Prof. Dr. Jörg Libuda, Friedrich‐Alexander‐Universität Erlangen‐Nürnberg, Germany

Model Interfaces in Catalysis, Energy, and Materials Science

Complex interfaces are the key to new functional materials in energy technology, molecular electronics, and energy‐related catalysis. Most of their functionalities arise from the properties of interfaces, i.e. from the transport of electrons, ions, or intermediates across nanostructured phase boundaries. In this presentation, we present model strategies, which provide detailed insight into the chemistry and physics at such interfaces. We prepare complex, yet atomically‐defined model interfaces and explore their functionality both under ‘ideal’ surface science conditions and under ‘real’ conditions, i.e. in contact with gases, liquids and in electrochemical environments.

The model approach is illustrated discussing selected examples from our recent research. In the first part, we discuss the design of model systems for complex oxide‐based electrocatalysts. Previously, it has been demonstrated that such systems can show very high stability and activity. Here, we describe how such complex model electrodes can be made and characterized by surface science methods in ultrahigh vacuum and, subsequently, be studied in liquid electrolytes to explore electrocatalytic reactions. For the specific case of a platinum/cobalt oxide model electrocatalyst, we investigate particle size effects and identify hitherto unknown metal‒support interactions that stabilize oxidized platinum at the nanoparticle interface. We show that such effects open a new synergistic reaction pathway that involves both metallic and oxidized platinum. Our results illustrate the potential of the concept, which makes available a systematic approach to build atomically‐defined model electrodes for fundamental electrocatalytic studies.

In the second part, we report on the design organic‐oxide hybrid interfaces. Their functionality arises from complex organic layers which are anchored to the oxide interface via specific linker groups. We have studied the anchoring mechanism for different anchor groups (e.g. carboxylates, phosphonates) on atomically‐defined oxide surfaces and showed that the binding motifs, molecular orientation, and the stability is controlled by the structure of the surface. Once understood for small test molecules, this knowledge can be used to build complex interfaces. This is demonstrated, for instance, showing the assembly of atomically‐defined hybrid interfaces with functionalized porphyrin derivatives, hybrid interfaces with functionalized ionic liquid, or hybrid interfaces with functionalized molecular photoswitches.

1. A. Bruix, Y. Lykhach, I. Matolínová, A. Neitzel, T. Skála, N. Tsud, M. Vorokhta, V. Stetsovych, K. Ševčíková, J. Mysliveček, K. C. Prince, S. Bruyère, V. Potin, F. Illas, V. Matolín, J. Libuda, K. M. Neyman, Angew. Chem. Int. Ed. 53, 10525 (2014).
2. Y. Lykhach, S. M. Kozlov, T. Skála., A. Tovt, V. Stetsovych, N. Tsud, F. Dvořák, V. Johánek, A. Neitzel, J. Mysliveček, S. Fabris, V. Matolín, K. M. Neyman, J. Libuda, Nat. Mater. 15, 284 (2016).
3. K. Werner, S. Mohr, M. Schwarz, T. Xu, M. Amende, T. Döpper, A. Görling, J. Libuda, J. Phys. Chem. Lett. 7, 555 (2016).
4. T. Xu, T. Waehler, J. Vecchietti, A. Bonivardi, T. Bauer, J. Schwegler, P. S. Schulz, P. Wasserscheid, J. Libuda, Angew. Chem. Int. Ed. 56, 9072 (2017)
5. C. Schuschke, M. Schwarz, C. Hohner, T.N. Silva, L. Fromm, T. Doepper, A. Görling, J. Libuda, J. Phys. Chem. Lett. 9, 1937 (2018)
6. F. Faisal, C. Stumm, M. Bertram, F. Waidhas, Y. Lykhach, S. Cherevko, F. Xiang, M. Ammon, M. Vorokhta, B. Šmíd, T. Skála, N. Tsud, A. Neitzel, K. Ševčíková, K. C. Prince, S. Geiger, O. Kasian, T. Wähler, R. Schuster, M. A. Schneider, V. Matolin, K. J.J. Mayrhofer, O. Brummel, J. Libuda, Nat. Mater. (2018) DOI:10.1038/s41563‐018‐0088‐3

Host: Associate professor Jeppe Vang Lauritsen, iNANO & Dept. of Physics and Astronomy, Aarhus University