Influence of Diameter, Length, and Chirality of Single-Walled Carbon Nanotubes on Their Free Radical Scavenging Capability

Density functional theory calculations have been used to model the influence of diameter, length, and chirality of single-walled carbon nanotubes (SWCNT) on their free radical scavenging activity. SWCNTs with wide distributions of different diameter, length, and chirality are proposed to have good free radical scavenging activity in the gas phase and in nonpolar environments. Therefore, they can be used as free radical traps with potential application in environmental and biological systems. In general, thinner tubes are expected to have better antiradical activities. However, the curvature of the tubes seems to modify the antiradical activity of armchair nanotubes. Therefore, for wide distributions of tube diameter, the zigzag SWCNTs are expected to be more efficient for free radical scavenging purposes than the armchair ones. The length of the tubes only has a minor influence on the free radical trapping efficiency of SWCNTs. From the results reported in this work, thin and zigzag nanotubes are recommended as those with the best antiradical activity, regardless of their length.