Probe into a New Material—Graphene

Posted by beauty33 on February 25th, 2020

When speak of Graphene, you may still be unfamiliar with it, but soon it will become a familiar and popular topic of science and technology like virtual reality, gene editing, and artificial intelligence.

As the thinnest, strongest and most conductive material, graphene is known as "black gold" by material scientists. So how does it really change our lives?

What is graphene?

The name graphene comes from the combination of English graphite (graphite) and -ene (ends of alkenes), and natural graphite is formed by stacking layers of planar carbon atoms arranged in a honeycomb order.

The interlayer forces of graphite are weak, and it is easy to peel off each other to form thin graphite sheets. If we strip the graphite sheet to a single layer with only one carbon atom thick, it becomes graphene.

How was graphene discovered?

Graphene was once thought to be a hypothetical structure that simply could not exist alone. It wasn't until 2004 that physicists Andley Heim and Constantine Novoselov of the University of Manchester, UK, experimentally isolated graphene using "micromechanical stripping" to make it stand alone.

Although this discovery is significant, the method used is very simple—using cellophane tape to stick to highly oriented pyrolytic graphite, fold the sticky face, and tear the tape apart, the graphite flakes are split in two. By repeating this process over and over again, the graphite sheet becomes thinner and thinner, eventually yielding graphene, a two-dimensional crystalline material with only one carbon atom thick.

Since then, after nearly five years of development, researchers have discovered more ways to prepare graphene, indicating that this new material is not far from entering the field of industrial production. Heim and Novoshorov also won the 2010 Nobel Prize in Physics for their pioneering experimental preparation of graphene, a new material.

In an interview with the Nobel Prize Foundation, Novoselov talked about the idea of preparing graphene, mainly from a small habit of the two men on Friday nights—a time when they would try to solve complex scientific problems with various "rough", simple experimental methods, and the whimsical idea of "tearing graphite with tape" was born.

What are the characteristics of graphene?

The advent of graphene has caused tremendous waves in the scientific community and triggered a boom in research. After more than a decade of research and development, people gradually realized the unique value of graphene.

First, the motion of electrons in graphene is extremely fast, reaching 1/300 of the speed of light, much faster than in general conductors, and very similar to the so-called neutrinos in relativity. At the same time, the resistivity of graphene is only 10^-6 Ohm · cm, which is much lower than that of copper or silver, and it has the world's smallest resistivity and best conductivity.

Second, graphene is harder than diamonds, 100 times stronger than steel, and is the most powerful substance known. If you use graphene to make a film about 100 nanometers thick, it will be able to withstand the pressure of about two tons of objects.

In addition, the light transmittance, thermal conductivity, and flexibility of graphene are also very good—the light transmittance reaches 97.4%, which is almost completely transparent; the thermal conductivity is as high as 5,300 W/(m · k), which is 10 times that of copper and 25 times that of aluminum; and the flexibility is better than that of indium tin oxide, a commonly used touch screen material, which is not easily damaged and can be comparable to that of single carbon nanotubes.

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