1成果简介

　　高度取向的多功能石墨烯薄膜在电导、电磁屏蔽、电加热、热管理及红外隐身等领域展现出广阔的应用前景。然而，其复杂的制备步骤和高昂成本严重制约了大规模实际应用。本文，燕山大学张瑞军 教授团队在《Materials & Design》期刊发表名为“Facile fabrication of high-performance multi-functional ultrathin GAs films with high orientation”的论文，研究提出一种开创性且简便的低成本制备方法，可制备出高取向性、高性能的多功能柔性石墨烯聚集体（GAs）压制薄膜。通过构建取向排列的GAs泡沫结构，再进行单向机械压缩，成功制备出兼具优异柔韧性与高取向性的GAs压制薄膜。其中，厚度为48.7微米的压制薄膜表现出：电导率达5.349×10⁵ S/m，电磁屏蔽值达106.2 dB； 在仅1.7V的极低驱动电压下，焦耳热温度高达256.70°C；面内热导率达768.2W·m⁻¹·K⁻¹，红外发射率极低（3-5μm波段为0.388； 8–12μm波段为0.284），赋予其卓越的红外隐身性能。因此，这种柔性超薄GAs压延薄膜凭借其在电导率、电磁屏蔽、电加热、热管理及红外隐身等多方面的优异表现，将成为极具前景的多功能薄膜材料。
　　2图文导读 

　　图1. Schematic illustration of the fabrication process of HCGAs.

　　图2. Comparison of the morphology, structural and compositional analysis of HCGAs foams. a Optical image, b-i Cross-sectional SEM image, J XRD patterns, k Raman spectra, l XPS survey spectra, m C1s spectra.

　　图3. Structural characteristic and mechanical property of HCGAs-GF-75.49. a Optical image, b Top-view SEM image, c AFM image, d Cross-sectional SEM image, e 2D SAXS pattern and corresponding azimuthal angle plot of HCGAs-GF-75.49. f flexibility property of HCGAs-GF-75.49.

　　图4. a Conductivity comparasion of HCGAs-GF-12.70, HCGAs-GF-25.97, HCGAs-GF-59.23 and HCGAs-GF-75.49, b stability test of HCGAs-GF-75.49, c EMI shielding performance comparasion of HCGAs-GF-12.70, HCGAs-GF-25.97, HCGAs-GF-59.23 and HCGAs-GF-75.49, d R,A and T values of HCGAs-GF-75.49. e Comparison of EMI SE of HCGAs-GF-75.49 with typical EMI shielding materials of different thicknesses (Graphene, rGO, MXene, CNT, conductive polymers, and metals, etc.) reported in recent years.

　　图5. a Curves of surface temperature with time at low driving voltage of 0.5–1.7 V, b Linear relationship between saturation temperature of HCGAs-GF and U2, c Temperature curve of HCGAs-GF-75.49 under a stepwise voltage from 0.5to 1.7 V, d Long-time heating performance of HCGAs-GF-75.49 at 1.7 V. e Temperature stability and repeatability of the HCGAs-GF-75.49 under ON/OFF of input voltage (1.7 V). f Practical application results of HCGAs-GF-75.49 as a electric heater g Comparison of Joule heating performance of HCGAs-GF-75.49 with other materials.

　　图6. a Thermal conductivity values of HCGAs-GF-12.70, HCGAs-GF-25.97, HCGAs-GF-50.23, and HCGAs-GF-75.49b Diagram of experimental setup for thermal conductive test c Heat dissipation Curve for LED d Comparison of infrared thermal images of HCGAs-GF-12.70, HCGAs-GF-25.97, HCGAs-GF-50.23, and HCGAs-GF-75.49 as LED heat dissipating substrate.

　　图7. a,b IR emissivity of HCGAs-GF-12.70, HCGAs-GF-25.97, HCGAs-GF-59.23 and HCGAs-GF-75.49, c IR image of a HCGAs-GF-75.49 placed on the palm of the hand. d,e Record the temperature profile of the palm and the HCGAs-GF-75.49 above it and the demonstration of the infrared stealth effect of HCGAs-GF-75.49 with a specific shape f The thermal Camouflage Performance Testing of HCGAs-GF-75.49 g-j The comparative of temperature curves between HCGAs-GF-75.49 and the heated substrate.
　　3小结
　　本文提出了一种简便策略，用于低成本制备具有高取向性的高性能多功能柔性GAs压制薄膜。主要步骤包括：通过真空辅助过滤含NG、H₂SO₄和KHSO₅的浆料实现NG取向排列；在室温下通过GAs限制取向生长形成取向排列的GAs泡沫；在450°C下对GAs泡沫进行酸去除；以及对GAs泡沫进行单向机械压缩。制备的超薄GAs压制薄膜展现出优异的柔韧性与高取向度。我们系统研究了石英片覆盖浆料表面时施加的C轴压力对最终GAs压制薄膜性能的影响，结果表明：C轴压力越高，薄膜性能越优异。厚度为48.7微米的超薄HCGAs-GF-75.49薄膜展现出高达5.349×10⁵ S/m的卓越电导率，并在X波段获得106.2 dB的优异电磁干扰抑制值。此外，HCGAs-GF-75.49可在仅1.7V的极低驱动电压下快速达到256.70°C的高温。该薄膜不仅具备卓越的导热性（768.2 W·m⁻¹·K⁻¹），更拥有极低的红外发射率（在3-5μm与8-12μm波段分别仅为0.388和0.284），因此作为红外隐形薄膜表现优异。凭借在电导率、电磁屏蔽、电加热、热传导及红外隐身等方面的卓越性能，采用新开发策略制备的高取向性GA压制薄膜有望作为高性能多功能超薄膜展现广阔应用前景。
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