Formation of polybromine anions and concurrent heavy hole doping in carbon nanotubes

Abstract

Using density-functional theory calculations, we investigate the atomic and electronic structure of the bromine species encapsulated in carbon nanotubes. We find that the odd-membered molecular structures (Br3 and Br5) are energetically favored than the common Br2 molecule. The transformation from bromine molecules (Br2) into Br3 or Br5 is found to be almost barrierless. A strong electron transfer from the nanotube to the adsorbates, which has been doubtful in previous studies, is accompanied by the formation of such odd-membered polybromine anions. We suggest that the tip-opened carbon nanotube samples can be heavily hole-doped after exposure to Br2 gas.

Bromine polycondensation in pristine and fluorinated graphitic carbons

“…Theoretical studies on the formation of polybromine chains inside small-diameter CNTs 32 and above graphene layers 33 have shown contradictory results. In particular, it was found that anions from an odd number of atoms, such as Br 3 − and when the last step is omitted, the Raman spectra of low-fluorinated matrices exhibit the peaks I-VI (see Fig.…”

“…Therefore, the formation of Br 3 -Br 3 chains over nanoscale graphene region will occur spontaneously in agreement with polymerization of bromine molecules encapsulated inside nanotubes. 32…”

“…As the result, bounded Br 3 -Br 3 chains are formed. Moreover, according to the study of bromine species encapsulated in CNTs, 32 Br 5 anions could be formed from Br 3 and Br 2 , and they are observed as the Raman resonances located around 206 cm −1 (peak II). 33 The weak intensity band at ca.…”

The Formation of High‐Order Polybromides in a Room‐Temperature Ionic Liquid: From Monoanions ([Br5]− to [Br11]−) to the Isolation of [PC16H36]2[Br24] as Determined by van der Waals Bonding Radii

“…Polybromides can play important roles across diverse areas, including carbon nanotube modification, [1] battery technology [2] and synthetic chemistry. [3] However, our understanding of the factors that control polybromide formation is still significantly less well developed than it is for polyiodides.…”

Intrinsic Dynamic and Static Nature of Halogen Bonding in Neutral Polybromine Clusters, with the Structural Feature Elucidated by QTAIM Dual-Functional Analysis and MO Calculations

“…Structures of halogen molecules (X 2 ) have been reported, as determined by X-ray crystallographic analysis for X = Cl, Br, and I [ 16 , 17 , 18 ]. The behavior of bromine–bromine interactions has been reported for the optimized structures of Br 2 –Br 5 in the neutral and/or charged forms, together with Br 1 , so far [ 19 , 20 ]. Figure 1 draws the observed structure of Br 2 , for example.…”