Crystallographic Orientation Dependence of Surface Segregation and Alloying on PdCu Catalysts for CO2Hydrogenation

Lukas Pielsticker, Ioannis Zegkinoglou, Zhong Kang Han, Juan J. Navarro, Sebastian Kunze, Osman Karslloǧlu, Sergey V. Levchenko, Beatriz Roldan Cuenya

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

The influence of the crystallographic orientation on surface segregation and alloy formation in model PdCu methanol synthesis catalysts was investigated in situ using near-ambient pressure X-ray photoelectron spectroscopy under CO2 hydrogenation conditions. Combined with scanning tunneling microscopy and density functional theory calculations, the study showed that submonolayers of Pd undergo spontaneous alloy formation on Cu(110) and Cu(100) surfaces in vacuum, whereas they do not form an alloy on Cu(111). Upon heating in H2, inward diffusion of Pd into the Cu lattice is favored, facilitating alloying on all Cu surfaces. Under CO2 hydrogenation reaction conditions, the alloying trend becomes stronger, promoted by the reaction intermediate HCOO*, especially on Pd/Cu(110). This work demonstrates that surface alloying may be a key factor in the enhancement of the catalytic activity of PdCu catalysts as compared to their monometallic counterparts. Furthermore, it sheds light on the hydrogen activation mechanism during catalytic hydrogenation on copper-based catalysts.

Original languageEnglish
Pages (from-to)2570-2575
Number of pages6
JournalJournal of Physical Chemistry Letters
Volume12
Issue number10
DOIs
Publication statusPublished - 18 Mar 2021

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