Rehybridization defects

Although a honeycomb lattice theoretically consists of sp2 atoms, the carbon s ability to represent intermediate states of hybridization leads to another kind of defect to counterbalance the strain energy induced by high curvature. This so-called rehybridization results in a higher n-character of the C-C bonds [24]. Furthermore, local sp3 hybridization can be induced though chemical treatment, such as after thermal elimination of functional groups. 

Defects in MWCNTs are always present. We can briefly differentiate between topological defects which lead to rehybridization (C5 and C7 rings instead of C6 lead to rehybridization between sp2 and sp3) and incomplete bonding defects (vacancies, dislocation) (Fig. 16.2). Functionalization or doping with heteroelements may add further modifications with respect to the ideal ordered structure, but are also the sites which allow for anchoring supported metals or metal oxides, or to functionalize the CNTs with organic groups. 

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