Oxygen Reduction on Ag(100) in Alkaline Solutions--A Theoretical Study

Area of Science:

• Surface Science
• Electrochemistry
• Computational Materials Science

Background:

• Silver is significantly more reactive towards oxygen than gold.
• Despite reactivity differences, oxygen reduction rates on silver and gold are comparable in alkaline solutions.
• Understanding the initial step of oxygen reduction is crucial for catalysis.

Purpose of the Study:

• To elucidate the rate-determining step of oxygen reduction on Ag(100) in alkaline media.
• To explain the similar oxygen reduction rates observed on silver and gold.
• To validate theoretical predictions with experimental data.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Molecular Dynamics (MD) simulations.
• Electrocatalysis theory.

Main Results:

• Oxygen adsorption on Ag(100) is energetically unfavorable in an electrochemical environment due to hydration energy loss.
• The first electron transfer in oxygen reduction on Ag(100) proceeds via an outer-sphere mechanism.
• Previous predictions for Au(100) were confirmed using an advanced electrocatalysis theory.

Conclusions:

• The outer-sphere electron transfer mechanism explains the similar rates of oxygen reduction on Ag(100) and Au(100) in alkaline solutions.
• Theoretical findings align well with experimental observations.
• This study provides a fundamental understanding of oxygen reduction mechanisms on coinage metals.