Why in news?
Two decades after its discovery, graphene continues to be hailed as a “wonder material” with research accelerating its move from laboratories to real‑world applications. Industry analysts predict wider commercial use in electronics, energy storage, composites and sensors over the coming years.
Background
Graphene consists of a single layer of carbon atoms arranged in a hexagonal lattice. It was first isolated in 2004 by physicists Andre Geim and Konstantin Novoselov using simple mechanical exfoliation of graphite, earning them the Nobel Prize in Physics in 2010. A sheet of graphene is only one atom thick, yet it is extremely strong, light and flexible. One millimetre of graphite contains about three million graphene layers.
Major properties
- Mechanical strength: Graphene is about 200 times stronger than steel while remaining flexible. Strong sp2 carbon–carbon bonds allow it to resist high stress without breaking and to stretch up to 20 percent of its original length.
- Electrical conductivity: Electrons move through graphene with minimal resistance, giving it higher conductivity than copper. This property makes it a potential replacement for silicon in transistors and microprocessors.
- Thermal conductivity: With a thermal conductivity of around 3 000–5 000 W/m·K, graphene dissipates heat far more efficiently than most metals, making it valuable for heat sinks and thermal management.
- Optical transparency: A single graphene sheet absorbs only about 2.3 percent of visible light, combining transparency with conductivity. This balance is ideal for touchscreens, solar cells and transparent electrodes.
- Chemical tunability: Graphene’s surface can be functionalised with various chemical groups to tailor its properties. Graphene oxide (GO) adds oxygen groups, making it dispersible in water for membranes and coatings, while reduced graphene oxide (rGO) partially restores conductivity for batteries and supercapacitors. Graphene nanoplatelets (GNPs) and few‑layer graphene offer cost‑effective options for composites.
Synthesis methods
- Mechanical exfoliation: The original “Scotch‑tape” method peels off thin layers of graphite to obtain high‑quality graphene flakes; however, it is labour‑intensive and unsuitable for mass production.
- Liquid‑phase exfoliation: Graphite is dispersed in solvents and subjected to ultrasonic waves, causing layers to peel apart. This top‑down method produces large quantities of graphene at relatively low cost, although the flakes may vary in thickness.
- Chemical oxidation–reduction: Graphite is oxidised to graphite oxide and then reduced to graphene oxide and further to reduced graphene oxide using chemical agents. Researchers are exploring green reducing agents such as ascorbic acid and plant extracts to minimise environmental impact.
- Chemical vapour deposition (CVD): A bottom‑up technique in which carbon‑containing gases (e.g., methane) decompose at high temperatures onto metal substrates like copper or nickel, forming continuous graphene films. Plasma‑enhanced CVD operates at lower temperatures. CVD enables scalable production of uniform graphene for electronics and optoelectronics.
Applications
- Electronics and photonics: Graphene’s high mobility and transparency make it suitable for flexible displays, touchscreens, photodetectors and high‑frequency transistors.
- Energy storage: Batteries and supercapacitors use graphene and its derivatives to increase energy density, charge speed and lifespan. rGO and GNPs are incorporated into electrodes.
- Composite materials: Adding graphene nanoplatelets to polymers, rubbers and metals improves their strength, toughness and thermal stability. Applications include automotive parts, sports equipment and 3D‑printing filaments.
- Water purification and membranes: Graphene‑based membranes filter contaminants and desalinate water due to their fine, tunable pores and chemical stability.
- Sensors and biomedical devices: Graphene’s large surface area and conductivity enable sensitive detection of gases, biomolecules and environmental pollutants. Functionalised graphene is also explored for drug delivery and tissue engineering.
Significance
- Revolutionary potential: Graphene combines extraordinary properties in one material. Continued research and improvements in large‑scale production could transform electronics, energy, transportation and healthcare.
- Market challenges: High‑quality monolayer graphene remains expensive to produce, and standards for different types are still developing. Cost‑effective methods like liquid‑phase exfoliation and flash graphene are helping to overcome these barriers.
- Sustainable innovation: Green synthesis methods and recyclable graphene products can minimise environmental impact as the material moves into widespread use.
Source: PIB
