Oxygen reduction of platinum low-index single-crystal surfaces in alkaline solution: Rotating ring disk{sub Pt(hkl)} studies
- Lawrence Berkeley Lab., CA (United States)
The first results of a study of the oxygen reduction reaction on a rotating ring-disk electrode using single-crystal Pt disk electrodes in alkaline solution are presented. The order of activity of Pt(hkl) in 0.1 M KOH increased in the sequence (100) < (110) < (111) for both oxygen and peroxide reduction. These differences are attributed to the structure sensitivity of hydroxyl anion (OH{sup -}) adsorption on Pt(hkl) and its inhibiting (site blocking) effect on oxygen kinetics. Two different types of OH{sub ads} occur on Pt(100) and Pt(110), a reversible OH{sub rv}, and an irreversible OH{sub ir}, while only the reversible form is formed on Pt(111). Very small fluxes (I{sub R}/N < 0.01I{sub D}) of peroxide were detected at the ring at potentials where the surfaces have only the reversible form of OH{sub ads}. More peroxide (I{sub R}N < 0.03I{sub D}) was found with the Pt(100) and Pt(110) surfaces in the potential region where irreversible adsorption occurs. The mechanism of O{sub 2} reduction was also affected by adsorbed hydrogen with increased formation of peroxide ions in this potential region; correspondingly, adsorbed hydrogen was found to have an inhibiting effect on peroxide reduction, the effect decreasing in the order (111) > (100) > (110). 34 refs., 6 figs.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 263163
- Journal Information:
- Journal of Physical Chemistry, Vol. 100, Issue 16; Other Information: PBD: 18 Apr 1996
- Country of Publication:
- United States
- Language:
- English
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