nickel plating solution is a 0.01-0.04 g / mL nickel sulfate solution; the chemical silver plating solution is a 0.05-0.1 g / mL silver nitrate solution; and the chemical copper plating solution is a 0.03-0.05 g / mL copper sulfate solution.
[0018] In a preferred embodiment, in step S3, 0.025 g / mL of sodium citrate is added to the chemical nickel plating solution or the chemical silver plating solution or the chemical copper plating solution as a complexing agent and a buffer, and a certain amount of ammonia water is added to adjust the pH to 8-9.
[0019] In a preferred embodiment, in step S1, the plant leaves include one or more of tree leaves, shrub leaves and crop leaves.
[0020] In a preferred embodiment, in step S2, the ultrasonic power is controlled to 20 to 40 watts, the processing time is controlled within 15 minutes, the solution freshness, the degree of leaf dryness and the environmental conditions, and the precise control of these parameters ensures the activation effect and provides a guarantee for the subsequent chemical reduction reaction and the preparation quality of the final electromagnetic shielding composite material.
[0021] In a preferred embodiment, in step S3, during the process of dropwise adding the sodium hypophosphite solution, the stirring rate of the solution needs to be maintained at 150-200 rpm to ensure sufficient mixing of the reducing agent and the metal ions and uniform deposition of the metal layer.
[0022] In a preferred embodiment, in step S4, after the reaction is completed, the sample needs to be washed with deionized water for multiple times to remove residual chemicals on the surface. The drying process should be carried out in a constant temperature oven at 60° C. for 6 hours to ensure that the sample is completely dried.
[0023] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:
[0024] In the present invention, plant leaves are used as templates, the favorable structure of plant leaves themselves is effectively utilized, the reflection effect of the material on electromagnetic waves is enhanced, the amount of metal used is reduced, resources are saved and the material is lightweight. Plant leaves are applied to the field of electromagnetic environmental safety protection to achieve high added value and sustainable utilization of biomass waste. The preparation method is simple, the production and processing cost is low, and it conforms to the concept of environmental friendliness and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 It is a schematic diagram of the electromagnetic shielding effectiveness of the Eucommia ulmoides leaf@Ni composite material of the present invention. DETAILED DESCRIPTION
[0026] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and 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.
[0027] Reference Figure 1,
[0028] A plant leaf-based electromagnetic shielding composite material, the composite material comprising a plant leaf substrate and a metal layer chemically plated on the plant leaf substrate;
[0029] The plant leaves are one or more of tree leaves, shrub leaves and crop leaves;
[0030] The chemically plated metal layer is a Ni metal layer, an Ag metal layer or a Cu metal layer;
[0031] Electromagnetic shielding composites based on plant leaves act on the X-band (frequency 8.2-12.4 GHz)
[0032] The total electromagnetic shielding effectiveness of the electromagnetic shielding composite material based on plant leaves is 20-40dB.
[0033] The preparation method comprises the following steps:
[0034] S1: Perform sensitization treatment: wash the plant leaf substrate with deionized water and then place it in a 0.01g / mL SnCl2 solution for 15 minutes of ultrasonic treatment for sensitization treatment, and then dry it with filter paper for later use; in step S1, the solvent of the SnCl2 solution is dilute hydrochloric acid with a volume fraction of concentrated hydrochloric acid: water = 5:95; in step S1, the plant leaves include one or more of Eucommia ulmoides leaves and Populus tomentosa leaves.
[0035] S2: Activation treatment: put the sensitized sample into a 0.0001 g / mL PdCl2 solution and perform ultrasonic treatment for 15 minutes for activation treatment, and then dry it with filter paper for later use; in step S2, the solvent of the PdCl2 solution is dilute hydrochloric acid with a volume fraction of concentrated hydrochloric acid: water = 1:99.
[0036] In step S2, the ultrasonic power is controlled to 20 to 40 watts, the processing time is controlled within 15 minutes, the solution freshness, the leaf dryness and the environmental conditions. The precise control of these parameters ensures the activation effect and provides a guarantee for the subsequent chemical reduction reaction and the preparation quality of the final electromagnetic shielding composite material.
[0037] S3: chemical reduction: placing the activated sample in a chemical nickel plating solution, a chemical silver plating solution, or a chemical copper plating solution, and adding 0.05 g / mL sodium hypophosphite (NaH2PO2·H2O) solution dropwise into the solution, the reaction temperature is controlled at 35-45° C., the dropping process is controlled within about 2 hours, and the total reaction time is 2-3 hours;
[0038] In step S3, the chemical nickel plating solution is a 0.01-0.04 g / mL nickel sulfate solution; the chemical silver plating solution is a 0.05-0.1 g / mL silver nitrate solution; and the chemical copper plating solution is a 0.03-0.05 g / mL copper sulfate solution.
