| 초록 |
In this study, we present the unique role of co-guest when it is additionally included in an ionic clathrate hydrate. First, the ionic conductivities of xTHF(n-Pr)4NOH32H2O hydrates at various co-guest THF concentrations (x = 2, 1, 0.5, 0.25, 0.13, 0) were measured in a temperature range from -40 to -10 ℃ and at ambient pressure. The double 2THF(n-Pr)4NOH32H2O hydrate (σ = 1.06×10-3 Scm-1) exhibits ionic conductivity two orders of magnitude higher than that of THF-free (n-Pr)4NOH32H2O hydrate (σ = 6.01×10-6 Scm-1) at -30 ℃. This considerably different ionic conductivity behavior strongly implies that the inclusion of co-guest THF induces a structural transformation via host-water lattice distortion, providing such high conductivity values for the double (THF + (n-Pr)4NOH) hydrate. We found a maximum conductivity of 0.0184 Scm-1 at 1.49 THF mol% and -10 ℃. The present results provide strong evidence that THF serves as a promoter for greatly enhancing the ionic conductivity in ionic clathrate hydrates. The structure-II host lattices formed by THF inclusion can provide an effective pathway for moving the charge carriers. |
