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Catalytic Activity of Alkali Metal Cations for the Chemical Oxygen Reduction Reaction in a Biphasic Liquid System Probed by Scanning Electrochemical Microscopy
Author(s) -
Rastgar Shokoufeh,
Teixeira Santos Keyla,
Angelucci Camilo Andrea,
Wittstock Gunther
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.202001967
Subject(s) - chemistry , inorganic chemistry , electrolyte , alkali metal , scanning electrochemical microscopy , electrochemistry , aqueous solution , catalysis , reagent , electron transfer , oxygen , photochemistry , electrode , organic chemistry
Abstract Chemical reduction of dioxygen in organic solvents for the production of reactive oxygen species or the concomitant oxidation of organic substrates can be enhanced by the separation of products and educts in biphasic liquid systems. Here, the coupled electron and ion transfer processes is studied as well as reagent fluxes across the liquid|liquid interface for the chemical reduction of dioxygen by decamethylferrocene (DMFc) in a dichloroethane‐based organic electrolyte forming an interface with an aqueous electrolyte containing alkali metal ions. This interface is stabilized at the orifice of a pipette, across which a Galvani potential difference is externally applied and precisely adjusted to enforce the transfer of different alkali metal ions from the aqueous to the organic electrolyte. The oxygen reduction is followed by H 2 O 2 detection in the aqueous phase close to the interface by a microelectrode of a scanning electrochemical microscope (SECM). The results prove a strong catalytic effect of hydrated alkali metal ions on the formation rate of H 2 O 2 , which varies systematically with the acidity of the transferred alkali metal ions in the organic phase.