Computational and Experimental Elucidation of the Charge-Dependent Acid-Etching Dynamics and Electrocatalytic Performance of Au25(SR)18q(q = −1, 0, +1) Nanoclusters

Abstract

Using thiolate-protected Au₂₅(SR)₁₈ nanocluster (NC) with different charge states as the test candidate, how the charge effect affects the etching dynamics of thiolate ligands in acid and the electrocatalytic performance is explored. The ab initio molecular dynamics (AIMD) simulations revealed the charge-dependent reaction kinetics in acid, where the anionic and neutral Au₂₅(SCH₃)₁₈^q (q = −1, 0) favorably react with the acid and partially remove the thiolate ligands via two-step proton attack, while the cationic Au₂₅(SCH₃)₁₈⁺ NC is acid-resistant with no tendency for -SR removal. Density functional theory (DFT) calculations further predict that the dethiolated Au sites exhibit enhanced catalytic activity for CO₂ electroreduction to CO, with the anionic Au₂₅⁻ showing significantly superior activity. Acid etching and electrocatalytic experiments further confirmed partial removal of thiolate ligands in Au₂₅(SCH₃)₁₈^q (q = −1, 0), with dethiolated Au₂₅ NCs showing enhanced catalytic performance in CO₂ electroreduction, particularly Au₂₅⁻ exhibiting better activity than Au₂₅⁰. This work revealed an interesting charge state-mediated interface dynamics and electrocatalytic behaviors in Au₂₅ NCs, which can be applied to modulate the interface and catalytic properties of other atomically precise metal nanoclusters.