Defect engineering serves as a pivotal strategy for improving the performance of CO₂ electrocatalytic reduction (CO₂RR). However, understanding the structure-activity relationship between defect configurations and catalytic activity at the atomic level remains a significant challenge. This study utilized a series of structurally well-defined Au₁Ag_24+2n(SR)_18+n (where n = 0, 1, 2; SR = adamantanethiol) nanoclusters as model catalysts to systematically explore the impact of defect engineering on CO₂RR. In the Au₁Ag₂₆ nanocluster, rearrangement of the peripheral ligands creates structural defects, which increases the exposure of the active surface area. This defect engineering leads to optimal catalytic performance, achieving a Faradaic efficiency (FE) for CO of 63% at −1.0 V (vs. RHE)—nearly double that of Au₁Ag₂₄, which has an FE of 32%. In contrast, due to the surface units of Au₁Ag₂₈ being fully covered, its catalytic activity is negligible (FE_CO < 5%). By integrating comprehensive structural characterization with electrocatalytic performance analysis, we have demonstrated at the atomic level that the Ag₁S₃ motif acts as the possible catalytic active center, with catalytic performance exhibiting a direct correlation with the degree of active site exposure. This research uncovers the fundamental mechanism by which defect engineering enhances CO₂RR catalyst performance by reconstructing the coordination environment and strategically exposing active sites of cluster-based catalysts.

The lack of effective charge transfer driving force and channel limits the electron directional migration in nanoclusters (NC)-based heterostructures, resulting in poor photocatalytic performance. Herein, a Z-scheme NC-based heterojunction (Pt₁Ag₂₈-BTT/CoP, BTT = 1,3,5-benzenetrithiol) with strong internal electric field is constructed via interfacial Co–S bond, which exhibits an absolutely superiority in photocatalytic performance with 24.89 mmol·h⁻¹·g⁻¹ H₂ production rate, 25.77% apparent quantum yield at 420 nm, and ~ 100% activity retention in stability, compared with Pt₁Ag₂₈-BDT/CoP (BDT = 1,3-benzenedithiol), Ag₂₉-BDT/CoP, and CoP. The enhanced catalytic performance is contributed by the dual modulation strategy of inner core and outer shell of NC, wherein, the center Pt single atom doping regulates the band structure of NC to match well with CoP, builds internal electric field, and then drives photogenerated electrons steering; the accurate surface S modification promotes the formation of Co–S atomic-precise interface channel for further high-efficient Z-scheme charge directional migration. This work opens a new avenue for designing NC-based heterojunction with matchable band structure and valid interfacial charge transfer.

Understanding the assembly pattern of metal nanoclusters in crystalline units at the atomic level is crucial for an in-depth understanding of their supramolecular interactions and structure–property correlations. In this study, two Au₉Ag₆ nanoclusters bearing a similar framework were controllably synthesized and structurally determined. By tailoring the peripheral thiol ligands from SPh^pOMe to SPh^oMe (HSPh^pOMe = 4-methoxythiophenol, HSPh^oMe = 2-methylbenzenethiol), the hierarchical assembly of cluster molecules in their superlattice varied from “ABAB” to “ABCDABCD”. Based on the atomically precise structures of the two nanoclusters, we proposed that such differences in crystalline packing modes resulted from a combination of their structural differences, including intramolecular coordination preferences (Au–P vs. Ag–Cl), steric hindrance effects of thiol ligands (SPh^pOMe vs. SPh^oMe), and intra-/inter-cluster interactions (C–H···π, π···π, and H···H). We also investigated the structure/assembly-dependent optical properties of the two clusters at different states and rationalized the obtained structure–property correlations at the atomic level. Moreover, this study presented an interesting case for analyzing the hierarchical assembly of metal nanoclusters, allowing an in-depth understanding of the ligand effect on the crystalline assemblies of metal nanoclusters with atomic precision.