Chronoamperometric response at nanoscale liquid–liquid interface arrays

In this work, potential step chronoamperometry (PSCA) was used to study the behaviour of arrays of nanoscale interfaces between two immiscible electrolyte solutions (nanoITIES). The nanoITIES arrays were formed at nanoporous silicon nitride membranes containing 400 nanopores in a hexagonal close-packed arrangement. Three membrane designs, with nanopore radii of 75, 50 and 17 nm, were studied by ion-transfer of tetrapropylammonium cations across the nanopore array-supported water|1,6-dichlorohexane interface. The cell time constants and charging times were determined prior to experimental PSCA. The three membrane designs studied exhibited charging times in the range of 0.08–0.46 s, with the smallest pore configuration (17 nm radius) exhibiting the longest charging time. The experimental steady-state currents were 30–50% lower than of the calculated inlaid disc model currents, due to diffusion zone overlap at adjacent interfaces. The three nano-interface arrays studied also showed response times of 6 ± 1 s, being the time required to reach 95% of the steady-state current.

► Nano liquid–liquid interface arrays studied by potential step chronoamperometry.
► RC time constant and charging times are large.
► Time to reach steady-state current following potential step is ca. 6 s.
► Steady-state currents are ca. 30–50% of those predicted for inlaid nano-interfaces.