Graphene composite film with electromagnetic shielding and method for preparation the same
Patent Information
- Application Number
- TW113151503
- Authority / Receiving Office
- TW · TW
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2026-07-11
- Estimated Expiration
- 2044-12-29
Smart Images
Figure IMG-2_DRAW_04_A0101_DRAWINGS_1 
Figure IMG-2_DRAW_04_A0101_DRAWINGS_2 
Figure IMG-2_DRAW_04_A0101_DRAWINGS_3
Abstract
Description
Technical Field
[0001] This invention relates to redox graphene films and their fabrication processes; in particular, it refers to an electromagnetically shielding graphene composite film and its preparation method. Prior Technology
[0002] With the rapid development of high-tech electronic devices and systems, many high-tech electronic devices now require miniaturization to provide portability and convenient operation. Similarly, in the field of electronic shielding material development, it is necessary to develop new types of lightweight electromagnetic shielding materials to be installed on these high-tech electronic devices to reduce or eliminate electromagnetic interference in the micro-environment in which they are located.
[0003] Currently, many companies are developing graphene films for use in electronic devices. However, existing graphene film technologies have not been proven to have high electromagnetic shielding transmittance and / or reflectivity. Moreover, traditional graphene film preparation methods typically use mechanical peeling to obtain single-layer graphene films, which is not only inefficient but also energy-intensive and costly. In addition, some companies have designed to optimize traditional graphene film manufacturing processes by first oxidizing graphite blocks into sheet-like graphene oxide (GO) using an oxidant, and then adding a reducing agent to obtain reduced graphene oxide (rGO) films through chemical reduction technology. However, most of these reducing agents contain hydrazine, hydroiodic acid, and strong bases, which pose high toxicity risks. This not only pollutes and harms the environment and operators but also causes agglomeration problems in the reduced graphene oxide (rGO) films, making the processing of these rGO films more difficult. Summary of the Invention
[0004] In view of this, the purpose of the present invention is to provide an electromagnetically shielding graphene composite film and its preparation method. The preparation method of the graphene composite film omits the addition of chemical reducing agents, reduces the pollution of the process environment by the chemical reducing agents, and increases the safety of the process operation. Moreover, the graphene composite film has the function of electromagnetic shielding, that is, it can be applied to a variety of electronic devices to achieve the effect of resisting electromagnetic wave interference.
[0005] To achieve the above objectives, the present invention provides an electromagnetic shielding graphene composite film comprising a graphene substrate with a nano-metal oxide attached to its surface. The electromagnetic wave absorption performance of the electromagnetic shielding graphene composite film is such that the electromagnetic wave transmittance does not exceed 60dB in the frequency range of 5 to 15GHz, and the electromagnetic wave reflectance is between 0 and 10dB.
[0006] Another embodiment of the present invention provides a method for preparing an electromagnetically shielding graphene composite film, comprising the following steps: Step S1, providing a graphene oxide solution; Step S2, immersing a metal plate in the graphene oxide solution to generate a spontaneous redox reaction, wherein the reaction time of the metal plate in the graphene oxide solution does not exceed 12 hours, so that the graphene oxide in the graphene oxide solution comes into contact with the surface of the metal plate and is reduced to a self-assembled graphene substrate; Step S3, removing the metal plate from the graphene oxide solution, and performing a defilming treatment on the graphene substrate generated on the metal plate using a 3.75wt% dilute hydrochloric acid solution, thereby peeling the graphene substrate off the metal plate to obtain the electromagnetically shielding graphene composite film, wherein the surface of the graphene substrate is coated with a nano-metal oxide corresponding to the oxidation reaction of the metal plate, and the electromagnetic wave absorption performance of the electromagnetically shielding graphene composite film is such that the electromagnetic wave transmittance does not exceed 60dB and the electromagnetic wave reflectance is between 0 and 10dB in the frequency range of 5 to 15 GHz.
[0007] The advantage of this invention is that the preparation method of the graphene composite film specifically selects iron or magnesium metal plates to generate a spontaneous redox reaction with the graphene oxide solution, omitting the need to add chemical reducing agents to the graphene oxide solution, reducing the pollution of the process environment by the chemical reducing agents, and increasing the safety of the process operation.
