A Highly Efficient Bifunctional Catalyst for Alkaline Air-Electrodes Based on a Ag and Co3O4 Hybrid: RRDE and Online DEMS Insights

• Published in: Electrochimica acta Vol. 151; pp. 332 - 339
• Main Authors: Amin, Hatem M.A., Baltruschat, Helmut, Wittmaier, Dennis, Friedrich, K.Andreas
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2015
• Subjects: bimetallic catalyst; cobalt oxide; metal-air battery; oxygen; silver; silver; cobalt oxide; oxygen; bimetallic catalyst; metal-air battery
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2014.11.017

[Display omitted] Enhanced catalytic activity towards oxygen reduction (ORR) and evolution (OER) reactions has been achieved by combination of spinel Co3O4 nanoparticles with Ag particles. Quasi-stationary polarization curves showed that the mixed catalyst, Ag+Co3O4 (10wt%), outperformed its components. Rotating ring-disc electrode (RRDE) measurements revealed a negligible peroxide species formation and a 4-electron pathway for ORR. A tafel slope of ca. 75mVdec−1 has been observed. The overpotential for ORR at 10% Co3O4 catalyst is ca. 70mV lower than that of Ag and only ca. 80mV higher than that of the commercial Pt catalyst. DEMS technique provided a direct evidence for oxygen evolution at these bimetallic catalysts. This hybrid is therefore one of the (or even the) most active, carbon-free, durable, non-precious ORR and OER electrocatalysts reported to date.