A Complex Oxide Containing Inherent Peroxide Ions for Catalyzing Oxygen Evolution Reactions in Acid

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Proton exchange membrane water electrolyzers are key for renewable hydrogen, but slow oxygen evolution reaction (OER) kinetics hinder efficiency.
• Developing effective electrocatalysts is crucial for advancing OER and improving electrolyzer performance.

Purpose of the Study:

• To design and characterize a novel, low-iridium catalyst for enhanced OER activity under acidic conditions.
• To understand the mechanism behind the catalyst's high performance for future electrocatalyst design.

Main Methods:

• Synthesis and structural characterization of the complex oxide La_1.2Sr_2.7IrO_7.33.
• Electrochemical evaluation of OER activity and stability.
• Spectroscopic analysis and density functional theory (DFT) calculations to elucidate the reaction mechanism.

Main Results:

• La_1.2Sr_2.7IrO_7.33 exhibits exceptional OER activity and stability in acidic media.
• The catalyst demonstrates an order of magnitude higher mass activity and 6-fold higher intrinsic activity compared to benchmark IrO₂, using significantly less iridium.
• Investigations revealed a peroxide-ion participation mechanism, driven by accessible nonbonded oxygen states in the peroxide ions.

Conclusions:

• La_1.2Sr_2.7IrO_7.33 represents a highly active and stable OER electrocatalyst, outperforming state-of-the-art Ir-based oxides.
• The unique hexagonal structure and peroxide-ion mechanism offer a new strategy for designing advanced catalysts.
• This work paves the way for more efficient and cost-effective renewable hydrogen production.