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Graphene-infused glass fiber fabric bridges conductivity with electromagnetic transparency
(Nanowerk Spotlight) The rapid integration of high-density multifunctional systems and modules in modern electronics has brought the issue of electromagnetic compatibility to the forefront. Conventional conductive materials like metals are crucial components in electronic instruments, but their inherent impedance mismatch with air causes strong reflection of incident electromagnetic waves. This low electromagnetic transparency, or transmissivity, can interfere with surrounding signal communications.
Achieving high electrical conductivity while maintaining low electromagnetic reflectivity and high transmissivity has been an elusive goal. Metals exhibit excellent conductivity due to their high carrier concentrations, but this results in considerably lower intrinsic wave impedance compared to air, leading to severe reflections. On the other hand, electromagnetic-transparent materials like glass fiber possess high transmissivity but lack conductivity. Attempts to combine these disparate properties often fell short.
Recent advancements in two-dimensional materials, particularly graphene, have opened new avenues to tackle this challenge. Graphene boasts exceptional electrical and electromagnetic properties thanks to its unique atomic structure and electronic band configuration. Its high carrier mobility enables conductivity rivaling metals, while the low carrier concentration promotes impedance matching with air. Theoretical analyses indicated that graphene could potentially achieve the sought-after synergy of high conductivity, low reflectivity, and high transmissivity.
Building upon this potential, researchers have now developed an innovative graphene glass fiber fabric that successfully merges the intrinsic properties of graphene with the dielectric attributes and porous structure of a glass fiber fabric substrate. The work, led by Professor Zhongfan Liu and his team, marks a significant step towards eliminating the incompatibility between electrical conductivity and electromagnetic transmissivity that plagues conventional conductive materials.
The findings have been reported in Advanced Materials ("Overcoming the Incompatibility Between Electrical Conductivity and Electromagnetic Transmissivity: A Graphene Glass Fiber Fabric Design Strategy").
Decoupling chemical vapor deposition (CVD)-grown graphene from surface-melted hydroxylated glass fibers
Decoupling chemical vapor deposition (CVD)-grown graphene from surface-melted hydroxylated glass fibers. a) Eb values of graphene on three representative glass fibers with different surface states: solid silica (Gra/SiO2(s)), surface-melted silica (Gra/SiO2(l)), and hydroxylated surface-melted silica (Gra/SiO2(l)-OH). b) Strategy for decoupling CVD-grown graphene from glass fibers, in which high-temperature annealing causes the surface of the glass fibers to melt, and methanol is used as the carbon precursor to achieve surface hydroxylation.
At the heart of their achievement is a novel decoupling chemical vapor deposition growth strategy that enables controlled preparation of high-quality, layer-limited graphene directly on the noncatalytic, nonmetallic glass fibers. The process involves melting the surface of the glass fiber fabric at high temperatures and using methanol as a carbon precursor to achieve surface hydroxylation.
This pivotal step allows the graphene to decouple from the glass fiber surface during growth, leading to larger domain sizes, fewer defects, and better control over the number of layers.
The resulting graphene glass fiber fabric exhibited remarkable properties. At comparable sheet resistance values, it demonstrated significantly lower electromagnetic reflectivity and higher transmissivity compared to its metal-based counterpart, copper-coated glass fiber fabric. The hierarchical, highly porous macrostructure of the glass fiber fabric also played a key role in lowering reflectivity and enhancing transmissivity.
Rigorous characterizations and simulations further corroborated the advantages of graphene glass fiber fabrics comprising few-layer graphene with large domain sizes and low defect densities. Compared to fabrics with multi-layer, defective graphene, the optimized samples exhibited superior permittivity, reflectivity, and transmissivity values in the gigahertz frequency range. The fabrics maintained high performance across a wide band from 2 to 18 GHz, highlighting their excellent broadband transparency.
Beyond their impressive electromagnetic properties, the graphene glass fiber fabrics also excelled in practical electrothermal applications. When fashioned into Joule heaters, they demonstrated rapid heating rates, uniform temperature distributions, and exceptional cycling stability that surpassed conventional metal-based heaters. The strong interfacial adhesion between the graphene layers and glass fibers, combined with graphene's atomic thinness, bestowed the fabrics with superior flexibility and deformation robustness compared to their metallic counterparts.
Comparisons of the electrical and EM properties of the graphene glass fiber fabric (GGFF) and copper-coated glass fiber fabric (CuGFF)
Comparisons of the electrical and EM properties of the graphene glass fiber fabric (GGFF) and copper-coated glass fiber fabric (CuGFF). a) Schematics for the comparisons of GGFF and CuGFF. b) Photographs of the GGFF and CuGFF samples. c) R□ mappings of GGFF and CuGFF with comparable sheet resistance and high uniformity (402.7 ± 14.2 and 394.2 ± 17.6 Ω·sq−1, respectively). d) Permittivity, e) EM reflectivity, and f) transmissivity data of GGFF and CuGFF with R□ values of 200–3000 Ω·sq−1 in the 8.2–12.4 GHz range.
The implications of this work extend beyond the immediate results. The successful integration of graphene's intrinsic properties with the glass fiber fabric substrate opens up new possibilities for multifunctional materials that can seamlessly blend electrical and electromagnetic capabilities. Potential applications span radar, antenna, and stealth technologies, where the fabric's unique properties could enable previously unattainable levels of performance and compatibility.
Moreover, the decoupling chemical vapor deposition growth strategy introduced in this study provides a valuable tool for the controlled synthesis of high-quality graphene on noncatalytic, nonmetallic substrates. This paves the way for exploiting graphene's exceptional properties in a wider range of composite materials and device architectures.
As with any groundbreaking research, challenges remain in terms of scalability, consistency, and long-term durability. Nevertheless, the graphene glass fiber fabric stands as a testament to the power of innovative material design and growth strategies in pushing the boundaries of what is possible. By overcoming the long-standing trade-off between electrical conductivity and electromagnetic transparency, this work opens new frontiers in electronic and electromagnetic technologies.
The development of graphene glass fiber fabric represents a significant advancement in the pursuit of multifunctional materials that can integrate electrical conductivity and electromagnetic transparency. The research team's innovative approach opens up new possibilities for applications in fields such as radar, antenna systems, and stealth technologies.
For instance, the fabric's unique properties could enable the creation of advanced radomes that protect radar systems while ensuring minimal signal attenuation. In antenna applications, the material could be used to design lightweight, conformal, and electromagnetically transparent structures that maintain high conductivity for efficient signal transmission and reception.
Moreover, the fabric's low reflectivity and high transparency make it a promising candidate for stealth technologies, where it could be employed in the construction of aircraft electromagnetic windows or radar-absorbing surfaces.
As the fabrication processes are further refined and scaled up, the potential for graphene glass fiber fabric to revolutionize these and other industries becomes increasingly evident. With continued research and development, this innovative material could play a pivotal role in shaping the future of advanced electronics and electromagnetic systems.
Michael Berger By – Michael is author of three books by the Royal Society of Chemistry:
Nano-Society: Pushing the Boundaries of Technology,
Nanotechnology: The Future is Tiny, and
Nanoengineering: The Skills and Tools Making Technology Invisible
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