High-temperature oxidation and reduction of the inverse ceria/Cu(111) catalyst characterized by LEED, STM, nc-AFM and KPFM - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Journal of Physics: Condensed Matter Année : 2021

High-temperature oxidation and reduction of the inverse ceria/Cu(111) catalyst characterized by LEED, STM, nc-AFM and KPFM

Résumé

The inverse catalyst 'cerium oxide (ceria) on copper' has attracted much interest in recent time because of its promising catalytic activity in the water-gas-shift reaction and the hydrogenation of CO 2. For such reactions it is important to study the redox behaviour of this system, in particular with respect to the reduction by H 2. Here, we investigate the high-temperature O 2 oxidation and H 2 reduction of ceria nanoparticles (NP) and a Cu(111) support by low energy electron diffraction (LEED), scanning tunnelling microscopy (STM), noncontact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM). After oxidation at 550°C, the ceria NPs and the Cu(111) support are fully oxidized, with the copper oxide exhibiting a new oxide structure as verified by LEED and STM. We show that a high H2 dosage in the kilo Langmuir range is needed to entirely reduce the copper support at 550°C. A work function (WF) difference of Dφ rCeria/Cu-Cu ≈-0.6 eV between the ceria NPs and the metallic Cu(111) support is measured, with the Cu(111) surface showing no signatures of separated and confined surface regions composed by a CuCe alloy. After oxidation, the WF difference is close to zero (Dφ Ceria/Cu-Cu ≈-0.1. .. 0 eV), which probably is due to a WF change of both, ceria and copper.
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Dates et versions

hal-03399014 , version 1 (23-10-2021)

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Ali El Barraj, Baptiste Chatelain, Clemens Barth. High-temperature oxidation and reduction of the inverse ceria/Cu(111) catalyst characterized by LEED, STM, nc-AFM and KPFM. Journal of Physics: Condensed Matter, 2021, ⟨10.1088/1361-648X/ac26f9⟩. ⟨hal-03399014⟩
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