[0039] In step S3, 0.025 g / mL of sodium citrate is added to the chemical nickel plating solution, the chemical silver plating solution, or the chemical copper plating solution as a complexing agent and a buffer, and a certain amount of ammonia water is added to adjust the pH to 8-9.
[0040] During the process of dropping the sodium hypophosphite solution, the stirring rate of the solution needs to be maintained at 150-200 rpm to ensure sufficient mixing of the reducing agent and the metal ions and uniform deposition of the metal layer.
[0041] S4: After the reaction is completed, the sample is washed and dried, and the obtained sample is collected, stored and packaged, and the entire preparation process of the electromagnetic shielding composite material based on plant leaves is completed. In step S4, after the reaction is completed, the sample needs to be washed with deionized water several times to remove residual chemicals on the surface. The drying process should be carried out in a constant temperature oven at 60°C for 6 hours to ensure that the sample is thoroughly dried. Example 1:
[0042] An electromagnetic shielding composite material based on plant leaves, the specific steps are as follows:
[0043] (1) Select intact Eucommia ulmoides leaves with abundant and strong veins, wash them with deionized water, and dry them with filter paper for later use.
[0044] (2) Immerse the washed Eucommia leaves in a 0.01 g / mL SnCl2 solution (with dilute hydrochloric acid as the solvent) and ultrasonicate for 15 minutes to sensitize the leaves. Dry the leaves with filter paper and set aside for later use.
[0045] (3) The sensitized Eucommia ulmoides leaves were immersed in a 0.0001 g / mL PdCl2 solution (with dilute hydrochloric acid as solvent) and ultrasonicated for 15 minutes to activate the leaves, and then dried with filter paper for later use.
[0046] (4) A 0.03 g / mL nickel sulfate hexahydrate solution was prepared, to which 0.025 g / mL sodium citrate was added as a complexing agent and buffer, and then ammonia water was added to adjust the pH of the mixed solution to 8, and the activated Eucommia leaves were immersed in the mixed solution.
[0047] (5) Add 0.05 g / mL sodium hypophosphite (NaH2PO2·H2O) solution dropwise to the mixed solution of step (4), the reaction temperature is controlled at 40°C, the addition process takes about 2.5 hours, and the total time from the start of the addition process to the end of the reaction is 3 hours. After the reaction is completed, the eucommia leaves plated with the nickel metal layer are removed, washed and dried to obtain the eucommia leaves@Ni composite material.
[0048] The total shielding effectiveness (SE) of the Eucommia ulmoides leaf@Ni composite material prepared in this example in the X-band (8.2-12.4 GHz) is T ) is 20.87~35.33dB, and the reflection shielding effectiveness (SE R ) is 2.57~3.58dB, absorption shielding effectiveness (SE A ) is 17.94~32.47dB (see Figure 1 The obtained Eucommia leaf@Ni composite material is very light and thin, weighing only 0.23g and with an average thickness of only 0.21mm. The structure and surface morphology of the Eucommia leaf are preserved in the Eucommia leaf@Ni composite material, and the rich natural Eucommia rubber in the veins of the Eucommia leaf also gives the composite material a certain toughness.
[0049] Embodiment 2:
[0050] An electromagnetic shielding composite material based on plant leaves, the specific steps are as follows:
[0051] (1) Select intact Eucommia ulmoides leaves with abundant and strong veins, wash them with deionized water, and dry them with filter paper for later use.
[0052] (2) Immerse the washed Eucommia leaves in a 0.01 g / mL SnCl2 solution (with dilute hydrochloric acid as the solvent) and ultrasonicate for 15 minutes to sensitize the leaves. Dry the leaves with filter paper and set aside for later use.
[0053] (3) The sensitized Eucommia ulmoides leaves were immersed in a 0.0001 g / mL PdCl2 solution (with dilute hydrochloric acid as solvent) and ultrasonicated for 15 minutes to activate the leaves, and then dried with filter paper for later use.
[0054] (4) Prepare a 0.1 g / mL silver nitrate solution, add 0.025 g / mL sodium citrate as a complexing agent and buffer, add ammonia water to adjust the pH of the mixed solution to 8, and immerse the activated Eucommia leaves in the mixed solution.
[0055] (5) Add 0.05 g / mL sodium hypophosphite (NaH2PO2·H2O) solution dropwise to the mixed solution of step (4), the reaction temperature is controlled at 42°C, the dropping process takes about 2.5 hours, and the total time from the start of the dropping process to the end of the reaction is 3 hours. After the reaction is completed, the eucommia leaves coated with the silver metal layer are removed, washed and dried to obtain the eucommia leaves@Ag composite material.
