Oxyanion Engineering on RuO₂ for Efficient Proton Exchange Membrane Water Electrolysis

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Acidic proton exchange membrane water electrolysis (PEMWE) requires efficient and stable anode oxygen evolution reaction (OER) catalysts.
• Iridium-based catalysts are effective but expensive and scarce.
• Ruthenium dioxide (RuO2) offers lower cost and higher activity but suffers from poor stability in acidic media.

Purpose of the Study:

• To develop a stable and active RuO2-based catalyst for acidic OER.
• To enhance the durability of RuO2 catalysts through anion modification.
• To investigate the mechanism behind improved catalyst stability and activity.

Main Methods:

• Anion modification strategy using sulfate anchoring on RuO2/MoO3.
• Electrochemical characterization including overpotential measurements at 10 mA cm⁻².
• Long-term stability testing in acidic electrolyte and within a PEMWE cell.
• Experimental and theoretical analyses to elucidate the stabilization mechanism.

Main Results:

• The sulfate-anchored RuO2/MoO3 catalyst achieved a low overpotential of 190 mV at 10 mA cm⁻².
• Exceptional stability was demonstrated, operating for 500 hours with a degradation rate of 20 μV h⁻¹ in acidic electrolyte.
• The catalyst exhibited excellent durability in a PEMWE cell, operating at 500 mA cm⁻² for 150 hours.
• MoO3 stabilized sulfate anions on the RuO2 surface, suppressing leaching and reducing intermediate formation energy.

Conclusions:

• Anion modification with sulfate anchored on RuO2/MoO3 effectively enhances OER activity and stability in acidic media.
• The MoO3-sulfate interaction stabilizes RuO2, preventing surface and lattice oxygen loss, leading to superior durability.
• This approach offers a promising alternative to iridium-based catalysts for efficient and long-lasting PEMWE systems.