Fundamental Understanding of Water's Role in the Oxygen Redox Process in Ionic Liquids

The O2/O2 •- redox couple is of particular interest for use in energy storage technology due to its abundance, sustainability, and potentially high energy density. Conversely, in the presence of a proton source, such as water, the O2/O2 •- redox couple may become unstable and irreversible. However, the fundamental understanding of this process is still not clear. In this work, O2/O2 •- redox process has been investigated in the presence of water using electrochemistry combined with in-situ spectroscopic methods in ionic liquid media. The findings for the redox reaction of oxygen in ionic liquids reported here indicate a complex mechanism on different electrode surfaces. This study is to elucidate the mechanism and reaction intermediates; it will also provide a fundamental understanding of oxygen chemistry and ionic liquid green chemistry for future emphasis on batteries, fuel cells, and gas sensor applications.