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Issue 3, 2015
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Catalysis of water oxidation in acetonitrile by iridium oxide nanoparticles

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Abstract

Water oxidation catalysed by iridium oxide nanoparticles (IrO2 NPs) in water–acetonitrile mixtures using [RuIII(bpy)3]3+ as oxidant was studied as a function of the water content, the acidity of the reaction media and the catalyst concentration. It was observed that under acidic conditions (HClO4) and at high water contents (80% (v/v)) the reaction is slow, but its rate increases as the water content decreases, reaching a maximum at approximately equimolar proportions (≈25% H2O (v/v)). The results can be rationalized based on the structure of water in water–acetonitrile mixtures. At high water fractions, water is present in highly hydrogen-bonded arrangements and is less reactive. As the water content decreases, water clustering gives rise to the formation of water-rich micro-domains, and the number of bonded water molecules decreases monotonically. The results presented herein indicate that non-bonded water present in the water micro-domains is considerably more reactive towards oxygen production. Finally, long term electrolysis of water–acetonitrile mixtures containing [RuII(bpy)3]2+ and IrO2 NPs in solution show that the amount of oxygen produced is constant with time demonstrating that the redox mediator is stable under these experimental conditions.

Graphical abstract: Catalysis of water oxidation in acetonitrile by iridium oxide nanoparticles

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Supplementary files

Article information


Submitted
23 Jul 2014
Accepted
21 Oct 2014
First published
27 Oct 2014

This article is Open Access
All publication charges for this article have been paid for by the Royal Society of Chemistry

Chem. Sci., 2015,6, 1761-1769
Article type
Edge Article
Author version available

Catalysis of water oxidation in acetonitrile by iridium oxide nanoparticles

J. C. Hidalgo-Acosta, M. A. Méndez, M. D. Scanlon, H. Vrubel, V. Amstutz, W. Adamiak, M. Opallo and H. H. Girault, Chem. Sci., 2015, 6, 1761
DOI: 10.1039/C4SC02196G

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