Regensburg 2022 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 8: Solid-Liquid Interfaces 1: Reactions and Electrochemistry
O 8.4: Vortrag
Montag, 5. September 2022, 11:30–11:45, S054
Pd nanoparticles supported on ordered Co3O4(111): Particle size effects in electrochemical environment — •Maximilian Kastenmeier1, Xin Deng1, Tomáš Skála2, Nataliya Tsud2, Lukáš Fusek1,2, Viktor Johánek2, Josef Mysliveček2, Yaroslava Lykhach1, Olaf Brummel1, and Jörg Libuda1 — 1FAU Erlangen-Nürnberg, Erlangen, Germany — 2Charles University, Prague, Czech Republic
Pd nanoparticles (NPs) are efficient electrocatalysts for oxidation of ethanol in alkaline direct ethanol fuel cells. We investigated the morphology and the oxidation state of Pd NPs supported on well-ordered Co3O4(111) films as a function of the particle size after treatment in ultrahigh vacuum and in alkaline electrolyte under potential control. We combined synchrotron radiation photoelectron spectroscopy and scanning tunneling microscopy. Electronic metal support interaction associated with the charge transfer at the Pd/Co3O4(111) interface yield partially oxidized ultra-small Pdδ+ aggregates and Pd2+ species at Pd coverages below 0.1 ML followed by the growth of two-dimensional metallic Pd0 NPs at higher coverages. The stabilities of ultra-small and conventionally-sized NPs supported on Co3O4(111) and HOPG were compared following an emersion from alkaline electrolyte at potentials between 0.5 and 1.5 VRHE. We observed different oxidation behavior related to two-dimensional and three-dimensional morphologies of supported Pd NPs on Co3O4(111) and HOPG, respectively. In sharp contrast, the oxidation state of the ultra-small Pd deposits remains unchanged between 0.5 and 1.5 VRHE.