[0008] Furthermore, the graphene oxide is reduced to a self-assembled graphene substrate upon contact with the surface of the metal plate. The graphene substrate formed on the metal plate is then subjected to a delamination treatment using dilute hydrochloric acid, allowing the graphene substrate to be completely peeled off from the metal plate. The surface of the graphene substrate is coated with nano-metal oxides corresponding to those produced by the oxidation reaction of the metal plate, thus obtaining an electromagnetic shielding graphene composite film. The graphene substrate of this electromagnetic shielding graphene composite film, after electromagnetic wave shielding testing, effectively blocks electromagnetic wave penetration and also reflects electromagnetic waves. Therefore, this electromagnetic shielding graphene composite film possesses electromagnetic shielding functionality and can be applied to various electronic devices to achieve the effect of resisting electromagnetic interference. Simple Explanation of the Diagram
[0009] Figure 1 is a flowchart of the steps of a preferred embodiment of the present invention for preparing an electromagnetically shielded graphene composite film. Figure 2 is a flowchart of step P1 in the method for preparing an electromagnetically shielded graphene composite film according to a preferred embodiment of the present invention. Figure 3A shows the Raman spectra of the nano-metal oxides iron oxide and magnesium oxide of the electromagnetically shielded graphene composite film according to a preferred embodiment of the present invention. Figure 3B shows the Raman spectra of the nano-metal oxides of the electromagnetically shielded graphene composite film of a preferred embodiment of the present invention, which are aluminum oxide, nickel oxide, tin oxide, manganese oxide and copper oxide. Figure 4 shows the XRD diffraction curves of the control group and experimental groups 1 and 2 of a preferred embodiment of the present invention, which contain iron oxide and have electromagnetic shielding graphene composite films. Figure 5A shows the electromagnetic wave reflectance data of the front and back sides of the electromagnetically shielding graphene composite film containing iron oxide in Experimental Group 1 of a preferred embodiment of the present invention. Figure 5B is a graph showing the electromagnetic wave transmittance data of the front and back sides of the electromagnetically shielding graphene composite film containing iron oxide in Experimental Group 1 of a preferred embodiment of the present invention. Figure 6A is a graph showing the electromagnetic wave reflectance data of the front and back sides of the electromagnetically shielding graphene composite film containing iron oxide after drying in experimental group 1' of a preferred embodiment of the present invention. Figure 6B is a graph showing the electromagnetic wave transmittance data of the front and back sides of the electromagnetically shielding graphene composite film containing iron oxide after drying in experimental group 1' of a preferred embodiment of the present invention. Figure 7A shows the electromagnetic wave reflectance data of the front and back sides of the electromagnetically shielding graphene composite film containing magnesium oxide in experimental group 3 of a preferred embodiment of the present invention. Figure 7B is a graph showing the electromagnetic wave transmittance data of the front and back sides of the electromagnetically shielding graphene composite film containing magnesium oxide in experimental group 3 of a preferred embodiment of the present invention. Figure 8A is a graph showing the electromagnetic wave reflectance data of the front and back sides of the electromagnetically shielding graphene composite film containing magnesium oxide after drying in experimental group 3' of a preferred embodiment of the present invention. Figure 8B is a graph showing the electromagnetic wave transmittance data of the front and back sides of the electromagnetically shielding graphene composite film containing magnesium oxide after drying in experimental group 3' of a preferred embodiment of the present invention. Implementation
[0010] To more clearly illustrate the present invention, preferred embodiments are described in detail below with reference to the accompanying drawings. Please refer to Figure 1, which illustrates a method for preparing an electromagnetically shielding graphene composite film according to a preferred embodiment of the present invention, comprising the following steps:
[0011] Step S1: Provide a graphene oxide solution, wherein the concentration of the graphene oxide solution is between 0.01 mg / ml and 50 mg / ml. In a preferred embodiment, the concentration of the graphene oxide solution is between 0.1 mg / ml and 25 mg / ml. In this embodiment, the concentration range of the graphene oxide solution can be adjusted as needed. If the concentration of the graphene oxide solution is higher than 50 mg / ml, the fluidity will be reduced due to the excessively high concentration, making it easy for the electromagnetic shielding graphene composite film to agglomerate after film formation. If the concentration of the graphene oxide solution is lower than 0.01 mg / ml, the film formation time of the electromagnetic shielding graphene composite film will be significantly increased, and the thickness of the electromagnetic shielding graphene composite film will be reduced.
[0012] As shown in Figure 2, in this embodiment, step P1 precedes step S1, in which sodium nitrate, graphite, and sulfuric acid are mixed to form a reaction solution. In this embodiment, the reaction solution is prepared with sodium nitrate at a concentration of 0.5~1.0M, graphite at a weight of 1.0~2.0g, and sulfuric acid solution (18M) at a weight of 25~30ml. The sodium nitrate, graphite, and sulfuric acid are continuously stirred at a temperature of 0~5°C to form the reaction solution. Then, potassium permanganate is added to the reaction solution and stirred continuously. The potassium permanganate is added to the reaction solution in batches at least twice. The reaction solution was stirred for 10-12 hours. The amount of potassium permanganate added to the reaction solution was between 5-10g. Under the stirring condition of the reaction solution, aqueous solution (H2O) and hydrogen peroxide were added dropwise in sequence. The addition of hydrogen peroxide to the reaction solution was to terminate the oxidation reaction of graphite in the reaction solution. Then, the reaction solution was subjected to multiple acid washing and centrifugation treatments with 37.5wt% hydrochloric acid. Finally, the reaction solution was centrifuged multiple times with aqueous solution until the pH of the supernatant of the reaction solution was neutral. The supernatant was then subjected to ultrasonic shaking to obtain the graphene oxide solution.
[0013] In other embodiments, the preparation method of the electromagnetically shielded graphene composite film can be modified according to process requirements. For example, the graphene oxide solution provided in step S1 is not limited to being obtained through step P1. That is, the graphene oxide solution can be purchased directly, so step P1 can be omitted, as long as step S1 in the preparation method of the electromagnetically shielded graphene composite film can provide the graphene oxide solution.
[0014] Step S2 involves immersing a metal plate in the graphene oxide solution to generate a spontaneous redox reaction. The reaction time of the metal plate in the graphene oxide solution does not exceed 12 hours, meaning the reaction time can be adjusted from a few minutes to 12 hours depending on the concentration of the graphene oxide solution. In this embodiment, the metal plate is selected from one of the groups consisting of iron, magnesium, aluminum, nickel, tin, manganese, and copper. In a preferred embodiment, the metal plate is selected from iron or magnesium, and the surface of the metal plate can be pre-polished. The graphene oxide solution does not contain any reducing agent. Since the graphene oxide in the graphene oxide solution has oxygen-containing functional groups, i.e., the graphene oxide has a strong oxidation potential, the metal plate can generate a spontaneous redox reaction with the graphene oxide, causing the graphene oxide to come into contact with the surface of the metal plate and be reduced to a self-assembled graphene substrate.
