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

Neale, Alex ORCID: https://orcid.org/0000-0001-7675-5432, Hardwick, Laurence ORCID: https://orcid.org/0000-0001-8796-685X, Yi-Ting, Lu ORCID: https://orcid.org/0000-0003-2128-1385 and Chi-Chang, Hu ORCID: https://orcid.org/0000-0002-4308-8474 (2021) Data for "Trapped interfacial redox introduces reversibility in the oxygen reduction reaction in a non-aqueous Ca2+ electrolyte". [Data Collection]

Data Catalogue DOI: 10.17638/datacat.liverpool.ac.uk/1309

Original publication URL: https://doi.org/10.1039/D0SC06991D

Description

Electrochemical investigations of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) have been conducted in Ca2+-containing dimethyl sulfoxide 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. The first electrochemical step involves generation of O2-, followed primarily by partial passivation of the surface by CaxOy product formation (the dominant initial reaction). Once this product matrix develops, the subsequent formation of TBA+--O2- is contained within the CaxOy product interlayer at the electrode surface and, consequently, undergoes a facile oxidation reaction to regenerate O2.

Keywords:

Oxygen electrochemistry, Calcium-air, Trapped interfacial redox

Divisions:

Faculty of Science and Engineering > School of Physical Sciences > Chemistry

Depositing User:

Alex Neale

Date Deposited:

03 Jun 2021 11:40

Last Modified:

03 Jun 2021 11:40

DOI:

10.17638/datacat.liverpool.ac.uk/1309