Graphene- A Miracle Material
Allotropes Of Carbon Diamond Graphite Fullerene
What is Graphene? Graphene is an allotrope of carbon 2-D crystalline, single layer of carbon, sp 2 hybridized carbon Basic building unit for other allotropes like graphite, CNTs Hexagonal (Honeycomb) like structure
Brief History Theory was first proposed in 1947 by P.R.Wallace But in 2004,graphene was successfully produced by Andre Geim And Konstantin Novoselov In 2010,Both got Noble Prize in physics for discovery of graphene
Why is this material so special? Hardest material known Thinnest compound known to man at one atom thick, the lightest material known Best conductor of heat at room temperature Best conductor of electricity known
Mechanical Properties Bond length is 0.142 nm long Strongest material ever discovered Ultimate tensile strength of 130 gigapascals compared to 400 megapascals for structural steel Very light at 0.77 milligrams per square meter, paper is 1000 times heavier Single sheet of graphene can cover a whole football field while weighing under 1 gram Also, graphene is very flexible, yet brittle(preventing structural use)
Electronic Properties Dirac Points are the transition between the valence band and the conduction band Graphene is a zero-gap semiconductor, because its conduction and valence bands meet at the Dirac points It is the best conductor of electricity known
Production Methods Chemical Vapour Deposition where a gas containing carbon (such as Methane) is broken down and reassembled on a hot metallic surface into a sheet of graphene. Solution Exfoliation where graphite is blasted into small fragments of graphene using ultrasonic energy.
TYPES OF GRAPHENE Graphene oxide (GO) – Chemically modified graphene prepared by oxidation and exfoliation. Graphene oxide is a monolayer material with a high oxygen content. Few-layer graphene (FLG) or multi-layer graphene (MLG) – a 2D,sheet-like material, either as a free-standing flake or substrate- bound coating, consisting of a small number (between two and about 10) of well-defined, countable, stacked graphene layers of extended lateral dimension. Reduced graphene oxide (rGO) – Graphene oxide (as above) that has been reductively processed by chemical, thermal, microwave, photo- chemical, photo-thermal or microbial/bacterial methods to reduce its oxygen content. Graphite oxide – This precursor to GO is a bulk solid made by oxidation of graphite through processes that functionalize the basal planes and increase the interlayer spacing.
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