Strain-Triggered Distinct Oxygen Evolution Reaction Pathway in Two-Dimensional Metastable Phase IrO₂ via CeO₂ Loading

Area of Science:

• Materials Science
• Catalysis
• Nanotechnology

Background:

• Strain engineering is vital for high-performance catalysts, but controlling strain in nanoscale two-dimensional (2D) materials is difficult.
• Metastable phase 2D materials offer unique properties but require precise strain control for optimal function.

Purpose of the Study:

• To investigate cerium dioxide (CeO2) as a loading material for tuning in-plane strain in 2D metastable 1T-phase iridium dioxide (1T-IrO2).
• To explore the impact of CeO2-induced strain on the catalytic activity and oxygen evolution mechanism of 1T-IrO2.

Main Methods:

• In situ growth method for loading CeO2 onto 1T-IrO2.
• Electrochemical measurements (three-electrode system and proton-exchange membrane device).
• Fourier transform infrared spectroscopy and density functional theory calculations.

Main Results:

• 5% CeO2 loading on 1T-IrO2 induced 8% compressive strain, achieving an overpotential of 194 mV at 10 mA cm-2.
• The strained catalyst demonstrated excellent stability, retaining 900 mA cm-2 at 1.8 V for 400 hours.
• CeO2-induced strain facilitated a direct *O-*O radical coupling mechanism for O2 generation, differing from the conventional adsorbate evolution mechanism.

Conclusions:

• CeO2 is an effective material for strain engineering of 2D metastable 1T-IrO2.
• Strain engineering via CeO2 loading significantly enhances catalytic performance and stability.
• The study reveals a novel *O-*O radical coupling mechanism driven by strain, offering new insights into catalytic pathways for oxygen evolution.