Dynamic analysis of the extended space charge layer using chronopotentiometric measurements

Abstract

In this paper, we experimentally verified the length (L ESC) and the concentration (c ESC) of the extended space charge (ESC) layer in front of the electrical double layer (EDL) using the chronopotentiometric measurement and the equivalent circuit model analysis. From the experimentation, the coupled-response of the EDL and the ESC layer was discriminated from the contribution of electro-osmotic flow (EOF). In addition, we derived the potential differences across the ESC (V ESC) layer using the circuit model of the ICP layer under rigorous consideration of ESC and EDL. As a result, we obtained that V ESC was linearly proportional to the square of the applied current (i applied). Hence, L ESC and c ESC were quantitatively provided, where L ESC is linear to the i applied and c ESC is constant regardless of i applied. Thus, this experimentation could not only clarify an essential ICP theory but also guide in ESC-based applications.