Oxygen-Vacancy-Mediated Dynamic Bidirectional Oxygen Migration for Enhanced Acidic Oxygen Evolution Reaction.

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Proton exchange membrane water electrolysis (PEMWE) requires catalysts with low iridium (Ir) loading and high stability.
• Developing efficient oxygen evolution reaction (OER) electrocatalysts is crucial for PEMWE technology.

Purpose of the Study:

• To synthesize a novel Ir-based catalyst (IrO_x@E-TiO_x) for enhanced PEMWE performance.
• To investigate the role of oxygen vacancies in catalyst activity and stability.
• To demonstrate long-term operational stability with reduced Ir loading.

Main Methods:

• One-step synthesis of IrO_x@E-TiO_x catalyst using an expanded Ti₃C₂T_x MXene template.
• Electrochemical characterization including OER activity and stability testing in PEMWE.
• In situ Raman spectroscopy and theoretical modeling to study interfacial dynamics and oxygen vacancy mediation.

Main Results:

• Achieved high specific mass activity (2630 ± 185 A g_Ir^-1 at 1.60 V) with low Ir loading (32.5 wt %).
• Demonstrated stable PEMWE operation exceeding 500 h at 0.33 mg_Ir cm^-2 with negligible decay.
• Identified in situ formation of oxygen vacancy-rich TiO_x promoting reversible oxygen migration and fine-tuning adsorption-desorption energetics.

Conclusions:

• The IrO_x@E-TiO_x catalyst offers a viable strategy for low-Ir, high-performance OER catalysts.
• Oxygen vacancies play a critical role in enhancing OER activity and stability in acidic media.
• The developed catalyst shows significant potential for practical PEMWE applications.