Atomically dispersed hexavalent iridium oxide from MnO₂ reduction for oxygen evolution catalysis.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Iridium oxides are crucial for oxygen evolution reaction (OER) in acidic media.
• Hexavalent iridium (Ir^VI) oxide shows theoretical promise for enhanced OER activity and stability.
• Experimental synthesis of Ir^VI oxide remains a significant challenge.

Purpose of the Study:

• To synthesize and characterize atomically dispersed Ir^VI oxide (Ir^VI-ado).
• To evaluate the performance of Ir^VI-ado as an anode material in proton exchange membrane (PEM) water electrolysis.
• To investigate the stability and durability of Ir^VI-ado under operational conditions.

Main Methods:

• Synthesis of Ir^VI-ado via oxidative ligand substitution of potassium hexachloroiridate(IV) with manganese oxide.
• Characterization using advanced spectroscopic and microscopic techniques.
• Electrochemical testing in a PEM water electrolyzer setup with in situ X-ray analysis.

Main Results:

• Achieved a mass-specific activity of 1.7 × 10⁵ A/g Ir, significantly higher than benchmark iridium oxides.
• Demonstrated a high turnover number of 1.5 × 10⁸.
• Confirmed the durability of Ir^VI-ado at current densities up to 2.3 A/cm² via in situ X-ray analysis during PEM operation.

Conclusions:

• Atomically dispersed Ir^VI oxide (Ir^VI-ado) has been successfully synthesized and characterized.
• Ir^VI-ado exhibits exceptional activity and stability for the oxygen evolution reaction in PEM water electrolysis.
• This material holds significant promise as a next-generation anode for efficient and durable water splitting.