24/05/2021

New type of atomically thin carbon material (not graphene)

Researchers at the University of Marburg in Germany and Aalto University in Finland have now discovered a new carbonnetwork, which is atomically thin like graphene, but is made up of squares, hexagons, and octagons forming an ordered lattice. The new material is made by assembling carbon-containing molecules on an extremely smooth gold surface. These molecules first form chains that consist of linked hexagons, and a subsequent reaction connects these chains together to form the squares and octagons.

They confirmed the unique structure of the network using high-resolution scanning probe microscopy and interestingly found that its electronic properties are very different from those of graphene. In contrast to graphene and other forms of carbon, the new Biphenylene network—as the new material is named—has metallic properties. Narrow stripes of the network, only 21 atoms wide, already behave like a metal, while graphene is a semiconductor at this size.

An important feature of the chains is that they are chiral, which means that they exist in two mirroring types, like left and right hands. Only chains of the same type aggregate on the gold surface, forming well-ordered assemblies, before they connect. This is critical for the formation of the new carbon material, because the reaction between two different types of chains leads only to graphene. 

The study is published in Science.

https://phys.org/news/2021-05-graphene-atomically-thin-carbon-material.html

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