Hexagons: Honeycombs and Graphene

This week’s lecture was particularly interesting to me as it delved deeper into the physical uses of graphite, especially in its journey as a component in a pencil. In the beginning of the lecture, I really liked the interpretation that we are composed of stardust. It made me feel a bit mystical in a way, haha. 

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Figure 1. We are made of stardust! This is my drawing of the hexagonal pattern similarities between graphite/graphene versus honeycombs. Nature has a wonderful way of displaying a structure that provides efficiency.

In regards to carbon compounds such as graphite and graphene, it was fascinating to look at these compounds through a more artistic lens. As a biochemistry major, the field primarily focuses on the chemical structures of organic compounds, so I had a fairly detailed background about carbon and its three allotropes. Additionally, my inorganic chemistry professor, Dr. Kaner., presented many lectures about his research into graphite, graphene, and its applications in nanotechnology when I took his class in the fall. If I remember correctly Dr. Kaner and his lab was quintessential in aiding in the discovery of graphene by Andre Geim1. I found it quite fascinating that pulling sheets of graphite into graphene was done by such a simple method with cellophane tape. Further researching into this method of peeling these graphite layers one-by-one, it was noted that the “tape is ultimately pressed down against [an appropriate] substrate to deposit a sample”.2 In reality, the carbons that are attached to the tape were thicker than one single layer. This is why it was necessary to utilize the van der Waal’s attraction between the layers to the substrate to divide these larger flakes once they were lifted.

Screen Shot 2022-04-05 at 11.26.37 AM_0.pngFigure 22. “Single layer graphene was first observed by Geim and others at Manchester University. Here a few layer flakes are shown, with optical contrast enhanced by an interference effect at a carefully chosen thickness of oxide.”  This process to successfully obtain a flake of graphene is extremely tedious, and patience is required. Additionally, those who are not as experienced obtain thick slabs of graphite where the single layer cannot be extracted.

Graphite in its natural (mined) state does not inherently demonstrate the hexagonal patterns that we have discussed in class when viewed under an electron micrograph even though we are aware of the fact that the carbon atoms in graphite do form such a structure. To view and try to make comparisons between graphite and other natural forms (in this case, honeycombs), it was necessary to expand the graphite via acid intercalation and thermal shock2.

Screen Shot 2022-04-05 at 9.02.18 AM_0.pngFigure 32. “Scanning electron micrographs of natural graphite before (a) and after (b) expansion by acid intercalation and thermal shock.”2 Dr. Kaner and his lab reported these structures as “honeycomb-like”, further drawing a connection between the natural formation of organics in nature to prefer efficient hexagonal structures.

Such comparison may be difficult to make out in Figure 3, however when a STM image of graphite was pictured, the structure had a striking resemblance to the hexagonal structure of honeycombs. From Dr. Kaner’s lab and the paper, “Honeycomb Carbon: A review”, the following image was specifically colorized in this yellow/orange format to make it clear the comparison between the two.

Screen Shot 2022-04-05 at 11.35.41 AM_0.pngFigure 42. (a and b) STM image of graphite. “(a) STM image of graphite showing only the three carbons that eclipse a neighbor in the sheet directly below. (b) In contrast, all six carbons are equivalent and thus visible in mechanically exfoliated single-layer graphene”2

Beehive-micro_large-min_0.jpegFigure 53. Hexagonal honeycomb for space efficiency. It is suggested that hexagon[s] inscribed in a circular figure encloses the greatest amount of space.”4

If I showed Figure 4 to someone without a background in chemistry and asked them what it was a picture of, I am pretty sure they would respond with saying it is a honeycomb. When colorized in this manner, it certainly does resemble it, doesn't it? 

Lastly, graphene and its discovery has opened up countless possibilities for advances in technology. In regards to electronics, the honeycomb/hexagonal lattice of graphine has been suggested to replace silicon. This would mean faster systems, electronics, and possibly extremely thing touchscreens in our devices.5 I look forward to seeing what the future has in store for us as we learn more and explore different aspects and chemical properities of this compound. 


References (Cited in ACS format) 

(1)

October 22, 2004: Discovery of Graphene http://www.aps.org/publications/apsnews/200910/physicshistory.cfm (accessed 2022 -04 -05).

(2)

Allen, M. J.; Tung, V. C.; Kaner, R. B. Honeycomb Carbon: A Review of Graphene. Chem. Rev. 2010, 110 (1), 132–145. https://doi.org/10.1021/cr900070d.

(3)

George, S. Why Are Honeycomb Cells Hexagonal? Science Friday.

​​(4)

Honeycomb Structure Is Space-Efficient and Strong — Biological Strategy — AskNature https://asknature.org/strategy/honeycomb-structure-is-space-efficient-and-strong/ (accessed 2022 -04 -05).

(5)

Nelson; Brian, S.; Houston, U. of. 11 Ways Graphene Could Change the World https://www.treehugger.com/ways-graphene-could-change-the-world-4863867 (accessed 2022 -04 -05).