Synergistic Fe/Co Doping and Vacancy Engineering for Stable RuO_x in Acidic OER

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Ruthenium dioxide (RuO2) is a key catalyst for the oxygen evolution reaction (OER) in proton-exchange membrane water electrolyzers (PEMWEs).
• Long-term stability of RuO2 is limited by ruthenium (Ru) dissolution under acidic electrochemical conditions.

Purpose of the Study:

• To enhance the stability and performance of RuO2-based catalysts.
• To investigate the combined effects of metal doping (Fe, Co) and oxygen vacancy engineering on RuO2 stability.

Main Methods:

• Synthesis of Fe-doped and Co-doped RuO2 (Fe-RuOx, Co-RuOx) catalysts.
• Electrochemical characterization of catalytic activity and stability in acidic electrolytes.
• Proton-exchange membrane water electrolyzer (PEMWE) testing.
• Density functional theory (DFT) simulations to elucidate reaction mechanisms.

Main Results:

• Fe-RuOx and Co-RuOx catalysts showed low overpotentials (191 mV and 203 mV at 10 mA cm-2) and sustained stability (>500 h) with negligible degradation.
• PEMWEs utilizing these doped catalysts operated stably for over 250 h at 100 mA cm-2.
• Doping decreased Ru valence and increased oxygen vacancies, enhancing catalytic activity and suppressing Ru dissolution.

Conclusions:

• Combined metal doping and oxygen vacancy engineering effectively improve the stability and performance of RuO2 catalysts for OER.
• Fe and Co doping weaken OOH* adsorption and increase surface reconstruction energy, leading to enhanced durability.
• This strategy offers valuable insights for designing advanced Ru-based catalysts for acidic water electrolysis.