Mesoporous Single-Crystalline Particles as Robust and Efficient Acidic Oxygen Evolution Catalysts.

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Iridium (Ir) scarcity hinders its use in acidic oxygen evolution reaction (OER).
• Conventional catalysts face challenges with stability and efficiency in acidic environments.
• Developing efficient and stable electrocatalysts is crucial for water electrolysis.

Purpose of the Study:

• To develop a mesoporous cobalt oxide (Co3O4) catalyst with atomically dispersed iridium for efficient and stable acidic oxygen evolution reaction (OER).
• To investigate the role of iridium doping in enhancing the structural stability and catalytic activity of Co3O4.
• To explore the potential of single-atom iridium on mesoporous Co3O4 for water electrolysis applications.

Main Methods:

• Synthesis of mesoporous single-crystalline spinel Co3O4.
• Atomic dispersion of low-valence-state iridium onto Co3O4.
• Surface Pourbaix diagram analysis to understand surface passivation and stability.
• Electrochemical testing for oxygen evolution reaction (OER) performance and stability.
• Leaching rate measurements for iridium and cobalt.

Main Results:

• Mesoporous Co3O4 with atomically dispersed Ir (13.8 wt%) was successfully synthesized.
• Ir doping enhanced the structural stability of Co3O4 under acidic OER conditions.
• The catalyst activated the O*-passivated Co3O4(111) surface via Co-Ir bridge sites, boosting intrinsic activity.
• Ir and Co leaching rates were significantly reduced (1/4 and 1/5, respectively) compared to conventional catalysts.
• The catalyst achieved a low overpotential (η10) of 248 mV for over 100 hours.

Conclusions:

• Atomically dispersed iridium on mesoporous Co3O4 is an effective strategy to overcome iridium scarcity for acidic OER.
• The developed catalyst demonstrates excellent activity, stability, and reduced metal leaching.
• This work shows significant potential for advanced electrocatalysts in water electrolysis.