DFT study of ionic peapod structures from single-walled carbon nanotubes and Lindqvist tungstates

Abstract

DFT investigations have been carried out on encapsulation of Lindqvist-type W₆O₁₉²⁻ anion inside hydrogenated (n,n) armchair single-walled carbon nanotubes (h-CNTs) with n = 8, 9, 10 to understand the confinement effect of the CNTs on the rotation of W₆O₁₉²⁻. The energy-decomposition analysis (EDA) of interaction between W₆O₁₉²⁻ and CNTs shows that with the increase of confinement effect from n = 8, 9, to 10, the destabilizing ΔE_Pauli plays a more important role in the relative orientation of W₆O₁₉²⁻ inside CNTs. For W₆O₁₉²⁻@(9,9) h-CNT, the most stable orientation appears at the y/z angle 45°/36°. The confinement effect reduces significantly the energy gap of W₆O₁₉²⁻@(n,n) h-CNT (n = 8, 9, 10) compared with free W₆O₁₉²⁻. Electron transfer from the W₆O₁₉²⁻ to CNT is observed.