Graphene and carbon nanotubes (CNTs) are the most talked-about allotropes of carbon after diamond and graphite. Discovered and characterised in the last four decades, they have extraordinary mechanical, electrical, thermal and optical properties. For an industrialising economy, they are the next-generation building blocks of batteries, electronics, composites, coatings and sensors. India has invested through DST, MeitY, DRDO, CSIR and specialised centres. For UPSC, this topic spans GS Paper III — Science & Technology, Economy, Environment.
The carbon family
Carbon, with its four valence electrons, takes multiple structural forms:
| Allotrope | Structure | Notes |
|---|---|---|
| Diamond | 3-D tetrahedral sp³ | Hardest natural material |
| Graphite | 2-D stacked hexagonal | Soft; electrical conductor along planes |
| Fullerene (C₆₀) | Spherical | Discovered 1985 (Curl, Kroto, Smalley) |
| Carbon Nanotubes (CNTs) | Rolled graphene sheet | First reported by Iijima, 1991 |
| Graphene | Single 2-D layer of sp² carbon | Isolated by Geim & Novoselov, 2004 (Nobel 2010) |
| Graphyne, Carbyne | Newer forms | Research stage |
Graphene — the 2-D wonder
Structure and isolation
Graphene is a one-atom-thick honeycomb lattice of sp² hybridised carbon. It was first cleanly isolated from bulk graphite using Scotch tape by Andre Geim and Konstantin Novoselov at Manchester in 2004.
Remarkable properties
| Property | Value | Comparison |
|---|---|---|
| Tensile strength | 130 GPa | ~200× steel |
| Young's modulus | ~1 TPa | Diamond-like stiffness |
| Thermal conductivity | ~5,000 W/m-K | 10× copper |
| Electron mobility | 200,000 cm²/V-s | 100× silicon |
| Optical transparency | ~97.7% | For white light |
| Impermeability | Blocks helium | Ultra-fine filter |
Production routes
- Mechanical exfoliation — research-scale, highest quality.
- Chemical Vapour Deposition (CVD) — wafer-scale on copper/nickel.
- Graphene Oxide (GO) route — chemical reduction; low-cost, large-area.
- Epitaxial growth on SiC.
- Electrochemical exfoliation of graphite.
Applications
| Domain | Use case |
|---|---|
| Energy storage | Supercapacitors; anodes and cathodes of advanced batteries |
| Electronics | Flexible transistors, transparent conductors for OLED/touchscreens |
| Composites | Light, strong polymer and cement composites; aerospace parts |
| Coatings | Anti-corrosion, barrier, conductive inks |
| Sensors | Chemical, biological and pressure sensors |
| Water purification | Graphene oxide membranes for desalination and heavy-metal removal |
| Biomedical | Drug delivery, tissue scaffolds, biosensors |
| Thermal management | Heat spreaders in chips and high-power electronics |
Carbon nanotubes (CNTs)
Structure
A CNT is a rolled-up graphene sheet. Chirality determines metallic vs semiconducting behaviour.
- Single-Walled CNT (SWCNT) — one cylinder.
- Multi-Walled CNT (MWCNT) — concentric cylinders.
Typical dimensions: diameter ~1-50 nm, length up to centimetres.
Properties
- Tensile strength up to 100 GPa (100× stronger than steel at 1/6 the density).
- Young's modulus ~1 TPa.
- Current density 10⁹ A/cm² (1000× copper).
- Thermal conductivity ~3,000 W/m-K.
- Chemically inert and flexible.
Production
- Arc discharge (Iijima, 1991).
- Laser ablation of graphite.
- Chemical Vapour Deposition (CVD) — industrial route.
- HiPco process — high-pressure CO decomposition.
- Aligned forests — "carpet growth" for mass applications.
Applications
| Domain | Use |
|---|---|
| Composites | Sporting goods, wind-turbine blades, spacecraft panels |
| Electronics | CNT transistors; flexible displays |
| Energy | Li-ion and Li-S batteries; supercapacitors; fuel cells |
| Healthcare | Drug carriers, tissue scaffolds, biosensors |
| Textiles | Conductive, anti-bacterial, thermal-regulating fabrics |
| Water & gas filtration | Membranes, oil-spill sponges |
| Defence | Ballistic armour, stealth coatings, sensor skins |
| Space | Proposed space elevator tether material |
Other advanced nanomaterials
- Boron nitride (BN) — "white graphene"; high-temp electrical insulator.
