Publisher: American Chemical Society (ACS)

Issue: 39

License: http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html

Publication date(s): 2016/10/06 (print) 2016/09/28 (online)

Pages: 22291-22297

Volume: 120 Issue: 39

Journal: The Journal of Physical Chemistry C

Link: http://pubs.acs.org/doi/pdf/10.1021/acs.jpcc.6b04781

URL: http://dx.doi.org/10.1021/acs.jpcc.6b04781

The electrochemical activity toward the oxygen reduction reaction (ORR) of carbon supported Ba0.5Sr0.5CoxFe1–xO3−δ electrode particles is studied for the first time as a function of chemical composition (1 < x < 0). Highly crystalline Ba0.5Sr0.5CoxFe1–xO3−δ particles with the full compositional range were synthesized by an ionic-liquid route, leading to a high degree of phase purity. The structure and composition of the materials were investigated by quantitative XRD and EDX. Electrochemical studies in oxygen-saturated alkaline solutions show that the overall reactivity of the catalyst supported on mesoporous carbon increases as the Co content increases above 50%. DFT calculations, based on the structural parameters obtained from XRD refinements, show that the oxygen-vacancy formation energy decreases as the Co content increases. Oxygen vacancies lead to a higher electron density at the Co atoms, which are identified as the key ORR active sites.