催 化 论 坛
Model Studies in Energy-Related Catalysis and Electrocatalysis
Prof. Jörg Libuda
Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany
Complex interfaces are the key to new functional materials in energy conversion, energy storage, and energy-related catalysis. Most of the functionalities arise from the physical and chemical properties of interfaces, i.e. from the transport of electrons, ions, atoms, or molecules via nanostructured phase boundaries, often in complex solid/liquid or electrochemical environments. Model strategies, which can provide detailed insights into the chemistry and physics at such interfaces, are illustrated through examples from our current research. We prepare complex yet atomically-defined model interfaces and explore their chemical functionality both under “ideal” surface science conditions and under “real” conditions, i.e. in contact with gases, liquids and in electrochemically controlled environments. In first part, we consider model systems for proton exchange membrane fuel cell catalysts based on Pt-ceria films. We show how Pt can be anchored to nanostructured ceria and explore electronic metal support interactions in this system. Finally, we demonstrate by means of in-situ spectroscopy at the electrified interface that the ceria support stabilizes sub-nanometer-sized Pt nanoparticles under conditions of dynamically changing electrode potential. In the second part we report on the preparation of complex, yet atomically-efined model systems for electrocatalysts using a surface science pproach in ultrahigh vacuum (UHV). First examples are shown, in which such model lectrodes are made in UHV and transferred into aqueous electrolytes, while preserving heir atomic structure (Pt nanoparticles on well-ordered Co3O4(111) films). We tudy simple test reactions on such models and obtain detailed information on tructure and size dependencies. Finally, we present the results of model studies of liquid organic hydrogen carriers (LOHCs). LOHCs allow for storing ultrapure hydrogen, e.g. for fuel cells, at ambient pressure and temperature. The operation principle of LOHCs is based on the reversible hydrogenation of N-containing or N-free aromatic compounds. We use a model catalysis approach to investigate the dehydrogenation mechanisms, characterize structure, size and materials dependencies and identify potential decomposition and deactivation mechanisms.
Dr. Jörg Libuda is a professor of Physical Chemistry in the department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany. His subjects are Chemistry, Materials Science, and Physics.
His previous position is Workgroup Leader at Fritz-Haber-Institut der Max-Planck-Gesellschaft from 1999 to 2005. He is the Guest Editor of Chemical Society Reviews, the Editorial Advisary Board of Catalysis Letters and Topics in Catalysis.
Libuda's Group explores the kinetics and dynamics of chemical processes at complex interfaces. Model interfaces are developed starting from a surface science approach and their functionalities are investigated from ultrahigh vacuum conditions to realistic environments. This includes in-situ and operando studies in reactive gases, liquids or at the electrified interfaces. Besides surface science techniques, the group employs molecular beam methods, reactor studies, operando spectroscopies, electrochemical and spectro-electrochemical methods, and photochemical methods, both in the laboratory and at the synchrotron. The model materials include metals, oxides, alloys, hybrid and nanomaterials, ionic liquids, and organic films. The group’s work aims at providing a mechanistic understanding of chemistry at complex interfaces, for applications in heterogeneous catalysis, electrocatalysis, energy storage and conversion, hydrogen storage, photoelectrochemistry, or molecular electronics.