## The Pros and Cons of Graphene Production Methods￼

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In the years following its discovery in 2004, graphene has been lauded in the media as the new promising material of the future. In fields ranging from drug delivery to space exploration, its use has been extensively discussed. The graphene layer is a single-atom thick layer of graphite that has strong covalent bonds between each carbon atom, arranged in a two-dimensional hexagonal lattice nanostructure (Chakraborty & Hashmi, 2018). Its covalent bonds contribute to its strength. Furthermore, graphene is a lightweight material, weighing only 0.77 milligrams per square meter (Osborne, 2021). It is also extremely flexible, having been shown to be able to be stretched to 25 percent of its length without breaking (Osborne, 2021). The structure has delocalized electrons as well, allowing the electrons to move more freely, contributing to its strong conductivity (Osborne, 2021). Due to graphene’s excellent properties, it has been utilized in a range of applications in the past eighteen years. These include consumer electronics, wearables, flexible radio frequency devices, supercapacitors, conductive inks, and sensors (Chakraborty & Hashmi, 2018). Its widespread use is hindered by a few problems, including the difficulty in making graphene quickly and in large quantities. Potential graphene mass production methods have finally caught up in the last few years, which will hopefully lead to a real-world application of this super material.

Chemical Vapour Deposition (CVD) is a common method for producing graphene. The process involves heating a mixture of gases – at least one of which contains carbon – until a plasma is formed (Owuor et al., 2020). A graphene layer is formed on the nickel or copper substrate by the plasma (Owuor et al., 2020). A waste gas pump then removes the waste gase (Owuor et al., 2020)s. It is vital that the temperature of the substrate is maintained at the appropriate level since it determines the type of reaction that will occur (Owuor et al., 2020). The advantage of this method is that it yields high-quality graphene (Owuor et al., 2020). The downside of this process is that it is temperature-dependent, which uses a significant amount of energy. Furthermore, it produces extremely toxic gaseous by-products during the process (Owuor et al., 2020). This method produces graphene at a cost to the environment and human health. Additionally, it is extremely expensive and not feasible for mass production.

Researchers from MIT have developed a process for fabricating long strips of high quality graphene tailored toward membrane applications (Gorey, 2018). A common industrial process for manufacturing thin foils, called roll-to-roll, is used in this method (Kidambi et al., 2018). In combination with the common graphene fabrication technique of chemical vapour deposition, copper foil is fed into a heated tube before mixing with methane and hydrogen gas to form graphene foil (Kidambi et al., 2018). By continuously feeding the foil through the system, they were able to produce high-quality graphene at a rate of 5 centimeters per minute (Kidambi et al., 2018). The longest run they conducted lasted almost four hours, during which they produced about ten meters of graphene (Kidambi et al., 2018). Although this method produces much more graphene, it is still very expensive for large scale production, and it is not environmentally friendly.

Another promising way of manufacturing graphene is the flash Joule heating method. Essentially, it turns garbage into useful graphene (Galeon, 2017). Chris Sorensen and other Kansas State University researchers devised a simple method of making graphene using three simple materials: hydrocarbon gas, oxygen, a spark plug, and a detonation of carbon-containing materials (Wyss et al., 2022). A spark plug is used to ignite oxygen and acetylene or ethylene gas contained in a chamber (Wyss et al., 2022). After detonation, graphene is formed (Wyss et al., 2022). A benefit of this process is that it is simple and inexpensive, and it can be easily adapted for industrial production  (Galeon, 2017). It is also sustainable as it uses any carbon-containing materials  (Galeon, 2017). One disadvantage is that the quality of graphene is not always ideal, and researchers at Sorensen’s lab are working to improve it  (Galeon, 2017).

In conclusion, the inability to produce graphene in bulk is one of the main obstacles in the way of wide-spread application of graphene. Even though some methods, such as CVD and roll-on-roll production methods, produce high quality graphene, they cannot be mass produced and are both expensive and energy intensive. Flash graphene offers a low-cost and highly adaptable industrial production of graphene, however, the quality is compromised. At the present time, there is no simple method for obtaining high-quality graphene in large quantities (Johnson & Meany, 2018). To realize graphene’s true potential, it must be made in mass quantities and at a reasonable price (Johnson & Meany, 2018). Only then will graphene transform the world.

References

Chakraborty, M., & Hashmi, M. S. (2018). Wonder material graphene: Properties, synthesis and practical applications. Advances in Materials and Processing Technologies, 4(4), 573–602. https://doi.org/10.1080/2374068x.2018.1484998

Galeon, D. (2017, January 28). We may finally have a way of mass producing graphene. Futurism. Retrieved March 10, 2022, from https://futurism.com/we-may-finally-have-a-way-of-mass-producing-graphene

Gorey, C. (2018, April 19). MIT may have just solved how to mass-produce graphene. Silicon Republic. Retrieved March 10, 2022, from https://www.siliconrepublic.com/machines/mass-produce-graphene-solved

Johnson, L., & Meany, J. E. (2018). Mass-producing graphene. American Scientist. Retrieved March 10, 2022, from https://www.americanscientist.org/article/mass-producing-graphene

Kidambi, P. R., Mariappan, D. D., Dee, N. T., Vyatskikh, A., Zhang, S., Karnik, R., & Hart, A. J. (2018). A scalable route to nanoporous large-area atomically thin graphene membranes by roll-to-roll chemical vapor deposition and polymer support casting. ACS Applied Materials & Interfaces, 10(12), 10369–10378. https://doi.org/10.1021/acsami.8b00846

Osborne, L. (2021, February 4). The current and future production of graphene. AZoNano.com. Retrieved March 10, 2022, from https://www.azonano.com/article.aspx?ArticleID=5613

Owuor, P. S., Khan, A., Leon, C. L., Ozden, S., Priestley, R., Arnold, C., Chopra, N., & Tiwary, C. S. (2020). Roadblocks faced by graphene in replacing graphite in large-scale applications. Oxford Open Materials Science, 1(1). https://doi.org/10.1093/oxfmat/itab004

Wyss, K. M., Luong, D. X., & Tour, J. M. (2022). Large‐scale syntheses of 2D materials: Flash Joule Heating and other methods. Advanced Materials, 34(8), 2106970. https://doi.org/10.1002/adma.202106970