(484e) Molecular Dynamics Simulation of the Ionlic Liquid [EMIM+][TFMSI-] Confined Inside a Slit Rutile (110) Nanopore

The unique properties of ionic liquids (ILs) make them a viable replacement for conventional electrolytes in dye-sensitized solar cells (DSSCs.) Therefore it is desirable to understand the atomic level interactions between the ILs and possible electrode materials such as titanium oxide, zinc oxide and copper oxide used in DSSCs. In the present work, structural and dynamical properties of the IL [EMIM⁺][TFMSI^-] confined inside a rutile (110) slit nanopore of size H = 5.2 nm are investigated by means of classical molecular dynamics simulations. The simulations are carried out at 333 K varying amounts of IL inside the pore. Various equilibrium and time dependent properties such as density profiles, radial density profiles (RDF), orientation of the ions, auto-correlation functions and mean square displacements (MSDs) are calculated and the effect of the confinement on the above properties are studied. It is found that confinement has profound effects on the properties of the ions; densities of the ions are inhomogeneous with higher densities near the rutile (110) surface. Variation in the amount of IL inside the pore has only slight effects on the densities of the ions in the first layers, whereas significant changes are observed in the center of the pore. RDF results indicate a completely different structure of the ions in the first layers at different loadings and in different regions of the pores. The imidazolium ring of the cations prefers to align tilted near the wall with the ring’s hydrogen atoms nearest to the surface, whereas no preferential orientation is observed in the center region of the pore. The dynamics of the IL decreased by an order of magnitude near the surface as compared to the ions in the center of the pore. Reductions in the amount if IL inside the pore can lead to the formation of small vacuum regions in the center of the pore. The dynamics of the ions close to the boundary with these vacuum regions are found to be very slow as compared to those observed in the bulk IL..