Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 40: Solid-Liquid Interfaces

O 40.6: Poster

Dienstag, 17. März 2015, 18:15–21:00, Poster A

Preparation, Characterization and Electrocatalytic Reactivity of Bimetallic Pt_xAg_y and Pd_xAg_y Nanocrystals — •Isabella Weber¹, Sylvain Brimaud¹, José Solla Gullón², Juan M. Feliu², and R. Jürgen Behm¹ — ¹Ulm University, Institute of Surface Chemistry and Catalysis, D-89069 Ulm, Germany — ²University of Alicante, Institute of Electrochemistry, 03080 Alicante, Spain

Bimetallic Pt_xAg_y and Pd_xAg_y nanoparticles with silver contents between 0-35 at% were prepared using water-in-oil microemulsion and seed-mediated growth synthesis, and characterized electrochemically by CO_ad electrooxidation. The decrease of CO_ad oxidation reactivity of the as-received samples with increasing nominal Ag content indicates an up-shift of the Pt (Pd) d-band center. In order to disentangle contributions from silver dissolution and CO_ad oxidation, a combination of in-situ attenuated total reflectance Fourier-transform infra-red spectroscopy (ATR-FTIRS) and on-line differential electrochemical mass spectrometry (DEMS) was employed. Ensemble effects are held responsible for the change of the preferential adsorption configuration from bridge-bonded to linearly bonded CO_ad for Pd_xAg_y nanoparticles with Ag >20 at%. After electrochemical dealloying, the samples exhibit the reactivity of pure Pt (Pd) towards CO_ad oxidation. An increase in the CO_ad saturation coverage with increasing nominal silver content, however, additionally indicates a subtle electronic effect induced by Ag atoms within the bimetallic core of the dealloyed particles.