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Updated: Jun 7, 2026

Photochemical Oxidative Growth of Iridium Oxide Nanoparticles on CdSe@CdS Nanorods
Published on: February 11, 2016
Half-sandwich iridium complexes for homogeneous water-oxidation catalysis
James D Blakemore1, Nathan D Schley, David Balcells
1Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520, United States.
Iridium complexes efficiently catalyze water oxidation to dioxygen, a crucial step for artificial photosynthesis. Studies reveal the catalytic mechanism and distinguish active homogeneous catalysts from heterogeneous ones.
Area of Science:
- Inorganic Chemistry
- Catalysis
- Electrochemistry
Background:
- Homogeneous water oxidation is key for artificial photosynthesis and clean energy.
- Iridium complexes are promising catalysts but require mechanistic understanding.
Purpose of the Study:
- To investigate iridium half-sandwich complexes as precursors for homogeneous water oxidation.
- To elucidate the catalytic mechanism and identify the active species.
Main Methods:
- Kinetic studies using cerium(IV) ammonium nitrate as oxidant.
- Aqueous electrochemical studies at varying pH.
- H(2)(18)O isotope incorporation and kinetic-isotope-effect studies.
- Density Functional Theory (DFT) calculations.
Main Results:
- Iridium complexes demonstrate rapid and sustained oxygen evolution.
- High turnover frequencies were observed for specific iridium complexes.
- Catalytic activity was pH-dependent, with oxidation occurring at pH > 7.
- Water was confirmed as the source of oxygen atoms.
- A mechanism for iridium-catalyzed water oxidation was proposed, identifying the rate-determining step.
Conclusions:
- Iridium half-sandwich complexes are effective homogeneous catalysts for water oxidation.
- Mechanistic insights were gained through kinetic and computational studies.
- Distinguishing homogeneous from heterogeneous iridium catalysts is crucial for catalyst design.
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