Graphene is a single two-dimensional layer of carbon atoms arranged in a hexagonal, honeycomb crystal lattice. It forms the basic structural foundation for all other graphitic carbon allotropes: stacking multiple layers creates three-dimensional graphite, rolling a single sheet produces one-dimensional carbon nanotubes, and wrapping a sheet into a sphere forms zero-dimensional fullerenes. Although theoretical physicists analyzed graphene for decades as an academic model, two-dimensional crystals were long considered thermodynamically unstable at ambient temperatures. In 2004, physicists Andre Geim and Konstantin Novoselov at the University of Manchester successfully isolated single-layer graphene from graphite using mechanical exfoliation with adhesive tape, a discovery that earned them the 2010 Nobel Prize in Physics.
Graphene exhibits extraordinary mechanical, electrical, and thermal properties arising from its atomic structure and two-dimensional electron confinement. Each carbon atom undergoes sp2 hybridization, forming three strong in-plane covalent sigma bonds with neighboring carbon atoms at 120-degree angles, with a bond distance of approximately 0.142 nanometers. This dense atomic framework makes pristine graphene roughly 200 times stronger than structural steel by weight, possessing an intrinsic tensile strength of 130 gigapascals and a Young's modulus of 1 terapascal. Electronically, graphene's delocalized pi electrons behave as massless Dirac fermions at the edges of the Brillouin zone. These charge carriers move through the crystal lattice at an effective velocity of approximately one million meters per second, enabling room-temperature electron mobilities exceeding 200,000 cm2/V·s. Graphene also features high thermal conductivity reaching 5,000 W/m·K and absorbs only 2.3% of incident white light, making it virtually transparent.
Graphene's combination of optical transparency, mechanical flexibility, and electrical conductivity enables broad industrial applications, including flexible touchscreens, wearable electronics, high-capacity lithium-ion batteries, supercapacitors, and aerospace composites. Its dense atomic lattice also makes pristine graphene impermeable to all gases except water vapor, making it useful for membrane desalination and molecular filtration. For competitive examinations like UPSC Civil Services and State PCS, graphene questions appear under General Science and Technology, testing carbon allotropy, sp2 hybridization, Dirac fermions, comparisons with nanotubes and fullerenes, and energy storage technologies.
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Graphene is an allotrope of carbon consisting of a single layer of carbon atoms arranged in a two-dimensional hexagonal honeycomb lattice.
Andre Geim and Konstantin Novoselov isolated single-layer graphene in 2004 at the University of Manchester using mechanical exfoliation with adhesive tape.
Geim and Novoselov were awarded the Nobel Prize in Physics in 2010 for experimental discoveries regarding the two-dimensional material graphene.
Graphene forms the structural parent of other graphitic allotropes: stacked into graphite, rolled into carbon nanotubes, and wrapped into fullerenes.
Carbon atoms in graphene are bonded through sp2 hybridization, forming three strong planar sigma bonds with adjacent atoms at 120-degree angles.
The carbon-carbon bond length in pristine graphene is approximately 0.142 nanometers (1.42 angstroms).
Graphene is approximately 200 times stronger than structural steel by weight, possessing an intrinsic tensile strength of 130 gigapascals.
Graphene has a Young's modulus of approximately 1 terapascal (TPa), confirming its extraordinary mechanical stiffness and elasticity.
Electrons in graphene move as relativistic quasiparticles known as massless Dirac fermions with an effective speed near 10^6 meters per second.
Graphene exhibits extraordinary electron mobility at room temperature, with values exceeding 200,000 cm2/V·s.
Graphene is a zero-bandgap semiconductor (semimetal), because its valence and conduction bands touch at conical discrete points known as Dirac points.
Graphene has an exceptionally high thermal conductivity of approximately 3,000 to 5,000 W/m·K, significantly exceeding that of copper and diamond.
Single-layer graphene is nearly transparent, absorbing only about 2.3% of incident white light across the visible spectrum.
Chemical vapor deposition (CVD) on copper foil substrates is the leading industrial method for synthesizing large-area, continuous graphene sheets.
Graphene oxide (GO) and reduced graphene oxide (rGO) are chemically modified derivatives used for mass-scale industrial applications and water treatment.
Graphene membranes are impermeable to all gases except water vapor, making them ideal candidates for sub-nanometer molecular sieves and water desalination.
Graphene enhances lithium-ion battery electrodes by accelerating charge transport, shortening charging durations, and extending operational life cycles.
Magic-angle twisted bilayer graphene, rotated at approximately 1.1 degrees, was discovered by Pablo Jarillo-Herrero in 2018 to exhibit unconventional superconductivity.