The current focus on graphene owes its legacy to the foundations of nanoscience laid down with the discovery of buckminsterfullerene (named in homage to the geodesic domes of architect Richard Buckminster Fuller) in 1985. (1) This sparked the search for other fullerenes, complex carbon nanostructures typically occurring as spheres (similar in appearance to a soccer ball, and colloquially known as “buckyballs”) or cylinders. The first cylindrical structures, quickly dubbed nanotubes, were isolated in 1991. (2) Graphene can be considered as an unzipped and flattened-out nanotube, and has been shown to have unique electronic properties under certain conditions. (3)

Explosive growth

The growth of the peer-reviewed journal literature on nanotubes and graphene is nothing short of remarkable. While articles on fullerenes have appeared in steadily increasing numbers annually since 1985 (see Figure 1), massive (and so far sustained) growth has been observed for both nanotubes and graphene. Early response to the “discovery” of each of these materials shows very different trends (see Figure 2). While fullerene and nanotube research expanded rapidly, graphene research has grown exponentially (at a rate of 58% per year) since the publication of Novoselov et al. (4), a landmark paper describing a new method for isolating stable graphene sheets. The citation impact of this paper is visualized in Figure 3, giving a clear sense of the citation ripples emanating from this paper out into the literature, like those from a brick dropped in a pond.

Figure 1. English-language research articles published in journals in the period 1985–2009. Keyword searches were conducted for fullerenes (*fullerene), nanotubes (nanotube*) and graphene (graphene*). Source: Scopus.

Figure 1. English-language research articles published in journals in the period 1985–2009. Keyword searches were conducted for fullerenes (*fullerene), nanotubes (nanotube*) and graphene (graphene*). Source: Scopus.

Figure 2. English-language research articles published in journals from the year indicated (i.e. for fullerenes, Y1 is 1985). Keyword searches were conducted for fullerenes (*fullerene), nanotubes (nanotube*) and graphene (graphene*). Source: Scopus.

Figure 2. English-language research articles published in journals from the year indicated (i.e. for fullerenes, Y1 is 1985). Keyword searches were conducted for fullerenes (*fullerene), nanotubes (nanotube*) and graphene (graphene*). Source: Scopus.

Figure 3. All documents citing Novoselov et al. (2004; shown at the centre of the figure). Each concentric ring of citing documents were published in 2005 through 2009 respectively and are identified by their first author – note how their number increases with each year, just like the broadening of the ripples in a pond. Source: Scopus.

Figure 3. All documents citing Novoselov et al. (2004; shown at the centre of the figure). Each concentric ring of citing documents were published in 2005 through 2009 respectively and are identified by their first author – note how their number increases with each year, just like the broadening of the ripples in a pond. Source: Scopus.

This paper effectively opened up research on the characterization and exploitation of the unique properties of graphene to a new field of scientists, many of whom had previously been working on carbon nanotubes. Indeed, the 100 most prolific authors on graphene to date have shown a recent decline in their share of publication output on nanotubes in favor of graphene, with the latter exceeding the former since 2008. These top 100 authors appear to have a low and decreasing output on fullerenes,
perhaps a carryover from the origins of the nanotube and graphene research fields.

Figure 4. Percentage shares of total article output of most prolific 100 graphene researchers on fullerenes, nanotubes or graphene. Keyword searches were conducted for fullerenes (*fullerene), nanotubes (nanotube*) and graphene (graphene*). Source: Scopus.

Figure 4. Percentage shares of total article output of most prolific 100 graphene researchers on fullerenes, nanotubes or graphene. Keyword searches were conducted for fullerenes (*fullerene), nanotubes (nanotube*) and graphene (graphene*). Source: Scopus.

Graphene research boom
How does the graphene revolution feel to those working in the field? Dr Jamie Warner, Glasstone Research Fellow in Science at the Department of Materials, Brasenose College, University of Oxford comments: “The main thing I see when visiting other research groups is the massive uptake of graphene-focused research. Everyone wants to get on board the graphene revolution. Laboratories that have facilities for examining carbon nanotubes are suitable for graphene as well. So there is no real investment cost required to expand the research into graphene. […] When combined with the ease with which graphene can be obtained from scotch (sticky) tape, it is evident why output in graphene research has boomed in such a short time.

“It’s clear that many researchers are riding the graphene wave in the hope of high-impact papers. The quest for all scientists is to be among those leading the field. But there are few who are setting the trend for others to follow. In such a fast-moving field, it may be hard to stay ahead.”

Contribution to the carbon community
How has this fundamental shift in research direction affected the communities of physicists (interested in graphene’s electronic properties), materials scientists (seeking potential applications in new carbon materials) and chemists and surface scientists working on its large-scale synthesis?

Dr Warner continues: “The coalescence of nano-carbon communities hasn’t really changed that much. Groups have always collaborated worldwide; that is the nature of science. More interesting is how established groups have shifted focus or expanded. Research groups that were previously working on nanotubes are now entering the graphene field.

“Groups with established expertise in examining carbon nanotubes with high-resolution transmission electron microscopy – such as Kazu Suenaga and Sumio Iijima at the National Institute of Advanced Industrial Science and Technology (AIST) in Japan, and Alex Zettl at UC Berkeley – were able to translate their expertise directly to graphene. The large-scale growth of graphene using chemical vapor deposition (CVD) was a similar case: groups with experience and apparatus set up for CVD of nanotubes – such as Rodney Ruoff at the University of Texas at Austin – were able to modify the catalyst structure to grow graphene. Surprisingly, it was two scientists with no background in carbon nanotubes or fullerenes, Kostya Novoselov and Andre Geim, who made the biggest contribution to the field of graphene. This highlights how people from outside the immediate field can make a massive impact.”

References:

(1) Kroto, H.W., Heath, J.R., O'Brien, S.C., Curl, R.F., Smalley, R.E. (1985) “C60: Buckminsterfullerene”, Nature, vol. 318, issue 6042, pp. 162-163.
(2) Iijima, S. (1991) “Helical microtubules of graphitic carbon”, Nature, vol. 354, issue 6348, pp. 56-58.
(3) Soldano, C., Mahmood, A., Dujardin, E. (2010) “Production, properties and potential of graphene”, Carbon, vol. 48, issue 8, pp. 2127-2150.
(4) Novoselov, K.S., Geim, A.K., Morozov, S.V., Jiang, D., Zhang, Y., Dubonos, S.V., Grigorieva, I.V., Firsov, A.A. (2004) “Electric field in atomically thin carbon films”, Science, vol. 306, issue 5696, pp. 666-669.
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