[0056] The total shielding effectiveness (SE) of the Eucommia ulmoides leaf@Ag composite material prepared in this example in the X-band (8.2-12.4 GHz) is T ) is 22.50~38.78dB, reflection shielding effectiveness (SE R) is 5.23~8.63dB, absorption shielding effectiveness (SE A ) is 17.26~30.25dB. The structure and surface morphology of Eucommia ulmoides leaves are preserved in the Eucommia ulmoides leaves@Ag composite material, and the rich natural Eucommia ulmoides rubber in the veins of Eucommia ulmoides leaves also gives the composite material a certain toughness.
[0057] Embodiment three:
[0058] An electromagnetic shielding composite material based on plant leaves, the specific steps are as follows:
[0059] (1) Select intact Eucommia ulmoides leaves with abundant and strong veins, wash them with deionized water, and dry them with filter paper for later use.
[0060] (2) Immerse the washed Eucommia leaves in a 0.01 g / mL SnCl2 solution (with dilute hydrochloric acid as the solvent) and ultrasonicate for 15 minutes to sensitize the leaves. Dry the leaves with filter paper and set aside for later use.
[0061] (3) The sensitized Eucommia ulmoides leaves were immersed in a 0.0001 g / mL PdCl2 solution (with dilute hydrochloric acid as solvent) and ultrasonicated for 15 minutes to activate the leaves, and then dried with filter paper for later use.
[0062] (4) Prepare a 0.05 g / mL copper sulfate solution, add 0.025 g / mL sodium citrate as a complexing agent and buffer, add ammonia water to adjust the pH of the mixed solution to 8, and immerse the activated Eucommia leaves in the mixed solution.
[0063] (5) Add 0.05 g / mL sodium hypophosphite (NaH2PO2·H2O) solution dropwise to the mixed solution of step (4), the reaction temperature is controlled at 45°C, the addition process takes about 2.5 hours, and the total time from the start of the addition process to the end of the reaction is 3 hours. After the reaction is completed, the eucommia leaves coated with the copper metal layer are removed, washed and dried to obtain the eucommia leaves@Cu composite material.
[0064] The total shielding effectiveness (SET) of the Eucommia leaf@Cu composite material prepared in this embodiment is 23.96-35.62dB, the reflection shielding effectiveness (SER) is 4.76-6.21dB, and the absorption shielding effectiveness (SEA) is 18.98-30.45dB in the X-band (8.2-12.4GHz). The structure and surface morphology of the Eucommia leaf are retained in the Eucommia leaf@Ni composite material, and the rich natural Eucommia rubber in the veins of the Eucommia leaf also gives the composite material a certain toughness.
[0065] Embodiment 4:
[0066] An electromagnetic shielding composite material based on plant leaves, the specific steps are as follows:
[0067] (1) Select intact Eucommia ulmoides leaves with abundant and strong veins, wash them with deionized water, and dry them with filter paper for later use.
[0068] (2) Immerse the washed Eucommia leaves in a 0.01 g / mL SnCl2 solution (with dilute hydrochloric acid as the solvent) and ultrasonicate for 15 minutes to sensitize the leaves. Dry the leaves with filter paper and set aside for later use.
[0069] (3) The sensitized Eucommia ulmoides leaves were immersed in a 0.0001 g / mL PdCl2 solution (with dilute hydrochloric acid as solvent) and ultrasonicated for 15 minutes to activate the leaves, and then dried with filter paper for later use.
[0070] (4) A 0.04 g / mL nickel sulfate hexahydrate solution was prepared, to which 0.025 g / mL sodium citrate was added as a complexing agent and buffer, and then ammonia water was added to adjust the pH of the mixed solution to 8, and the activated Eucommia leaves were immersed in the mixed solution.
[0071] (5) Add 0.05 g / mL sodium hypophosphite (NaH2PO2·H2O) solution dropwise to the mixed solution of step (4), the reaction temperature is controlled at 40°C, the addition process takes about 2.5 hours, and the total time from the start of the addition process to the end of the reaction is 3 hours. After the reaction is completed, the eucommia leaves plated with the nickel metal layer are removed, washed and dried to obtain the eucommia leaves@Ni composite material.
