Unveiling the Valence-Driven Charge Compensation Mechanism to Direct Phase Engineering in Ru-Based Catalysts for...

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Phase engineering is crucial for optimizing electrocatalyst performance, but principles of phase evolution are unclear.
• Balancing single-phase efficiency with mixed-phase synergy is key for advanced catalysts.

Purpose of the Study:

• Establish a valence-driven phase engineering paradigm for deterministic control over Ru-based catalysts.
• Understand the fundamental principles governing phase formation in electrocatalysts.

Main Methods:

• Investigated phase formation trajectories based on dopant valence states and charge compensation mechanisms.
• Engineered Ru-based catalysts with varying dopant valences (tetravalent, trivalent, divalent).
• Characterized catalyst performance in acidic media and integrated into a proton-exchange membrane water electrolysis (PEMWE) cell.

Main Results:

• Tetravalent dopants maintained single-phase RuO2; trivalent dopants induced synergistic RuO2-Ru hetero-phase structures; divalent dopants caused phase separation.
• The RuGa mixed-phase catalyst demonstrated an excellent overpotential (180 mV at 10 mA cm-2) and stability (500 h).
• The catalyst achieved 1 A cm-2 at 1.63 V in a PEMWE cell with 100 h stability at 500 mA cm-2.

Conclusions:

• Developed a valence-controlled phase regulation framework for designing durable acidic oxygen evolution reaction (OER) catalysts.
• Demonstrated the effectiveness of mixed-phase catalysts for enhanced electrochemical performance and stability.
• Provided fundamental insights into charge compensation mechanisms driving phase evolution in electrocatalysts.