An image of a nanocrawler, a horizontal nanowire that crawls along a graphene surface. (Image courtesy of Carnegie Mellon University.)
A team of engineering researchers recently made a novel discovery about nanowires purely by accident: the team created nanowires that “crawled” along the surface of graphene film. These so-called nanocrawlers were surprising because the team was expecting the nanowires to grow vertically out of the graphene surface.
“We looked at the results, and they were kind of mind-blowing,” said Tzahi Cohen-Karni, a professor of materials science and engineering at Carnegie Mellon University who was involved in the research. “We set forth to understand why the nanowires crawled on the surface.”
But in addition to the vertical GeNWs, the team found they had also synthesized horizontal nanocrawlers (GeNCs). By studying this result, the team determined they were able to control the amount of nanocrawlers on the graphene by introducing hydrogen chloride gas (HCl) during the nucleation phase of their experiment. By adjusting variables such as temperature and time lag before HCl introduction, the team could control the fraction of GeNCs compared to GeNWs.
Harvesting Light with Nanocrawlers
The team’s discovery is exciting because of the potential application of nanocrawlers as photodetectors. Nanocrawlers could prove to be much more sensitive to light – that is, more useful in converting it to electricity – than the vertical nanowires the team set out to create.
“Photodetectors made with nanocrawlers could potentially detect smaller amounts of light than their vertical nanowire counterparts,” said Cohen-Karni.
To learn more about the discovery, you can access the team’s paper in Nano Letters.
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