Loopy graphene scrubs up nicely, thanks to new research

Researchers at the Oak Ridge National Laboratory in the states have found a way to sharpen up an experimental cleaning process that is crucial if graphene is to take its place at the heart of future electronics design.

Back in 2009 it was reported that 'Joule heating process' could actually introduce a fatal defect into the chickenwire structure of graphene: as well as cleaning the edges, it could connect the layers to one another, rendering the material useless.

Vincent Meunier, one of the scientists who originally demonstrated the Joule heating process as a cleaning method, said: "Imagine you have a fancy sports car, but then you realize it has square wheels. What good is it? That's like having jagged edges on graphene.”

Now Meunier and his colleagues Bobby Sumpter and Eduardo Cruz-Silva at the ORNL, have run super computer simulations of the process to better understand how the loops were forming. They discovered that if the graphene was irradiated with electrons at an intermediate step, the loop formation was minimised.

From the press announcement: Imaging with a transmission electron microscope, or TEM, subjected the graphene to electron irradiation, which ultimately prevented loop formation. The ORNL simulations showed that by injecting electrons to collect an image, the electrons were simultaneously changing the material's structure.

"Taking a picture with a TEM is not merely taking a picture," Sumpter said. "You might modify the picture at the same time that you're looking at it."

A rather lovely high res image is here. The top image shows two layers of graphene forming a tube. The second shows two layers that have been irradiated during the cleaning process. Loopiness is all but gone.