Role of Anodic Passive Potential on the Electrochemical Response of Pure Tantalum in 0.1 M H2SO4 Solution

In this work, the role of anodic passive potential on the passive and electrochemical response of pure Ta in 0.1 M H2SO4 solution was studied. Electrochemical impedance spectroscopy (EIS) plots showed that corrosion resistance of the passive film on the pure Ta increased with the increasing of anodic passive potential. In addition, the semiconductive behavior of the passive films formed on pure Ta in 0.1 M H2SO4 solution is evaluated by employing Mott–Schottky (M–S) analysis. Although, semiconducting response of pure Ta in 0.1 M H2SO4 solution remains the same as n-type, anodic passive potential significantly affect the levels of donor concentrations. Indeed, M–S analysis revealed that less donor densities in passive film due to higher anodic passive potential deteriorated corrosion resistance of the pure Ta. Also, M–S analysis revealed that flat band potential is quite sensitive to anodic passive potential.