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Direct Detection of the Superoxide Anion as a Stable Intermediate in the Electroreduction of Oxygen in a Non‐Aqueous Electrolyte Containing Phenol as a Proton Source
Author(s) -
Peng Zhangquan,
Chen Yuhui,
Bruce Peter G.,
Xu Ye
Publication year - 2015
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201502039
Subject(s) - chemistry , aqueous solution , oxygen , superoxide , electrolyte , hydrogen peroxide , inorganic chemistry , phenol , ion , photochemistry , organic chemistry , electrode , enzyme
The non‐aqueous Li–air (O 2 ) battery has attracted intensive interest because it can potentially store far more energy than today′s batteries. Presently Li–O 2 batteries suffer from parasitic reactions owing to impurities, found in almost all non‐aqueous electrolytes. Impurities include residual protons and protic compounds that can react with oxygen species, such as the superoxide (O 2 − ), a reactive, one‐electron reduction product of oxygen. To avoid the parasitic reactions, it is crucial to have a fundamental understanding of the conditions under which reactive oxygen species are generated in non‐aqueous electrolytes. Herein we report an in situ spectroscopic study of oxygen reduction on gold in a dimethyl sulfoxide electrolyte containing phenol as a proton source. It is shown directly that O 2 − , not HO 2 , is the first stable intermediate during the oxygen reduction process to hydrogen peroxide. The unusual stability of O 2 − is explained using density functional theory (DFT) calculations.