Oxygen reduction reaction catalyst size effect

Yano H, Inukai J, Uchida H, Watanabe M, Babu PK, Kobayashi T, Chung JH, Oldfield E, Wieckowski A. 2006b. Particle-size effect of nanoscale platinum catalysts in oxygen reduction reaction an electrochemical and Pt EC-NMR study. Phys Chem Chem Phys 8 4932-4939. 

In this chapter we review studies, primarily from our laboratory, of Pt and Pt-bimetallic nanoparticle electrocatalysts for the oxygen reduction reaction (ORR) and the electrochemical oxidation of H2 (HOR) and H2/CO mixtures in aqueous electrolytes at 274—333 K. We focus on the study of both the structure sensitivity of the reactions as gleaned from studies of the bulk (bi) metallic surfaces and the resultant crystallite size effect expected or observed when the catalyst is of nanoscale dimension. Physical characterization of the nanoparticles by high-resolution transmission electron microscopy (HRTEM) techniques is shown to be an essential tool for these studies. Comparison with well-characterized model surfaces have revealed only a few nanoparticle anomalies, although the number of bimetallics... 

Nesselberger M, Ashton S, Meier JC, Katsounaros I, Mayrhofer KJJ, Arenz M (2011) The particle size effect on the oxygen reduction reaction activity of pt catalysts influence of electrolyte and relation to single crystal models. J Am Chem Soc 133(43) 17428-17433... 

Depending on the amount and the distribution of selenium, up to 5% hydrogen peroxide formation has been observed in the oxygen reduction reaction. As hydrogen peroxide leads to a rapid degradation of the membrane and the gas diffusion media and enhances the corrosion of the carbon catalyst support and finally to a loss of performance due to this side reaction, the formation of hydrogen peroxide has to be minimized. Further details on the effect of particle size, particle distribution and the effect of the carbon support on the hydrogen peroxide production has been mentioned above. 

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