When a solid surface is immersed in a liquid, various physical and chemical phenomena induce the creation of the electrical double layer (EDL), corresponding to a space charge distribution in the vicinity of the interface, both in the solid and the liquid parts. The literature on EDL mainly focuses on “ideal” interfaces, experimentally obtained with liquid metals (Hg) or noble metals (Pt, Au). On the contrary this study is dedicated to an “applied” surface, made of austenitic stainless steel (ASS) 304L, immersed in a low-concentrated (0.01 M) NaCl aqueous solution. Cyclic voltammetry (CV) measurements were performed to study the electrical behavior of the interface, and an electrical model enables the determination of several characteristics of the charge distribution in the 304L/passive film/electrolyte interface. The effective resistance Reff includes the resistance of the passive film and the charge transfer resistance. The effective capacitance Ceff corresponds to the space charge separation in the EDL and in the oxide film. The evolution of Reff and Ceff with the applied potential in the range [-0.6 V; 0.6 V] vs Ag/AgCl during the CV measurements was studied to determine the interval of stability of the interface, to avoid any faradic reaction as much as possible. It is demonstrated that the transfer resistance is kept very high in the interval [-0.1 V, 0.25 V] vs Ag/AgCl where the electrical behavior is mainly capacitive, with Ceff = 50 ± 5 μF.cm-2. Outside this potential range, the surface becomes modified and is likely to evolve during the CV measurement, leading to unreproducible characterization of the charge distribution in the solid/liquid interface.
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