Enhanced Reactivity of Water Clusters towards Oxidation in Water/Acetonitrile Mixtures

Jonnathan C. Hidalgo-Acosta, Micheál D. Scanlon, Manuel A. Méndez, Pekka Peljo, Marcin Opallo, Hubert H. Girault*

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)

Abstract

The water oxidation process in acidified water/acetonitrile mixtures was studied by cyclic voltammetry using fluorinated tin oxide (FTO) electrodes modified layer-by-layer with deposited bilayers of positively charged poly(diallyldimethylammonium chloride) (PDDA) polymer and negatively charged citrate-stabilized iridium oxide (IrO2) nanoparticles. The voltammetric profiles obtained at high water contents resemble those in aqueous media and remain approximately unchanged. However, as the water content decreases below a water mole fraction (XH2O) of 0.6, a tipping point is reached and the onset potential for water oxidation gradually decreases. This reflects an enhanced reactivity, and therefore lower overpotential, of water molecules towards oxidation in water/acetonitrile mixtures. These lower kinetic barriers towards water oxidation are rationalized based on the degradation of the hydrogen bond network upon the formation of water/acetonitrile mixtures. Thus, as the ice-like structure of neat water transitions to clusters and low-bonded oligomers, these water molecules in more “free” states exhibit an enhanced susceptibility to water oxidation.

Original languageEnglish
Pages (from-to)2003-2007
Number of pages5
JournalCHEMELECTROCHEM
Volume3
Issue number12
DOIs
Publication statusPublished - 1 Dec 2016
MoE publication typeA1 Journal article-refereed

Keywords

  • iridium oxide
  • layer-by-layer assembly
  • nanoparticles
  • water oxidation
  • water/acetonitrile mixtures

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