Interface potential drop in electroosmosis: An electrochemical perspective

Recent studies have increasingly highlighted the critical role of interfacial electrochemical reactions in electroosmotic processes. However, existing theoretical frameworks often fail to adequately capture the coupling between electrochemical reactions and electroosmosis, while experimental approaches struggle to directly characterize the evolving electrochemical behavior. In this study, Linear Sweep Voltammetry (LSV), an advanced technique capable of directly capturing electrochemical reaction characteristics, was employed to investigate the interfacial potential. From an electrochemical perspective, the interfacial potential was shown to comprise an equilibrium potential and multiple overpotentials, including activation, concentration, and Ohmic components. The results demonstrate that the equilibrium potential plays a decisive role in electroosmotic initiation. When the anodic potential remains below the equilibrium potential, no current is generated, demonstrating the absence of both electrochemical reactions and electroosmotic flow. As electroosmosis proceeds, the contribution of the anodic equilibrium potential increases progressively, accounting for 16%–23% of the total potential drop. Polarization curve analysis further confirms the coexistence of multiple overpotentials beyond the Ohmic component. Compared with a conventional electrolysis system, the electroosmotic system exhibits a substantially higher anodic potential drop, primarily attributed to enhanced concentration and activation overpotentials. Moreover, the evolution of polarization resistance closely follows the early-stage current response, providing additional evidence for the dominance of concentration overpotential. Building on the clarified composition of the anodic potential, this study validates the feasibility of using the anodic potential drop as a reliable indicator of electroosmotic drainage performance. A strong correlation with drainage rate is established, confirming its practical applicability as an engineering indicator. These findings provide new insights into the electrochemical mechanisms governing electroosmosis and offer a foundation for integrating electrochemical reaction dynamics into the optimization of electroosmotic systems.