Visualizing the gas-sensitive structure of the CuZn surface in methanol synthesis catalysis

• Published in: Nature communications Vol. 15; no. 1; p. 3865
• Main Authors: Jensen, Sigmund, Mammen, Mathias H. R., Hedevang, Martin, Li, Zheshen, Lammich, Lutz, Lauritsen, Jeppe V.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 08-05-2024; Nature Publishing Group; Nature Portfolio
• Subjects: 140/146; 147/138; 639/638/542/968; 639/638/77/886; 639/638/77/887; 639/766/119/544; Carbon dioxide; Carbon monoxide; Catalysis; Catalysts; Chemical synthesis; Copper; Electrons; Experiments; Gas composition; Gas mixtures; Humanities and Social Sciences; Hydrogenation; Image resolution; Methanol; Microscopy; Morphology; multidisciplinary; Nanoparticles; Photoelectron spectroscopy; Photoelectrons; Scanning tunneling microscopy; Science; Science (multidisciplinary); Spectrum analysis; Surface alloying; X ray photoelectron spectroscopy; Zinc; Zinc oxide
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-48168-6

Methanol formation over Cu/ZnO catalysts is linked with a catalytically active phase created by contact between Cu nanoparticles and Zn species whose chemical and structural state depends on reaction conditions. Herein, we use variable-temperature scanning tunneling microscopy at elevated pressure conditions combined with X-ray photoelectron spectroscopy measurements to investigate the surface structures and chemical states that evolve when a CuZn/Cu(111) surface alloy is exposed to reaction gas mixtures. In CO
2
hydrogenation conditions, Zn stays embedded in the CuZn surface, but once CO gas is added to the mixture, the Zn segregates onto the Cu surface. The Zn segregation is CO-induced, and establishes a new dynamic state of the catalyst surface where Zn is continually exchanged at the Cu surface. Candidates for the migrating few-atom Zn clusters are further identified in time-resolved imaging series. The findings point to a significant role of CO affecting the distribution of Zn in the multiphasic ZnO/CuZn/Cu catalysts.
Industrial methanol synthesis uses materials based on Cu and ZnO. We present high-resolution imaging of active surfaces which reveals how Zn species are transported at the active Cu interface in diffusion processes controlled by the reactant gas composition.