Data for "Trapped interfacial redox introduces reversibility in the oxygen reduction reaction in a non-aqueous Ca2+ electrolyte"

While the ORR appears irreversible, the introduction of a tetrabutylammonium perchlorate (TBAClO4) co-salt in excess concentrations results in the gradual appearance of a quasi-reversible OER process. Combining the results of systematic CV investigations, the degree of reversibility depends on the ion pair competition between Ca2+ and TBA+ cations to interact with generated superoxide (O2-).

When TBA+ is in larger concentrations, and large reductive overpotentials are applied, a quasi-reversible OER peak emerges with repeated cycling (characteristic of formulations without Ca2+ cations). In situ Raman microscopy and rotating ring-disc electrode (RRDE) experiments revealed more about the nature of species formed at the electrode surface and indicated the progressive evolution of a charge storage mechanism based upon trapped interfacial redox.