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| Home > Publications database > Shape changes of Pd nanoparticles on MgO(001) in O$_2$ and H$_2$ environments |
| Home > Publications database > Shape changes of Pd nanoparticles on MgO(001) in O$_2$ and H$_2$ environments |
| Master Thesis | PUBDB-2025-04542 |
; ;
2020
Abstract: Palladium nanoparticles are widely studied in various fields of science. In biology, Pd parti-cles are studied for possible medical applications, in chemistry the particles are often synthe-sised in solution and then applied to a support via, for example, spin coating. A commonapproach in the field of physics is the growth of particles on a single crystal support withmolecular beam epitaxy (MBE), producing extremely well defined samples compared to theother approaches, wich allows the study of more intricate processes. The strong attentionon Pd particles is due to the exceptional catalytic activity of Pd surfaces. Industrial usesare predominately in the synthesis of chemicals via a catalytic process involving palladiumand catalytic converters for car exhaust treatment.In the form of nanoparticles the surface area and number of surface defects, often foundto be most active, of Pd are highly increased compared to bulk crystals, which increasesefficiency. The drawback in using nanoparticles are processes that reduce the performanceand the instability of the particles. Literature reports considerable size and shape changes ofPd particles on MgO(0 0 1) in oxygen atmosphere at elevated temperatures [1]. The changein facet sizes are accompanied by a change in catalytic activity, since different surface termi-nations show different throughput in catalytic reactions. Additionally, the number of edges,often providing the most active sites, changes, which can also change the catalytic activity.In order to understand these processes and develop tailor made catalysts with improved ef-ficiency and lifetime in the environment they are used in, an understanding of the particleson an atomic level is needed.Hence, this work aims to build upon the results published in [1] studying the behaviour ofepitaxial Pd particles on MgO(0 0 1), an often used material combination in catalysis. Theinvestigated particles properties were size and shape, in plane and out of plane orientation,as well as the relaxation states of the exposed particle surfaces. The method used was graz-ing incidence X-ray diffraction which allows access to all these parameters in an ensemblemeasurement.
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