[0015] Step S3: The metal plate is removed from the graphene oxide solution. The graphene substrate formed on the metal plate is then subjected to a demolding treatment using 3.75 wt% dilute hydrochloric acid, ensuring the graphene substrate is completely detached from the metal plate without any damage or defects on its surface. After detachment, the graphene substrate is further acid-washed with 1.875 wt% dilute hydrochloric acid for 2-12 hours to remove impurities. The substrate is then dried to obtain the electromagnetic shielding graphene composite film. The surface of the graphene substrate is coated with a nano-metal oxide corresponding to the oxidation reaction of the metal plate. The material is selected from one of the groups consisting of iron oxide (Fe2O3), magnesium oxide (MgO), aluminum oxide (Al2O3), nickel oxide (NiO), tin oxide (SnO2), manganese oxide (MnO2), and copper oxide (CuO). In this embodiment, the graphene substrate comprises a plurality of stacked graphene sheets, and the stacking of these graphene sheets creates a plurality of voids, thereby forming a porous electromagnetic shielding graphene composite film. The nano-metal oxide generated by the oxidation reaction of the metal plate in the graphene oxide solution is attached to the voids of the graphene sheets, wherein the content of the nano-metal oxide accounts for 0.001~20wt% of the total content of the electromagnetic shielding graphene composite film.
[0016] Furthermore, the electromagnetically shielded graphene composite film exhibits diffraction peaks of 15°±3° and 25°±3° in 2θ during XRD diffraction. The thickness of the graphene substrate is between 1 μm and 2 mm. Electromagnetic wave absorption and conductivity tests show that the electromagnetically shielded graphene composite film has an electromagnetic wave transmittance of no more than 60 dB in the frequency range of 5–15 GHz, and an electromagnetic wave reflectivity of 0–10 dB. In a preferred embodiment, the electromagnetic wave absorption of the electromagnetically shielded graphene composite film is... The absorption performance has an electromagnetic wave transmittance of 15-40 dB and an electromagnetic wave reflectance of 0-2.5 dB in the frequency range of 8-13 GHz. When the nano-metal oxide is iron oxide, the conductivity of the electromagnetic shielding graphene composite film is between 0.1 and 1000 S / cm. In a preferred embodiment, the conductivity of the electromagnetic shielding graphene composite film is between 50 and 300 S / cm. When the nano-metal oxide is magnesium oxide, the conductivity of the electromagnetic shielding graphene composite film is between 0 and 750 S / cm.
[0017] Experiments revealed that variations in the thickness of the graphene substrate affect the conductivity of the electromagnetically shielded graphene composite film. In this embodiment, when the thickness of the graphene substrate containing iron oxide is 0.0029 mm, the conductivity of the electromagnetically shielded graphene composite film is approximately 260 S / cm; when the thickness of the graphene substrate containing iron oxide is 0.031 mm, the conductivity of the electromagnetically shielded graphene composite film is approximately 60 S / cm; when the thickness of the graphene substrate containing magnesium oxide is 0.003 mm, the conductivity of the electromagnetically shielded graphene composite film is approximately 700 S / cm; and when the thickness of the graphene substrate containing iron oxide is 0.096 mm, the conductivity of the electromagnetically shielded graphene composite film is approximately 0.00003 S / cm.
[0018] Furthermore, the electromagnetically shielded graphene composite film exhibits a first peak at 1300 cm⁻¹ ± 100° in its Raman spectrum, and a second peak at 1600 cm⁻¹ ± 100°. The electromagnetically shielded graphene composite film satisfies the following range: 0.6 ≦ ID / IG ≦ 3, where the peak value of the first peak is ID and the peak value of the second peak is IG. In a preferred embodiment, the electromagnetically shielded graphene composite film satisfies the following range: 0.8 ≦ ID / IG ≦ 2. Figures 3A and 3B show the Raman spectra of the nano-metal oxides in the electromagnetically shielded graphene composite film selected from iron oxide (Fe₂O₃), magnesium oxide (MgO), aluminum oxide (Al₂O₃), nickel oxide (NiO), tin oxide (SnO₂), manganese oxide (MnO₂), or copper oxide (CuO), as shown in Figure 3A. The measured ID / IG ratios for the electromagnetically shielded graphene composite film containing iron oxide (Fe-rGO) were 1.2, and those containing magnesium oxide (Mg-rGO) were 0.8. As shown in Figure 3B, the measured ID / IG ratios for the electromagnetically shielded graphene composite film containing magnesium oxide (Al-rGO) were 1.71, those containing nickel oxide (Ni-rGO) were 1.36, those containing tin oxide (Sn-rGO) were 1.25, those containing manganese oxide (Mo-rGO) were 1.22, and those containing copper oxide (Cu-rGO) were 1.5.
[0019] Therefore, the preparation method of this graphene composite film uses a metal plate to generate a spontaneous redox reaction with the graphene oxide solution, eliminating the need to add chemical reducing agents to the graphene oxide solution, reducing the pollution of the process environment by the chemical reducing agents, and increasing the safety of the process operation.
[0020] Furthermore, the graphene oxide is reduced to a self-assembled graphene substrate upon contact with the surface of the metal plate. The graphene substrate formed on the metal plate is then subjected to a delamination treatment using dilute hydrochloric acid, allowing the graphene substrate to be completely peeled off from the metal plate. The surface of the graphene substrate is coated with nano-metal oxides corresponding to those produced by the oxidation reaction of the metal plate, thus obtaining an electromagnetic shielding graphene composite film. This electromagnetic shielding graphene composite film has been tested for electromagnetic wave shielding and has proven to effectively block electromagnetic wave penetration while also reflecting electromagnetic waves. Therefore, this electromagnetic shielding graphene composite film can be applied to various electronic devices to achieve the effect of resisting electromagnetic interference.
