Electrochemical Stress Development during CO and NO Oxidation on Pt

The adsorption and oxidation of CO on Pt electrodes is among the most studied electrochemical reactions due to its fundamental importance as a simple model system and practical importance as CO is a well-known poison in fuel cells.¹ We use in situ electrochemical surface stress measurements to monitor the surface stress development during the oxidation of CO on Pt electrodes where adsorbed CO reacts with oxygen-containing species on the surface via Langmuir-Hinshelwood mechanism.^1-2 The nature of adsorbed CO layer and the role of oxygenated species are studied in both acid and alkaline media. Further, the effect of dissolved CO is examined. Another strong adsorbate, NO, is oxidized on Pt surface and the surface stress change is monitored. Despite the similarity in the electronic structure, the oxidation of NO follows a different mechanism where the complete oxidation of adsorbed NO is very difficult due to surface oxide formation.³The different role of oxygenated species on the surface can be seen from the surface stress response.

References

 1.             Garcia, G.; Koper, M. T., Carbon monoxide oxidation on Pt single crystal electrodes: understanding the catalysis for low temperature fuel cells. Chemphyschem : a European journal of chemical physics and physical chemistry 2011, 12(11), 2064-72.

2.             Arenz, M.; Mayrhofer, K. J. J.; Stamenkovic, V.; Blizanac, B. B.; Tomoyuki, T.; Ross, P. N.; Markovic, N. M., The Effect of the Particle Size on the Kinetics of CO Electrooxidation on High Surface Area Pt Catalysts. J. Am. Chem. Soc. 2005, 127(18), 6819-6829.

3.             de Vooys, A. C. A.; Beltramo, G. L.; van Riet, B.; van Veen, J. A. R.; Koper, M. T. M., Mechanisms of electrochemical reduction and oxidation of nitric oxide. Electrochim. Acta 2004, 49 (8), 1307-1314.