Graphene the Ubiquitous
Every once in a while, a (revolutionary-in-hindsight) scientific discovery is made that’s at first treated as an anomaly, and then verified. Once established as a credible find, it goes through a period where it is subject to great curiosity and intriguing reality checks – whether it was a one-time thing, if it can actually be reproduced under different circumstances at different locations, if it has properties that can be tracked through different electrical, mechanical and chemical circumstances.
After surviving such tests, the once-discovery then enters a period of dormancy: while researchers look for ways to apply their find’s properties to solve real-world problems, science must go on and it does. What starts as a gentle trickle of academic papers soon cascades into a shower, and suddenly, one finds an explosion of interest on the subject against a background of “old” research. Everybody starts to recognize the find’s importance and realize its impending ubiquity – inside laboratories as well as outside. Eventually, this accumulating interest and the growing conviction of the possibility of a better, “enhanced” world of engineering drives investment, first private, then public, then more private again.
Enter graphene. Personally, I am very excited by graphene as such because of its extremely simple structure: it’s a planar arrangement of carbon atoms a layer thick positioned in a honeycomb lattice. That’s it; however, the wonderful capabilities that it has stacked up in the eye of engineers and physicists worldwide since 2004, the year of it’s experimental discovery, is mind-blowing. In the fields of electronics, mensuration, superconductivity, biochemistry, and condensed-matter physics, the attention it currently draws is a historic high.
Graphene’s star-power, so to speak, lies in its electronic and crystalline quality. More than 70 years ago, the physicist Lev Landau had argued that lower-dimensional crystal lattices, such as that of graphene, are thermodynamically unstable: at some fixed temperature, the distances through which the energetic atoms vibrated would cross the length of the interatomic distance, resulting in the lattice breaking down into islands, a process called “dissolving”. Graphene broke this argument by displaying extremely small interatomic distances, which translated as improved electron-sharing to form strong covalent bonds that didn’t break even at elevated temperatures.
As Andre Geim and Konstantin Novoselov, experimental discoverers of graphene and joint winners of the 2010 Nobel Prize in physics, wrote in 2007:
The relativistic-like description of electron waves on honeycomb lattices has been known theoretically for many years, never failing to attract attention, and the experimental discovery of graphene now provides a way to probe quantum electrodynamics (QED) phenomena by measuring graphene’s electronic properties.
(On a tabletop for cryin’ out loud.)
What’s more, because of a tendency to localize electrons faster than could conventional devices, using lasers to activate the photoelectric effect in graphene resulted in electric currents (i.e., moving electrons) forming within picoseconds (photons in the laser pulse knocked out electrons, which then traveled to the nearest location in the lattice where it could settle down, leaving a “hole” in its wake that would pull in the next electron, and so forth). Just because of this, graphene could make for an excellent photodetector, capable of picking up on small “amounts” of eM radiation quickly.
An enhanced current generation rate could also be read as a better electron-transfer rate, with big implications for artificial photosynthesis. The conversion of carbon dioxide to formic acid requires a catalyst that operates in the visible range to provide electrons to an enzyme that its coupled with. The enzyme then reacts with the carbon dioxide to yield the acid. Graphene, a team of South Korean scientists observed in early July, played the role of that catalyst with higher efficiency than its peers in the visible range of the eM spectrum, as well as offering up a higher surface area over which electron-transfer could occur.
Another potential area of application is in the design and development of non-volatile magnetic memories for higher efficiency computers. A computer usually has two kinds of memories: a faster, volatile memory that can store data only when connected to a power source, and a non-volatile memory that stores data even when power to it is switched off. A lot of the power consumed by computers is spent in transferring data between these two memories during operation. This leads to an undesirable difference arising between a computer’s optimum efficiency and its operational efficiency. To solve for this, a Singaporean team of scientists hit upon the use of two electrically conducting films separated by an insulating layer to develop a magnetic resistance between them on application of a spin-polarized electric field to them.
The resistance is highest when the direction of the magnetic field is anti-parallel (i.e., pointing in opposite directions) in the two films, and lowest when the field is parallel. This sandwiching arrangement is subsequently divided into cells, with each cell possessing some magnetic resistance in which data is stored. For maximal data storage, the fields would have to be anti-parallel as well as that the films’ material spin-polarizability high. Here again, graphene was found to be a suitable material. In fact, in much the same vein, this wonder of an allotrope could also have some role to play in replacing existing tunnel-junctions materials such as aluminium oxide and magnesium oxide because of its lower electrical resistance per unit area, absence of surface defects, prohibition of interdiffusion at interfaces, and uniform thickness.
In essence, graphene doesn’t only replace existing materials to enhance a product’s (or process’s) mechanical and electrical properties, but also brings along an opportunity to redefine what the product can do and what it could evolve into in the future. In this regard, it far surpasses existing results of research in materials engineering: instead of forging swords, scientists working with graphene can now forge the battle itself. This isn’t surprising at all considering graphene’s properties are most effective for nano-electromechanical applications (there have been talks of a graphene-based room-temperature superconductor). More precise measurements of their values should open up a trove of new fields, and possible hiding locations of similar materials, altogether.