[0021] In addition, to fully understand the purpose, features and effects of the present invention, XRD diffraction patterns, electromagnetic wave penetration and electromagnetic wave reflection data diagrams corresponding to multiple experimental groups and control groups in this embodiment are provided.
[0022] I. Exploring the diffraction peaks of the electromagnetically shielding graphene composite film fabricated using iron metal sheets:
[0023] (I) Preparation of electromagnetically shielded graphene composite films for experimental groups 1 and 2:
[0024] Control group: Prepare graphene oxide, which can be synthesized by itself as described in step P1 above, or the graphene oxide can be sourced from Jiangsu XFNANO Materials Tech Co., Ltd.
[0025] Experimental Group 1: The preparation method of the electromagnetic shielding graphene composite film, in step S2, an iron metal plate is immersed in the graphene oxide solution to generate a spontaneous redox reaction. The reaction time of the iron metal plate in the graphene oxide solution does not exceed 12 hours. The graphene oxide solution does not contain any reducing agent, so that the graphene oxide comes into contact with the surface of the iron metal plate and is reduced to the self-assembled graphene substrate. Then, in step S3, the iron metal plate is taken out of the graphene oxide solution. The graphene substrate generated on the iron metal plate is then subjected to a demolding treatment using 3.75wt% dilute hydrochloric acid, so that the graphene substrate is completely peeled off from the iron metal plate, and the surface of the graphene substrate is free of any damage or defects, thus obtaining the electromagnetic shielding graphene composite film containing iron oxide.
[0026] Experimental Group 2: The preparation method of the electromagnetic shielding graphene composite film, in step S2, involves immersing an iron metal sheet in the graphene oxide solution to generate a spontaneous redox reaction. The reaction time of the iron metal sheet in the graphene oxide solution does not exceed 12 hours. The graphene oxide solution does not contain any reducing agent, allowing the graphene oxide to contact the surface of the iron metal sheet and be reduced to the self-assembled graphene substrate. Then, in step S3, the iron metal sheet is removed from the graphene oxide solution. The graphene substrate formed on the iron metal plate is removed and subjected to a demolding treatment using 3.75wt% dilute hydrochloric acid, so that the graphene substrate is completely peeled off from the iron metal plate without any damage or defects on the surface. After peeling off the graphene substrate from the iron metal plate, the graphene substrate is then acid-washed with 1.875wt% dilute hydrochloric acid for 2-12 hours to remove impurities from the graphene substrate, thereby obtaining the electromagnetic shielding graphene composite film containing iron oxide.
[0027] (II) Detection of diffraction peaks of electromagnetically shielded graphene composite films containing iron oxide in experimental groups 1-2:
[0028] In this experiment, XRD diffraction tests were performed on the electromagnetically shielded graphene composite films containing iron oxide in experimental groups 1 and 2. The XRD instrument used in this embodiment was a Bruker D8 Advance. Figure 4 shows the XRD diffraction test results for experimental groups 1 and 2. Figure 4 shows that the control group has a diffraction peak at 2θ = 10° in the XRD diffraction; experimental group 1 has diffraction peaks at 2θ = 15° and 24° in the XRD diffraction; and experimental group 2 has diffraction peaks at 2θ = 13° and 24° in the XRD diffraction. Moreover, experimental group 2 has significantly less noise interference compared to experimental group 1 in the XRD diffraction. This indicates that the preparation method of the electromagnetically shielded graphene composite film, in step S3, effectively reduces impurities on the graphene substrate by peeling it from the iron metal plate and then washing it with dilute hydrochloric acid, resulting in a more concentrated diffraction peak in the XRD diffraction test of the electromagnetically shielded graphene composite film.
[0029] II. Exploring the electromagnetic wave reflectivity and transmittance of the graphene composite film containing iron oxide, which is used to fabricate an electromagnetic shielding film using ferrous metal sheets:
[0030] (I) The electromagnetic wave absorption performance of the graphene composite film containing iron oxide with electromagnetic shielding in experimental group 1 was tested, corresponding to the electromagnetic wave reflectivity and transmittance on the front and back sides:
[0031] In this embodiment, the device used to test the electromagnetic wave reflectivity and transmittance of the electromagnetically shielded graphene composite films in each experimental group was a Keysight E8364A. Figure 5A shows the electromagnetic wave absorption performance of the electromagnetically shielded graphene composite film containing iron oxide in experimental group 1, corresponding to the electromagnetic wave reflectivity on the front and back sides. From the test results in Figure 5A, it can be seen that the electromagnetic wave reflectivity of the front side of experimental group 1 in the frequency range of 8-13 GHz is between 0.1 and 1.0 dB. Specifically, the electromagnetic wave reflectivity of the front side of experimental group 1 in the frequency range of 8-9 GHz is between 0.1 and 0.2 dB; the electromagnetic wave reflectivity of the front side of experimental group 1 in the frequency range of 9-10 GHz is between 0.2 and 0.7 dB; the electromagnetic wave reflectivity of the front side of experimental group 1 in the frequency range of 10-11 GHz is between 0.4 and 0.7 dB; and the electromagnetic wave reflectivity of the front side of experimental group 1 in the frequency range of 11-12 GHz is between 0.4 and 0.7 dB. The reflectivity is between 0.4 and 1.0 dB. The electromagnetic wave reflectivity of the back side of experimental group 1 in the frequency range of 8 to 13 GHz is between -0.2 and 1.0 dB. Specifically, the electromagnetic wave reflectivity of the back side of experimental group 1 in the frequency range of 8 to 9 GHz is between -0.1 and 0.2 dB, the electromagnetic wave reflectivity of the back side of experimental group 1 in the frequency range of 9 to 10 GHz is between -0.2 and 0.5 dB, the electromagnetic wave reflectivity of the back side of experimental group 1 in the frequency range of 10 to 11 GHz is between 0 and 0.5 dB, and the electromagnetic wave reflectivity of the back side of experimental group 1 in the frequency range of 11 to 12 GHz is between 0.5 and 1.0 dB. Therefore, both the front and back sides of experimental group 1 can provide high electromagnetic wave reflection efficiency in the frequency range of 11 to 12 GHz.
