Highly active and robust Cp* iridium complexes for catalytic water oxidation

Area of Science:

• Inorganic Chemistry
• Catalysis
• Electrochemistry

Background:

• Water oxidation is a critical process for energy conversion.
• Developing efficient catalysts for water oxidation remains a significant challenge.
• Cerium(IV) offers a promising oxidant for water oxidation studies.

Purpose of the Study:

• To investigate the catalytic activity of Cp*Ir complexes for water oxidation.
• To identify the active species involved in the catalytic cycle.
• To explore the mechanistic pathway using computational methods.

Main Methods:

• Synthesis and characterization of Cp*Ir catalysts.
• Electrochemical measurements to assess catalytic activity.
• Density Functional Theory (DFT) calculations to model reaction mechanisms.

Main Results:

• Cp*Ir catalysts exhibit unprecedented activity for water oxidation with Ce(IV), exceeding known catalysts by over an order of magnitude.
• DFT calculations indicate that a Cp*Ir=O complex is the active intermediate.
• The proposed mechanism involves a high-valent iridium-oxo species.

Conclusions:

• Cp*Ir complexes represent a new class of highly efficient water oxidation catalysts.
• The active species is likely a high-valent iridium-oxo complex.
• This work provides fundamental insights into the mechanism of iridium-catalyzed water oxidation.