What are Carbon Nanotubes (CNT)?
Carbon Nanotubes (CNTs), or carbon nanotubes, are cylindrical structures made of carbon atoms arranged in a rolled graphene sheet. These tubes measure just a few nanometers in diameter (1 nanometer equals one billionth of a meter). Scientists recognize carbon nanotubes as one of the strongest and most remarkable materials ever discovered.
History and Discovery
In 1991, Dr. Sumio Iijima, a Japanese scientist at NEC Corporation, made the widely recognized discovery of carbon nanotubes. While studying byproducts from fullerene synthesis, he observed tubular carbon structures that would later become foundational to nanomaterials research.
Researchers have found evidence that Russian scientists observed carbon nanotube-like structures as early as the 1950s to 1970s. Still, Sumio Iijima presented his findings with clarity and precision, which helped his work gain widespread recognition in the modern scientific community.
Carbon Nanotube Structure
Scientists create carbon nanotubes (CNTs) by rolling graphene sheets into cylindrical nanostructures composed of carbon atoms. These tubes, which can be either single-walled or multi-walled, contain π bonds similar to those in graphene. These bonds enable electrons to move freely along the tube walls, giving CNTs exceptional electrical conductivity and remarkable mechanical strength.
Types of Carbon Nanotubes
Multi-Walled Carbon Nanotubes (MWCNT)
Composed of multiple graphene layers stacked as concentric tubes. They offer high strength and are suitable for general applications.
Single-Walled Carbon Nanotubes (SWCNT)
Feature a single graphene layer rolled into a tube. They possess excellent electrical properties and flexibility.
Double-Walled Carbon Nanotubes (DWCNT)
Consist of two layers, providing balance between strength and electrical properties.
COOH Functionalized SWCNT
Single-walled carbon nanotubes with added COOH functional groups to enhance binding capabilities with other substances, suitable for research and specialized applications.
COOH Functionalized MWCNT
Multi-walled carbon nanotubes with enhanced functionality for use with other materials such as polymers or biological substances.
Size and Properties of Carbon Nanotubes
Carbon nanotubes (CNTs) are cylindrical nanostructures composed of carbon atoms arranged in a rolled graphene sheet. These tubes typically measure just a few nanometers in diameter, with lengths that can extend up to several micrometers. Their unique geometry gives rise to extraordinary physical, chemical, and electronic properties.
1. Diameter and Structure
CNTs have diameters ranging from 0.4 to 2 nanometers for single-walled types, and up to 100 nanometers for multi-walled variants. Their aspect ratio—length divided by diameter—can exceed 1000:1, making them ideal for reinforcing materials without compromising flexibility or weight.
2. Electrical Conductivity
Thanks to their π-bonded carbon network, CNTs allow electrons to move freely along the tube walls. This results in exceptional electrical conductivity, especially in metallic single-walled CNTs, which can carry current densities far beyond those of copper.
3. Mechanical Strength
CNTs are among the strongest known materials. Their tensile strength can reach up to 100 times that of steel, while maintaining a fraction of the weight. This makes them highly suitable for lightweight structural composites and impact-resistant materials.
4. Thermal Properties
CNTs also exhibit excellent thermal conductivity, especially along the tube axis. This property enables their use in heat dissipation systems for electronics, as well as in thermally conductive coatings and films.
5. Chemical Stability
Carbon nanotubes resist chemical degradation and corrosion, making them suitable for harsh environments such as chemical processing, filtration systems, and biomedical implants.
Applications and Benefits of Carbon Nanotubes
Carbon nanotube research involves collaboration across physics, chemistry, biology, medicine, materials science, and engineering. As a result, CNTs are applied in many industries:
- Automotive & Aerospace: CNTs enhance strength and reduce weight, ideal for high-performance components.
- Electronics: Used in circuits, batteries, and supercapacitors to improve conductivity and energy efficiency.
- Photovoltaics & Energy Devices: Found in solar panels, LEDs, sensors, transistors, fuel cells, and actuators.
- Environmental Cleanup: CNTs adsorb toxins, heavy metals, and pollutants from air, water, and soil.
- Chemical Industry: Act as catalysts or supports to boost reaction rates and reduce energy use.
- Biomedicine: Enable biosensing, bioimaging, nanorobots, gene therapy, and tissue regeneration.
- Agriculture: Support bioremediation and water treatment, improving soil and water quality.
- Protective Materials: CNTs are blended into composites for sportswear and bulletproof vests, enhancing durability.
With their unique properties and broad potential, CNTs are considered one of the most important material innovations of the 21st century.
The Future of CNT Technology
Carbon nanotube technology is growing quickly. The main challenges are lowering production costs, keeping quality consistent, and making large-scale manufacturing possible. As techniques improve and prices drop, CNTs will become more useful in many industries.
Because of their special properties and wide range of uses, carbon nanotubes are seen as one of the most important material breakthroughs of the 21st century. They will play a key role in future technology.
References
Ossila. Carbon Nanotube: Uses, Structure and Properties. Available at https://www.ossila.com/pages/what-are-carbon-nanotubes
NEC. The Discovery and Future of Carbon Nanotube – Sumio Iijima. Available at https://www.nec.com/en/global/rd/special/202007/index.html
Cheap Tubes. Carbon Nanotube Properties and Applications. Retrieved from https://www.cheaptubes.com/carbon-nanotubes-properties-and-applications/
Related Article: From CNTs to Graphene – The Path of Nanomaterials in the Future
Carbon atoms form two important nanomaterials: carbon nanotubes (CNTs) and graphene. CNTs take shape when graphene sheets roll into tiny tubes. In contrast, graphene forms a flat, one-atom-thick layer arranged in a hexagonal pattern.
Graphene is strong, transparent, and conducts electricity very well. Because of these qualities, people often call it a “wonder material.” Today, many researchers are exploring its use in new technologies like flexible electronics, nanosensors, lithium-ion batteries, and advanced filters.
Carbon nanotubes (CNTs) are strong and useful for building three-dimensional structures. In contrast, graphene is extremely thin and conducts electricity very well. Today, researchers are working to combine the strengths of both materials to create better nanotechnologies that serve many different uses.