Abstract
Electrochemical impedance spectroscopy (EIS) is a powerful technique that can detect and provide information about different phenomena that occur on the corroding surface using alternating current signals. Several electrochemical reactions and associated phenomena, such as mass transfer and chemical reactions happening at and near the metal surface, occur simultaneously. Therefore, the EIS data conducted at a specific DC potential often contain mixed information about several of those reactions, while at other potentials the EIS data are dominated by a single electrochemical reaction. To be able to focus on a single electrochemical reaction and its associated phenomena, it is important to identify the DC potential at which the EIS data provide the most relevant information about this reaction, otherwise, the analysis of the impedance data becomes very difficult. This work aims to show an example of how to select the DC potential range at which the hydrogen evolution reaction is dominant. Following this step, the EIS data can be used to determine the diffusion coefficient of hydrogen ion in a strong acid aqueous solution.