Durable Anion Exchange Membrane Water Electrolysis in Low-Alkaline Concentration Electrolyte

Area of Science:

• Electrochemistry
• Materials Science
• Green Chemistry

Background:

• Anion-exchange-membrane water electrolysis (AEMWE) is key for scalable green hydrogen production.
• High-alkalinity conditions in AEMWE cause membrane degradation, necessitating low-alkalinity operation for stability.
• Ruthenium (Ru) catalysts show promise for water dissociation in low-alkalinity electrolytes but suffer from high hydrogen coverage, limiting kinetics and durability.

Purpose of the Study:

• To develop a novel catalyst for stable and efficient AEMWE under low-alkalinity conditions.
• To overcome the kinetic limitations and durability issues associated with Ru catalysts at high current densities.
• To investigate the mechanism behind enhanced catalytic performance in AEMWE.

Main Methods:

• Synthesis of an iridium-ruthenium (Ir-Ru) solid solution catalyst.
• Electrochemical characterization of the catalyst in an AEMWE cell under low-alkalinity conditions (0.05 M KOH).
• In situ characterization techniques and isotope labeling studies to elucidate the catalytic mechanism.

Main Results:

• The Ir-Ru solid solution catalyst achieved a cell voltage of 1.75 V at 1 A cm⁻² in 0.05 M KOH.
• The AEMWE cell demonstrated exceptional durability exceeding 1000 hours of operation.
• Confirmed a hydrogen spillover mechanism where hydrogen atoms transfer from Ru to Ir sites, reducing coverage and improving kinetics and stability.

Conclusions:

• The Ir-Ru solid solution catalyst significantly enhances the activity and durability of low-alkalinity AEMWE.
• The hydrogen spillover mechanism is critical for improving performance at high current densities.
• This advancement offers a pathway for more stable and efficient green hydrogen production via AEMWE.