Effect of High Pressure on the Transformations of Ferrocene-Filled, Single-Wall, Carbon Nanotubes: Density Functional Theory and Raman Spectroscopy Studies

摘要

Metallocene-filled single-walled carbon nanotubes (SWCNTs) have tunable electronic properties and a large potential in creating new structures due to their tunable electron doping and unique chemical reaction in a nanoscale confinement environment. Here we study the effect of high pressure on the transformations of ferrocene (FeCpi)-filled SWCNTs (FC@SWCNTs), by theoretical simulation and Raman spectroscopy. It is found that the filling of FeCp2 into carbon nanotube leads to higher transition pressures for the nanotube cross section changes and the intertubular bonding compared with the unfilled nanotubes. These results can be explained by the different charge distribution on the nanotubes due to, Charge transfer and the effect from host guest interactions. Band structure analysis shows a pressure-induced decrease of band gap below 11 GPa, a transformation into a semimetal structure at 11 GPa, and subsequently, an abrupt increase of band gap due to the formation of intertube bonding. The increased host guest interaction also leads to a decomposition of FeCp2 and the formation of a new 3D zeolite-like structure, which is quenchable to ambient conditions. Our preliminary experimental results confine that the encapsulation of FeCp2 affects the transformations of nanotubes, which can be explained by the host guest interactions, as demonstrated by our simulations.