Master thesis defence by Martin Kühnel – Københavns Universitet

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Master thesis defence by Martin Kühnel

C60 intercalated bilayer graphene

The main objective of this thesis was to synthesize a two-dimensional heterostructure consisting of two remarkable carbon structures: two graphene sheets with a C60 fullerene monolayer in between, also known as "Carbon Burger". The possibility of synthesizing this structure from two different intercalation methods of the C60 molecules into bilayer graphene samples was studied. The motivation behind the presented work is the promising prospect of the Carbon Burger being a two-dimensional semiconductor with the in-plane properties of pristine graphene.

The first method is thermal intercalation of C60 molecules directly into graphene samples. The synthesized structure was characterized by a series of techniques including: AFM, SEM, XRD, Raman spectroscopy and CAFM. With these it is demonstrated that the thermal experiments does not yield the proposed structure, as none of the samples showed signs of successful intercalation.

Another approach presented in this thesis is to ease the intercalation of the large C60 molecules by expanding the interlayer distance of graphite by potassium intercalation. The C60 molecules are intercalated in solution or thermally.

The unsuccessful experiments inspired a very critical discussion of the results obtained by two articles suggesting the two difference intercalation methods to synthesize C60 intercalated graphite. From this discussion a slightly alternative interpretation of the results obtained in the two articles are given.

All in all the work in this project shows no sign of successful intercalation of C60 molecules into bilayer graphene nor graphite, hence it is concluded that thermal intercalation is not a suitable route to production of the Carbon Burger, regardless of what is stated in the literature.