Structure Engineering Enabled O-O Radical Coupling in Spinel Oxides for Enhanced Oxygen Evolution Reaction.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing cost-effective spinel oxide catalysts is vital for sustainable energy conversion.
• Limitations in oxygen evolution reaction (OER) activity and stability hinder practical applications.
• Current catalysts face challenges with adsorbate evolution mechanism (AEM) and lattice oxygen mechanism (LOM).

Purpose of the Study:

• To enhance OER activity and stability in spinel oxide catalysts.
• To investigate structural changes induced by phase transformation in Co1.5Mn1.5 spinel oxides.
• To explore a direct O-O radical coupling mechanism for improved catalysis.

Main Methods:

• Phase transformation of Co1.5Mn1.5 spinel oxides.
• Structural optimization to create active octahedral sites with shortened intersite distance.
• Electrochemical testing, including chronopotentiometry, to evaluate OER performance.

Main Results:

• Optimized CoMn-400 catalyst exhibits an overpotential of 268 mV at 10 mA cm-2, outperforming commercial RuO2 (310 mV).
• The catalyst maintained negligible activity loss over 300 hours of testing at 100 mA cm-2.
• Structure optimization favored a direct O-O radical coupling mechanism, preventing overoxidation.

Conclusions:

• Structural changes via phase transformation significantly enhance OER activity and stability.
• The direct O-O radical coupling mechanism offers a pathway to overcome limitations of AEM and LOM.
• This strategy provides fundamental insights for designing efficient transition metal oxide catalysts for electrochemical energy conversion.