Exceptional oxygen evolution reactivities on CaCoO₃ and SrCoO₃

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• The oxygen evolution reaction (OER) is crucial for energy conversion technologies.
• Transition metal oxides are promising OER electrocatalysts.
• Understanding structure-activity relationships is key to designing efficient catalysts.

Purpose of the Study:

• To investigate the influence of covalent bonding, surface oxygen separation, and electrolyte pH on OER.
• To compare the catalytic performance of CaCoO3 and SrCoO3 for OER.
• To elucidate the surface reaction mechanisms governing OER activity.

Main Methods:

• Comparative study of CaCoO3 and SrCoO3 perovskites.
• Analysis of catalytic onset potentials and OER activity.
• Investigation of surface reaction pathways.

Main Results:

• Both CaCoO3 and SrCoO3 are cubic, metallic perovskites with similar Co(IV) intermediate spin states and onset potentials.
• CaCoO3 exhibits a smaller lattice parameter and shorter surface oxygen separation.
• CaCoO3 demonstrates increased OER stability and activity compared to SrCoO3.

Conclusions:

• Surface oxygen separation significantly impacts OER activity.
• A smaller surface oxygen separation favors a faster OER pathway involving peroxide formation and oxygen vacancy attack.
• CaCoO3 is a more stable and active OER catalyst due to its optimized surface structure.