Adsorption of Multiple CO on Single Atom Substituents in Copper Alloy Surfaces
Magnus Christiansen a, Wei Wang b, Elvar Jónsson a, Giancarlo Cicero b, Hannes Jónsson a
a Science Institute and Faculty of Physical Sciences, University of Iceland, 107 Reykjavík, Iceland
b Department of Applied Science and Technology, Politecnico di Torino, Italy
Materials for Sustainable Development Conference (MATSUS)
Proceedings of MATSUS Fall 2024 Conference (MATSUSFall24)
#C&T - electrocat - Computational and theoretical electrocatalysis
Lausanne, Switzerland, 2024 November 12th - 15th
Organizers: Federico Calle-Vallejo and Max Garcia-Melchor
Poster, Magnus Christiansen, 395
Publication date: 28th August 2024

Copper is a promising catalyst for CO2 reduction reaction (CO2RR), as it enables the formation of various products beyond CO, such as ethylene. The advantage of copper over other unalloyed transition metals can be explained using a two parameter descriptor: the binding energy of a CO molecule versus that of a hydrogen atom on the catalyst surface. Copper is unique because the CO intermediate adsorbs strongly enough to undergo further reduction, while the hydrogen coverage remains low, limiting the hydrogen evolution reaction from dominating [1]. However, the efficiency and selectivity of copper are still insufficient for large scale practical applications. One approach, pursued by several researchers to improve copper’s performance, involves introducing other transition metals into the copper surface. This poster presents the results of density functional theory (DFT) calculations on the adsorption of CO on first- and second-row transition metal substitutional atoms that replace a copper atom in Cu(100) and Cu(111) surfaces. The calculations reveal that up to two, three, or four CO molecules can adsorb more strongly to the transition metal substituent atoms than to the unalloyed copper surface [2]. For most transition metals, the expected trend of decreasing differential binding energy is observed as more CO molecules adsorb. However, for V, Cr, and Mn, the reverse trend is seen for the first three adsorbed CO molecules. Thus, the adsorption energy of only the first CO molecule may not be a reliable descriptor for CO2RR. Additionally, the results indicate that the positions of the substituent atoms in the surface are strongly affected, with some being displaced by more than an Ångström, and others being pulled out of the surface at higher CO concentrations. These findings show that multiple CO adsorptions on the same atoms must be considered in computational screening studies of CO2RR on copper surfaces with substitutional atoms. In a broader context, similar trends may apply to other single-atom alloy catalysts.

This work was funded by the Icelandic Research Fund (grant no. 207283-053) and the EU’s Horizon 2021 programme under the Marie Skłodowska-Curie Doctoral Networks (MSCA-DN) grant agreement No 101072830 (ECOMATES).

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