Article pubs.acs.org/crystal
Size of Au-Nanoparticles Supported on Mesostructural Cellular Foams Studied by the Pair Distribution Function Technique Agnieszka Poulain,*,† Izabela Sobczak,‡ and Maria Ziolek‡ †
European Synchrotron Radiation Facility (ESRF), 71 avenue des Martyrs, CS 40220, Grenoble Cedex 9, France Faculty of Chemistry, Department of Heterogeneous Catalysis, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznan, Poland
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S Supporting Information *
ABSTRACT: Mesostructural cellular foam (MCF) materials that were modified by Zr, Nb, and Mo incorporation, followed by APTMS (3-aminopropyl-trimethoxysilane) grafting and gold loading were studied using the pair distribution function (PDF) technique. Measurements were focused on changes in gold crystallite sizes and on local geometry changes in the supports. Initially, ex situ prepared samples were investigated at different stages of synthesis and after catalytic oxidation of carbon monoxide. The crystallization and agglomeration of gold species as well as carbon monoxide oxidation were then tracked by in situ high energy diffraction measurements. The influence of metal type (Nb or Mo) and incorporation method in the MCF material on the agglomeration of metallic gold particles during increasing calcination temperature was determined. The structure of MCF materials was preserved during calcination and oxidation of CO and local symmetry of gold particles is not changed under CO oxidation conditions. In samples oxidized in the laboratory flow reactor, the interaction of gold particles with the reagents (CO and O2) leads to slight decrease in gold particle size.
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INTRODUCTION Many factors, such us nanoparticle (NP) size, method of synthesis, or chosen support, can influence the efficiency of gold catalysts. Several studies have been carried out on this subject,1−5 since the discovery of gold nanoparticle catalytic activity by Haruta in the late 1980s,6 who postulated that completely inert bulk gold may reveal unexpected catalytic activity when the particles are
