Graphene and Fullerenes

This lesson covers graphene and fullerenes as required by the AQA GCSE Combined Science Trilogy specification (8464), section 4.2.2. You need to know about these newer forms of carbon, their structures, properties and potential applications.

---

Graphene

What Is Graphene?

Graphene is a single layer of graphite — a sheet of carbon atoms arranged in a hexagonal lattice that is just one atom thick. It was first isolated in 2004 by Andre Geim and Konstantin Novoselov at the University of Manchester, who won the Nobel Prize for this work in 2010.

Structure of Graphene

• Each carbon atom is covalently bonded to 3 other carbon atoms in a flat hexagonal pattern.
• This leaves one delocalised electron per carbon atom free to move across the layer.
• Graphene is essentially a 2D material — a single sheet.

Properties of Graphene

Property	Explanation
Excellent electrical conductor	One delocalised electron per carbon atom is free to move and carry charge across the entire sheet
Excellent thermal conductor	Delocalised electrons transfer kinetic energy rapidly; strong covalent bonds also transmit vibrations efficiently
Extremely strong	Despite being one atom thick, the strong covalent bonds in the hexagonal lattice make it the strongest material ever measured
Lightweight and flexible	It is a single atomic layer, making it incredibly thin and light
Transparent	Only one atom thick, so it absorbs very little light
Very high melting point	Strong covalent bonds throughout the structure

Exam Tip (AQA 8464): Graphene has the same basic structure as one layer of graphite. Like graphite, each carbon bonds to 3 others (not 4 like diamond), so there is one delocalised electron per carbon atom. This is why both graphene and graphite conduct electricity.

Applications of Graphene

• Electronics — transparent conductive coatings, flexible touchscreens, faster transistors.
• Composites — adding graphene to materials to make them stronger and lighter.
• Sensors — detecting individual molecules due to its sensitivity.
• Energy — improving batteries and supercapacitors.
• Medical — potential drug delivery and tissue engineering applications.

---

Fullerenes

What Are Fullerenes?

Fullerenes are molecules of carbon with hollow shapes — they can be spherical (balls), tubular (tubes), or other shapes. Like graphite and graphene, each carbon atom in a fullerene is bonded to 3 other carbon atoms, leaving delocalised electrons.

Fullerenes are different from diamond, graphite and graphene because they form closed structures — discrete molecules rather than infinite lattices or sheets.

Buckminsterfullerene (C₆₀)

The most famous fullerene is buckminsterfullerene (C₆₀), sometimes called a "buckyball":

• It contains 60 carbon atoms arranged in a hollow sphere.
• The structure is made of 12 pentagons and 20 hexagons — like a football (soccer ball).
• Named after the architect Buckminster Fuller, who designed geodesic domes with a similar shape.
• It has the molecular formula C₆₀.

graph TD
    A["Fullerenes"] --> B["Buckminsterfullerene<br/>C₆₀ — hollow sphere"]
    A --> C["Carbon Nanotubes<br/>Cylindrical tubes"]
    B --> D["12 pentagons<br/>20 hexagons"]
    B --> E["Each C bonded<br/>to 3 others"]
    C --> F["Extremely strong<br/>and lightweight"]
    C --> G["Excellent electrical<br/>conductors"]

    style A fill:#2c3e50,color:#fff
    style B fill:#8e44ad,color:#fff
    style C fill:#e67e22,color:#fff
    style D fill:#8e44ad,color:#fff
    style E fill:#8e44ad,color:#fff
    style F fill:#e67e22,color:#fff
    style G fill:#e67e22,color:#fff

Properties of C₆₀

Property	Detail
Molecular formula	C₆₀
Structure	Hollow spherical cage
Bonding	Each carbon bonded to 3 others
Delocalised electrons?	Yes — can conduct electricity
Solubility	Slightly soluble in some organic solvents

Carbon Nanotubes

Carbon nanotubes are cylindrical fullerenes — essentially tubes made from rolled-up sheets of graphene:

• Each carbon atom bonds to 3 others in hexagons.
• They have very high length-to-diameter ratios (very long and thin).
• They have delocalised electrons, so they conduct electricity.
• They are extremely strong for their weight.

Properties and Uses of Carbon Nanotubes

Property	Use
Very strong and lightweight	Reinforcing materials (e.g. sports equipment, body armour)
Excellent electrical conductors	Electronics, nanoscale wiring
High tensile strength	Engineering composites
Hollow interior	Drug delivery systems (carrying molecules inside the tube)
Large surface area	Catalysts

---

Uses of Fullerenes in General

Fullerenes have several important applications:

1. Drug delivery — the hollow structure can carry drug molecules to specific parts of the body.
2. Lubricants — the spherical shape of C₆₀ means it can act like molecular ball bearings.
3. Catalysts — fullerenes and nanotubes have large surface areas.
4. Electronics — nanotubes can be used as semiconductors or conductors.
5. Strengthening materials — nanotubes can reinforce composites.

---

Allotropes of Carbon — Complete Summary

graph TD
    A["Carbon Allotropes"] --> B["Diamond"]
    A --> C["Graphite"]
    A --> D["Graphene"]
    A --> E["Fullerenes"]
    B --> B1["4 bonds per C<br/>3D lattice<br/>Very hard<br/>Insulator"]
    C --> C1["3 bonds per C<br/>Layers<br/>Soft/slippery<br/>Conductor"]
    D --> D1["3 bonds per C<br/>Single layer<br/>Strong/flexible<br/>Conductor"]
    E --> E1["3 bonds per C<br/>Hollow shapes<br/>C₆₀ and nanotubes<br/>Conductor"]

    style A fill:#2c3e50,color:#fff
    style B fill:#3498db,color:#fff
    style C fill:#27ae60,color:#fff
    style D fill:#e67e22,color:#fff
    style E fill:#8e44ad,color:#fff

Allotrope	Bonds per C	Structure	Hardness	Conductivity
Diamond	4	3D tetrahedral lattice	Very hard	Does not conduct
Graphite	3	Hexagonal layers	Soft	Conducts
Graphene	3	Single hexagonal sheet	Very strong	Conducts
Fullerenes (C₆₀)	3	Hollow sphere	N/A (molecules)	Can conduct
Carbon nanotubes	3	Hollow cylinder	Very strong	Conducts

---

Common Mistakes