Graphene is the most renowned celebrity in the nanomaterial world, reaching more than 130,000 monthly searches for the word “graphene” in the Google while the word “nanotechnology” barely reaches 110,000. The big question is, could graphene prove its worth in the next few years to come and disruptively change the ways things are done now. Would it open new markets and revolutionized the ways we live our lives. Many scientists and entrepreneurs agree that it would, and probably lot sooner than we might expect. When we look at graphene properties, it undoubtedly have the potential. Since it was first isolated and analyzed in 2003, by famous Andre Geim and Konstantin Novoselov at the University of Manchester, it instantly became very popular among scientific community and many researchers investigated different ways to exploit its many of the supreme properties. Graphene is one of the strongest material known to man, and its electrical and thermal conductivity and many other properties beat conventional materials few hundred times over. The global market for graphene only is 24.3 million US dollars for 2015 and also expected to see an exponential growth in next few years to come.
The million or sometimes billion dollar question is how to use graphene in everyday applications or in other words, how soon we can start graphene technology instead of graphene science. Well, scientists in all over the world, has made tremendous advances of graphene science. Let’s look at the top ten technologies that will soon expected to spin off as an independent graphene technologies with commercial worth.
#1: Flexible electronics with transparent conductive electrodes
Imagine a phone that can wrap around your arm or an e-paper that you can fold and put in your pocket. Many interesting applications like these would fall in a special category of electronic devices called flexible electronics. One of the major challenge to overcome in flexible electronics is transparent conductors that would allow light to pass while maintaining the electrical conductivity and still flexible enough. The conventional indium tin oxide (ITO) material used in transparent conductive electrodes is great at both transparency and conductivity but extremely lacks the flexibility. Also, ITO is increasingly become expensive due to depletion of rare metal indium. Graphene has stepped up to the challenge, with conductivities and transparency comparable to ITO. This is due to high conductivity of the graphene sheet and very low light absorbance (single graphene layer is almost transparent). Due to extremely small thickness of graphene, it can flex and bend in extreme angles that were never possible with conventional materials, while keeping the conductivity unchanged.
#2: Graphene field effect transistors
Due to the unique bad-gap structure of the graphene, the charge carriers such as electrons can be continuously tuned by an electric field. This satisfies the fundamental requirement of a field effect transistor and graphene has step forward as a great candidate for future material for field effect transistors. Already, field effect transistor devices have been fabricated by number of research groups all over the world with different techniques and have reported one order high field effect ability of graphene based devices compared to the conventional silicone based field effect transistors.
#3: Graphene sensors
Graphene is among the materials with highest surface to volume ratio. It’s only one carbon atom thick and practically reach to length and width measured in centimeter scale. All the carbon atoms in the graphene are exposed to the environment which makes the surface area of graphene extremely high. Graphene show interesting absorption affinities towards certain molecules and its adsorption selectivity can be tuned by introducing certain functional groups in to the graphene structure. More interestingly conductance of graphene change depending upon the adsorbed species and the concentration of adsorption. This makes graphene a perfect material to sense other molecules such as gases to biomolecules. Adsorption of a molecule in to the graphene surface would trigger a charge transfer between the adsorbed molecule and graphene, which result in change of conductance. Graphene sensors have been developed to sense gases like Ammonia and carbon monoxide and biomolecules such as certain proteins and DNAs.
#4: Graphene based lithium ion battery
Use of graphene in next generation batteries such as improved lithium ion batteries is a hot area of research primarily due to the broad application spectrum and already available market for the product. Graphene can easily help resolve one of the major problems associated with the conventional lithium ion batteries which is poor electrical conductivity of the cathode electrode. Graphene is already used in some lithium ion batteries as a conductive filler in cathode coating materials due to its high conductivity and inherently sheet like structure that facilitate charge transfer. Due to the same reason, graphene can be easily sandwiched in between special nanomaterials to make nanocomposite structures. Both the increase in cathode conductivity and special nanocomposite structures can increase the specific power density(amount of power that could be obtained from unit weight of the battery). Graphene can also help dissipate the heat generated during charging and discharging of the battery more efficiently due to its high thermal conductivity. This would help increase the lifetime and charging capacity of the graphene battery.
