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J Am Chem Soc. 2011 Nov 30;133(47):19024-7. doi: 10.1021/ja203095k. Epub 2011 Nov 7.

Evolution of iridium-based molecular catalysts during water oxidation with ceric ammonium nitrate.

Author information

1
Department of Chemistry and Biochemistry, 5500 Campanile Drive, San Diego State University, San Diego, California 92182, USA. grotjahn@chemistry.sdsu.edu

Abstract

Organometallic iridium complexes have been reported as water oxidation catalysts (WOCs) in the presence of ceric ammonium nitrate (CAN). One challenge for all WOCs regardless of the metal used is stability. Here we provide evidence for extensive modification of many Ir-based WOCs even after exposure to only 5 or 15 equiv of Ce(IV) (whereas typically 100-10000 equiv are employed during WOC testing). We also show formation of Ir-rich nanoparticles (likely IrO(x)) even in the first 20 min of reaction, associated with a Ce matrix. A combination of UV-vis and NMR spectroscopy, scanning transmission electron microscopy, and powder X-ray diffraction is used. Even simple IrCl(3) is an excellent catalyst. Our results point to the pitfalls of studying Ir WOCs using CAN.

PMID:
22059883
DOI:
10.1021/ja203095k
[Indexed for MEDLINE]

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