Oxidized Overlayers of Ruthenium and Iridium as Electrocatalysts for Anodic Reactions

Area of Science:

• Electrochemistry
• Materials Science
• Renewable Energy

Background:

• Rutile tetravalent oxides (e.g., ruthenium(IV) oxide, iridium(IV) oxide) are crucial catalysts for anodic reactions in renewable energy.
• Developing efficient and stable electrocatalysts is essential for advancing fuel formation technologies.

Purpose of the Study:

• To synthesize and characterize angstrom-scale and nanoscale oxidized overlayers of ruthenium (o-RuO₂) and iridium (o-IrO₂).
• To evaluate the catalytic activity of these novel overlayers for key anodic reactions.

Main Methods:

• Synthesis of oxidized overlayers from aqueous precursors on various supports.
• Characterization using cyclic voltammetry, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS).
• Electrocatalytic performance testing for oxygen evolution reaction (OER) and chlorine evolution reaction.

Main Results:

• The synthesized o-RuO₂ and o-IrO₂ overlayers exhibited distinct redox features and chemical states.
• Annealed o-RuO₂ on TiO₂ (a-TiO₂/o-RuO₂) demonstrated significantly reduced overpotentials for OER in acid and base, and chlorine evolution.
• A substantial increase in mass activity was observed for a-TiO₂/o-RuO₂ compared to traditional RuO₂.

Conclusions:

• Oxidized overlayers of ruthenium and iridium possess unique chemistry beneficial for electrocatalysis.
• These advanced materials show great promise for enhancing the efficiency of renewable energy technologies.
• The findings pave the way for developing next-generation electrocatalysts meeting demanding operational requirements.