#5: Graphene in solar cells
Graphene has also been intensively researched in the area of solar cells, primarily as an active material in light absorption or energy conversion and as a transparent or a distributed electrode material that would allow light to pass through but maintain the conductivity. Unlike ITO, graphene has uniform absorption capability in broad range, thus allows maximum amount of light to pass through the transparent conductive electrode and in to solar cell. Use of graphene in its pristine form as an active material in the solar cell however, suffer from the low responsiveness due to inferior absorption of light by graphene.
#6: Graphene photodetectors
Graphene can be used in broad spectrum photodetection (light detection) applications due to uniform absorption of light across all UV, visible and infrared light wavelength. This is a one major limitation in most of the conventional, semiconductor based photodetectors that was overcame by graphene photodetectors. Conventional photodetectors can only detect very narrow range of frequencies that would hinder their application scope. These would have immediate applications in optical sensors, security, process control, environmental sensing and astronomy applications.
#7: Graphene in paints and coatings
Due to high electrical conductivity of the graphene it has been tested as additives in paint and coatings to impart functional performances such as conductivity, antistatic, electromagnetic interference shielding. Due to the sheet like nature of graphene sheets, they can self-assemble in layer by layer fashion inside a film or a coating, making it harder for certain gas molecules to penetrate. This has immediate applications in modified atmosphere packaging of food items and gas barrier coatings. Graphene is also highly inert, and can act as a barrier against water and oxygen. Applied on to a metal surface, this can help reduce the corrosion.
#8: Graphene nanocomposites
All the atoms in the graphene sheet are exposed to the environment which make it a material with one of the highest surface to volume ratio. Theoretically it reaches to 2630 m2/g. This makes easier for graphene to make interactions with polymer molecules making it an ideal nano filler in nanocomposites. When graphene is incorporated as a nanocomposites, it can contribute to increase gas and moisture barrier properties, electrical conductivity, electromagnetic shielding, thermal conductivity and mechanical properties of the end composite material. Graphene can also be functionalized with suitable groups to incorporate functional groups that makes it more compatible with the polymer.
#9: Graphene as a drug delivery material
Graphene has number of favorable properties that makes it ideal for biomedical applications. Graphene has high surface area that can be exploited specially in drug delivery applications. Also, graphene can be surface modified with relative ease and made to bind in to specific drug and can be used as drug delivery vehicles. The surface modification can also be used to impart certain functional groups that have higher affinity towards important cell types through specific ligands. These smart carriers, can specifically bind to cell types to deliver drug, make cell easier to image and sometimes to perform cellular diagnostics. Due to the lipophilic nature of graphene they can pass through cell membranes in to the cells. Most of the research in this field however, is still in the lab level and would take some time since we see graphene enhanced drugs in the market.
#10: Graphene in photocatalysts
Photocatalysts are special class of nanomaterials, that can catalyze a reaction with the presence of light. These materials can absorb certain wavelengths of light and produce an electron and a hole. These electrons and holes can migrate in to the surface and directly reduce or oxidize an organic material in the vicinity of the catalyst surface. Photocatalysts are heavily investigated for their use as a water purification or pollutant removal materials.The most commonly used photocatalysts such as Titanium dioxide and Zinc oxide however surfer from low efficiency primarily due to recombination of electrons and holes prior to their migration to the surface of the catalyst. Graphene can be incorporated in to the photocatalytic particle or to the structure to help capture the produce electron made during photo-excitation. This will effectively separate the electron and hole and reduce the recombination probability. This can dramatically increase the efficiency of the photocatalysts.