Effects of Sidewall Functionalization on Conducting Properties of Single Wall Carbon Nanotubes

Abstract

We investigated the conducting properties of functionalized single wall nanotubes (SWNTs) with a finite addend concentration. Robust differences are found between monovalent and divalent additions. For the former a small number of addends can significantly disrupt the ballistic conductance of nanotubes near the Fermi level. As the concentration increases the conductance decreases rapidly and approaches zero at addend to C ratio around 25%. In contrast, divalent functionalizations have weak effects, and the nanotube quantum conductance remains above 50% of that of a perfect tube even for an addend concentration as large as 25%. These differences can be attributed to the formation of impurity states near the Fermi level for monovalent additions, while divalent addends create impurity states far away from the Fermi level.

Quantum transport properties of chemically functionalized long semiconducting carbon nanotubes

“…This is at odds with the case of metallic armchair tubes for which (a) the parallel configuration does not exist, and (b) bonds perpendicular to the tube axis offer preferential addition sites [20]. In each case, the equilibrium position is reached when the carbon atom of CH 2 is located on top of the C-C tube bond forming a bridge-like structure [14,20,21,25]. Our calculations shows that the (\) conformation is always more stable than the (||) one.…”

“…On the contrary, the parallel (||) bonding geometry, with closed C-C bond, yields a more significant drop of conductance at nearly all energies (red curve inset). Such a contrasting behavior can be rationalized by observing that in the open geometry, the carbon atoms remain three-fold coordinated preserving thus the conjugated character of the sp 2 pristine nanotube network [14,20,21]. In contrast, in the closed geometry, the bridged carbon atoms are four-fold coordinated, destroying the local conjugated character of the π-network and thus reinforcing backscattering efficiency [12][13][14].…”

“…This functionalization is driven by grafted carbene (or nitrene) groups that induce bond cleaving between adjacent sidewall carbon atoms, maintaining the sp 2 hybridization and providing sites for further attachment of complex molecules and related functionalities [19]. First-principles calculations have shown that high conductance is preserved in functionalized metallic nanotubes with random coverage of addends [14,20,21], but the situation for semiconducting nanotubes remains unexplored.…”

New strategies for the chemical characterization of multi-walled carbon nanotubes and their derivatives

“…In general, a covalent functionalization of a CNT π-system decreases the nanotubes conductivity and absorption against electromagnetic radiation or magnetic fields. [32][33][34] In addition, the alteration of a single layer of a π conjugated system decreases the electrical conductivity of CNTs. Looking at the possibilities offered by functionalized CNT, it is important to consider that the amount of SWCNTs produced is considerably lower than that of MWCNTs.…”

Voltammetric behavior of 3,5-dinitrobenzoic acid in solution on GCE and encapsulated on multiwalled carbon nanotube modified electrode

“…Probably this fact causes the extraordinary large peak current values obtained in our system when compared with those obtained in the prior art. It is a well-known fact [10] that the formation of covalent bonds in the wall of the CNT change the configuration of carbon atoms from sp 2 to sp 3 . This change affects the conductivity properties of the CNTs due to loss of π electrons of the nanostructure.…”