| Sumario: | Using density functional theory, we have theoretically studied dioxin binding on a graphene sheet or carbon nanotubes (CNT), finding that they can be effective adsorbents for dioxin in the presence of calcium atoms. This is due to a cooperative formation of sandwich complexes of graphene sheet or (5,5) CNT through the interaction π—Ca—π with the total binding energy of more than 3 eV. This correlates with the band structure analysis, which indicates charge transfer from the carbon systems and calcium atoms to dioxin when the molecule binds to the metal-doped carbon systems. For CNT with small radii, the relative strength of CNT—dioxin interaction is dependent on their chiralities. Upon dioxin binding, a large increase in the electronic density of states near the Fermi level also suggests that they can be used for dioxin sensing. Fe-doped CNT is also found to bind dioxin strongly, revealing an important role played by remnants of metallic catalysts in the chemical properties of CNT.
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