Tips for Nanographene Production | Mirage News



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Some orange spheres form an inverted pyramid at the top of the image.  Below is a shape made up of black spheres.  Between the two there is a blue light.

Atomic force microscope. The copper probe can manipulate matter on an atomic scale. © 2020 Shiotari et al.

Nanographene is a material that is expected to radically improve solar cells, fuel cells, LEDs, and more. Typically the synthesis of this material has been imprecise and difficult to control. For the first time, researchers have discovered an easy way to gain precise control over the fabrication of nanographene. In doing so, they shed light on the previously unclear chemical processes involved in the production of nanographene.

You’ve probably heard of graphene, atom-thick sheets of carbon molecules, which are supposed to revolutionize technology. Units of graphene are known as nanographene; these are adapted to specific functions and as such their manufacturing process is more complicated than that of generic graphene. Nanographene is produced by selectively removing hydrogen atoms from organic carbon and hydrogen molecules, a process called dehydrogenation.

“Dehydrogenation occurs on a metal surface such as that of silver, gold or copper, which acts as a catalyst, a material that enables or accelerates a reaction,” said Assistant Professor Akitoshi Shiotari of the Department of Materials Science. advanced. “However, this surface is large compared to the target organic molecules. This contributes to the difficulty in creating specific nanographic formations. We needed a better understanding of the catalytic process and a more precise way to control it. “

A grid of four images.  The first two are grayscale images with white backgrounds on top that are dark masses.  The lower images are diagrams of atoms shown with colored spheres.

Dehydrogenation. An organic molecule with an unwanted hydrogen atom (left) and the same molecule with the removed atom (right). © 2020 Shiotari et al.

Shiotari and his team, exploring various ways to perform nanographene synthesis, have come up with a method that offers the precise control needed and is also very efficient. They used a specialized type of microscope called an atomic force microscope (AFM), which measures the details of molecules with a needle-shaped nanoscopic probe. This probe can be used not only to detect certain characteristics of individual atoms, but also to manipulate them.

“We found that the metal AFM probe could break the carbon-hydrogen bonds in organic molecules,” Shiotari said. “It could do this very precisely since its tip is so small and it could break bonds without the need for heat energy. This means that we can now fabricate nanographene components in a more controlled way than ever. “

To verify what they were seeing, the team repeated the process with a variety of organic compounds, most notably two molecules with very different structures called benzonoids and non-benzonoids. This shows that the AFM probe in question is capable of extracting hydrogen atoms from different types of materials. Such a detail is important if this method is to be extended to a commercial means of production.

“I imagine this technique could be the best way to create functional nanomolecules from the bottom up,” Shiotari said. “We can use an AFM to apply other stimuli to target molecules, such as electron injection, electron fields or repulsive forces. It’s exciting to be able to see, control and manipulate structures on such an incredibly tiny scale. “

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