| AVS 63rd International Symposium & Exhibition | |
| Surface Science | Monday Sessions |
| Session SS+AS+HC-MoA |
| Session: | Metals, Alloys, and Oxides: Reactivity and Catalysis |
| Presenter: | Jan Hulva, Vienna University of Technology, Austria |
| Authors: | J. Hulva, Vienna University of Technology, Austria M. Meier, Universität Wien, Austria J. Pavelec, Vienna University of Technology, Austria S. Maaß, Vienna University of Technology, Austria R. Bliem, Vienna University of Technology, Austria M. Schmid, Vienna University of Technology, Austria U. Diebold, Vienna University of Technology, Austria C. Franchini, Universität Wien, Austria G.S. Parkinson, Vienna University of Technology, Austria |
| Correspondent: | Click to Email |
The interaction of water with metal-oxide surfaces is an important topic for a wide range of technological and environmental applications. This is particularly true for the iron oxides because of their abundance in nature and their use in chemical processes where water is involved e.g. the water-gas shift reaction [1]. Recent studies of water on iron oxide surfaces have found significant complexity, with evidence for pressure dependent adsorption, mixed-mode adsorption and coverage dependent hydrogen bonding [2-4]. Here we use a multi-technique experimental approach combined with ab-initio calculations including molecular dynamics to disentangle the coverage and temperature dependent behavior of water on the reconstructed Fe3O4(001)-(√2x√2)R45° surface [5].
Temperature programmed desorption shows that the first monolayer of water desorbs from the surface in four distinct peaks between 150 K and 250 K. Based on XPS, STM images and ab-initio calculations, we conclude that the first three peaks originate from molecular water desorbing from a coverage-dependent hydrogen-bonded network, while the last peak results from recombinative desorption from a partially dissociated water trimer species. Two additional desorption states at 340 K and 520 K are ascribed to desorption from surface defects and recombinative desorption of the surface surface hydroxyl groups, respectively.
[1] Parkinson, G.S., " Iron oxide surfaces", Surface Science Reports (2016)
[2] Dementyev, P., et al. "Water Interaction with Iron Oxides." Angew.Chem. Int. Ed. 54 (2015): 13942
[3] Mulakaluri, N., et al. "Partial dissociation of water on Fe3O4 (001): Adsorbate induced charge and orbital order." Phys. Rev. Lett. 103 (2009): 176102.
[4] Kendelewicz, T., et al. "X-ray photoemission and density functional theory study of the interaction of water vapor with the Fe3O4 (001) surface at near-ambient conditions." J. Phys. ChemC 117 (2013): 2719-2733.
[5] Bliem, R., et al. "Subsurface cation vacancy stabilization of the magnetite (001) surface." Science 346 (2014): 1215-1218.