Multidisciplinary Investigation of the Structural and Electronic Properties of the Pt/$\gamma $-Al$_{\mathrm{2}}$O$_{\mathrm{3}}$ interface

Pt/$\gamma $-Al$_{\mathrm{2}}$O$_{\mathrm{3}}$ is arguably the most important heterogeneous catalyst system. Despite the numerous studies on this system, the detailed structural and electronic properties of this interface remain uncertain. Through controlled oxidation of NiAl (110), we were able to obtain single crystalline Pt/$\gamma $-Al$_{\mathrm{2}}$O$_{\mathrm{3}}$ thin films. We also prepared Pt/$\gamma $-Al$_{\mathrm{2}}$O$_{\mathrm{3}}$ samples. STEM observations show that use of cryo-electron microscopy techniques prevented electron-beam damage, including direct sample damage, and changes in the EELS oxygen K pre-peak (\textasciitilde 532 eV). The oxygen K pre-peak was consistently present in spectra taken at the Pt/$\gamma $-Al$_{\mathrm{2}}$O$_{\mathrm{3}}$ interface at cryo-temperatures, but not in those acquired at room temperature. The theoretically calculated EELS oxygen K signals for the Pt on (110) Pt/$\gamma $-Al$_{\mathrm{2}}$O$_{\mathrm{3}}$ exhibited a similar pre-peak at 532 eV correlating to the experimental EELS oxygen K data, and we attribute to this feature to the formation of Pt-O complex. This points out an important factor in understanding the reactivity of this catalysis.