| Summary: | The inhibitory effect of La3+ on the hydrogen permeation of X70 pipeline steel was investigated via steady-state hydrogen permeation current (i∞) through electrochemical hydrogen permeation tests. The experimental permeation data were fitted with a constant concentration model and Electrochemical Impedance Spectroscopy (EIS) tests were conducted to characterize the activity of Hydrogen Evolution Reaction (HER) after the optimization of electrochemically active surface area. Additionally, the kinetics of HER and the adsorption/desorption process is calculated by Iyer-Pickering-Zamanzadeh (IPZ) and surface effect models, of which the results demonstrate that the La3+ in the corrosion products could effectively reduce the rate of Volmer reaction and hydrogen adsorption process, and accelerate the process of hydrogen atom desorption, thus leading to the remarkable decrease in C0.
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