| AVS 64th International Symposium & Exhibition | |
| Surface Science Division | Monday Sessions |
| Session SS+AS+MI-MoM |
| Session: | Organic/Inorganic Surfaces and Interfaces |
| Presenter: | Joerg Libuda, University Erlangen-Nuernberg, Germany |
| Authors: | M. Schwarz, University Erlangen-Nuernberg, Germany T. Xu, University Erlangen-Nuernberg, Germany S. Mohr, University Erlangen-Nuernberg, Germany C. Schuschke, University Erlangen-Nuernberg, Germany J. Libuda, University Erlangen-Nuernberg, Germany |
| Correspondent: | Click to Email |
Organic-oxide interfaces are at the heart of various emerging technologies, ranging from organic electronics to solar energy conversion. Their functionality arises from complex organic layers which are normally anchored to the oxide surface via specific linker groups. Typically, the anchoring groups release protons, thus forming surface hydroxyl groups. The role of these protons, the surface hydroxyl groups, and the interfacial water is one the most essential but, simultaneously, also one of the most poorly understood aspects in organic film formation.
We studied the interaction of water, carboxylic acids, and organic phosphonic acids with different cobalt oxide surfaces, namely Co3O4(111), CoO(111) and CoO(100), prepared in form of thin well-ordered films on Ir(100). The interaction of water with these surfaces is strongly structure-dependent and ranges from weak molecular adsorption on CoO(100) to the formation very strongly bound OH groups on Co3O4(111). Similarly, pronounced structure dependencies are observed upon anchoring of benzoic acid. Time-resolved and temperature-programmed vibrational spectroscopies with deuterated carboxylic acids indicate the formation of well-defined mixed adsorbate layers consisting of bridging benzoates and OD groups formed in the anchoring reaction. For phthalic acid, which may bind via one or via two linker groups, the adsorption geometry is controlled by the arrangement of the surface Co2+ ions. Organophosphonic acids, on the other hand, show a complex temperature-dependent anchoring behavior, which originates from the multiple adsorption geometries which these molecules can adopt. Finally, we investigated the anchoring behavior of larger organic species, such as carboxylated porphyrin derivatives, for which differently oriented phases can be observed by time-resolved in-situ spectroscopy during organic film growth in UHV. Intriguingly, the same reactions can also be monitored by in-situ vibrational spectroscopy at the solid/liquid interface on the same oxide surfaces prepared in UHV. We present first spectroscopic data, in which we directly compare these anchoring reactions in UHV and at the solid/liquid interface.
[1] K. Werner, S. Mohr, M. Schwarz, T. Xu, M. Amende, T. Döpper, A. Görling, J. Libuda, Journal of Physical Chemistry Letters 7, 555 (2016)
[2] T. Xu, M. Schwarz, K. Werner, S. Mohr, M. Amende, J. Libuda, Chemistry - A European Journal 15, 5384 (2016)
[3] T. Xu, M. Schwarz, K. Werner, S. Mohr, M. Amende, J. Libuda, Physical Chemistry Chemical Physics 18, 10419 (2016)