| AVS 66th International Symposium & Exhibition | |
| Complex Oxides: Fundamental Properties and Applications Focus Topic | Tuesday Sessions |
| Session OX-TuP |
| Session: | Complex Oxides: Fundamental Properties and Applications Poster Session |
| Presenter: | Constantin Walenta, Harvard University |
| Authors: | C.A. Walenta, Harvard University F. Xu, Harvard University W. Chen, Harvard University C.R. O'Connor, Harvard University C.M. Friend, Harvard University |
| Correspondent: | Click to Email |
The surface composition and structure of reducible oxides, including oxides of Fe, are complex and difficult to control because of the mobility and multiple oxidation states of cations. The magnetite phase of iron oxide is a material with a complex structure and controversial surface terminations that is widely used in heterogeneous catalysis, including the water gas shift reaction and formaldehyde synthesis.
A new, unique termination of oxygen adatoms forms on top of Fe3O4(111) film on a α-Fe2O3(0001) single crystal in oxygen-deficient environments. By using a combination of chemical and activity analysis (XPS and TPRS), structure analysis (STM and LEED) and DFT calculations, we identify the atomic structure of the as-prepared Fe3O4(111) surface and distinguish electronic structure of oxygen adatom and uncovered iron sites. The latter is an active Lewis site for alcohol dissociation at room temperature. Further oxidation of the alkoxy intermediate to the aldehyde occurs at 700 K, and the surface fully recovers after product desorption.
The work establishes a clear understanding of a unique magnetite surface and provides insights in the selective oxidation of alcohols on iron oxide-based catalysts and a rare direct observation of oxygen mobility in iron-oxide based materials.