A new mechanism was proposed for the bi-molecular healing of the vacancy defect in single-walled carbon nanotubes. The mechanism was of particular importance in avoiding the errors often encountered in the electronic properties of carbon nanotubes. Using density functional theory calculations with the Perdew-Burke-Ernzerhof functional, the reaction mechanism of the healing process of the monatomic vacancy defect in the (8,0) single-walled carbon nanotubes via carbon monoxide disproportionation was investigated. It was found that the proposed mechanism was theoretically possible. The activation energy was only 9.37kcal/mol for the 4-membered ring-opening step at high CO concentrations. No catalyst was needed, and thus no purification step was needed to remove the catalyst. The CO could be used as a reactant. No oxygen by-product was found, and there was a high selectivity of CO for vacancy defect sites. The present findings established that a carbon nanotube with a vacancy defect, as generally obtained by synthesis, could be healed completely and resume its function as a perfect carbon nanotube displaying the original electronic properties.

Healing of a Vacancy Defect in a Single-Walled Carbon Nanotube by Carbon Monoxide Disproportionation. T.Nongnual, J.Limtrakul: Journal of Physical Chemistry C, 2011, 115[11], 4649-55