Unifying theoretical framework for deciphering the oxygen reduction reaction on platinum.

Area of Science:

• Electrochemistry
• Materials Science
• Surface Chemistry

Background:

• The oxygen reduction reaction (ORR) is critical for polymer electrolyte fuel cells.
• Oxygen intermediates in ORR have dual roles: vital intermediates and site-blockers.
• Understanding these roles is key for catalyst development and predictive modeling.

Purpose of the Study:

• To present a theoretical framework for surface phenomena in ORR.
• To incorporate double-layer effects into the ORR model.
• To link oxygen intermediate behavior to catalyst activity and electrode performance.

Main Methods:

• Developed a theoretical framework incorporating double-layer effects.
• Analyzed the roles of oxygen intermediates in the ORR mechanism.
• Formulated Tafel slope and exchange current density as functions of electrode potential.

Main Results:

• The framework elucidates the dual roles of oxygen intermediates.
• Tafel slope and exchange current density are continuous functions of electrode potential.
• Introduced the concept of a 'rate determining term' for multielectron reactions.

Conclusions:

• The new framework provides a deeper understanding of ORR mechanisms.
• It offers a new perspective on catalyst activity and the volcano relation in ORR.
• This work aids in developing advanced catalysts and predictive models for electrochemical devices.