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Applications

Other Graphene Enabled "Killer Applications"

Industry experts and scientists believe that graphene is the miracle material that can enable new categories of "killer applications" that have not been possible with existing materials. Graphene's capabilities and commercial potential have not been fully understood or explored. However, its properties, which have been demonstrated and confirmed in laboratories around the world, suggest that graphene is a very promising material with potentially revolutionary applications.




Energy Storage

One of the hottest application areas for graphene is energy storage. Since it is a single sheet of carbon, graphene has the highest surface-to-volume ratio of all carbon materials used in energy storage devices. Its high conductivity allows electrons to quickly move in and out of the material. Its high surface area allows it to hold more charge. Its impermeability feature allows it to prevent corrosion. In supercapacitor applications, graphene enables high power rapid charge and discharge, as well as the ability to hold many times more charge than existing supercapacitors. In battery applications, researchers at Northwestern University have demonstrated that graphene anode electrodes charge 10 times faster. Also, Rice University researchers have found that graphene mixed with vanadium oxide (a relatively inexpensive solution) can create battery cathodes that recharge in 20 seconds and retain more than 90% of their capacity, even after 1,000 cycles of use. The impact of these capabilities could result in the rapid storage of daytime solar energy for nighttime use, or fully charging an iPhone or electric vehicle in just a few minutes.

Solar Cells

Offering very low levels of light absorption (at around 2.7% of white light) while also offering high electron mobility means that graphene can be used as an alternative to silicon or ITO in the manufacture of photovoltaic cells. Silicon is currently widely used in the production of photovoltaic cells, but while silicon cells are very expensive to produce, graphene based cells are potentially much less so. When materials such as silicon turn light into electricity it produces a photon for every electron produced, meaning that a lot of potential energy is lost as heat. Recently published research has proved that when graphene absorbs a photon, it actually generates multiple electrons. Also, while silicon is able to generate electricity from certain wavelength bands of light, graphene is able to work on all wavelengths, meaning that graphene has the potential to be as efficient as, if not more efficient than silicon, ITO or (also widely used) gallium arsenide. Being flexible and thin means that grapheme-based photovoltaic cells could be used in clothing; to help recharge mobile phones, or even used as retro-fitted photovoltaic window screens or curtains to help power homes.

Optical Electronics

One particular area in which we will soon begin to see graphene used on a commercial scale is in optoelectronics; specifically touchscreens, liquid crystal displays (LCD) and organic light emitting diodes (OLEDs). For a material to be able to be used in optoelectronic applications, it must be able to transmit more than 90% of light and also offer electrical conductive properties exceeding 1 x 106 O1m1 and therefore low electrical resistance. Graphene is an almost completely transparent material and is able to optically transmit up to 97.7% of light. It is also highly conductive, so it would work very well in optoelectronic applications such as LCD touchscreens for smartphones, tablet and desktop computers and televisions. Currently, the most widely used material is indium tin oxide (ITO). However, indium is a rare earth material. Therefore, the cost will increase as demand increases, which will hamper industry's goal of continual cost reduction in delivering billions of touchscreen devices every year. Because graphene is as strong as diamonds and yet flexible, the science-fiction vision of foldable and flexible paper-thin display may finally become a reality.

Integrated Circuits

Fundamental electronic markets such as transistors have been out of reach for graphene in the past, due to the absence of a bandgap. However, the Carbon Sciences Graphene Process may favorably impact this market segment. Through the precise and controlled features of its CVD process, Carbon Sciences expects to achieve precise and specific stacking order of graphene sheets to produce tunable bandgaps for various semiconductor applications, such as high-speed graphene transistors and circuits.

Researchers at UCSB have successfully demonstrated graphene transistors switching at very high speeds in "all-graphene" integrated circuits. Since graphene can operate at a much higher frequency and at lower power than silicon, the significance is that graphene-based integrated circuits can overcome the inevitable limits of silicon. The methodologies are still experimental and expensive, but the potential for graphene- based electronics, considering the upsides of the material, is simply too good to ignore.

Composites

The composite sector is also large and fragmented with many needs. In this case, graphene can deliver value as an additive, perhaps through the use of graphene nanoplatelets. A strong point for graphene is that it can create multi-functionality. In other words, it can help increase electrical conductivity, thermal conductivity, impermeability and mechanical strength, etc. A key value add will be achieving the equivalent of, or better than, what graphite or black carbon can do with much less material usage, allowing graphene producers to charge a premium.

Currently, aerospace engineers are incorporating carbon fiber into the production of aircraft as it is also very strong and light. However, graphene is much stronger while being also much lighter. Ultimately it is expected that graphene will be utilized (probably integrated into plastics such as epoxy) to create a material that can replace steel in the structure of aircraft, improving fuel efficiency, range and reducing weight. Due to its electrical conductivity, it could even be used to coat aircraft surface material to prevent electrical damage resulting from lightning strikes. In this example, the same graphene coating could also be used to measure strain rate, notifying the pilot of any changes in the stress levels that the aircraft wings are under. These characteristics can also help in the development of high strength requirement applications such as body armor for military personnel and vehicles.

Biological Engineering

Bioengineering will certainly be a field in which graphene will become a vital part of in the future; though some obstacles need to be overcome before it can be used. However, the properties that it displays suggest that it could revolutionize this area in a number of ways. With graphene offering a large surface area, high electrical conductivity, thinness and strength, it would make a good candidate for the development of fast and efficient bioelectric sensory devices, with the ability to monitor such things as glucose levels, haemoglobin levels, cholesterol and even DNA sequencing. Eventually we may even see engineered 'toxic' graphene that is able to be used as an antibiotic or even anticancer treatment.

Also, due to its molecular make-up and potential biocompatibility, it could be utilized in the process of tissue regeneration. A March 2012 issue of Nature predicted graphene could be used to create bionic implants, but more recently, the University of Manchester's Aravind Vijaraghavan said graphene could interact with one's biological systems or "talk with one's cells," as he put it which could eventually take the Internet of Things to new heights. Graphene isn't the material doing the actual talking. Instead, the graphene simply lies beneath the synthetic phospholipid layers that do all the work.

Ultrafiltration

Pure graphene is resistant to water (H2O). However, membranes made from graphene have been demonstrated to allow rapid water permeation, while filtering out everything else such as other liquids and gases (even relatively small helium molecules). This means that graphene-based membranes can be used as an ultrafiltration medium to act as a barrier between two substances. Because it is only one atom thick, another benefit of using graphene for membranes is that it can be developed as a barrier that electronically measures strain and pressures between the two substances (amongst many other variables).

A research team at the University of Manchester has managed to create a graphene-based membrane with an astonishingly accurate mesh that allows observers to distinguish between atomic species that are only a few percent different in size. The membrane filter is ultrafast, a phenomenon of graphene, with a speed similar to that of warm liquid passing through a coffee filter. The goal of this research team is to make a filter device that will produce a glass of drinkable water made from seawater after a few minutes of hand pumping.