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Graphene: The Future BeyondAman Gupta

Mentor: Mr. Vimal Kishore YadavAmity University, Madhya Pradesh

INTRODUCTIONIn simple terms, graphene is a thin layer of pure carbon; it is a single, tightly packed layer of carbon atoms that are bonded together in a hexagonal honeycomb lattice. In more complex terms, it is an allotrope of carbon in the structure of a plane of sp2 bonded atoms with a molecule bond length of 0.142 nanometres. Layers of graphene stacked on top of each other form graphite, with an interplanar spacing of 0.335 nm. It is the thinnest compound known to man at one atom thick, lightest material (with 1 sq meters coming in at around 0.77 mg), the strongest compound (between 100-300 times stronger than steel and with a tensile stiffness of 150,000,000 psi), the best conductor of heat at room temperature (at (4.84±0.44) × 103 to (5.30±0.48) × 103 W·m−1·K−1) and also best conductor of electricity known (studies have shown electron mobility at values of more than 15,000 cm2·V−1·s−1). 

Other notable properties of graphene are its unique levels of light absorption at πα ≈ 2.3% of white light, and its potential suitability for use in spin transport. André Geim and Konstantin Novoselov at the University of Manchester won the Nobel Prize in Physics in 2010 for ground breaking experiments regarding the two-dimensional material graphene. 

NEED OF GRAPHENE

•The efficiency of the super capacitor is the important factor to bear in mind. In the past, scientists have been able to create supercapacitors that are able to store 150 Farads per gram, but some have suggested that the theoretical upper limit for graphene-based supercapacitors is 550 F/g. This is particularly impressive when compared against current technology: a commercially available capacitor able to store 1 Farad of electrostatic energy at 100 volts would be about 220mm high and weigh about 2kgs, though current super capacitor technology is about the same, in terms of dimensions relative to energy storage values, as a graphene-based super capacitor would be.

INVENTION OF GRAPHENERussian-émigré scientists at the University of Manchester, Andrei Geim and Kostya Novoselov, were playing about with flakes of carbon graphite in an attempt to investigate its electrical properties when they decided to see if they could make thinner flakes with the help of sticky Scotch tape.

They used the tape to peel off a layer of graphite from its block and then repeatedly peeled off further layers that were only a few atoms thick. They soon realized that by repeatedly sticking and peeling back the Scotch tape they could get down to thinnest of all possible layers, one atom thick – a material with unique and immensely interesting properties.

GRAPHENE: HOW IT LOOKS

WHAT FUTURE HOLDS?

CVD PROCESS OF GRAPHENE PRODUCTIONChemical vapour deposition, or CVD, is a method which can produce relatively high quality graphene, potentially on a large scale. The CVD process is reasonably straightforward, although some specialist equipment is necessary, and in order to create good quality graphene it is important to strictly adhere to guidelines set concerning gas Vol., pressure, temp., and time duration.

GRAPHENE APPLICATIONS

CONCLUSION

REFRENCES

1.Lee, Changgu et al. Frictional Characteristics of Atomically Thin Sheets. Sci. 328, 76-80 (2010).2.Avouris, Phaedon. Graphene: Electronic and Photonic Properties and Devices. Nano Letters 10, 4285-4293 (2010).3.Neto, A. H. Castro et al. Electronic properties of graphene. Rev. Mod. Phys. 81, 109-162 (2009).4.Radisavljevic, B. et al. Single-layer MoS2 transistors. Nature Nanotechnology 6, 147-150 (2011).5.Ni, Z. H. et al. Graphene Thickness Determination Using Reflection and Contrast Spectroscopy. Nano Letters 40, A-F (2007).6.Ferrari, A. C. et al. Raman Spectrum of Graphene and Graphene Layers. Physical Review Letters 97, 1847401 (2006).

Graphene has rapidly changed its status from being an unexpected and sometimes unwelcome newcomer to a rising star and to a reigning champion. The professional scepticism that initially dominated the attitude of many researchers (including myself) with respect to graphene applications is gradually evaporating under the pressure of recent Developments. Still, it is the wealth of new physics – observed, expected and hoped for – which is driving the area form the moment.

Research on graphene’s electronic properties is now matured but is unlikely to start fading any time soon, especially because of the virtually unexplored opportunity to control quantum transport by strain engineering and various structural modifications. Even after that, graphene will continue to stand out as a truly unique item in them arsenal of condensed matter physics. Research on graphene’s non-electronic properties is just gearing up, and this should bring up new phenomena that can hopefully prove equally fascinating and sustain, if not expand, the graphene boom.

Biological Engineering-

Andre Geim Konstantin Novoselov

One area of research that is being very highly studied is energy storage. While all areas of electronics have been advancing over a very fast rate over the last few decades (in reference to Moore’s law which states that the number of transistors used in electronic circuitry will double every 2 years), the problem has always been storing the energy in batteries and capacitors when it is not being used. These energy storage solutions have been developing at a much slower rate. The problem is this: a battery can potentially hold a lot of energy, but it can take a long time to charge, a capacitor, on the other hand, can be charged very quickly, but can’t hold that much energy (comparatively speaking). The solution is to develop energy storage components such as either a supercapacitors or a battery that is able to provide both of these positive characteristics without compromise.

 

Currently, scientists are working on enhancing the capabilities of lithium ion batteries (by incorporating graphene as an anode) to offer much higher storage capacities with much better longevity and charge rate. Also, graphene is being studied and developed to be used in the manufacture of supercapacitors which are able to be charged very quickly, yet also be able to store a large amount of electricity. 

GRAPHENE BASED SUPERCAPACITORS

Ultrafiltration-Another standout property of graphene is that while it allows water to pass through it, it is almost completely impervious to liquids and gases (even relatively small helium molecules).  This means that graphene could be used as an ultrafiltration medium to act as a barrier between two substances. The benefit of using graphene is that it is only 1 single atom thick and can also be developed as a barrier that electronically measures strain and pressures between the 2 substances (amongst many other variables). A team of researchers at Columbia University have managed to create monolayer graphene filters with pore sizes as small as 5nm (currently, advanced nonporous membranes have pore sizes of 30-40nm).

 

While these pore sizes are extremely small, as graphene is so thin, pressure during ultrafiltration is reduced. Currently, graphene is much stronger and less brittle than aluminium oxide. It could mean graphene is developed to be used in water filtration systems, desalination systems and efficient and economically more viable biofuel creation. 

Print Technology-The use of Graphene and polymer compositions filled them are topic of interest in fabrication of new type printed electronics circuits, dedicated to transparent electrodes, elastic displays and photovoltaics, various types of sensors( pressure, temp., biochemical) and in tectonics. We can build printed circuits using graphene nanoplates. We can produce resistive and conductive layers containing graphene with use of screen printing and spray coating techniques