Dynamic analysis of the extended space charge layer using chronopotentiometric measurements

Abstract

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.

Keywords

• Ion concentration polarization
• Chronopotentiometric measurement
• Extended space charge layer