Oxygen reduction on Pt in aqueous K sub 2 CO sub 3 and KOH

Journal Article · Wed Oct 31 23:00:00 EST 1990 · Journal of the Electrochemical Society; (United States)

DOI:https://doi.org/10.1149/1.2086221· OSTI ID:5752676

Striebel, K; McLarnon, F R; Cairns, E J ^[1]

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1. Applied Science Div., Lawrence Berkeley Lab., Dept. of Chemical Engineering, Univ. of California, Berkeley, CA (US)

This paper reports on the electrolyte concentration dependences of platinum oxidation and oxygen reduction (OR) on Pt investigated in KOH and K{sub 2}CO{sub 3} electrolytes. Cyclic voltammetry was used to characterize the oxidation processes on the Pt electrode, and the rotating ring-disk electrode (RRDE) technique was used to evaluate the kinetic processes for OR in 0.1--6.9 {ital M} KOH and 0.1--4.0 {ital M} K{sub 2}CO{sub 3}, at room temperature. The charge due to Pt oxidation reached a maximum at a KOH concentration of about 2--3 {ital M} for a range of electrode potentials. This is consistent with changes in the rates and the relative importances of the reversible and aging processes with changes in hydroxide-ion activity. No maxima were observed with carbonate electrolytes at comparable ionic strengths. At high overpotentials, in both electrolytes, current densities were limited by the rate of O{sub 2} adsorption onto Pt. The Tafel slope for this process was essentially infinite for the more-oxidized surfaces. At lower overpotentials, the observed Tafel slope decreased and the fraction of current passing through the 2-electron pathway increased with increasing hydroxide-ion activity.

• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5752676
• Journal Information: Journal of the Electrochemical Society; (United States), Journal Name: Journal of the Electrochemical Society; (United States) Vol. 137:11; ISSN JESOA; ISSN 0013-4651
• Country of Publication: United States
• Language: English

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