Highly Aligned Graphene Aerogels for Multifunctional Composites

Highly Aligned Graphene Aerogels for Multifunctional Composites

15 February 2024 | Ying Wu, Chao An, Yaru Guo, Yangyang Zong, Naisheng Jiang, Qingbin Zheng, Zhong-Zhen Yu
Highly aligned graphene aerogels have emerged as a promising class of materials due to their exceptional properties and diverse applications. These materials, composed of interconnected graphene sheets, exhibit remarkable mechanical, electrical, thermal, and photo-thermal characteristics. However, the random orientation of graphene sheets in conventional aerogels limits their potential. To address this, researchers have focused on developing highly aligned graphene aerogels, where the preferential alignment of graphene sheets in a three-dimensional network structure offers unique advantages and enables novel functionalities. Alignment plays a crucial role in enhancing the properties and performance of graphene aerogels. Highly aligned graphene aerogels are characterized by the preferential orientation of individual graphene sheets, resulting in a high aspect ratio and a common directionality. This controlled alignment imparts several notable benefits over their randomly oriented counterparts. Firstly, the aligned structure of graphene aerogels significantly enhances their mechanical strength and stiffness, making them capable of withstanding higher loads and exhibiting remarkable structural integrity. This enhanced mechanical robustness is particularly advantageous for applications requiring materials with high strength-to-weight ratios, such as lightweight structural components, flexible electronics, and aerospace materials. Secondly, alignment greatly influences the electrical conductivity of graphene aerogels. The ordered arrangement of graphene sheets allows for efficient charge transport pathways along the aligned direction, resulting in anisotropic electrical conductivity. This can be applied in electronic devices, such as field-effect transistors, where aligned graphene aerogels enable improved charge mobility and device performance. Moreover, the anisotropic conductivity of aligned graphene aerogels facilitates the development of directional electronic devices and sensors, opening up new avenues for electronic and sensing applications. Thirdly, alignment plays a vital role in facilitating efficient heat and mass transfer within graphene aerogels. The highly ordered structure enables preferential pathways for thermal conduction, enabling rapid heat dissipation and effective thermal management. Furthermore, the aligned channels within the aerogel structure provide efficient transport pathways for gases and liquids, making aligned graphene aerogels suitable for applications such as thermal steam and organic absorption. Significant progress has been made in the synthesis and characterization of highly aligned graphene aerogels. Researchers have employed various techniques, including directional freeze casting, self-assembly, and shear-induced alignment to achieve controlled alignment of graphene sheets. These methods allow precise tuning of the alignment degree and directionality, offering the ability to tailor properties of graphene aerogels for specific applications. Given the multitude of advantages offered by highly aligned graphene aerogels, their applications span across diverse fields. The highly aligned graphene aerogels and their composites have been explored as electrodes in energy storage devices, such as supercapacitors and lithium-ion batteries, to enhance their power and energy density. The anisotropic conductivity and efficient transport properties of aligned graphene aerogels have also been leveraged in sensors, oil spill cleanup, and templates for the growth of other nanomaterials. This review provides a comprehensive overview of the state-of-the-artHighly aligned graphene aerogels have emerged as a promising class of materials due to their exceptional properties and diverse applications. These materials, composed of interconnected graphene sheets, exhibit remarkable mechanical, electrical, thermal, and photo-thermal characteristics. However, the random orientation of graphene sheets in conventional aerogels limits their potential. To address this, researchers have focused on developing highly aligned graphene aerogels, where the preferential alignment of graphene sheets in a three-dimensional network structure offers unique advantages and enables novel functionalities. Alignment plays a crucial role in enhancing the properties and performance of graphene aerogels. Highly aligned graphene aerogels are characterized by the preferential orientation of individual graphene sheets, resulting in a high aspect ratio and a common directionality. This controlled alignment imparts several notable benefits over their randomly oriented counterparts. Firstly, the aligned structure of graphene aerogels significantly enhances their mechanical strength and stiffness, making them capable of withstanding higher loads and exhibiting remarkable structural integrity. This enhanced mechanical robustness is particularly advantageous for applications requiring materials with high strength-to-weight ratios, such as lightweight structural components, flexible electronics, and aerospace materials. Secondly, alignment greatly influences the electrical conductivity of graphene aerogels. The ordered arrangement of graphene sheets allows for efficient charge transport pathways along the aligned direction, resulting in anisotropic electrical conductivity. This can be applied in electronic devices, such as field-effect transistors, where aligned graphene aerogels enable improved charge mobility and device performance. Moreover, the anisotropic conductivity of aligned graphene aerogels facilitates the development of directional electronic devices and sensors, opening up new avenues for electronic and sensing applications. Thirdly, alignment plays a vital role in facilitating efficient heat and mass transfer within graphene aerogels. The highly ordered structure enables preferential pathways for thermal conduction, enabling rapid heat dissipation and effective thermal management. Furthermore, the aligned channels within the aerogel structure provide efficient transport pathways for gases and liquids, making aligned graphene aerogels suitable for applications such as thermal steam and organic absorption. Significant progress has been made in the synthesis and characterization of highly aligned graphene aerogels. Researchers have employed various techniques, including directional freeze casting, self-assembly, and shear-induced alignment to achieve controlled alignment of graphene sheets. These methods allow precise tuning of the alignment degree and directionality, offering the ability to tailor properties of graphene aerogels for specific applications. Given the multitude of advantages offered by highly aligned graphene aerogels, their applications span across diverse fields. The highly aligned graphene aerogels and their composites have been explored as electrodes in energy storage devices, such as supercapacitors and lithium-ion batteries, to enhance their power and energy density. The anisotropic conductivity and efficient transport properties of aligned graphene aerogels have also been leveraged in sensors, oil spill cleanup, and templates for the growth of other nanomaterials. This review provides a comprehensive overview of the state-of-the-art
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[slides and audio] Highly Aligned Graphene Aerogels for Multifunctional Composites