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Preparation of Flexible Ferromagnetic Graphene Quartz Fiber Fabric with Super-large Size and Ultra-wideband Strong Electromagnetic Shielding Properties

Release time:

Jul 07,2022

Liu Zhongfan of Peking University and Beijing Graphene Research Institute-The research team has made important progress in the preparation and application of flexible graphene quartz fibers. The team reported for the first time the use of roll-to-roll chemical vapor deposition (CVD) technology to batch prepare large-area, lightweight, flexible, ferromagnetic graphene quartz fiber fabric (FGQF) with ultra-wideband strong electromagnetic shielding effectiveness. The relevant results are titled "Ultra-broadband strong electromagnetic interference shielding with ferromagnetic graphene Quartz fabric. In this work, an oversized flexible ferromagnetic graphene quartz fiber fabric (FGQF) was first prepared using a roll-to-roll CVD batch growth system. By precisely controlling the nitrogen doping type of graphene, the preparation of ferromagnetic graphene layers with high conductivity (3906 S · cm-1) and high magnetic response (saturation magnetization of 0.14 emu · g-1 at room temperature) was achieved (Figure 1a). At the same time, the special woven structure of FGQF fabric introduces additional multiple reflection and multi-channel absorption of electromagnetic waves into the material, which further enhances the electromagnetic shielding effectiveness of the material. The 1 mm thick FGQF exhibits a superior shielding effectiveness of 107 dB at an ultra-wide band of 1-18 GHz, while achieving high EMI shielding efficiency and a wide EMI immunity band (Figure 1c). Using the graphene roll-to-roll continuous CVD growth system independently developed by the team (Figure 1b), the large-scale preparation of FGQF was realized, with a single batch preparation size of up to 10 × 0.5 m2 (Figure 1d), which provides an important basis for the practical application of materials. Based on the high conductivity, ferromagnetism and special woven structure of FGQF, when the electromagnetic wave reaches the surface of the material, it interacts with the free carriers on the surface of graphene, and part of the electromagnetic wave is reflected. By optimizing the impedance matching at the air-material interface, the remaining electromagnetic waves will enter the inside of the FGQF, match with the FGQF conductive network, and produce multiple internal reflections in its woven structure. Therefore, the ferromagnetic graphene layer with high conductivity and high magnetic response can achieve effective absorption and attenuation of electromagnetic wave energy (Figure 2a). The shielding mechanism of single ferromagnetic graphene quartz fiber (about 7 μm in diameter) in FGQF fiber cloth is analyzed in detail. The electromagnetic wave is reflected multiple times in the adjacent fiber array, and the multilayer ferromagnetic graphene can efficiently absorb the reflected electromagnetic wave, further attenuate the electromagnetic wave energy, so as to obtain high electromagnetic shielding effectiveness.

In this work, an oversized flexible ferromagnetic graphene quartz fiber fabric (FGQF) was first prepared using a roll-to-roll CVD batch growth system. By precisely controlling the nitrogen doping type of graphene, the preparation of ferromagnetic graphene layers with high conductivity (3906 S · cm-1) and high magnetic response (saturation magnetization of 0.14 emu · g-1 at room temperature) was achieved (Figure 1a). At the same time, the special woven structure of FGQF fabric introduces additional multiple reflection and multi-channel absorption of electromagnetic waves into the material, which further enhances the electromagnetic shielding effectiveness of the material. The 1 mm thick FGQF exhibits a superior shielding effectiveness of 107 dB at an ultra-wide band of 1-18 GHz, while achieving high EMI shielding efficiency and a wide EMI immunity band (Figure 1c). Using the graphene roll-to-roll continuous CVD growth system independently developed by the team (Figure 1b), the large-scale preparation of FGQF was realized, with a single batch preparation size of up to 10 × 0.5 m2 (Figure 1d), which provides an important basis for the practical application of materials.

Based on the high conductivity, ferromagnetism and special woven structure of FGQF, when the electromagnetic wave reaches the surface of the material, it interacts with the free carriers on the surface of graphene, and part of the electromagnetic wave is reflected. By optimizing the impedance matching at the air-material interface, the remaining electromagnetic waves will enter the inside of the FGQF, match with the FGQF conductive network, and produce multiple internal reflections in its woven structure. Therefore, the ferromagnetic graphene layer with high conductivity and high magnetic response can achieve effective absorption and attenuation of electromagnetic wave energy (Figure 2a). The shielding mechanism of single ferromagnetic graphene quartz fiber (about 7 μm in diameter) in FGQF fiber cloth is analyzed in detail. The electromagnetic wave is reflected multiple times in the adjacent fiber array, and the multilayer ferromagnetic graphene can efficiently absorb the reflected electromagnetic wave, further attenuate the electromagnetic wave energy, so as to obtain high electromagnetic shielding effectiveness.

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