Berlin 2012 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 46: Nanomaterials I
MM 46.2: Vortrag
Donnerstag, 29. März 2012, 10:30–10:45, H 1029
Evolution of nanoporosity via dealloying in binary and ternary Pt alloys — •Henning Galinski1, Thomas Ryll1, Yang Lin1, Ludwig J. Gauckler1, and Max Döbeli2 — 1Nonmetallic Inorganic Materials, ETH Zurich, Zurich, Switzerland — 2Ion Beam Physics, ETH Zurich, Zurich, Switzerland
The controlled tailoring of nano-porosity in metallic thin films of several 100 nm thickness using dealloying has gained renewed attention in recent years, as such nanoporous thin films are candidates for applications in sensors, micro-fuel cells and super-capacitors. In this contribution the physical mechanism of nanoporosity formation during the dealloying process of binary PtAl- and ternary PtYAl-alloy thin films is examined using focused ion beam (FIB) nanotomography and Rutherford backscattering spectrometry (RBS). The dynamics of nanoporosity formation is found to obey a superposition of a reaction-diffusion
equation describing a linearly propagating diffusion front1 and a secondary slower dissolution process away from the moving interface. An increased Al content as well as a partial substitution of Pt by Y results in a slower dealloying kinetics with a slower linearly propagating diffusion front. The resulting nanoporous Pt thin
films perform exceptionally well as oxygen reduction electrodes in a micro-solid oxide fuel cell setup2 in the temperature range from 473 to 1073 K.
1 PRL 107, 225503 (2011), 2 PRB 84, 184111 (2011)