Vacancy-induced modulation of the interfacial properties of Au ₂₅ (SCH ₃ ) ₁₈ nanoclusters supported on defective graphene

Atomically precise metal nanoclusters (NCs) are frequently loaded onto various substrates for numerous catalytic applications, yet the interfacial interaction remains poorly understood. In this study, we performed ab initio molecular dynamics (AIMD) simulations to systematically investigate the interfacial dynamics of thiolated-protected Au₂₅(SR)₁₈ NCs on graphene substrates with varying vacancy defect sizes. The results revealed that when the vacancy defects feature a convex-shaped armchair edge, the vacancy edges would undergo severe reconstruction and reduce the substrate reactivity, which cannot effectively anchor the Au₂₅ NCs and induce high mobility on graphene. In contrast, when the vacancy defects feature a concave-shaped armchair edge, the present unsaturated sp² dangling bond imparts high reactivity to the vacancy edge, which enables strong chemical interaction with Au₂₅ and leads to facile and spontaneous removal of the staple Au-SCH₃ moiety from the protecting -S-Au-S-Au-S- motif. The etched Au₂₅ NCs with exposed active Au sites can efficiently facilitate the electrocatalytic CO₂ reduction to CO with moderate energy barriers. This work reveals the significant role of the defect edges of graphene in modulating the interfacial behavior of metal NCs, providing a promising strategy for regulating the interfacial and catalytic properties of atomically precise metal NCs.