Selective Interactions between Free-Atom-like d-States in Single-Atom Alloy Catalysts and Near-Frontier Molecular Orbitals

In the limit of dilute alloying-the so-called "single-atom alloy" (SAA) regime-certain bimetallic systems exhibit weak mixing between constituent metal wave functions, resulting in sharp, single-atom-like electronic states localized on the dilute component of the alloy. This work shows that when these sharp states are appropriately positioned relative to given molecular orbitals, selective hybridization is enhanced, in accordance with intuitive principles of molecular orbital theory. We demonstrate the phenomenon for activation pathways of crotonaldehyde, a model α,β-unsaturated aldehyde relevant to a wide range of chemical manufacturing. This analysis suggests new possible strategies for selectivity control in heterogeneous catalysis.