- Transition metal dichalcogenides (MoS₂, WS₂) — semiconducting 2-D.
- MXenes (Ti₃C₂) — conductive, high-capacitance.
- Perovskites — photovoltaics, LEDs.
- Black phosphorus — tunable bandgap.
- Silicene, Germanene — 2-D analogues of Si/Ge.
India's advanced materials programme
Institutions
- DST Nano Mission (2007-ongoing).
- MeitY Centre of Excellence on Graphene — India Innovation Centre for Graphene (IICG), Kerala (2024).
- CSIR labs — NCL Pune, CECRI Karaikudi, CSIR-CMERI, CSIR-IMMT.
- IISc, IITs (Bombay, Madras, Kanpur, Delhi).
- DRDO laboratories — DMRL, DMSRDE — develop graphene composites for armour and stealth.
- ARCI Hyderabad — Advanced Materials and Processes.
India Innovation Centre for Graphene, Kerala (2024)
Located at Digital University Kerala, Thiruvananthapuram. Supported by MeitY, Tata Steel and Kerala government with Rs ~90 crore outlay. Focus: CVD graphene for electronics, composites for defence, coatings for steel, sensor arrays.
Private players
- Tata Steel Graphene Centre.
- Carborundum Universal, KIC Metaliks — research partnerships.
- Graphene Manufacturing Group (India) Pvt Ltd, Log 9 Materials — startups in battery and supercapacitor tech.
Challenges
| Challenge | Detail |
|---|---|
| Scale-up | High-quality graphene at industrial scales is expensive |
| Dispersibility | CNTs agglomerate in polymer matrices |
| Toxicity | CNT fibres comparable to asbestos in some studies |
| Standardisation | BIS/ISO standards for graphene variants still maturing |
| IPR thickets | Patents dominated by Samsung, BASF, IBM |
| Regulatory uncertainty | Nano-material approvals in cosmetics, food, medicine |
| Capital intensity | CVD reactors, ALD tools costly |
Sustainability angle
- Graphene from biomass ("flash Joule heating" method — Rice University, 2020) converts waste to high-quality graphene.
- CNTs for lightweight composites cut vehicle fuel burn.
- Graphene membranes enable energy-efficient desalination and carbon capture.
Latest developments (2024-26)
- India Innovation Centre for Graphene (IICG) Kerala launched (2024).
- Perovskite-Si tandem solar cells (IIT Bombay + Tata) crossed 27% efficiency (2024).
- MXene electromagnetic shielding films demonstrated by CECRI (2024).
- Graphene-hardened railway axle boxes tested by Indian Railways-DMRL (2025).
- AI Action Summit, Paris (Feb 2025) — AI-for-materials-discovery panels featured Indian teams.
- India Semiconductor Mission — advanced materials required for photoresists, ALD etch gases.
- DeepTech Policy 2024 — advanced materials as sovereign priority.
- National Quantum Mission (2024) — 2-D materials for qubit substrates.
- Chandrayaan-4 plan and Gaganyaan progress — graphene composites for heat-shields and payload reduction under study.
- DMRL graphene composite armour plates inducted for Army trials (2025).
- Log9 Materials commercialised aluminium fuel cells using CNT electrodes in 2024-25.
UPSC Relevance
GS Paper III — Science & Technology
- Graphene/CNT properties, production, applications.
GS Paper III — Economy & Environment
- Advanced manufacturing, green hydrogen, filtration.
GS Paper III — Defence / Internal Security
- Lightweight armour, stealth, directed-energy weapon components.
GS Paper II — Governance
- BIS nanomaterials standards, IPR strategy.
Prelims pointers — Graphene (Geim & Novoselov, 2004, Nobel 2010), CNTs (Iijima 1991), IICG Kerala, MXenes, perovskite PV, ARCI, Nano Mission.
Interview probes — commercialisation barriers; nanotoxicity and labelling; strategic materials sovereignty; role of CSIR-labs.
Advanced carbon materials sit at the crossroads of chemistry, physics and engineering — tiny sheets and tubes that will quietly reshape electronics, energy, mobility and defence through the next two decades.
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