Accessing Molecular Dimeric Ir Water Oxidation Catalysts from Coordination Precursors

Area of Science:

• Inorganic Chemistry
• Catalysis Science
• Materials Science

Background:

• Developing molecular precatalysts for iridium-based water oxidation is crucial for understanding active species.
• Previous studies identified μ-oxo-bridged iridium dimers as resting states, but active species structures remained elusive.
• Ligand degradation during activation complicates catalysis and affects reaction outcomes.

Purpose of the Study:

• To synthesize and evaluate a dinuclear iridium species as a molecular precatalyst for water oxidation.
• To investigate a catalyst that bypasses the need for oxidative ligand removal.
• To gain insights into designing well-defined active species for efficient oxygen evolution.

Main Methods:

• Synthesized a mixture of dinuclear iridium species from a coordination precursor, Na[Ir(pyalk)Cl4].
• Assayed catalytic activity for oxygen evolution using sodium periodate (NaIO4) as the oxidant.
• Compared activity to previously reported organometallic precursors.

Main Results:

• The synthesized dinuclear iridium species demonstrated comparable oxygen-evolution activity to previous catalysts.
• This new catalyst operates effectively without requiring oxidative activation to remove sacrificial ligands.
• Unlike previous attempts, this approach avoids ligand degradation into acetic acid or other products.

Conclusions:

• A dinuclear iridium species derived from a coordination precursor shows promising catalytic activity for water oxidation.
• This precatalyst offers a pathway to well-defined active species without ligand degradation issues.
• Further research can leverage these findings to establish design principles for advanced iridium-based water oxidation catalysts.