Establishing the potential dependent equilibrium oxide coverage on platinum in alkaline solution and its influence on the oxygen reduction

TY - JOUR

T1 - Establishing the potential dependent equilibrium oxide coverage on platinum in alkaline solution and its influence on the oxygen reduction

AU - Wiberg, Gustav

AU - Arenz, Matthias

PY - 2012/11/1

Y1 - 2012/11/1

N2 - The oxidation process of polycrystalline platinum subjected to alkaline solution is re-examined using a combination of cyclic voltammetry and potential hold techniques in Ar, H 2 and O 2 purged 0.1 M KOH solution. The hydrogen oxidation reaction is used as a probe for forming a complete OH adlayer, whereas the comparison of cyclic voltammetry with potential hold techniques allows the investigation of the dynamics as well as a charge balance of the processes. Comparing the different findings in a parameterized form, we are able to discern the potential regions of OH and O adlayers as well as PtO formation at quasi steady state conditions: only low amount of OH exists up to 0.7 V RHE. Increasing the potential the OH coverage increases and a OH monolayer is formed at 0.93 V RHE, which gradually further oxidizes to O ad increasing the potential up to 1.08 V, above which PtO oxide is formed. Comparing the oxidation process to the oxygen reduction reaction it is shown that there is a clear correlation between the formation of a full OH adlayer and the inhibition of the oxygen reduction.

AB - The oxidation process of polycrystalline platinum subjected to alkaline solution is re-examined using a combination of cyclic voltammetry and potential hold techniques in Ar, H 2 and O 2 purged 0.1 M KOH solution. The hydrogen oxidation reaction is used as a probe for forming a complete OH adlayer, whereas the comparison of cyclic voltammetry with potential hold techniques allows the investigation of the dynamics as well as a charge balance of the processes. Comparing the different findings in a parameterized form, we are able to discern the potential regions of OH and O adlayers as well as PtO formation at quasi steady state conditions: only low amount of OH exists up to 0.7 V RHE. Increasing the potential the OH coverage increases and a OH monolayer is formed at 0.93 V RHE, which gradually further oxidizes to O ad increasing the potential up to 1.08 V, above which PtO oxide is formed. Comparing the oxidation process to the oxygen reduction reaction it is shown that there is a clear correlation between the formation of a full OH adlayer and the inhibition of the oxygen reduction.

KW - engineering

U2 - 10.1016/j.jpowsour.2012.06.019

DO - 10.1016/j.jpowsour.2012.06.019

M3 - Journal article

SN - 0378-7753

VL - 217

SP - 262

EP - 267

JO - Journal of Power Sources

JF - Journal of Power Sources

ER -