In the cold winter, when you want to buy some warm clothes on the e-commerce platform, a search will definitely pop up all kinds of products containing the word "graphene".
It can also be said that thanks to these commodities, many people seem to be no strangers to graphene. But at the end of the day, do you really know what graphene is?
Superior graphene material
Graphene, also known as two-dimensional carbon material, as an allotrope of carbon, has superior conductivity and mechanical advantages that are incomparable with other substances, and it can be said that it has its presence in most high-precision fields.
Just in 2004, two scientists from the United Kingdom discovered the predecessor of graphene materials, graphite flakes, for the first time. So how did they extract this material?
Initially, two scientists decomposed graphite flakes in a substance called highly directional pyrolytic graphite. The graphite sheets were then bonded and re-decomposed with special tape. When the graphite flakes were broken down to their fullest extent, they got a thin sheet with only carbon atoms left, which is what we know as graphene.
At that time, the mainstream idea in the physics community was that thermodynamic fluctuations could not exist at the ordinary temperature of two-dimensional crystals, but graphene materials were able to break this convention. As a result, as they became more proficient and scientific in the extraction of graphene, they won the Nobel Prize in Physics that year just six years later.
Andrei Geim (left) Kostya Novoselov (right)
With the deepening of people's research on graphene materials, the superior properties of this material have also been discovered. Since graphene is formed by the continuous decomposition of graphite flakes, the carbon atomic structure of the monolayer also makes it very lightweight.
However, after testing the hardness of graphene, scholars found that the hardness of this material can reach 100 times that of steel. And because the internal arrangement of carbon atoms in the graphene material presents a honeycomb structure, the material itself also has excellent conductivity and optical advantages.
Graphene under an electron microscope
Generally speaking, in fact, the graphite paper decomposed from graphite flakes is very brittle, but through the later artificial improvement, the oxidized graphite paper can form graphene with strong toughness, and the graphene material in this state can even be greatly bent and bent, and it will not break.
Because the material itself has too many advantageous qualities, most of the high-tech industries of human society can find its shadow. Among them, it is well known in the fields of communication equipment, aerospace, and energy batteries. But what is puzzling is that in ordinary daily life, graphene materials are very rare, and few graphene products are available.
Behind the superior performance is the high cost of manufacturing
Since the invention of graphene in 2004, this material has actually made great progress in two decades, and even plays a pivotal role in the high-tech industry.
Although graphene materials have been popularized in many fields, it is still difficult for the general market to become mainstream, and the root cause of all this is that graphene manufacturing is too expensive and complex. In 2020, graphene materials were even sold for $100 per gram.
Some people may ask, why is it difficult to mass produce graphene even though the refills of pencils are graphite. In fact, this is because graphene is also a carbon substance, but in terms of structure, it is different from the three-dimensional structure of graphite.
As we said, graphene is also called a two-dimensional carbon material, and the main reason is that its internal structure presents a hexagonal grid in a honeycomb state. This structure has really given it a stable structure that has catapulted it into a darling in many material fields.
But because of this, people have not been able to fully quantify graphene materials, because whenever factories expand the scale of production, the structure of graphene will be damaged and it will not be able to meet the standards for the use of materials.
At present, the most common extraction method of graphene materials is chemical vapor deposition. This method refers to a process that uses gaseous substances to react to produce solid deposits. In this way, it is possible to peel off a wide range of materials with maximum film integrity.
Graphene extraction requires this method because the material itself is born from a graphite flake. Although we found the most suitable method when it came to extraction, the most suitable does not mean the most perfect.
Although the integrity of the material is maintained, the reaction process requires a lot of energy to carry out properly, and in addition to this, we have to add many additional harmful raw materials to participate in the chemical vapor deposition process.
Epitaxial growth method and process of silicon carbide
In addition to chemical vapor deposition, we also have methods for extracting graphene materials such as silicon carbide surface epitaxial growth method, but they all require a lot of energy to support.
This is destined to require a lot of production costs when graphene materials are being produced. But for the general market, most civilian products do not have such high material requirements. Therefore, this has formed a strange phenomenon that graphene shines in high-tech industries, but is unknown in ordinary industries.
Perhaps only when we can reduce the production cost of graphene materials can we usher in the future of graphene civilian use.
Civil graphene products still need to be viewed dialectically
Do the well-known graphene batteries and graphene thermal underwear really have advantages that other products do not have?
In fact, graphene materials have excellent thermal conductivity. According to the testing of this material by scholars over the years, it has been found that the thermal conductivity of pure single-layer graphene materials can even reach more than 5,000 W/mK, which is much higher than that of nanotubes in the same form. From this point of view, graphene thermal underwear does have a large market.
However, the excellent thermal conductivity can only prove that graphene thermal underwear is extremely functional, and from the perspective of the merchant's sales cost, will this be a high-yield business?
The answer, of course, is no, as we said, in the process of extraction and manufacturing of graphene, it requires the use of special skills, and even because the material itself has many limitations, so the factory cannot expand the scale of production indefinitely when processing.
Under the superposition of various limitations, can graphene thermal underwear really be mass-produced? I think everyone will put a big question mark. Therefore, in fact, a considerable number of products on the market are over-advertised, and we must keep our eyes open when buying.
Although the honeycomb hexagonal structure of graphene does give it superior conductivity, this does not mean that graphene materials can bring very large profit space to product manufacturers.
If graphene batteries and graphene thermal underwear really use graphene materials, these products will undoubtedly form superior competitiveness in the market competition, but it is precisely because of the high extraction cost of the material that false publicity on the market is not uncommon.
Therefore, when selecting civilian graphene products, we must pay attention to the product brand and whether it has a reasonable after-sales service, so as to prevent being deceived and suffering losses in the transaction process.