[0072] The total shielding effectiveness (SE) of the Eucommia ulmoides leaf@Ni composite material prepared in this example in the X-band (8.2-12.4 GHz) is T ) is 23.34~39.86dB, and the reflection shielding effectiveness (SE R ) is 3.37~4.21dB, absorption shielding effectiveness (SE A ) is 20.47~35.94dB. The obtained Eucommia leaf@Ni composite material is very light and thin, with a mass of only 0.26g and an average thickness of only 0.20mm. The structure and surface morphology of Eucommia leaf are preserved in the Eucommia leaf@Ni composite material, and the rich natural Eucommia rubber in the veins of Eucommia leaf also gives the composite material a certain toughness.
[0073] Embodiment five:
[0074] An electromagnetic shielding composite material based on plant leaves, the specific steps are as follows:
[0075] (1) Select intact Eucommia ulmoides leaves with abundant and strong veins, wash them with deionized water, and dry them with filter paper for later use.
[0076] (2) Immerse the washed Eucommia leaves in a 0.01 g / mL SnCl2 solution (with dilute hydrochloric acid as the solvent) and ultrasonicate for 15 minutes to sensitize the leaves. Dry the leaves with filter paper and set aside for later use.
[0077] (3) The sensitized Eucommia ulmoides leaves were immersed in a 0.0001 g / mL PdCl2 solution (with dilute hydrochloric acid as solvent) and ultrasonicated for 15 minutes to activate the leaves, and then dried with filter paper for later use.
[0078] (4) A 0.03 g / mL nickel sulfate hexahydrate solution was prepared, to which 0.025 g / mL sodium citrate was added as a complexing agent and buffer, and then ammonia water was added to adjust the pH of the mixed solution to 8, and the activated Eucommia leaves were immersed in the mixed solution.
[0079] (5) Add 0.05 g / mL sodium hypophosphite (NaH2PO2·H2O) solution dropwise to the mixed solution of step (4), the reaction temperature is controlled at 45°C, the addition process takes about 2.5 hours, and the total time from the start of the addition process to the end of the reaction is 3 hours. After the reaction is completed, the eucommia leaves plated with the nickel metal layer are removed, washed and dried to obtain the eucommia leaves@Ni composite material.
[0080] The total shielding effectiveness (SE) of the Eucommia ulmoides leaf@Ni composite material prepared in this example in the X-band (8.2-12.4 GHz) is T ) is 18.7~30.16dB, reflection shielding effectiveness (SE R ) is 1.29~2.21dB, absorption shielding effectiveness (SE A ) is 16.55~28.43dB. The obtained Eucommia leaf@Ni composite material is very light and thin, with a mass of only 0.13g and an average thickness of only 0.17mm. The structure and surface morphology of Eucommia leaf are preserved in the Eucommia leaf@Ni composite material, and the rich natural Eucommia rubber in the veins of Eucommia leaf also gives the composite material a certain toughness.
[0081] Embodiment six:
[0082] An electromagnetic shielding composite material based on plant leaves, the specific steps are as follows:
[0083] (1) Select intact, undamaged leaves of Populus tomentosa with rich and strong veins, wash them with deionized water, and dry them with filter paper for later use.
[0084] (2) Immerse the washed Eucommia leaves in a 0.01 g / mL SnCl2 solution (with dilute hydrochloric acid as the solvent) and ultrasonicate for 15 minutes to sensitize the leaves. Dry the leaves with filter paper and set aside for later use.
[0085] (3) The sensitized leaves of Populus tomentosa were immersed in a 0.0001 g / mL PdCl2 solution (with dilute hydrochloric acid as solvent) and ultrasonicated for 15 minutes to activate the leaves, and then dried with filter paper for later use.
[0086] (4) A 0.03 g / mL nickel sulfate hexahydrate solution was prepared, to which 0.025 g / mL sodium citrate was added as a chelating agent and buffer, and then ammonia water was added to adjust the pH of the mixed solution to 8, and the activated Populus tomentosa leaves were immersed in the mixed solution.
[0087] (5) Add 0.05 g / mL sodium hypophosphite (NaH2PO2·H2O) solution dropwise to the mixed solution of step (4), the reaction temperature is controlled at 40°C, the addition process takes about 2.5 hours, and the total time from the start of the addition process to the end of the reaction is 3 hours. After the reaction is completed, the Eucommia leaves coated with the nickel metal layer are removed, washed and dried to obtain the Populus tomentosa leaf@Ni composite material.
[0088] The total shielding effectiveness (SE) of the Populus tomentosa leaf@Ni composite material prepared in this example in the X-band (8.2-12.4 GHz) is T ) is 15.73~23.46dB, and the reflection shielding effectiveness (SE R ) is 1.54~2.07dB, absorption shielding effectiveness (SE A ) is 14.29~21.34dB.
