Acid-Stable Ruthenium-Based Solid Solution for Oxygen Evolution in Proton Exchange Membrane Electrolyzers.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Proton exchange membrane (PEM) water electrolysis is key for green hydrogen.
• Developing efficient and durable oxygen evolution reaction (OER) catalysts in acidic media, especially non-iridium alternatives, is a significant challenge.
• Metal-organic frameworks (MOFs) offer tunable structures for catalyst design.

Purpose of the Study:

• To synthesize a novel MOF-derived multi-metal oxide solid solution catalyst for acidic OER.
• To investigate the catalytic performance, durability, and reaction mechanism of the developed catalyst.
• To evaluate the catalyst's potential in a PEM electrolyzer for cost-effective hydrogen production.

Main Methods:

• Template-guided synthesis of MOF-derived RuZrCoCrCeO2 solid solution.
• Electrochemical characterization of OER activity and durability in acidic media.
• Operando analysis to elucidate the reaction mechanism.
• Fabrication and testing of a PEM electrolyzer cell with the developed catalyst.

Main Results:

• The RuZrCoCrCeO2 catalyst exhibited excellent OER performance with a low overpotential (179 mV at 10 mA cm⁻²).
• Exceptional durability was demonstrated (>1500 h at 50 mA cm⁻² with negligible decay).
• A PEM electrolyzer using this catalyst achieved 1 A cm⁻² at 1.66 V with low hydrogen cost ($0.89 kg⁻¹).

Conclusions:

• The MOF-derived catalyst shows significant potential as an efficient and durable non-Ir OER catalyst for PEM water electrolysis.
• The proposed vicinal deprotonation mechanism and electronic buffer effect contribute to the catalyst's superior performance.
• This work paves the way for scalable and cost-effective green hydrogen production using iridium-free electrolyzers.