Résumé
Investigating ions and water transport through single-walled carbon nanotube (SWCNTs) is of special interest thanks to the unique properties of this nano-object: perfect tubular structure, high aspect-ratio and low friction walls in addition to other remarkable mechanical, electronic and optical properties. However, creating and studying SWCNT-based nanofluidic systems free of defects, plugs or leaks and re-usable remain extremely challenging [1]. Here, we will present experimental data and theoretical analyses of ionic currents measured on nanofluidic devices containing one or several µ-m long SWCNTs, with diameters between 1.2 to 2 nm, separating two reservoirs filled with various alkali chloride aqueous electrolytes [1]. First, we will compare our data to various values of ionic conductivity reported in the literature on similar CNT nanofluidic systems and we will emphasize that electrical charge and low friction effects at the wall of the nanotube must be coupled to account for the observed behavior and level of ionic conductivity [2]. Second, we will show that the non-ohmic behavior observed in some cases could arise from local energy barriers along or at the ends of the nanotube, in particular from the presence of carboxyl groups grafted at the tube ends. Last, special focus will be proposed on the origin of the surface electrical potential which plays a critical role on ionic selectivity.