Double Perovskites as Model Bifunctional Catalysts toward Rational Design: The Correlation between Electrocatalytic...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Double perovskites are promising electrocatalysts.
• Oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are crucial for energy conversion.

Purpose of the Study:

• Investigate OER and ORR properties of La₂CoMnO₆-δ and La₂NiMnO₆-δ.
• Correlate electrocatalytic activity with e<0xE2><0x82><0x9Eg> orbital occupation.
• Propose a new descriptor for perovskite catalyst design.

Main Methods:

• Electrochemical characterization of La₂CoMnO₆-δ and La₂NiMnO₆-δ.
• Analysis of e<0xE2><0x82><0x9Eg> orbital occupation numbers.
• Validation of the e<0xE2><0x82><0x9Eg>-filling rule.

Main Results:

• Both La₂CoMnO₆-δ and La₂NiMnO₆-δ exhibit efficient OER and ORR.
• La₂CoMnO₆ annealed at 600 °C shows a low ORR half-wave potential of 0.75 V.
• The e<0xE2><0x82><0x9Eg>-filling rule is valid for La₂CoMnO₆-δ but needs amendment for La₂NiMnO₆-δ.

Conclusions:

• The e<0xE2><0x82><0x9Eg>-filling rule requires considering all transition metal ions.
• Average deviation from unity e<0xE2><0x82><0x9Eg> occupation is a suitable descriptor for perovskite catalysts.
• This descriptor can guide the design of novel perovskite electrocatalysts.