Known as biphenylene, the substance consists of an orderly lattice of squares, hexagons, and octagons, rather than just the honeycomb hexagons that make up graphene’s atom-thin layer. Theoretical studies had shown that different flat network patterns like this were possible, but none had been achieved until now. It’s claimed that the new material could have a range of exciting applications in electronics and advanced engineering.
Published in Science, the work saw researchers from the University of Marburg in Germany and Aalto University in Finland assembling carbon-containing molecules on an extremely smooth gold surface. These molecules first form chains consisting of linked hexagons. A subsequent reaction connects these chains together to form the squares and octagons.
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 biphenylene because the reaction between two different types of chains leads to the creation of graphene rather than the new material.
"The new idea is to use molecular precursors that are tweaked to yield biphenylene instead of graphene" said Linghao Yan, who carried out the high-resolution microscopy experiments at Aalto University.
According to the researchers, biphenylene has metallic properties not found in graphene. Narrow strips of the material just 21 atoms wide behave like metal, while similar strips of graphene behave like semiconductors.
"These stripes could be used as conducting wires in future carbon-based electronic devices," said Marburg’s Professor Michael Gottfried, who led the team who developed the idea.
Lead author Qitang Fan, also from Marburg University, believes biphenylene could one day play a role in electrification and advanced battery technology.
"This novel carbon network may also serve as a superior anode material in lithium-ion batteries,” he said, “with a larger lithium storage capacity compared to that of the current graphene-based materials."