Effect of chemisorbed carbon monoxide on Pt/C electrode on the mechanism of the hydrogen oxidation reaction
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AuthorsElezović, Nevenka R.
Gajić Krstajić, Ljiljana
Radmilović, Velimir R.
Krstajić, Nedeljko V.
Article (Published version)
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The influence of poisoning of Pt catalyst by CO on the kinetics and mechanism of H2 oxidation reaction (HOR) at Pt/C electrode in 0.5 mol dm-3 HClO4, saturated with H2 containing 100 ppm CO, was examined with rotating disc electrode (RDE) at 22 °C. Commercial carbon black, Vulcan XC-72 was used as support, while Pt/C catalyst was prepared by modified polyol synthesis method in an ethylene glycol (EG) solution. The kinetically controlled current (Ik) for the HOR at Pt/C decreases significantly at CO coverage (ΘCO) > 0.6. For ΘCO < 0.6 the HOR takes place through Tafel-Volmer mechanism with Tafel reaction as rate-determining step at the low CO coverage, while Volmer step controls the overall reaction rate at the medium CO coverage. When CO coverage is higher then 0.6, Heyrovsky-Volmer mechanism is operative for the HOR with Heyrovsky as the rate-determining step (rds). © 2008 Elsevier Ltd. All rights reserved.
Keywords:CO adsorption / hydrogen oxidation / mechanism / RDE / Pt nanosized catalyst
Source:Electrochimica Acta, 2009, 54, 4, 1375-1382