Peer-Reviewed Journal Details
Mandatory Fields
Hidalgo-Acosta, Jonnathan C.; Scanlon, Micheál D.; Méndez, Manuel A.; Peljo, Pekka; Opallo, Marcin; and Girault, Hubert H
Enhanced reactivity of water clusters towards oxidation in water/acetonitrile mixtures
Optional Fields
Water oxidation Layer-by-layer assembly Water/acetonitrile mixtures
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. doi=10.1002/celc.201600190
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