Recent research breakthroughs shed light on the potential applications of impermeable graphene, offering hope for a more sustainable and resilient future.
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The Significance of Impermeability in Nanomaterials
The ability of a nanomaterial to prevent the passage of gases or liquids is known as impermeability. In the realm of graphene, achieving impermeability could open up a host of transformative applications. For instance, a material so impermeable that it could store gases like methane with unprecedented efficiency could revolutionize clean energy solutions, making it safer and more feasible to store and transport gases for fuel cells and energy storage.
The impermeable nature of graphene could be harnessed to create advanced water filtration systems since its precise atomic structure allows it to sieve out even the tiniest impurities and contaminants, promising a more sustainable solution to clean drinking water worldwide.
Similarly, graphene's impermeability could lead to ultra-thin yet ultra-strong protective coatings for various surfaces and materials, preventing corrosion, wear, and tear in a wide range of industries, from aerospace to automotive. Moreover, impermeable graphene could be a game-changer in developing more durable and reliable electronic devices, as it can protect sensitive components from environmental factors like moisture and corrosive gases.
Challenges in Developing Impermeable Graphene
Graphene is a two-dimensional material composed of a single layer of carbon atoms arranged in a hexagonal, having exceptional electrical conductivity, strength, and thermal properties.
While the potential benefits of impermeable graphene are immense, achieving this property is not without its challenges. For instance, perfectly pristine graphene, composed of a single layer of carbon atoms in a hexagonal lattice, is theoretically impermeable to even the smallest gas molecules. However, imperfections and defects, including structural irregularities, impurities, and vacancies in the atomic lattice, can compromise its impermeability, providing pathways for gas molecules to permeate.
Another challenge is the size of the gas or liquid molecules being blocked since graphene may be impermeable to small molecules like helium and it might not effectively block larger molecules or ions, which makes tailoring of graphene impermeable to a broad range of materials a complex endeavor. Similarly, graphene's impermeability can also be influenced by environmental factors such as temperature, pressure, and humidity as well.
Permeability for Hydrogen
Researchers in a 2020 study investigated the impermeability of defect-free graphene. The study reveals that defect-free graphene is indeed impermeable to most gases, except for hydrogen, which surprisingly shows some permeation. This unexpected hydrogen permeation is attributed to a two-stage process involving hydrogen chemisorption on active graphene ripples and subsequent flipping to the other side of the graphene sheet with relatively low energy. This discovery challenges conventional notions and underscores the unique properties of graphene. The findings have significant implications for understanding the impermeability of two-dimensional materials and their potential applications.
Graphene Coatings and Their Impermeability
In another 2020 study, researchers demonstrated that graphene coatings, particularly those deposited by chemical vapor deposition, can significantly reduce corrosion rates. Electrophoretically deposited graphene oxide coatings also show promise but may require careful control of deposition parameters for optimal performance. The study further explores the inorganic functionalization of graphene coatings, including nitrogen doping and other additives.
These modifications enhance corrosion resistance by improving coating conductivity and structure. Additionally, graphene can be integrated into organic coatings, where its dispersion, hydrophobicity, and adhesion to the polymer matrix enhance corrosion protection. Water-based coatings with well-dispersed graphene offer a more environmentally friendly alternative.
In a more recent 2022 study, researchers explored the impermeability of graphene-based films for various applications, including protective coatings and encapsulation of electronic devices. Ideally, monolayer graphene should be impermeable to all gases and liquids due to its small geometric gap. Still, actual graphene-based barrier films showed less impressive performance due to defects and pores.
The researchers developed a super-barrier film with a water vapor transmission rate (WVTR) as low as 4.1 x 10-5 g/m².day. This remarkable performance was achieved through a combination of strategies. Large-sized graphene oxide (GO) sheets, both gly-nGO and pGO, were used to maximize coverage, reaching nearly 100%. Additionally, a sequential reduction process closed the interlayer gaps and enhanced surface hydrophobicity.
The study demonstrated that this scalable and cost-effective approach could produce high-performance super-barrier films, potentially finding applications in various fields where impermeability is crucial. These films surpassed existing graphene-based barriers, showcasing their effectiveness in preventing the ingress of water vapor and other small molecules.
Future Prospects for Impermeable Graphene
The quest for impermeable graphene holds immense promise across various applications. It could revolutionize clean energy storage by efficiently storing gases like methane, improving global access to clean drinking water through advanced filtration systems, and enhancing protective coatings for industries such as aerospace and automotive. Moreover, it could safeguard sensitive electronic components from environmental factors.
However, achieving impermeability is not without its challenges. Imperfections and defects in the atomic lattice, as well as variations in gas molecule size, pose obstacles.
Recent studies have shed light on the impermeability of graphene, revealing its unique properties and potential applications. Additionally, researchers have made strides in graphene coatings, demonstrating their effectiveness in reducing corrosion rates and creating high-performance super-barrier films for various crucial impermeability applications. These findings underscore the ongoing pursuit of unlocking the full potential of graphene in diverse fields.
References and Further Reading
Lee, W. J., Kim, C. S., Yang, S. Y., Lee, D., & Kim, Y. S. (2022). Ultrathin Super-barrier film via 100% surface coating coverage of Self-assembled graphene oxide sheets. Chemical Engineering Journal. https://doi.org/10.1016/j.cej.2022.135913
Ollik, K., & Lieder, M. (2020). Review of the application of graphene-based coatings as anticorrosion layers. Coatings. https://doi.org/10.3390/coatings10090883
Pei, J., Liao, Y., Li, Q., Shi, K., Fu, J., Hu, X., ... & Liu, K. (2022). Single-layer graphene prevents Cassie-wetting failure of structured hydrophobic surface for efficient condensation. Journal of Colloid and Interface Science. https://doi.org/10.1016/j.conbuildmat.2022.128947
Safarkhani, M., & Naderi, M. (2023). Enhanced impermeability of cementitious composite by different content of graphene oxide nanoparticles. Journal of Building Engineering. https://doi.org/10.1016/j.jobe.2023.106675
Sun, P. Z., Yang, Q., Kuang, W. J., Stebunov, Y. V., Xiong, W. Q., Yu, J., ... & Geim, A. K. (2020). Limits on gas impermeability of graphene. Nature. https://doi.org/10.1038/s41586-020-2070-x