| AVS 58th Annual International Symposium and Exhibition | |
| In Situ Spectroscopy and Microscopy Focus Topic | Monday Sessions |
| Session IS+AS+SS-MoM |
| Session: | In Situ Studies of Catalysis and Gas-Solid Reactions |
| Presenter: | Sara Blomberg, Lund University, Sweden |
| Authors: | S. Blomberg, Lund University, Sweden J. Gustafson, Lund University, Sweden N.M. Martin, Lund University, Sweden M.E. Messing, Lund University, Sweden K. Deppert, Lund University, Sweden J.N. Andersen, Lund University, Sweden L.E. Walle, Norwegian University of Science and Technology, Norway A. Borg, Norwegian University of Science and Technology, Norway H. Grönbeck, Chalmers University of Technology, Sweden M.E. Grass, Lawrence Berkeley National Laboratory Z. Liu, Lawrence Berkeley National Laboratory E. Lundgren, Lund University, Sweden |
| Correspondent: | Click to Email |
Due to the economic and environmental rewards, one goal in catalysis related research is to create cheaper catalysts. One way to realize this is to dilute the more expensive active catalyst material with a less costly one. This requires that the active material stays at the surface. This could be achieved by using a material which is less prone to interact with the reactant gases, such as a noble metal. In most catalysts, the active material is dispersed in a high area complex oxide support as nanoparticles. In order to maintain the high activity, it would be necessary to ensure that the active material is at the surface of the nanoparticle.
In the present contribution we report on our initial findings from attempts to produce PdAg alloy particles using an aerosol deposition technique [1]. The particles have a diameter of 10 nm distributed over a SiOx wafer. The samples was characterized by high pressure XPS, SEM and TEM as was done previously for aerosol Pd particles [2,3]. By comparing to XPS data from a single crystal Pd75Ag25(100) and from The X-ray Energy Dispersive Spectoscopy (XEDS) analysis we show that the PdAg particles have a similar alloy composition.
The in-situ high pressure XPS data from the 10 nm PdAg particles demonstrates that the Pd segregates to the surface in an oxygen rich environment and that the core of the particles are rich in Ag. Although a thin PdOx shell is formed, bulk oxidation is inhibited. The limited oxide formation is promising for the full oxidation of methane, since recent investigations [4] suggest that the PdO is less active for methane oxidation than the metallic Pd.
[1] M. E. Messing, K. A. Dick, L. R. Wallenberg, K. Deppert, Gold Bull. 42 (2009) 20.
[2] M. E. Messing et al, J. Phys. Chem. C. 114 (2010) 9257 .
[3] R. Westerström et al, Phys. Rev. B. 83, (2011) 115440.
[4]A. Hellman et al., submitted.