Differentiating Oxygen Exchange Reaction Mechanisms across Phase Boundaries

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Controlling anion stoichiometry in functional oxides can tune electrocatalytic activity via phase transitions.
• Understanding reaction mechanisms across different phases requires accurate phase boundary mapping during electrochemical reactions, which is challenging.

Purpose of the Study:

• To establish a feasible electrochemical method for resolving critical stoichiometry at phase boundaries under operando conditions.
• To demonstrate the utility of chemical capacitance measurements for probing phase transitions and differentiating reaction mechanisms.

Main Methods:

• Utilized chemical capacitance measurements to detect phase transitions in a model system.
• Applied an electrochemical method to map phase boundaries under operando conditions.
• Investigated the PrOx system as a proof-of-principle for high-temperature oxygen incorporation and evolution reactions (OIR/OER).

Main Results:

• Successfully demonstrated that chemical capacitance can sensitively probe phase transitions in PrOx.
• Quantified critical stoichiometry at phase boundaries using the developed electrochemical method.
• Differentiated OIR/OER mechanisms across the PrOx phase boundary by analyzing chemical capacitance changes.

Conclusions:

• The study provides a new framework for exploring phase engineering in electrocatalyst design.
• The developed electrochemical method offers a reliable approach for mapping phase boundaries and understanding reaction mechanisms.
• Chemical capacitance is a powerful tool for characterizing functional oxides and optimizing their electrocatalytic performance.