Effects of mechanical deformation on outer surface reactivity of carbon nanotubes

An ab initio approach of Car-Parrinello molecular dynamics is used to study the chemisorption of a single oxygen atom on outer surface of zigzag single-wall carbon nanotubes under various uniaxial strains and bending deformation. The effect of mechanical deformation on adsorption of oxygen atom on CNT is demonstrated by linking the chemical reactivity and structural deformation. The adsorption energy Eb and pyramidalization angle thetasP are obtained by structural relaxation calculations, and ground- state electronic structures are described according to density functional theory (DFT) within a plane-wave pseudopotential framework. Our results show that the surface reactivity of CNT is mostly determined by its pyramidalization angle of carbon atom. For bending SWCNT, both Eb and thetasP vary with adsorption sites, the Eb is higher at sites with larger pyramidalization angle. An approximate linear relation of strain and adsorption energy can be obtained. It is indicated that the structure of CNT is crucial for its surface reactivity, and the mechanical deformation can be a method for controlling the surface reactivity of CNT and offering adsorption site selectivity as the adsorption is facilitated on the sites with higher pyramidalization angle.