Insight into restructuring of Pd-Au nanoparticles using EXAFS

Publication date: Available online 29 April 2019Source: Radiation Physics and ChemistryAuthor(s): Alexey Boubnov, Janis Timoshenko, Cody J. Wrasman, Adam S. Hoffman, Matteo Cargnello, Anatoly I. Frenkel, Simon R. BareAbstractWe acquired Pd K-edge and Au L3-edge EXAFS spectra of two libraries of titania-supported Pd-doped Au nanoparticle catalysts representing the as-prepared and post-catalysis state. The nanoparticles have narrow particle size distributions, in the range 2.8–6.6 nm, and were synthesized to preferentially locate the palladium atoms on the surface of a gold core, with Pd mole fractions of 1.4–38%. EXAFS spectra of both the as-prepared samples and post-catalysis Pd-Au particles were collected and modeled. EXAFS refinement of all samples showed contributions from both Pd-Au and Pd-Pd scattering paths, revealing that Pd and Au components alloyed together. Pd was in a partially oxidized state as evidenced by a Pd-O scattering contribution, unlike Au. Overlaying measured coordination numbers from the libraries with predicted values, using models of surface and bulk alloying, showed that Pd restructures among Au as a result of exposure to the reaction conditions.
Source: Radiation Physics and Chemistry - Category: Physics Source Type: research