Atomic Iridium Incorporated in Cobalt Hydroxide for Efficient Oxygen Evolution Catalysis in Neutral Electrolyte

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Highly efficient catalysts for oxygen evolution reaction (OER) in neutral media are critical for advancing microbial electrolysis cells and electrochemical CO2 reduction.
• Current catalysts often struggle to meet the demands for efficiency and stability in neutral aqueous environments.

Purpose of the Study:

• To develop a facile one-step synthesis for a novel iridium (Ir) incorporated cobalt-based hydroxide nanosheet catalyst (CoIr) for efficient OER in neutral media.
• To elucidate the structural features and catalytic mechanisms responsible for the superior OER performance.

Main Methods:

• Facile one-step synthesis of cobalt-based hydroxide nanosheets incorporating iridium species.
• Advanced characterization using synchrotron radiation-based X-ray spectroscopy and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM).
• Electrochemical testing in 1.0 m phosphate buffer solution to evaluate OER performance.

Main Results:

• The synthesized CoIr catalyst, with 9.7 wt% Ir, demonstrated highly efficient OER activity, requiring an overpotential of 373 mV to reach 10 mA cm⁻².
• The optimized CoIr catalyst significantly outperformed commercial IrO2 catalysts in neutral media.
• Post-OER characterization revealed the formation of unique cobalt oxyhydroxide and high-valence iridium species with low-coordination structures, contributing to the enhanced performance.

Conclusions:

• The developed CoIr catalyst represents a state-of-the-art material for OER in neutral media.
• The study successfully identified the structural origins of the catalyst's superior performance, linking it to the synergistic effects between cobalt and iridium species.
• This work provides valuable insights for designing advanced electrocatalysts for energy conversion applications.