No, it wasn’t a selfie, but the latest graphene news to cross our radar started out when someone took a snapshot of something in some restaurant. The photo could have ended up on Instagram, buried among however many millions of food shots whizzing along the Intertubes at the dinner hour. Instead, it provided the inspiration for penta-graphene, a newly discovered variant of graphene.
For those of you new to the topic, we’ve called graphene the nano-material of the new millennium because its unique and powerful electronic properties lend themselves to solar cells, EV batteries, and all kinds of other cleantech applications. So, is penta-graphene five times better than graphene?
Is Penta-Graphene Five Times Better Than Graphene?
The short answer to that question is maybe.
The “penta” in penta-graphene refers to the five-sided structure of the new variant, not to any particular enhancement over the now familiar six-sided structure of graphene.
More to the point, the research is still in the computer modeling phase. However, the researchers are pretty confident that the new material will exhibit some improvements.
According to a newly published study in the journal Proceedings of the National Academy of Sciences, under the title “Penta-Graphene: A New Carbon Allotrope,” the new material could outrun graphene in some respects.
Here’s a snippet from the abstract:
…State-of-the-art theoretical calculations confirm that the new carbon polymorph is not only dynamically and mechanically stable, but also can withstand temperatures as high as 1000 K [Kelvin]. Due to its unique atomic configuration, penta-graphene has an unusual negative Poisson’s ratio and ultrahigh ideal strength that can even outperform graphene.
As described by Commonwealth University of Virginia, penta-graphene is a semiconductor (graphene is a conductor), and it will remain a semiconductor even when you roll it up into a nanotube (graphene can be metallic or a semiconductor in that state).
What Is A Negative Poisson’s Ratio?
Okay, we had to look that up, too, but Poisson’s ratio refers to what happens when you stretch a material, for instance a rubber band. It expands in the direction of stretching, but it becomes thinner, or contracts, in the opposite direction.
Graphene is stretchable in a normal Poisson’s kind of way. Penta-graphene, on the other hand, expands in both directions when stretched, which is why the abstract calls it a “negative” Poisson’s ratio.
If that’s a little hard to wrap you head around, some types of polymer foam exhibit the negative effect, and you can kind of mimic it by pulling a square of rubber from opposite corners.
How To Make Penta-Graphene
Speaking of rubber, here’s where the rubber hits the road — how are you going to make the leap from a computer model to penta-graphene?
Keep in mind that the original discoverers of graphene used a piece of sticky tape to lift a layer of carbon atoms from a chunk of graphite (graphite is a soft form of carbon), and you’re on the right track.
According to the abstract, penta-graphene can be similarly “exfoliated” from T12-carbon.
About That Inspirational Snapshot
As for the inspiration behind the new discovery, that happened when researcher Qian Wang of Peking University and Virginia Commonwealth University (VCU) was dining out in Beijing, and noticed an artwork displaying the distinctive five-sided pattern of Cairo street paving.
For the record, Wang is co-author of the study. The senior author is Puru Jena of VCU, and also on the author list are Shunhong Zhang (Peking University), Jian Zhou (VCU), Xiaoshuang Chen, (Chinese Academy of Science in Shanghai), and Yoshiyuki Kawazoe (Tohoku University in Japan).
Image by Virginia Commonwealth University.
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