Confined Catalysis in Carbon Nanotube Systems

Carbon nanotubes (CNTs) have emerged as versatile platforms for confined catalysis, exploiting their one-dimensional cavities and tunable surface chemistry to modulate reaction pathways. By hosting catalytic species either within the inner channels or in engineered defects on their walls, CNT-based systems can enhance activity, selectivity and stability compared with conventional heterogeneous catalysts. Confinement alters local concentration, electronic interactions and diffusion profiles, often leading to unique mechanistic behaviours. Strategies for creating catalytic CNT reactors include endohedral encapsulation of metal nanoparticles or organometallic complexes, controlled defect etching to form nanopores, and chemical functionalisation to anchor single-atom active sites. These approaches have been applied to cross-coupling reactions, hydrogenation and hydrosilylation in the liquid phase, as well as gas-phase processes such as CO₂ sorption and oxidation. Advances in in situ characterisation and computational modelling have deepened understanding of how nanoscale confinement influences elementary steps, enabling the rational design of next-generation catalysts with improved efficiency and recyclability. The global significance of this field spans fine chemical synthesis, environmental remediation and sustainable energy conversion, positioning confined CNT reactors at the forefront of nanocatalysis research.

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Confined Catalysis in Carbon Nanotube Systems publication trend

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Technical terms

Carbon nanotube (CNT): A cylindrical allotrope of carbon with a high aspect ratio and a hollow interior, used as a host for confined catalysts.

Confinement effect: Modulation of chemical reactivity arising from spatial restriction, leading to altered kinetics, selectivity and stability.

Endohedral catalysis: Catalytic processes that occur within the internal cavity of a nanotube by encapsulated active species.

Defect etching: The deliberate creation of vacancies or nanopores in CNT walls to enable access to the inner cavity and anchor catalytic centres.

Suzuki–Miyaura reaction: A palladium-catalysed cross-coupling between organoboron compounds and aryl halides to form biaryl products.

Hydrosilylation: Addition of a silicon–hydrogen bond across unsaturated organic substrates, often catalysed by transition-metal complexes.

References

1. Enter the Tubes: Carbon Nanotube Endohedral Catalysis. Catalysts (2019).
2. Palladium nanoparticles in catalytic carbon nanoreactors: the effect of confinement on Suzuki–Miyaura reactions. Journal of Materials Chemistry A (2015).
3. Defect Etching in Carbon Nanotube Walls for Porous Carbon Nanoreactors: Implications for CO2 Sorption and the Hydrosilylation of Phenylacetylene. ACS Applied Nano Materials (2022).