In the limit of very dilute alloying—the so-called “single-atom-alloy” (SAA) regime—certain bimetallic systems exhibit weak mixing between constituent metal wavefunctions, 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 in energy 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, which can be representative of moieties in biomass feedstocks or derived from aldol condensation of acetaldehyde, a green product of CO2RR or biomass derived ethanol oxidation. The mechanistic understanding gathered can be used to steer selectivity towards highly synthetically valuable unsaturated alcohols. Mechanisms of selectivity control and the implications for experiment results will be discussed.

Steering selectivity with free-atom-like states on single atom alloys

ACS Spring 2022

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