The effects of hydrogen on anodic dissolution and passivation of iron in alkaline solutions

• Hydrogen shifts iron from passivity to active dissolution in bicarbonate solutions.
• Effects of hydrogen on various types of passivity and passive films.
• The primary effect of hydrogen distinguished from the clean-surface effect.
• Accelerated anodic reaction and multiple current peaks in hydrogen-charged iron.
• Enhanced anodic dissolution by hydrogen confirmed by ICP.

Effects of hydrogen on anodic dissolution and passivation of iron in alkaline solutions are investigated by electrochemical measurements on iron, hydrogen-charged iron and catholically pre-cleaned iron using a Devanathan dual cell. Shifting of open circuit state of iron in bicarbonate solutions from passivity to active dissolution and the appearance of active dissolution range for hydrogen-charged iron are primarily caused by the surface cleaning effect. Hydrogen hinders the transition from active dissolution to passivation. Inductive coupled plasma analyses of solutions confirm the enhancing effect of hydrogen on anodic dissolution. The effects of hydrogen and solution compositions on anodic reactions are analyzed.