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O: Fachverband Oberflächenphysik

O 93: Heterogeneous Catalysis: Experiment

O 93.2: Hauptvortrag

Donnerstag, 23. März 2017, 15:30–16:00, TRE Phy

Oxide model interfaces from ultrahigh vacuum conditions to liquid environments — •Jörg Libuda — Friedrich-Alexander-Universität Erlangen-Nürnberg

Oxide-based hybrid interfaces are at the heart of many functional materials: Organic films on oxides find applications in molecular electronics and solar energy conversion; metal nanoparticles on oxides are used in heterogeneous catalysis and electrocatalysis. Studies on atomically-defined model hybrid interfaces can provide detailed insights into their chemical and physical functionalities.

Model electrocatalyst are prepared by deposition of active metals on ordered oxide films. Surface science studies of such systems in UHV provide a detailed understanding of electronic metal-support interactions, reaction mechanisms and catalytic activities. Recently, we showed that UHV-born model systems may preserve their atomic structure when used as electrocatalysts in liquid environments. This allows us to explore electrocatalytic reactions at complex atomically-defined model interfaces.

Model organic-oxide hybrid interfaces are prepared by anchoring of organic molecules, e.g. porphyrines, on ordered oxide surfaces. Exemplifying anchoring reactions with carboxylates, we explore the molecular orientation, metalation and the formation kinetics. Strong structure dependencies are observed for the film stability which are rationalized on the basis of the cation arrangement at the surface. Finally, we discuss the role of water and hydroxyl groups in molecular anchoring, both under UHV conditions and in liquid environments.