[0032] Figure 5B shows the electromagnetic wave absorption performance of the graphene composite film containing iron oxide with electromagnetic shielding in Experimental Group 1, corresponding to the electromagnetic wave transmittance on the front and back sides. From the test results in Figure 5B, it can be seen that the electromagnetic wave transmittance of the front side of Experimental Group 1 in the frequency range of 8-13 GHz is between 30-34 dB. Specifically, the electromagnetic wave transmittance of the front side of Experimental Group 1 in the frequency range of 8-9 GHz is between 31-33.5 dB, in the frequency range of 9-10 GHz is between 30.0-32.0 dB, in the frequency range of 10-11 GHz is between 30.5-32.5 dB, and in the frequency range of 11-12 GHz is between 30.5-32.5 dB. The electromagnetic wave transmittance of the back side of Experimental Group 1 in the frequency range of 8-13 GHz is between 30-34 dB. The electromagnetic wave penetration rate measured in the 8-13 GHz range is between 29 and 34 dB. Specifically, the electromagnetic wave penetration rate measured on the back side of experimental group 1 in the 8-9 GHz range is between 29.5 and 33.5 dB, the electromagnetic wave penetration rate measured on the back side of experimental group 1 in the 9-10 GHz range is between 29.0 and 31.5 dB, the electromagnetic wave penetration rate measured on the back side of experimental group 1 in the 10-11 GHz range is between 30.0 and 32.0 dB, and the electromagnetic wave penetration rate measured on the back side of experimental group 1 in the 11-12 GHz range is between 29.5 and 31.5 dB. Therefore, the front and back sides of experimental group 1 can provide high impedance electromagnetic wave penetration efficiency in the 8-9 GHz range, and the front and back sides of experimental group 1 can also provide electromagnetic wave penetration rate of 29-32 dB in the 11-12 GHz range.
[0033] (II) The electromagnetic wave absorption performance of the graphene composite film containing iron oxide with electromagnetic shielding in experimental group 1' after drying was tested, corresponding to the electromagnetic wave reflectivity and transmittance on the front and back sides:
[0034] Figure 6A shows the electromagnetic wave absorption performance of the electromagnetically shielding graphene composite film containing iron oxide after drying in experimental group 1', corresponding to the electromagnetic wave reflectivity on the front and back sides. Experimental group 1' is the dried electromagnetically shielding graphene composite film containing iron oxide obtained from the aforementioned experimental group 1 after drying treatment. The drying treatment method for this electromagnetically shielding graphene composite film can be either oven drying or freeze drying, and is not limited to this. From the detection results in Figure 6A, it can be seen that the electromagnetic wave reflectivity measured on the front side of experimental group 1' in the frequency range of 8~13GHz is between... Specifically, the electromagnetic wave reflectivity measured on the front side of experimental group 1' was 1.1–1.4 dB in the 8–9 GHz frequency range, 0.1–1.4 dB in the 9–10 GHz frequency range, 0.1–0.7 dB in the 10–11 GHz frequency range, and 0.3–0.7 dB in the 11–12 GHz frequency range. The range was 0–1.6 dB. dB; The electromagnetic wave reflectivity measured on the back side of experimental group 1' in the frequency range of 8~13GHz was between 0~0.6dB. Specifically, the electromagnetic wave reflectivity measured on the back side of experimental group 1' in the frequency range of 8~9GHz was between 0.25~0.5dB, in the frequency range of 9~10GHz was between 0.2~0.65dB, and in the frequency range of 10~11GHz was between 0.4~0.65dB. The electromagnetic wave reflectivity of the back side of Group 1' measured at frequencies between 11 and 12 GHz was between 0.1 and 0.6 dB. Therefore, the electromagnetic wave reflection efficiency of the front and back sides of this experimental group 1' was significantly improved compared to the aforementioned experimental group 1. In particular, the front side of this experimental group 1' showed a greater improvement in electromagnetic wave reflection efficiency at frequencies between 8 and 9 GHz compared to frequencies between 11 and 12 GHz, while the back side of this experimental group 1' also showed a greater improvement in electromagnetic wave reflection efficiency at frequencies between 8 and 11 GHz compared to frequencies between 11 and 12 GHz.
[0035] Figure 6B shows the electromagnetic wave absorption performance of the dried graphene composite film containing iron oxide with electromagnetic shielding in experimental group 1', corresponding to the electromagnetic wave transmittance on the front and back sides. From the test results in Figure 6B, it can be seen that the electromagnetic wave transmittance of the front side of experimental group 1' in the frequency range of 8-13 GHz is between 33-39 dB. Specifically, the electromagnetic wave transmittance of the front side of experimental group 1' in the frequency range of 8-9 GHz is between 35-39 dB. The electromagnetic wave transmittance measured in the 9-10 GHz range was between 33.5 and 36.0 dB. The front side of experimental group 1' measured electromagnetic wave transmittance between 34.0 and 36.0 dB in the 10-11 GHz range, and the front side of experimental group 1' measured electromagnetic wave transmittance between 33.5 and 36.0 dB in the 11-12 GHz range. The back side of experimental group 1' measured electromagnetic wave transmittance between 33 and 38 dB in the 8-13 GHz range. Specifically, the electromagnetic wave penetration efficiency of the back side of experimental group 1' was measured to be between 34.0 and 37.5 dB in the frequency range of 8-9 GHz, between 33.5 and 36.0 dB in the frequency range of 9-10 GHz, between 33.5 and 35.5 dB in the frequency range of 10-11 GHz, and between 33.0 and 35.0 dB in the frequency range of 11-12 GHz. Therefore, the impedance electromagnetic wave penetration efficiency of the front and back sides of experimental group 1' is significantly improved compared to the aforementioned experimental group 1. In particular, the front side of experimental group 1' has a higher impedance electromagnetic wave penetration efficiency in the frequency range of 8-9 GHz compared to the frequency range of 11-12 GHz, while the back side of experimental group 1' also has a higher impedance electromagnetic wave reflection efficiency in the frequency range of 8-9 GHz compared to the frequency range of 11-12 GHz.
