Nanostructured composite electrode materials play a major role in the fields of catalysis and electrochemistry. The self-assembly of metallic nanoparticles on oxide supports via metal exsolution relies on the transport of reducible dopants towards the perovskite surface to provide accessible catalytic centres at the solid-gas interface. At surfaces and interfaces, however, strong electrostatic gradients and space charges typically control the properties of oxides. Here we reveal that the nature of the surface-dopant interaction is the main determining factor for the exsolution kinetics of nickel in SrTi0.9Nb0.05Ni0.05O3-δ. The electrostatic interaction of dopants with surface space charge regions forming upon thermal oxidation results in strong surface passivation, which manifests in a retarded exsolution response. We furthermore demonstrate the controllability of the exsolution response via engineering of the perovskite surface chemistry. Our findings indicate that tailoring the electrostatic gradients at the perovskite surface is an essential step to improve exsolution-type materials in catalytic converters.

Central Institute for Engineering Electronics and Analytics Forschungszentrum Juelich GmbH Juelich Germany

Department of Surface and Plasma Science Charles University Prague Czech Republic

Institute for Electronic Materials RWTH Aachen University Aachen Germany

Institute of Energy and Climate Research Materials Synthesis and Processing Forschungszentrum Juelich GmbH Juelich Germany

Institute of Mineral Engineering RWTH Aachen University Aachen Germany

Juelich Aachen Research Alliance Juelich Germany

Peter Gruenberg Institute Electronic Materials Forschungszentrum Juelich GmbH Juelich Germany

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Thermal stability and coalescence dynamics of exsolved metal nanoparticles at charged perovskite surfaces