First-principles study on the atomistic corrosion processes of iron

Area of Science:

• Materials Science
• Electrochemistry
• Surface Science

Background:

• Iron corrosion is a significant economic and scientific issue.
• Understanding the initiation sites and mechanisms of iron corrosion is crucial.
• Iron corrosion is an electrochemical process linked to oxygen reduction reactions.

Purpose of the Study:

• To investigate the initial stages of iron corrosion.
• To understand the role of surface defects in iron corrosion.
• To elucidate the reaction pathways from first-principles.

Main Methods:

• Utilized density functional theory (DFT) for first-principles calculations.
• Modeled iron corrosion initiation on Fe(100) surfaces with protruding Fe dimers.
• Analyzed reaction pathways and activation energies for intermediate species.

Main Results:

• Fe dimers on Fe(100) surfaces spontaneously react with O2 and H2O, forming Fe2(OH)4 + 4OH-.
• Fe dimers act as catalysts for water splitting, facilitating oxygen molecule reactions.
• Subsequent reactions lead to the formation of Fe2O(OH)4, Fe2(OH)6 complexes, and finally Fe2O3·2H2O with calculated activation energies.

Conclusions:

• Surface defects, specifically Fe dimers, play a critical role in initiating iron corrosion.
• The study provides a detailed, atomistic understanding of iron corrosion pathways induced by water and oxygen.
• Findings offer insights into preventing iron corrosion in atmospheric conditions.