Graphene given recycling boost
10 Aug 2015
Engineers at the Graphene Flagship have demonstrated a recyclable technique that yields cost-effective, high-quality graphene.
The technique, which has been designed to enhance the traditional method of synthesising graphene via the chemical vapour deposition (CVD) of methane gas onto a copper substrate, permits researchers to peel graphene flakes from a CVD substrate with minimal chemical contamination.
To avoid such chemical contamination, the research team – which comprised Flagship-affiliated physicists from RWTH Aachen University, Germany and German research centre, Forschungszentrum Jülich – incorporated strong van der Waals interactions between graphene and boron nitride into its method.
Until now, graphene synthesised this way has been significantly lower in quality
Lead researcher Christoph Stampfer
The van der Waals interaction is the attractive sum of short-range electric dipole interactions between uncharged molecules – a force that ultimately allowed the Graphene Flagship research team to separate CVD graphene from the copper substrate and transfer it to an arbitrary substrate.
According to the research team, the newly developed process also allows for the re-use of the catalyst copper foil in further growth cycles, and minimises contamination of the graphene due to processing.
What’s more, no noticeable performance changes were detected between devices developed in the first and subsequent growth cycles – a breakthrough that confirms the copper as a recyclable resource in the graphene fabrication process, the researchers said.
“Chemical vapour deposition is a highly scalable and cost-efficient technology,” said Christoph Stampfer, head of the 2nd Institute of Physics A at Aachen University.
“Until now, graphene synthesised this way has been significantly lower in quality than that obtained with the ‘scotch-tape’ method, especially when it comes to the material’s electronic properties. But no longer,” Stampfer said.
Via the scotch-tape method, layers of sticky tape are used to peel graphene flakes from a piece of graphite, thereby obtaining micrometre graphene sheets – a process that is not considered industrially viable.
However, Stampfer said his team’s process is, “in principle”, suitable for industrial-scale production, and narrows the gap between graphene research and its technological applications.
A full account of the research has been published in the journal Sciences Advances.
