(376bo) Stability of Ligand Protected Au Nanoclusters Under Electrochemical Reduction of CO2

Ligand-protected gold nanoclusters (NCs) are a novel class of particles that have attracted great interest in the field of catalysis due to their atomically precise structure, high surface area-to-volume ratio, and unique electronic structure. In particular, the anionic thiolate-protected Au₂₅ NC, [Au₂₅(SR)₁₈]^1-, with partially lost ligands, has been demonstrated to act as an active catalyst for the electrochemical reduction of CO₂^{1, 2}. However, the stability of this and other thiolate-protected NCs after partial ligand removal remains elusive. Using density functional theory (DFT) calculations and the recently developed thermodynamic stability model (TSM)³, we investigate the stability of [Au₂₅(SR)₁₈]^1-, [Au₁₈SR₁₄]⁰, [Au₂₃(SR)₁₆]^1-, and [Au₂₈(SR)₂₀]⁰ NCs when a single ligand (–R or –SR) is removed from the surface. Additionally, we examine the stability of the partially protected NCs upon the adsorption of CO₂ reduction reaction intermediates (H, CO, and COOH) on the S or Au active site generated after single –R or –SR ligand removal respectively. Our results reveal that the partially protected Au₂₅ NC shows the highest stability compared to the other partially protected NCs. Additionally, we find that the presence of the COOH intermediate on the Au or S active sites stabilizes the Au₂₅ NC as the removed ligand, which agrees with experimental observations on the stability of these NCs under electrochemical conditions. This study offers molecular level insights into the stability of ligand-protected gold NCs during the electrochemical reduction of CO₂ to CO.

1. S. Zhao, N. Austin, M. Li, Y. Song, S. D. House, S. Bernhard, J. C. Yang, G. Mpourmpakis and R. Jin, ACS Catalysis, 2018, 8, 4996-5001.
2. N. Austin, S. Zhao, J. R. McKone, R. Jin and G. Mpourmpakis, Catalysis Science & Technology, 2018, 8, 3795-3805.
3. M. G. Taylor and G. Mpourmpakis, Nat Commun, 2017, 8, 15988.