The properties of graphene, carbon sheets that are only one atom thick, have caused researchers and companies to consider using this material in several fields. The following survey of research activity introduces you to many potential applications of graphene.
Lithium-ion batteries that recharge faster. These batteries use graphene on the surface of the anode surface. Defects in the graphene sheet (introduced using a heat treatment) provide pathways for the lithium ions to attach to the anode substate. Studies have shown that the time needed to recharge a battery using the graphene anode is much shorter than with conventional lithium-ion batteries.
Ultracapacitors with better performance than batteries. These ultracapacitiors store electrons on graphene sheets, taking advantage of the large surface of graphene to provide increase the electrical power that can be stored in the capacitor. Researchers are projecting that these ultracapacitors will have as much electrical storage capacity as lithium ion batteries but will be able to be recharged in minutes instead of hours.
Lower cost fuel cells. Researchers at Ulsan National Institute of Science and Technology have demonstrated how to produce edge-halogenated graphene nanoplatelets that have good catalytic properties. The researchers prepared the nanoplatelets by ball-milling graphene flakes in the presence of chlorine, bromine or iodine. They believe these halogenated nanoplatelets could be used as a replacement for expensive platinum catalystic material in fuel cells.
More efficient dye sensitized solar cells. Researchers at Michigan Technological University have developed a honeycomb like structure of graphene in which the graphene sheets are held apart by lithium carbonate. They have used this "3D graphene" to replace the platinum in a dye sensitized solar cell and achieved 7.8 percent conversion of sunlight to electricity.
Lower cost solar cells: Researchers have built a solar cell that uses graphene as a electrode while using buckyballs and carbon nanotubes to absorb light and generate electrons; making a solar cell composed only of carbon. The intention is to eliminate the need for higher cost materials, and complicated manufacturing techniques needed for conventional solar cells.
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Lower cost of display screens in mobile devices. Researchers have found that graphene can replace indium-based electrodes in organic light emitting diodes (OLED). These diodes are used in electronic device display screens which require low power consumption. The use of graphene instead of indium not only reduces the cost but eliminates the use of metals in the OLED, which may make devices easier to recycle.
Transistors that operate at higher frequency. The ability to build high frequency transistors with graphene is possible because of the higher speed at which electrons in graphene move compared to electrons in silicon. Researchers are also developing lithography techniques that can be used to fabricate integrated circuits based on graphene.
Sensors to diagnose diseases. These sensors are based upon graphene's large surface area and the fact that molecules that are sensitive to particular diseases can attach to the carbon atoms in graphene. For example, researchers have found that graphene, strands of DNA, and fluorescent molecules can be combined to diagnose diseases. A sensor is formed by attaching fluorescent molecules to single strand DNA and then attaching the DNA to graphene. When an identical single strand DNA combines with the strand on the graphene a double strand DNA if formed that floats off from the graphene, increasing the fluorescence level. This method results in a sensor that can detect the same DNA for a particular disease in a sample.
Chemical sensors effective at detecting explosives. These sensors contain sheets of graphene in the form of a foam which changes resistance when low levels of vapors from chemicals, such as ammonia, is present.
Membranes for more efficient separation of gases. These membranes are made from sheets of graphene in which nanoscale pores have been created. Because graphene is only one atom thick researchers believe that gas separation will require less energy than thicker membranes.
Low cost water desalination: Researchers have determined that graphene with holes the size of a nanometer or less can be used to remove ions from water. They believe this can be used to desalinate sea water at a lower cost than the reverse osmosis techniques currently in use.
Lightweight natural gas tanks: Researchers at Rice University have developed a composite material using plastic and graphene nanoribbons that block the passage of gas molecules. This material may be used in applications ranging from soft drink bottles to lightweight natural gas tanks.
Components with higher strength to weight ratios. Researchers have found that adding graphene to epoxy composites may result in stronger/stiffer components than epoxy composites using a similar weight of carbon nanotubes. Graphene appears to bond better to the polymers in the epoxy, allowing a more effective coupling of the graphene into the structure of the composite. This property could result in the manufacture of components with high strength to weight ratio for such uses as windmill blades or aircraft components.
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Compiled by Earl Boysen of Hawk's Perch Technical Writing, LLC and UnderstandingNano.com. You can find him on Google+.
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