[0036] In summary, the electromagnetic wave absorption performance of the iron oxide-containing electromagnetic shielding graphene composite film in Experiment 1 is indeed effective in providing electromagnetic wave reflection and impedance to electromagnetic wave penetration under the frequency range of 8~13GHz. After drying, the iron oxide-containing electromagnetic shielding graphene composite film in Experiment 1' showed significantly improved electromagnetic wave reflection and impedance to electromagnetic wave penetration efficiency on both the front and back sides. Therefore, the iron oxide-containing electromagnetic shielding graphene composite film does indeed possess electromagnetic shielding function, thereby achieving the effect of impedance to electromagnetic wave interference.
[0037] III. Exploring the electromagnetic wave reflectivity and transmittance of the electromagnetically shielding graphene composite film fabricated using magnesium metal sheets:
[0038] (I) The electromagnetic wave absorption performance of the magnesium oxide-containing graphene composite film with electromagnetic shielding in experimental group 3 was tested, corresponding to the electromagnetic wave reflectivity and transmittance on the front and back sides:
[0039] Figure 7A shows the electromagnetic wave absorption performance of the magnesium oxide-containing electromagnetically shielding graphene composite film in Experiment Group 3, corresponding to the electromagnetic wave reflectivity on the front and back sides. Experiment Group 3 was fabricated using magnesium metal sheets to produce the magnesium oxide-containing electromagnetically shielding graphene composite film. The fabrication steps for Experiment Group 3 are largely the same as those for Experiment Group 1, and will not be repeated here. The test results in Figure 7A show that the electromagnetic wave reflectivity of the front side of Experiment Group 3 in the frequency range of 8–13 GHz is between 0.6 and 1.8 dB. Specifically, the electromagnetic wave reflectivity measured on the front side of experimental group 3 was 0.8–1.2 dB in the 8–9 GHz frequency range, 0.9–1.8 dB in the 9–10 GHz frequency range, 0.6–1.4 dB in the 10–11 GHz frequency range, and 0.8–1.3 dB in the 11–12 GHz frequency range. The electromagnetic wave reflectivity measured on the back side of Experimental Group 3 in the frequency range of 8-13 GHz was between 0.5 and 1.5 dB. Specifically, the electromagnetic wave reflectivity measured on the back side of Experimental Group 3 in the frequency range of 8-9 GHz was between 0.7 and 1.0 dB, in the frequency range of 9-10 GHz was between 0.7 and 1.5 dB, and in the frequency range of 10-11 GHz was between 0.5 and 1.3 dB. The electromagnetic wave reflectivity of the back side of Group 3 was measured to be between 0.5 and 1.1 dB in the frequency range of 11 to 12 GHz. Therefore, both the front and back sides of Group 3 can provide high electromagnetic wave reflection efficiency in the frequency range of 9 to 10 GHz. Moreover, the electromagnetic wave reflectivity of the front and back sides of Group 3 is significantly higher than that of Group 1. This indicates that the electromagnetic shielding graphene composite film containing magnesium oxide in Group 3 provides a better electromagnetic reflection effect than that in Group 1.
[0040] Figure 7B shows the electromagnetic wave absorption performance of the magnesium oxide-containing graphene composite film with electromagnetic shielding in Experiment Group 3, corresponding to the electromagnetic wave transmittance on the front and back sides. From the test results in Figure 7B, it can be seen that the electromagnetic wave transmittance of the front side of Experiment Group 3 in the frequency range of 8-13 GHz is between 19-23 dB. Specifically, the electromagnetic wave transmittance of the front side of Experiment Group 3 in the frequency range of 8-9 GHz is between 20.0-23.0 dB. The electromagnetic wave penetration rate measured in the 9-10 GHz range was between 19.0 and 21.0 dB. For the front side of experimental group 3, the electromagnetic wave penetration rate measured in the 10-11 GHz range was between 19.5 and 21.5 dB. For the front side of experimental group 3, the electromagnetic wave penetration rate measured in the 11-12 GHz range was between 19.0 and 21.0 dB. For the back side of experimental group 3, the electromagnetic wave penetration rate measured in the 8-13 GHz range was between 18 and 22 dB. Specifically... The electromagnetic wave transmittance measured on the back side of experimental group 3 was 19.5–22.0 dB in the frequency range of 8–9 GHz, 18.5–20.5 dB in the frequency range of 9–10 GHz, 19.0–21.0 dB in the frequency range of 10–11 GHz, and 18.5–20.5 dB in the frequency range of 11–12 GHz. Therefore, both the front and back sides of experimental group 3 provide high electromagnetic wave penetration efficiency in the frequency range of 8–9 GHz. However, the electromagnetic wave transmittance measured on the front and back sides of experimental group 3 is lower than that measured on the front and back sides of experimental group 1. This indicates that the graphene composite film containing iron oxide in experimental group 1, which provides electromagnetic shielding, is more effective at absorbing electromagnetic waves and reducing electromagnetic penetration compared to experimental group 3, thus improving the electromagnetic wave penetration resistance.
