Laplace-Pressure-Stabilized Rutile Solid-Solution Catalysts for Acidic Water Oxidation: Enabling DSA-Inspired...

Area of Science:

• Materials Science
• Inorganic Chemistry
• Electrochemistry

Background:

• Early studies showed immiscibility in rutile-type IrO2-TiO2 and IrO2-SnO2 systems despite structural and ionic similarities.
• Thermodynamic challenges limit the formation of IrO2-based solid solutions, particularly with oxides of different structures.

Purpose of the Study:

• To investigate the effect of crystal size on the miscibility of IrO2-based systems.
• To explore the synthesis and properties of nanoscale solid solutions for catalytic applications.

Main Methods:

• Synthesis of rutile-type (Ir, M)O2 and (Sn, M)O2 solid solutions with varying crystal sizes (down to 10 nm).
• Characterization of solid solution formation using techniques sensitive to crystal size and composition.
• Electrochemical testing of synthesized nanocrystals for catalytic activity and durability in oxygen evolution reaction.

Main Results:

• Single-phase rutile solid solutions (Ir, M)O2 and (Sn, M)O2 containing up to 30 at.% M were formed at nanoscale (<10 nm).
• Submicron crystals showed immiscible behavior, confirming the critical role of crystal size.
• Complete solid solutions were achieved in the nanoscale IrO2-SnO2 system.
• Synthesized quaternary nanocrystals exhibited high corrosion resistance and catalytic activity, comparable to IrO2 despite lower Ir content.

Conclusions:

• High Laplace pressure in nanocrystals significantly enhances miscibility in IrO2-based systems, a general phenomenon.
• Nanoscale engineering of solid solutions offers a pathway to develop cost-effective and high-performance catalysts for acidic water electrolysis.