1/6/2024 0 Comments Sno2 core shell6,11 However, it should be noted that the introduction of silica at the interface between the Au particles and the catalyst supports usually leads to a depressed catalytic activity. 10 The growth of oxide shell over the gold particles in wet chemical approaches usually needed a pre-covered silica layer modifying the gold surfaces. One example is to create the core/shell structure. Consequently, an ideal catalyst should in general be developed into aggregation- and poison-resistant catalyst of high catalytic activities. In addition, the poisoning and deactivating of the Au particles inevitably exist in the conventional solution-based methods, such as coprecipitation 7 and deposition-precipitation, 8,9 in which chloride can adsorb on the gold active sites. 6 Therefore, deliberate tailoring of the nanostructured catalysts and optimization of the catalyst structure are still under broad investigation. This is caused by the increased mobility of the gold particles on the support at higher temperatures. However, the gold nanoparticles are unstable against sintering, accompanied by a corresponding loss of catalytic activity, which is a serious problem in many applications. 2-4 In these applications, CO oxidation over the supported gold nanoparticles has been investigated the most extensively since 1987 when Haruta 5 highlighted the remarkable high activity of supported gold catalysts for low-temperature CO oxidation. 1 Among them, oxide-supported gold nanocomposites had long been regarded for the highly efficient catalysts in many areas, such as CO oxidation, water-gas shift reaction, NO reduction, oxidation of hydrocarbons, and so forth. Recently, materials with multicomponent functional properties have been the subject of extensive research in contrast with their single-component compounds because the synergistic interactions between each component could strongly affect the properties. XPS spectra showed that the interactions between the Au catalyst and oxide support in the well-encapsulated 2 core/shell nanoparticles are much stronger than those in the non-encapsulated Au−SnO 2 nanoparticles, further indicating the synergetic confinement effect in such nanoscaled catalyst/support core/shell systems. Moreover, the 2 core/shell supported catalysts showed superior catalytic activity compared to non-encapsulated Au−SnO 2. 15 nm were highly encapsulated by the SnO 2 shell. In the as-prepared supported catalysts, Au particles with a mean size of ca. The change of their structure was investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). High-temperature-stable 2 core/shell supported catalyst was prepared by a simple intermetallics-based dry-oxidation approach in which the size of the core can be controlled easily by varying the size of the pre-made Au seeds.
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