[0041] (II) The electromagnetic wave absorption performance of the magnesium oxide-containing electromagnetically shielding graphene composite film in experimental group 3' after drying was tested, corresponding to the electromagnetic wave reflectivity and transmittance on the front and back sides:
[0042] Figure 8A shows the electromagnetic wave absorption performance of the magnesium oxide-containing electromagnetically shielding graphene composite film of experimental group 3' after drying, corresponding to the electromagnetic wave reflectivity on the front and back sides. Experimental group 3' is the magnesium oxide-containing electromagnetically shielding graphene composite film obtained by drying experimental group 3. The test results in Figure 8A show that the electromagnetic wave reflectivity of the front side of experimental group 3' is between -0.4 and 1.0 dB in the frequency range of 8–13 GHz. Specifically, the electromagnetic wave reflectivity of the front side of experimental group 3' is between 0.1 and 0.5 dB in the frequency range of 8–9 GHz, between 0.1 and 0.9 dB in the frequency range of 9–10 GHz, between -0.4 and 0.7 dB in the frequency range of 10–11 GHz, and between -0.4 and 0.7 dB in the frequency range of 11–12 GHz. The electromagnetic wave reflectivity of the front and back sides of experimental group 3' is between 0.2 and 0.7 dB. The electromagnetic wave reflectivity of the back side of experimental group 3' is between -0.3 and 1.2 dB in the frequency range of 8 to 13 GHz. Specifically, the electromagnetic wave reflectivity of the back side of experimental group 3' is between 0.3 and 0.9 dB in the frequency range of 8 to 9 GHz, between 0.2 and 1.2 dB in the frequency range of 9 to 10 GHz, between -0.3 and 1.0 dB in the frequency range of 10 to 11 GHz, and between 0.1 and 1.1 dB in the frequency range of 11 to 12 GHz. Therefore, the electromagnetic wave reflection efficiency of the front and back sides of experimental group 3' is significantly lower than that of the aforementioned experimental group 3, indicating that the electromagnetic shielding graphene composite film containing magnesium oxide will significantly reduce the electromagnetic wave reflection efficiency after drying.
[0043] Figure 8B shows the electromagnetic wave transmittance of the front and back sides of the magnesium oxide-containing electromagnetically shielding graphene composite film of experimental group 3' after drying. The test results in Figure 8B show that the electromagnetic wave transmittance of the front side of experimental group 3' in the frequency range of 8-13 GHz is between 34-39 dB. Specifically, the electromagnetic wave transmittance of the front side of experimental group 3' in the frequency range of 8-9 GHz is between 36.0-39.0 dB, the electromagnetic wave transmittance of the front side of experimental group 3' in the frequency range of 9-10 GHz is between 35.0-38.0 dB, the electromagnetic wave transmittance of the front side of experimental group 3' in the frequency range of 10-11 GHz is between 34.5-37.5 dB, and the electromagnetic wave transmittance of the front side of experimental group 3' in the frequency range of 11-12 GHz is between 34.5-37.5 dB; the electromagnetic wave transmittance of the back side of experimental group 3' in the frequency range of 8-13 GHz is between 34-39 dB. The electromagnetic wave penetration efficiency measured in the ~13GHz range was between 34 and 38 dB. Specifically, the electromagnetic wave penetration efficiency measured on the back side of experimental group 3' was between 34.5 and 38.0 dB in the 8-9GHz range, between 34.0 and 36.0 dB in the 9-10GHz range, and between 34.5 and 37.0 dB in the 10-11GHz range. The electromagnetic wave penetration efficiency measured on the back side of experimental group 1' was between 34.5 and 37.5 dB in the 11-12GHz range. Therefore, the electromagnetic wave penetration efficiency of the front and back sides of experimental group 3' was significantly improved compared to the aforementioned experimental group 3, and there was no significant difference between the electromagnetic wave penetration efficiency measured on the front and back sides of experimental group 3' and that measured on the front and back sides of experimental group 1'.
[0044] In summary, the electromagnetic shielding graphene composite film of experimental group 3, containing magnesium oxide, provides a more effective electromagnetic wave reflection effect under the frequency range of 8~13GHz, and has the effect of impeding electromagnetic wave penetration. After drying treatment, the electromagnetic shielding graphene composite film of experimental group 3' will significantly reduce the electromagnetic wave reflection efficiency on the front and back sides and improve the electromagnetic wave penetration resistance effect. Thus, the electromagnetic shielding graphene composite film containing magnesium oxide does indeed have the function of electromagnetic shielding, so as to achieve the effect of impeding electromagnetic wave interference.
[0045] It is worth noting that the electromagnetic wave absorption performance of the electromagnetic shielding graphene composite film in this experiment is based on an example containing iron oxide and magnesium oxide, and is not limited thereto. In other examples, the electromagnetic wave absorption performance of the electromagnetic shielding graphene composite film containing aluminum oxide, nickel oxide, tin oxide, manganese oxide or copper oxide can also achieve the effect of resisting electromagnetic wave interference.
[0046] The above description is only a preferred embodiment of the present invention. Any equivalent changes made by applying the present invention specification and the claims should be included within the patent scope of the present invention.
[0047] P1, S1~S3: Steps
Claims
1. An electromagnetic shielding graphene composite film, comprising: a graphene substrate with a nano-metal oxide attached to its surface, wherein the electromagnetic wave absorption performance of the electromagnetic shielding graphene composite film is such that the electromagnetic wave transmittance is not more than 60 dB in the frequency range of 5 to 15 GHz, and the electromagnetic wave reflectance is between 0 and 10 dB, wherein the nano-metal oxide is selected from one of the group consisting of magnesium oxide, aluminum oxide, tin oxide and copper oxide.
