Single Atom Substituents in Copper Surfaces May Adsorb Multiple CO Molecules

TL;DR

This study reveals that single atom substituents in copper surfaces can adsorb multiple CO molecules, affecting magnetic and structural properties, which has implications for CO2 electroreduction catalysis.

Contribution

It demonstrates that multiple CO molecules can bind to substitutional metal atoms in copper, challenging the single-molecule adsorption assumption used in prior screening methods.

Findings

Multiple CO molecules bind to substitutional metal atoms in copper.

Binding energies vary with different metal atoms, decreasing for Fe, Co, Ni and increasing for V, Cr, Mn.

CO adsorption significantly alters magnetic moments and atomic positions.

Abstract

Copper is a good CO2 electroreduction catalyst as products beyond CO form, but efficiency and selectivity is low. Experiments have shown that admixture of other elements can help, and computational screening studies have pointed out various promising candidates based on the adsorption of a single CO molecule as a descriptor. Our calculations of CO adsorption on surfaces where a first row transition metal atom replaces a Cu atom show that multiple CO molecules, not just one, bind to the substitutional atom. For Fe, Co, and Ni atoms, a decrease in binding energy is found, but the reverse trend, namely increasing bond strength, is found for V, Cr, and Mn and the first three CO molecules. Magnetic moment, charge, and position of the substitutional atom are also strongly affected by the CO adsorption in most cases. Magnetic moment is stepwise reduced to zero, and the outward displacement of the substitutional atom increased.