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AIR+HDO:ESO:LLI:PVEPlatinum nanoparticles of narrow size distribution (similar to 2.5 nm) were synthesized using a modified polyol method and deposited on yttria-stabilized zirconia (Pt/YSZ), carbon (Pt/C) and gamma-alumina (Pt/gamma-Al2O3) supports, resulting in 1 wt % of Pt loading. Pt/YSZ has the highest catalytic activity toward CO oxidation among the studied catalysts. Decrease in the average particle size of Pt/YSZ led to the increase in CO conversion at low temperatures. Enhanced performances can be explained by the thermally induced O2- backspillover from YSZ over Pt nanoparticles in agreement with the electrochemical promotion mechanism. Observed effect becomes more pronounced with decreasing the particle size. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.024203esl] All rights reserved

Recently, metal support interaction (MSI) has been demonstrated to be closely related to electrochemical promotion of catalysis (EPOC) in the functionality of the process through spillover/backspillover of ionic species to/from the conductive support. In the present work, the interaction that iridium oxide (IrOx) nanoparticles have with two mixed ionic-electronic conducting (MIEC) materials (i.e., ceria, CeO2 and titania, TiO2) for ethylene oxidation is evaluated. To this end, the open circuit catalytic oxidation of ethylene as well as steady-state polarization measurements were carried out for free-standing (unsupported) IrOx and ceria- and titania-supported IrOx (~1 nm). The presence of these two supports was found to increase the catalytic reaction rate when compared to the free-standing IrOx, and decrease the electrochemical reaction rate at the three-phase boundary, as confirmed by the exchange current density (i0). In the light-off experiments, the IrOx/CeO2 catalyst showed a higher reaction rate until 3000C; however IrOx/TiO2 was superior at 3500C. It was also shown that the catalysts with lower i0 resulted in higher open-circuit reaction rates due to the larger amount of thermally-induced backspillover promoters to the gas exposed catalyst surface, in agreement with the EPOC phenomenon.