2. The electromagnetic shielding graphene composite film as described in claim 1, wherein the electromagnetic wave absorption performance of the electromagnetic shielding graphene composite film is such that the electromagnetic wave transmittance is between 15 and 40 dB in the frequency range of 8 to 13 GHz, and the thickness of the graphene substrate is between 1 μm and 2 mm.
3. The electromagnetically shielded graphene composite film as described in claim 1, wherein the electromagnetically shielded graphene composite film contains a first peak at 1300 cm⁻¹ ± 100 and a second peak at 1600 cm⁻¹ ± 100 in the Raman spectrum, the peak value of the first peak is ID and the peak value of the second peak is IG; wherein the electromagnetically shielded graphene composite film satisfies the following range: 0.6 ≤ ID / IG ≤ 3.
4. The electromagnetically shielding graphene composite film as described in claim 1, wherein when the nano-metal oxide is iron oxide, the conductivity of the electromagnetically shielding graphene composite film is between 0.1 and 1000 S / cm; and when the nano-metal oxide is magnesium oxide, the conductivity of the electromagnetically shielding graphene composite film is between 0 and 750 S / cm.
5. The electromagnetically shielded graphene composite film as claimed in claim 1, wherein the electromagnetically shielded graphene composite film has diffraction peaks of 15°±3° and 25°±3° in 2θ of XRD diffraction.
6. The electromagnetic shielding graphene composite film as described in claim 1, wherein the content of the nano metal oxide accounts for 0.001 to 20 wt% of the total content of the electromagnetic shielding graphene composite film.
7. A method for preparing an electromagnetically shielding graphene composite film, comprising the following steps: Step S1, providing a graphene monoxide solution; Step S2: Immerse a metal plate in the graphene oxide solution to generate a spontaneous redox reaction. The reaction time of the metal plate in the graphene oxide solution does not exceed 12 hours, so that the graphene oxide in the graphene oxide solution comes into contact with the surface of the metal plate and is reduced to a self-assembled graphene substrate. Step S3: Remove the metal plate from the graphene oxide solution. The graphene substrate generated on the metal plate is subjected to a demolding treatment with 3.75wt% dilute hydrochloric acid, so that the graphene substrate is peeled off from the metal plate. The surface of the graphene substrate is coated with a nano-metal oxide corresponding to the metal plate generated by the oxidation reaction, so as to obtain the electromagnetic shielding graphene composite film. The electromagnetic wave absorption performance of the electromagnetic shielding graphene composite film is such that the electromagnetic wave transmittance does not exceed 60dB and the electromagnetic wave reflectance is between 0 and 10dB in the frequency range of 5~15GHz.
8. The method for preparing an electromagnetically shielding graphene composite film as described in claim 7, wherein before step S1, a further step P1 is included, in which sodium nitrate, graphite and sulfuric acid are mixed to form a reaction solution, potassium permanganate is added to the reaction solution and stirred continuously, and aqueous solution (H2O) and hydrogen peroxide are added dropwise in sequence under the stirring condition of the reaction solution, followed by repeated acid washing and centrifugation of the reaction solution with hydrochloric acid, and finally repeated centrifugation of the reaction solution with aqueous solution until the pH of the supernatant of the reaction solution is neutral, and the supernatant is subjected to ultrasonic vibration to obtain the graphene oxide solution.
9. A method for preparing an electromagnetically shielding graphene composite film as described in claim 8, wherein in step P1, the sodium nitrate, the graphite, and the sulfuric acid are stirred and mixed at 0°C to 5°C to form a reaction solution, and the potassium permanganate is added to the reaction solution in batches at least twice, and the stirring time of the reaction solution is 10 to 12 hours, wherein the concentration of the graphene oxide solution is between 0.01 and 50 mg / ml.
10. A method for preparing an electromagnetically shielding graphene composite film as described in claim 7, wherein in step S2, the graphene oxide solution does not contain any added reducing agent, and the metal plate is selected from one of the group consisting of iron, magnesium, aluminum, nickel, tin, manganese, and copper; in step S3, after the graphene substrate is peeled from the metal plate, it is acid-washed with dilute hydrochloric acid at a concentration of 1.875 wt% for 2 to 12 hours, and the nano metal oxide is selected from one of the group consisting of iron oxide, magnesium oxide, aluminum oxide, nickel oxide, tin oxide, manganese oxide, and copper oxide.
11. The method for preparing an electromagnetically shielded graphene composite film as described in claim 10, wherein when the nano-metal oxide is iron oxide, the conductivity of the electromagnetically shielded graphene composite film is between 0.1 and 1000 S / cm; and when the nano-metal oxide is magnesium oxide, the conductivity of the electromagnetically shielded graphene composite film is between 0 and 750 S / cm.
12. A method for preparing an electromagnetically shielded graphene composite film as described in claim 10, wherein the electromagnetically shielded graphene composite film contains a first peak at 1300 cm⁻¹ ± 100 and a second peak at 1600 cm⁻¹ ± 100 in the Raman spectrum; wherein the electromagnetically shielded graphene composite film satisfies the following range: 0.6 ≦ ID / IG ≦ 3, the peak value of the first peak is ID, and the peak value of the second peak is IG.
13. The method for preparing an electromagnetically shielded graphene composite film as described in claim 10, wherein the electromagnetically shielded graphene composite film has diffraction peaks of 15°±3° and 25°±3° in 2θ of XRD diffraction.