A Graphene Primer
Due to its unique combination of exceptional properties, graphene has emerged as one of the most promising nanomaterials. In addition to being the thinnest, it is also one of the strongest materials. It conducts heat better than any other. This material is an excellent conductor of electricity, optically transparent, and so dense that it is impermeable to gases — not even helium, the smallest gas atom, can pass through it.
With its unique properties, a graphene sheet offers a fascinating material platform for developing next-generation technologies. They include wearables, superfast electronics, ultrasensitive sensors, multifunctional composites and coatings, membranes, medicine, biotechnology, and energy harvesting and storage.
In the decade since its first demonstration in 2004, graphene research has developed into a vast field, with approximately 10,000 papers published every year on a wide range of topics.
What is graphene?
Graphene is a layer (monolayer) of carbon atoms bonded in a hexagonal pattern. A single atom thick. Graphite is composed of layers of graphene stacked on top of each other. Carbon atoms have a diameter of about 0.33 nanometers, so a sheet of graphite with a thickness of 1 mm contains about 3 million layers of graphene.
Stronger than diamond, yet more elastic than rubber; tougher than steel, yet lighter than aluminum — graphene is the strongest known material.
It would take the force exerted by 2,000 kg, or a large car, to puncture a sheet of cling film (like kitchen wrap film) with a pencil.
A graphene sheet is a conceptually new type of material that is only one atom thick, which is called a two-dimensional (2D) material (the 2D refers to the two dimensions of its length and width; the third dimension, height, is considered to be zero due to its thinness). Graphene only shows its exceptional properties at this single- or few-layer state.
Electronic properties of graphene
Nanotechnology researchers working on molecular electronics are intrigued by graphene because of its electronic properties — it has one of the highest electrical conductivities on Earth. Due to the unique arrangement of carbon atoms in graphene, electrons can travel at extremely high speeds without significant chances of scattering, thus saving energy compared to other conductors.
The electrons in graphene do not seem to slow down or localize even at the limit of no carrier concentration because the electrons don’t seem to slow down or localize. Carbon atom electrons interact with graphene’s honeycomb lattice, which produces new quasiparticles that have lost their mass, or rest mass. As a result, graphene conducts forever. They also travel much faster than electrons in other semiconductors.
Mechanical properties of graphene
One of the reasons graphene stands out both as an individual material and as a reinforcing agent in graphene composites is its impressive intrinsic mechanical properties, such as stiffness, strength, and toughness. The sp2 bonds form the hexagonal lattice and oppose various in-plane deformations due to their stability.
Energy storage and solar cells
Energy-related applications of graphene-based nanomaterials are numerous. Energy-storage supercapacitors made of activated graphene have superior energy capacity and charge rates.
In addition, graphene electrodes may lead to inexpensive, lightweight, and flexible solar cells, and graphene mats may be suitable for catalytic systems.
Additionally, researchers discovered a critical and unexpected connection between graphene’s chemical and structural weakness as a host material for electrodes and its ability to suppress the growth of dendrites — branch-like filament deposits on electrodes that can penetrate the barrier between the two halves of a battery and cause electrical shorts, overheating, and fires.