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Large stable pieces of graphene with a unique edge pattern

Different patterns are formed along the edges of nanograph. Zigzags are especially interesting – and especially unstable. The FAA researchers managed to create stable layers of carbon with this pattern at the edges. Provided by: FAU / Konstantin Amsharov.

Bay, fjord, bay, armchair and zigzag – chemists use such terms to describe the forms taken by the edges of nanograph. Graphene consists of a single-layer carbon structure, in which each carbon atom is surrounded by three others. This creates a pattern resembling a honeycomb, with atoms in each of the corners. Nanograph is a promising candidate for bringing microelectronics to nanoscale and, probably, a silicon substitute.

The electronic properties of a material strongly depend on its shape, size and, above all, on the periphery, in other words, on how the edges are structured. Zigzag periphery is particularly suitable – in this configuration, electrons that act as charge carriers are more mobile than in other edge structures. This means that the use of pieces of zigzag graphene in the components of nanoelectronics can provide higher frequencies for switches.

Scientists who want to investigate only zigzag nanographies face the problem that this form makes the connections unstable and difficult to produce in a controlled way. This is imperative, however, if electronic properties must be investigated in detail.

Researchers led by Dr. Konstantin Amsharov from the Department of Organic Chemistry II have now succeeded in this. Their study was published in Nature connection, Not only did they discover the simple method of synthesizing zigzag nanographen, their procedure provides a yield close to 100 percent, and is suitable for large-scale production. They have already produced a technically significant amount in the laboratory.

A very popular zigzag pattern can be found either in the chess series of honeycombs (blue and purple) or in the four-pointed stars surrounding the center point of four graphene honeycombs (red and green). Provided by: FAU / Konstantin Amsharov.

The researchers first created preliminary molecules, which then combine to form a honeycomb structure for several cycles in a process known as cyclization. In the end, graphene fragments are formed from chess rows of honeycombs or four-pointed stars surrounding the center point of four graphene honeycombs, with the desired zigzag pattern at the edges. The product crystallizes directly, even during synthesis. In the solid state, the molecules are not in contact with oxygen. In solution, however, oxidation causes rapid destruction of structures.

This approach allows scientists to produce large pieces of graphene, while maintaining control over their shape and periphery. This breakthrough in research on graphene means that scientists will soon be able to produce and explore various interesting structures of nanographs, which is an important step towards using the material in nanoelectronic components.

Explore further:
Holey graphene as an alternative to Holy Grail silicon chips

Additional Information:
Dominik Lunderich et al., Dehydrating π-elongation to nanografen with zigzag edges, Nature connection (2018). DOI: 10.1038 / s41467-018-07095-z

Link to the magazine:
Nature connection

Provided by:
University of Erlangen-Nuremberg

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