AVS 63rd International Symposium & Exhibition
    Surface Science Monday Sessions
       Session SS+AS+HC-MoA

Invited Paper SS+AS+HC-MoA3
Structure and Reactivity of Model Iron Oxide Surfaces

Monday, November 7, 2016, 2:20 pm, Room 104E

Session: Metals, Alloys, and Oxides: Reactivity and Catalysis
Presenter: Gareth Parkinson, TU Wien, Austria
Correspondent: Click to Email

Iron oxides are abundant in nature and extensively utilized in modern technologies including heterogeneous catalysis [1]. Magnetite (Fe3O4), for example, is the active phase of the industrial water-gas shift catalyst, while hematite (Fe2O3) is used as the photoanode for photoelectrochemical water splitting. In this talk I will discuss our recent investigations of the Fe3O4(100) and Fe2O3(1-102) surfaces using a combined experiment/theory approach. The Fe3O4(100) surface forms a reconstruction based on an ordered array of subsurface cation vacancies that contains exclusively Fe3+, and is relatively inert [2]. Although formic acid adsorbs dissociatively at regular lattice sites [3], methanol adsorption is restricted to defects containing Fe2+ [4]. The bulk of the talk will focus on a detailed study of water adsorption on Fe3O4(100) by TPD, STM, XPS, UPS, DFT+U and molecular dynamics calculations. In the remaining time I will demonstrate that a bulk terminated Fe2O3(1-102) surface can be prepared by annealing in 10-6 mbar O2, and a reduced (2x1) surface forms rapidly when heating in UHV. The structure of the (2x1) reconstruction and its reactivity toward water will be discussed.

[1] G.S. Parkinson, Iron oxide surfaces, Surface Science Reports (2016), http://dx.doi.org/10.1016/j.surfrep.2016.02.001

[2] R. Bliem, E. McDermott, P. Ferstl, M. Setvin, O. Gamba, J. Pavelec, M.A. Schneider, M. Schmid, U. Diebold, P. Blaha, L. Hammer, G.S. Parkinson, Subsurface Cation Vacancy Stabilization of the Magnetite (001) Surface, Science 346 (2014) 1215-1218.

[3] O. Gamba, H. Noei, J. Pavelec, R. Bliem, M. Schmid, U. Diebold, A. Stierle, G.S. Parkinson, Adsorption of Formic Acid on the Fe3O4(001) Surface, The Journal of Physical Chemistry C 119 (2015) 20459-20465.

[4] O. Gamba, J. Hulva, J. Pavelec, R. Bliem, M. Schmid, U. Diebold, G.S. Parkinson, The role of surface defects in the adsorption of methanol on Fe3O4(001), Topics in Catalysis submitted (2016).