Accelerated Deprotonation Triggered by Fluorinated RuO₂ Enables Efficient and Stable Acidic Water Electrolysis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Ruthenium-based catalysts are crucial for cost-effective proton exchange membrane water electrolyzers (PEMWEs).
• Harsh acidic conditions in oxygen evolution reactions (OER) cause ruthenium (Ru) overoxidation, reducing catalytic activity and stability.

Purpose of the Study:

• To investigate a fluoride ion (F⁻)-mediated mechanism in RuO₂ to enhance OER activity and stability.
• To develop a high-performance catalyst for acidic OER applications.

Main Methods:

• Synthesis of a modified ruthenium oxide catalyst (RuO₁.₈₆F₀.₁₄) incorporating fluoride ions.
• Electrochemical characterization of the catalyst's performance in acidic OER.
• Long-term stability testing of the catalyst under OER conditions and in PEMWEs.

Main Results:

• The optimized RuO₁.₈₆F₀.₁₄ catalyst exhibited an ultralow overpotential of 153 mV at 10 mA cm⁻².
• The catalyst demonstrated excellent stability, sustaining operation for over 980 h with a low degradation rate of 27 μV h⁻¹.
• In PEMWEs, RuO₁.₈₆F₀.₁₄ required only 1.63 V and operated stably for over 100 h at 1 A cm⁻².

Conclusions:

• A hydrogen-bond-mediated mechanism triggered by fluoride ions enhances acidic OER kinetics and catalyst stability.
• Fluoride incorporation stabilizes RuO₂ by diminishing Ru-O bond covalency.
• Anion modulation offers a promising strategy for designing high-performance acidic OER catalysts for water electrolysis.