Oxygen reduction catalyzed by a Carbohydrazone based compound at liquid/liquid interfaces

•Oxygen reduction at liquid-liquid interface by using hydrazone based ligand as catalyst.•Using a Schiff base ligand as proton transfer agent at liquid-liquid interface.•Using ionophore with more than one site for proton transfer at liquid-liquid interface.

Ferrocen, (Fc), can reduce oxygen to water or hydrogen peroxide at a water/1,2-dichloroethane (DCE) interface which proceeds as a proton coupled electron transfer process. In this work, the oxygen reduction reaction (ORR) by Fc has been investigated in the presence of bis-[(E-N′-(phenyl(pyridin-2-yl)methylene)]carbohydrazide (H2L) that acts as proton ionophore for transferring of protons from the aqueous phase to the organic phase. H2L shows two peaks at low pH (less than pH = 3.5) and one peak at pH = 3.5. The two waves of H2L shift to negative potentials with increasing the acidity of aqueous phase. It can be said that both waves correspond to a facilitated proton transfer reaction.

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