Electride-Stabilized Iridium Nanoparticles with Subsurface Oxygen Confinement for Oxygen Evolution Electrocatalysis

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Electrides possess unique electron-rich structures beneficial for catalysis.
• Challenges include instability and synthesis limitations in electrochemical applications.
• Titanium oxide electrides offer potential but require optimized synthesis and characterization.

Purpose of the Study:

• To develop a method for synthesizing phase-pure titanium oxide (Ti3O) electride nanoparticles.
• To investigate the performance of Ti3O as a support for iridium (Ir) nanocatalysts in the oxygen evolution reaction (OER).
• To explore the electronic structure engineering capabilities of electrides in electrocatalysis.

Main Methods:

• Kinetically controlled gas-solid reaction for Ti3O electride nanoparticle synthesis.
• Characterization of Ti3O electrical conductivity and electrochemical stability window.
• Electrocatalytic testing of Ir/Ti3O catalysts for OER in acidic media using three-electrode cells and proton exchange membrane water electrolyzers.

Main Results:

• Synthesized phase-pure Ti3O electride nanoparticles with high conductivity (617 S cm⁻¹) and a wide stability window (-0.4 to 2.1 V vs RHE).
• Ti3O support induced strong metal-support interactions, preventing Ir nanoparticle amorphization and coalescence during OER.
• Formation of subsurface oxygen-confined Ir nanoparticles, shifting the OER mechanism to adsorbate evolution mechanism (AEM) and enhancing activity and stability.

Conclusions:

• Ti3O electrides are effective supports for Ir nanocatalysts, significantly improving OER performance.
• The unique metal-support interactions and formation of novel active sites enable superior catalytic activity and stability.
• Electrides represent a promising class of materials for advanced electrocatalyst design and stabilization of unique catalytic phases.