Interpretation of the Electrochemical Impedance under Diffusion and Charge Transfer Controls

Abstract

The electrochemical impedance for infinite and finite diffusion processes was described, and the locus of the impedance was discussed through comparison of the experimental results with the theoretical ones. The charge transfer resistance R_ct and the polarization resistance R_p were compared with the current i and the slope of the polarization curve for the reduction of K₃Fe(CN)₆. The physical meanings of R_ct and R_p in the diffusion impedance were discussed. It was confirmed that R_ct^-1 was related to the reaction rate. The theory to apply the diffusion impedance to the analysis of corrosion reaction was revealed.