The functionality of ceria-based supported catalysts is controlled by various types of interactions between the active metal nanoparticles and the oxide support. Using a model catalysis approach, we investigate these interactions and discuss their relation to catalytic performance, both for heterogeneously catalyzed reactions and for electrocatalytic reactions. In specific, we discuss electronic metal support interactions, spillover of reactants, and reversible anchoring of metals on the support.[1-3]<br/>Considering electronic metal support interactions (EMSI), an important quantity is the charge transfer between supported nanoparticles and the oxide. We investigate the charge transfer for different noble metals, using model systems prepared by surface science methods. For these systems, the electronic structure is probed by synchrotron-radiation X-ray photoelectron spectroscopy (XPS) and resonant photoelectron spectroscopy (RPES). Spontaneous transfer of electrons across the metal/oxide interface is observed to be a general phenomenon and is quantified by RPES. Combining this information with structural data, we demonstrate that the charge transfer can be tuned by adjusting structural parameters such as the particle size and structure of the support. Besides EMSI, spillover and reverse spillover are common phenomena on ceria supported noble metal catalysts. We investigate the kinetics and energetics of oxygen reverse spillover as a function of the structure of the support. Finally we discuss the anchoring of atomically-dispersed metals on ceria. Specific sites on nanostructured ceria bind metal centers so strongly that they withstand sintering, even under harsh conditions. All of these phenomena critically depend on the oxidation state of ceria: With increasing degree of reduction, charge transfer can be suppressed, spillover of oxygen can be stopped or even be reversed, and atomically dispersed metal species can be release from their anchoring sites. Therefore, all phenomena may be controlled by materials design, for instance by modification of ceria through dopants or by modification of the supported particles by alloying.[4-5]<br/><br/>

Model catalysis with ceria-based materials: Surface science models for heterogeneous catalysis and electrocatalysis

2019 Fall National Meeting

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