Thermodynamic Descriptors to Predict Oxide Formation in Aqueous Solutions

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Thermodynamic stability is crucial for predicting aqueous surface scale formation and material corrosion.
• Existing methods may not fully capture the complexity of oxide formation on multielement alloys under varying environmental conditions.

Purpose of the Study:

• To formulate the maximum driving force (MDF) as a descriptor for thermodynamic stability in aqueous surface scale creation.
• To demonstrate the utility of MDF in analyzing corrosion trends and subsurface oxidation behavior.
• To enhance the understanding of oxide formation on complex alloys.

Main Methods:

• Utilizing free energies of formation (Δ_fG's) from high-throughput density functional theory (DFT) calculations and experimental databases.
• Computing the maximum driving force (MDF) for various oxides and hydroxides.
• Applying MDF to experimental linear sweep voltammetry data for nickel thin films.
• Incorporating depth-dependent effective chemical potentials to model subsurface oxidation.

Main Results:

• The MDF parameter effectively captures thermodynamic stability for aqueous surface scale formation across diverse conditions.
• MDF successfully describes trends in aqueous corrosion of nickel thin films.
• Subsurface oxidation behavior can be accounted for using depth-dependent effective chemical potentials.

Conclusions:

• The maximum driving force (MDF) parameter offers a robust method for assessing thermodynamic stability in aqueous environments.
• This approach provides insights into corrosion mechanisms and oxide phase competition in complex alloys.
• The MDF descriptor is anticipated to advance the understanding of oxide formation in materials science and electrochemistry.