Structural Evolution of Stapes Controls the Electrochemical CO₂ Reduction on Bimetallic Cu-doped Gold Nanoclusters

Abstract

Ligand protected gold nanoclusters have been proposed for electrochemical CO2 reduction (eCO2R) as an alternative to polycrystalline catalysts, showing higher selectivity control due to the tailored composition and precise microenvironment. Here, two gold cluster families are studied with different staple motifs (Au25(SR)18 and Au144(SR)60, where SR = thiolate) doped with Ag or Cu to understand the interplay between the composition and the performance of these catalysts. Detailed cluster characterization and Density Functional Theory simulations demonstrate that the dynamic aspects involving ligand removal are crucial to unraveling the role of the dopant, the cluster curvature, and the staple structure. The best activity performance toward CO is obtained for Cu-doped Au144(SR)60 at U = -0.8 VRHE as ligands are only partially depleted and the staple can bend to stabilize *CO intermediate, while Cu-containing Au25(SR)18 can produce formate but shows worse CO selectivity. This study points toward the importance of ligand stability during eCO2R on bimetallic gold nanoclusters, paving the way for improving the design and operation of this family of catalysts.