What is Graphene and How Does it Generate Heat?

Graphene is a single layer of carbon atoms arranged in a two-dimensional honeycomb lattice. It is known for its remarkable properties, including high electrical conductivity, mechanical strength, and thermal conductivity.

When an electric current passes through graphene, it generates heat through a mechanism known as the Joule heating effect. Here’s how it works:

1. Electric Current Passage: As the current flows through the graphene sheet, electrons move through the carbon lattice.
2. Phonon Generation: The movement of electrons creates vibrations in the carbon atoms, known as phonons.
3. Brownian Motion: Phonons, along with ions and electrons, undergo Brownian motion, which involves random friction and collisions among these particles and the carbon atoms.
4. Heat Production: The friction and collisions during Brownian motion generate thermal energy, causing the material to heat up.
5. Heat Conduction: Graphene’s high thermal conductivity allows this heat to be efficiently transferred and dissipated.

Thermal Conductivity

Thermal conductivity is a measure of a material’s ability to conduct heat. It is defined as the quantity of heat transmitted through a material of unit thickness in a direction normal to a surface of unit area, due to a unit temperature gradient under steady state conditions. The unit of thermal conductivity is watts per meter per Kelvin (W/m·K).

Thermal Conductivity of Common Materials

• Single-layer Graphene: 5300 W/(m·K)
• Single-walled Carbon Nanotubes: 3500 W/(m·K)
• Multi-walled Carbon Nanotubes: 3000 W/(m·K)
• Silver: 412 W/(m·K)
• Copper: 377 W/(m·K)
• Aluminum: 230 W/(m·K)
• Graphite: 151 W/(m·K)
• Steel (1% C): 45 W/(m·K)
• Concrete: 1.28 W/(m·K)
• Glass: 1.09 W/(m·K)
• Refractory Brick: 1.04 W/(m·K)
• Building Brick: 0.69 W/(m·K)
• Water (at 20°C): 0.599 W/(m·K)
• Asbestos: 0.15 W/(m·K)
• Cotton Wool: 0.050 W/(m·K)
• Air (at 100°C): 0.024 W/(m·K)

Heat Generation Mechanism in Graphene

The heat generated in graphene primarily arises from the Joule heating effect, where the movement of electrons under an applied voltage leads to energy dissipation in the form of heat. Due to graphene’s exceptional thermal conductivity, this heat is quickly spread across the material, making it highly efficient for applications requiring rapid heat dissipation.

Applications

Graphene’s unique thermal properties make it suitable for various applications, including:

• Thermal Management: Used in electronics to manage and dissipate heat efficiently.
• Heaters: Incorporated in flexible and efficient heating elements.
• Composites: Integrated into materials to enhance their thermal conductivity.

Graphene’s ability to efficiently conduct and dissipate heat, combined with its strength and flexibility, positions it as a revolutionary material in the fields of electronics, materials science, and beyond.