Regulating lattice oxygen participation through Ta-enabled high-entropy engineering for durable acidic oxygen...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Developing efficient catalysts for the oxygen evolution reaction (OER) is critical for proton exchange membrane water electrolyzers (PEMWEs) used in sustainable hydrogen production.
• A key challenge is the activity-stability trade-off, particularly in acidic conditions, hindering the use of lattice oxygen activation.

Purpose of the Study:

• To design and synthesize a robust catalyst overcoming the activity-stability trade-off in acidic OER.
• To investigate the role of tantalum (Ta) in regulating electronic properties and local coordination for enhanced catalyst performance and durability.

Main Methods:

• Synthesis of a RuMnCoNiTa-O high-entropy oxide catalyst.
• Electrochemical characterization including overpotential measurements at 10 mA cm^-2 and durability tests (>500 h).
• Operando spectroscopic studies and ruthenium dissolution analysis.

Main Results:

• The optimized RuMnCoNiTa-O catalyst achieved a low overpotential of 196 mV at 10 mA cm^-2 and demonstrated durability exceeding 500 hours under acidic OER conditions.
• The Ta-mediated high-entropy structure enhanced lattice oxygen participation while suppressing structural degradation and Ru dissolution.
• The catalyst showed stable operation for over 280 hours at 200 mA cm^-2 as an anode catalyst in a membrane electrode assembly (MEA).

Conclusions:

• The developed high-entropy oxide catalyst effectively decouples lattice oxygen activation from catalyst instability.
• This provides a viable strategy for advancing OER catalysis and enabling efficient, durable hydrogen production via PEMWEs.