The influence of the curvature of surface and π electrons on adsorption of nanocarbons

Takumi Araki, Syogo Tejima, Shatoshi Nakamura, Hisashi Nakamura, David Tomanek, Morinobu Endo
Division of Computational Science and Technology, Research Organization for Information Science & Technology, Shinagawa, Tokyo, Japan
Physics and Astronomy Department, Michigan State University, East Lansing, Michigan, United States
Faculty of Engineering, Shinshu University, Wakasato, Nagano, Japan
Nano carbons structures as CNTs, graphenes, fullerene, Mackay crystal and their composite have been attracting scientists and engineers to finding of novel functional materials for water technology and electronics. We have investigated the adsorption of nanocarbons as adsorbent with varying their surface curvature at adsorption point by use of ab initio simulation. The adsorption of CNTs, fullerene, graphene and Mackay crystals, has been simulated for Cesium, Cs, as adsorbate. The results show commonly that π-electron extending beyond the surface of carbons plays important role for catching the valence 6s electron of alkali metal Cs. The valence 6s electron of Cs flows into nanocarbon's π orbitals. It helps for nanocarbons to adsorb Cs stably by the charge transfer interaction. The surface curvature of the adsorption point clearly influences on the adsorption strength. The adsorption becomes more stable if curvature radius of CNTs increases. For the negative Gaussian curvature of Mackay crystals, the adsorption is enhanced around octagonal rings among the hexagons. This result points out that such a sophisticated configuration by the spread of π electrons contributes to the adsorption strength. The feature is useful for nanocarbon filter or film in novel water technology or future carbon electronic materials.