Please enable JavaScript.
Coggle requires JavaScript to display documents.
Graphene - Coggle Diagram
Graphene
The developments in chemistry that led to the discovery
Carbon
Atomic number 6 - Electron arrangement 2,4 → 4 valence electrons
Forms strong covalent bonds
Can form different allotropes
Carbon allotropes
Scientists discovered carbon can form different structures - Diamond, graphite, carbon nanotubes, graphene
Carbon's structure affects its properties
Graphite structure
Carbon atoms arranged in hexagonal layers
Strong C–C covalent bonds within layers
Weak van der Waals forces between layers - suggested that individual layers could be separated
1947 – P. R. Wallace
Developed a theoretical model of graphite's electronic structure
Helped predict unusual properties of a single carbon layer
1985 – C₆₀ discovered
Buckminsterfullerene discovered
Demonstrated complex nanoscale carbon structures
Increased interest in carbon nanomaterials
1987 – "Graphene"
Term introduced for a single layer of graphite
→ 2004: Discovery - Understanding of carbon + allotropes + graphite's layered structure + theoretical work → Geim & Novoselov successfully isolated graphene
The chemistry of graphene
Formula = C
Each carbon atom forms 3 σ covalent bonds and has 1 delocalised electron
Structure = Hexagonal lattice
Each C is bonded to 3 other C atoms
Strong covalent network = high strength/breaking point
Delocalised E- mean electrons move easily making the element have high electrical conductivity
1 atom thickness = extremely lightweight, flexible, and transparent
The discovery of graphene
Graphene was discovered in 2004 by Andre Geim & Konstantin Novoselov at the University of Manchester.
Scotch tape method
Putting graphite on some tape, removing the tape (and therefore a layer or few layers of graphite), and repeating the process until there was a single layer left – graphene.
Graphene has been guessed at being approx 0.335–0.345 nm thick – the thickness of one carbon atom.
This discovery won Geim and Novoselov a Nobel prize in physics.
The chemistry of the discovery
Mechanical exfoliation
Starting material = graphite
Graphite = many layers of graphene stacked together
Graphite to graphene
Between layers = weak forces
Within layers = strong forces (C-C covalent bonds)
Tape applies enough force to separate layers
Repeating the process creates thinner layers.
IMPORTANT
Throughout the chemical composition does not change
Carbon remains carbon
Physical process, not a chemical reaction
Other methods
Chemical exfoliation - uses chemical reactions/oxidation to separate layers
Chemical vapour deposition - can produce large graphene sheets, useful for industrial application
The main issue of producing graphene is producing large quantities of high quality graphene cheaply and without defects.