An electrochemical method for characterizing the structure of double-layer capacity

Purpose The relation between metal corrosion behavior and double-layer capacity remains unclear. This study aims to put forward a novel method to measure double-layer capacity. Design/methodology/approach A novel model based on generalized Frumkin–Butler–Volmer equation was put forward. Combining this model with potentiodynamic polarization test and electrochemical impedance spectroscopy, the structure of double-layer capacity can be characterized. Findings This study found that the corrosion rate of iron increased with NaCl solution concentration and temperature at the experimental range, but an essential difference existed. The capacity of the diffuse layer and Stern layer increased with temperature and decreased with NaCl solution concentration. The ratio of diffuse layer capacity and Stern layer capacity influences the corrosion rate directly, which can be regarded as one of the judging criteria for corrosion resistance of metal materials. Originality/value The convenient means of double-layer structure characterization is still blank. With this method, the corrosion behavior of metal materials can be further analyzed, especially in high-temperature and pressure environments.