Breaking Scaling Relations for Enhanced Electrochemical CO₂ Reduction to CO by Introducing Soft Metal Dopants to Thiolates-Protected Coinage Metal Nanoclusters

Density functional theory calculations are employed to investigate the effects of various metal dopants on thiolates-protected transition metal nanoclusters (NCs) for CO₂ reduction, focusing on deviations from the linear scaling relation between COOH* and CO* for high CO selectivity. We first explore the most favorable positions for different dopants in several M₂₅ (M=parent metal) NCs and assess the potential for ligand removal under reducing conditions. Furthermore, we construct an activity volcano for CO production in D₁M₂₄ (D=dopant) NCs, revealing that NCs composed of coinage parent metals with group 12 metal dopants exhibit the most significant deviation from the scaling relation. This behavior is attributed to the tendency of these NCs to bind COOH* in a bidentate form, which stabilizes the O atom of COOH* through interactions with the oxyphilic dopants. As a result, several group 12 metal doped coinage metal NCs are identified as new promising candidates for syngas production due to their high activity towards both CO and H₂ production.