The oxygen reduction reaction (ORR) is one of the most studied redox process in electrocatalysis because of its key role in fuel cells1 and, more recently, metal-air batteries2. Trace amounts of ionic3 and molecular species4 are known to cause deleterious effects on this reaction. In particular, trace amounts of halides can poison the four-electron reduction of dioxygen, promoting instead, the two-electron reduction to peroxide. This work describes a new approach that allows correlations to be established between the rates of ORR, on the Pt disk of a rotating Pt-ring|Pt-disk electrode, the coverage of adsorbed halide, qX-, X- = Cl- or Br-, the amount of solution phase hydrogen peroxide, H2O2, generated at the disk, and the applied potential, using a rotating ring-disk electrode coupled with transient techniques. Measurements were performed in 0.1 M HClO4 containing either 10 mM NaCl or 10 mM KBr. References 1. J. Zhang, Frontiers in Energy, 5, 137, 2011. 2. Wang, Z.-L.; Xu, D.; Xu, J.-J.; Zhang, X.-B., Chem. Soc. Rev. 2014. 3. N. M. Markovic, H. A. Gasteiger, B. N. Grgur, and P. N. Ross, J. Electroanal.Chem., 467, 157, 1999. 4. N. M. Markovic, R. R. Adzic, B. D. Cahan, and E. B. Yeager, J. Electroanal.Chem., 377, 249, 1994.

Impurity effects on the oxygen reduction reaction (ORR)

249th National Meeting (2015)

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