[0089] From the above, it can be seen that: in the present invention, plant leaves are used as templates, the favorable structure of plant leaves themselves is effectively utilized, the reflection effect of the material on electromagnetic waves is enhanced, the amount of metal used is reduced, and resources are saved while being conducive to the lightweight of materials. The application of plant leaves in the field of electromagnetic environmental safety protection can achieve high added value and sustainable utilization of biomass waste. Its preparation method is simple, the production and processing cost is low, and it conforms to the concept of environmental friendliness and sustainable development.
[0090] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the term "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.
[0091] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. An electromagnetic shielding composite material based on plant leaves, characterized in that: The composite material comprises a plant leaf substrate and a metal layer chemically plated on the plant leaf substrate; The plant leaf substrate is one or more of tree leaves, shrub leaves and crop leaves; The chemically plated metal layer is a Ni metal layer, an Ag metal layer or a Cu metal layer; the electromagnetic shielding composite material based on plant leaves acts on the X-band with a frequency of 8.2 to 12.4 GHz, and a total electromagnetic shielding effectiveness of 20 to 40 dB.
2. A method for preparing an electromagnetic shielding composite material based on plant leaves, characterized in that: The preparation method comprises the following steps: S1: Sensitization treatment: wash the plant leaf substrate with deionized water and place it in a 0.01 g / mL SnCl2 solution for 15 minutes for sensitization treatment, then dry it with filter paper for later use; S2: Activation treatment: put the sensitized sample into 0.0001 g / mL PdCl2 solution and ultrasonicate for 15 minutes for activation treatment, and then dry it with filter paper for later use; S3: chemical reduction: placing the activated sample in a chemical nickel plating solution, a chemical silver plating solution, or a chemical copper plating solution, and adding 0.05 g / mL sodium hypophosphite (NaH2PO2·H2O) solution dropwise into the solution, the reaction temperature is controlled at 35-45° C., the dropping process is controlled within about 2 hours, and the total reaction time is 2-3 hours; S4: After the reaction is completed, the samples are washed and dried, and the prepared samples are collected, stored and packaged, thereby completing the entire preparation process of the electromagnetic shielding composite material based on plant leaves.
3. The method for preparing an electromagnetic shielding composite material based on plant leaves according to claim 2, characterized in that: In the step S1, the solvent of the SnCl2 solution is dilute hydrochloric acid with a volume fraction of concentrated hydrochloric acid: water = 5:
95.
4. The method for preparing an electromagnetic shielding composite material based on plant leaves according to claim 2, characterized in that: In step S2, the solvent of the PdCl2 solution is dilute hydrochloric acid with a volume fraction of concentrated hydrochloric acid: water = 1:
99.
5. The method for preparing an electromagnetic shielding composite material based on plant leaves according to claim 2, characterized in that: In step S3, the chemical nickel plating solution is a 0.01-0.04 g / mL nickel sulfate solution; the chemical silver plating solution is a 0.05-0.1 g / mL silver nitrate solution; and the chemical copper plating solution is a 0.03-0.05 g / mL copper sulfate solution.
6. The method for preparing an electromagnetic shielding composite material based on plant leaves according to claim 2, characterized in that: In step S3, 0.025 g / mL of sodium citrate is added to the chemical nickel plating solution, the chemical silver plating solution, or the chemical copper plating solution as a complexing agent and a buffer, and a certain amount of ammonia water is added to adjust the pH to 8-9.
7. The method for preparing an electromagnetic shielding composite material based on plant leaves according to claim 2, characterized in that: In step S1, the plant leaves include one or more of tree leaves, shrub leaves or crop leaves.
8. The method for preparing an electromagnetic shielding composite material based on plant leaves according to claim 2, characterized in that: In step S2, the ultrasonic power is controlled to 20 to 40 watts, the processing time is controlled within 15 minutes, the solution freshness, the leaf dryness and the environmental conditions are precisely controlled to ensure the activation effect, and provide guarantee for the subsequent chemical reduction reaction and the preparation quality of the final electromagnetic shielding composite material.
9. The method for preparing an electromagnetic shielding composite material based on plant leaves according to claim 2, characterized in that: In the step S3, during the process of dropwise adding the sodium hypophosphite solution, the stirring rate of the solution needs to be maintained at 150-200 rpm to ensure sufficient mixing of the reducing agent and the metal ions and uniform deposition of the metal layer.
10. The method for preparing an electromagnetic shielding composite material based on plant leaves according to claim 2, characterized in that: In step S4, after the reaction is completed, the sample needs to be washed with deionized water for multiple times to remove residual chemicals on the surface. The drying process should be carried out in a constant temperature oven at 60° C. for 6 hours to ensure that the sample is completely dried.