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2017
Journal Article
Titel
Quantitative determination of residual silver distribution in nanoporous gold and its influence on structure and catalytic performance
Abstract
Large efforts have been made trying to understand the origin of the high catalytic activity of dealloyed nanoporous gold as a green catalyst for the selective promotion of chemical reactions at low temperatures. Residual silver, left in the sample after dealloying of a gold-silver alloy, has been shown to have a strong influence on the activity of the catalyst. But the question of how the silver is distributed within the porous structure has not finally been answered yet. We show by quantitative energy dispersive X-ray tomography measurements that silver forms clusters that are distributed irregularly, both on the surface and inside the ligaments building up the porous structure. Furthermore, we find that the role of the residual silver is ambiguous. Whereas CO oxidation is supported by more residual silver, methanol oxidation to methyl formate is hindered. Structural characterisation reveals larger ligaments and pores for decreasing residual silver concentration.
Author(s)
Mahr, Christoph
Institute of Solid State Physics, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany & MAPEX Center for Materials and Processes, Universität Bremen, Bibliothekstr. 1, 28359 Bremen, Germany
Lackmann, Anastasia
MAPEX Center for Materials and Processes, Universität Bremen, Bibliothekstr. 1, 28359 Bremen, Germany & Institute of Applied and Physical Chemistry, Universität Bremen, Leobener Str. UFT, 28359 Bremen, Germany
Schowalter, Marco
Institute of Solid State Physics, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany & MAPEX Center for Materials and Processes, Universität Bremen, Bibliothekstr. 1, 28359 Bremen, Germany
Schwan, Martin
MAPEX Center for Materials and Processes, Universität Bremen, Bibliothekstr. 1, 28359 Bremen, Germany & Institute of Applied and Physical Chemistry, Universität Bremen, Leobener Str. UFT, 28359 Bremen, Germany
Wittstock, Arne
MAPEX Center for Materials and Processes, Universität Bremen, Bibliothekstr. 1, 28359 Bremen, Germany & Institute of Applied and Physical Chemistry, Universität Bremen, Leobener Str. UFT, 28359 Bremen, Germany