Deciphering potential-dependent oxygen reduction kinetics in spinel manganese ferrite.
Junxiang Wang1, Zhaoyi Jiang1, Jingwen Wei1
1China-UK Low Carbon College, Shanghai Jiao Tong University, Shanghai 200240, China. yezhou_lcc@sjtu.edu.cn.
Physical Chemistry Chemical Physics : PCCP
|September 4, 2025
Summary
The oxygen reduction reaction (ORR) activity of spinel manganese ferrite (MnFe2O4) depends on the applied potential window. Optimizing this window is crucial for accurately evaluating transition metal oxide catalysts.
Area of Science:
- Electrochemistry
- Materials Science
- Catalysis
Background:
- Accurate evaluation of oxygen reduction reaction (ORR) catalysts is essential for energy technologies.
- Transition metal oxides are promising ORR catalysts but require precise testing conditions.
- Spinel manganese ferrite (MnFe2O4) is a potential candidate for ORR catalysis.
Purpose of the Study:
- To investigate the influence of the potential window on the ORR activity of spinel manganese ferrite (MnFe2O4).
- To elucidate the underlying mechanisms responsible for the observed potential-window-dependent ORR behavior.
- To provide guidelines for the accurate assessment of transition metal oxide ORR catalysts.
Main Methods:
- Electrochemical testing of MnFe2O4 under varying cathodic potential scan limits.
- Surface characterization techniques to analyze catalyst composition and oxidation states.
- Joint density-functional theory (JDFT) calculations to model reaction pathways and energetics.
Main Results:
- A volcano-shaped dependence of ORR activity on the lower potential limit was observed.
- Changes in surface Mn site density and oxidation state were identified as key factors.
- Irreversible iron segregation and potential-dependent reaction free energies contribute to the activity variations.
- The sweeping potential window significantly impacts measured ORR performance.
Conclusions:
- The ORR performance of MnFe2O4 is highly sensitive to the applied electrochemical potential window.
- Understanding and controlling the potential window is critical for reliable catalyst evaluation.
- This work emphasizes the need for optimized testing protocols for transition metal oxide ORR catalysts.
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