Carbon Nanotube Synthesis and Characterization

Carbon nanotubes (CNTs) are cylindrical nano-structures composed of rolled graphene sheets exhibiting extraordinary mechanical, electrical and thermal properties. Their synthesis relies on methods such as arc discharge, laser ablation and chemical vapour deposition (CVD), each offering distinct control over tube diameter, length, chirality and purity. Catalytic CVD has emerged as the most versatile technique, employing transition-metal nanoparticles to nucleate tube growth from hydrocarbon precursors under controlled temperature and atmosphere. Fine tuning of catalyst composition, support materials and gas feedstock enables the production of single-walled (SWCNTs), multi-walled (MWCNTs) or doped variants with tailored morphologies, including aligned arrays and nested structures. Characterisation of CNTs utilises a suite of techniques: Raman scattering probes vibrational modes to assess diameter distribution, crystallinity and defects; transmission and scanning electron microscopy reveal structural features at the atomic scale; electron energy loss and X-ray spectroscopies provide chemical and bonding information; and electrical measurements quantify conductivity and semiconducting content. Together, these methods underpin advances in understanding growth mechanisms, structural perfection and functional performance, supporting applications from nanoelectronics and composite materials to energy storage and sensing.

Research from Nature Portfolio

Deep machine-learning-driven molecular simulations have elucidated atomic-level mechanisms of CNT nucleation and growth at the catalyst interface, revealing stochastic defect formation and healing pathways that enable defect-free tube elongation under optimised conditions. A tailored cobalt-based nanoparticle catalyst with a carbon-coating layer has facilitated the growth of semiconducting SWCNTs with a narrow diameter distribution centred at 1.7 nm, achieving over 95 % semiconducting content and record-high thin-film transistor performance. A novel catalyst strategy has produced ultra-dense, horizontally aligned SWCNT arrays at densities exceeding 130 tubes µm⁻¹, yielding field-effect and radio-frequency transistors with drive currents and frequency responses surpassing previous benchmarks.

Carbon Nanotube Synthesis and Characterization publication trend

The graph below shows the total number of articles in carbon nanotube synthesis and characterization across all publications each year (not limited to Nature Index journals).

Technical terms

Chemical vapour deposition (CVD): A synthesis method in which gaseous precursors decompose on a catalyst surface to form carbon nanotubes.

Radial breathing mode (RBM): A low-frequency Raman vibration corresponding to uniform expansion and contraction of the nanotube diameter.

Chiral angle: The angle defining the orientation of the graphene lattice roll-up, governing electrical characteristics of CNTs.

Machine learning force field (MLFF): A computational model trained on quantum mechanical data to predict interatomic forces in simulations.

Catalyst nanoparticle: A metal particle that nucleates and directs the growth of carbon nanotubes from hydrocarbon feedstocks.

References

1. Dynamics of growing carbon nanotube interfaces probed by machine learning-enabled molecular simulations. Nature Communications (2024).
2. Atomic-Scale Time-Resolved Imaging of Krypton Dimers, Chains and Transition to a One-Dimensional Gas. ACS Nano (2024).
3. A Review of Carbon Nanomaterials’ Synthesis via the Chemical Vapor Deposition (CVD) Method. Materials (2018).
4. Characterizing carbon nanotube samples with resonance Raman scattering. New Journal of Physics (2003).
5. Growth of high-density horizontally aligned SWNT arrays using Trojan catalysts. Nature Communications (2015).
6. Growth of semiconducting single-wall carbon nanotubes with a narrow band-gap distribution. Nature Communications (2016).