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.

A³ coupling reaction is a three-component reaction widely used in pharmaceutical and is an important and practical method for constructing new C–N and C–C bonds. Here, two low-nuclear Cu₄Cl₂/C₃N₄ and Cu₂Cl₄/C₃N₄ catalysts were specifically designed for A³ coupling under mild conditions, with TON up to 8702.3 and 3461.8, respectively, much higher than reported catalysts. Additionally, we captured the key intermediate and confirmed its structures by electrospray ionization mass spectrometry (ESI-MS), revealing the halogen exchange process at the atomic level by experiments and density function theory (DFT) studies. These results increase our understanding of low-nuclear catalysts and provide guidance for the design and preparation of more efficient and targeted catalytic materials.

Metal-organic frameworks (MOFs) have emerged as superior hosting matrices for atomically precise nanoclusters (NCs) encapsulation, offering excellent physical and chemical protections for advanced catalysis. Nevertheless, the MOF coating significantly reduces the NC catalytic efficiency due to the diffusion barriers and the confined microenvironments. Herein, a hierarchically engineered MOF nanoreactor was constructed by controlled structural etching for NC immobilization. This nanoreactor possesses hierarchical pores to accelerate the diffusion rate of reactants and creates hollow structures to unleash the confined NC molecules from the rigid MOF network to a capacious microenvironment. The enhanced mass transfer, improved freedom of NCs, and outstanding stability collectively boosted the catalytic activity of the nanoreactor. By controlling the etching time, freestanding Pd₈@zeolitic imidazolate framework-8 (ZIF-8)-TA₁₀ displayed a catalytic efficiency that was 3.17 times greater than that of the initial confined Pd₈@ZIF-8 and even better than free Pd₈. This work opens a new strategy to reduce the inherent limitations of porous matrixes for developing high-performance 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.

Carbon-supported noble-metal-free single-atom catalysts (SACs) have aroused widespread interest due to their green chemistry aspects and excellent performances. Herein, we propose a “ligand regulation strategy” and achieve the successful fabrication of bifunctional SAC/MOF (MOF = metal–organic framework) nanocomposite (abbreviated NiSA/ZIF-300; ZIF = ZIF-8) with exceptional catalytic performance and robustness. The designed NiSA/ZIF-300 has a planar interfacial structure with the Ni atom, involving one S and three N atoms bonded to Ni(II), fabricated by controllable pyrolysis of volatile Ni-S fragments. For CO₂ cycloaddition to styrene epoxide, NiSA/ZIF-300 exhibits ultrahigh activity (turnover number (TON) = 1.18 × 10⁵; turnover frequency (TOF) = 9830 mol_SC·mol_Ni⁻¹·h⁻¹; SC = styrene carbonate) and durability at 70 °C under 1 atm CO₂ pressure, which is much superior to Ni complex/ZIF, NiNP/ZIF-300, and most reported catalysts. This study offers a simple method of bifunctional SAC/MOF nanocomposite fabrication and usage, and provides guidance for the precise design of additional original SACs with unique catalytic properties.

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.

Bimetallic nanocluster with atomic precision has gained widespread attention due to its unique synergism. The coreless Au₄Cu₅ bimetallic nanoclusters were selected as models to explore the relationship between their microstructure and performance, and compare with the coreless monometallic nanoclusters, core–shell nanoclusters, and single atom catalyst (SAC). The experimental results show that the coreless bimetallic nanocluster catalyst Au₄Cu₅/activated carbon (AC) exhibits high activity and stability in the Ullmann C–O coupling reaction, much higher than coreless monometallic nanoclusters (Au₁₁/AC and Cu₁₁/AC), core–shell nanoclusters (Au₂₅/AC, Cu₂₅/AC, and Au₁Cu₂₄/AC), and single atom catalysts (Au SAC and Cu SAC). Moreover, the coreless Au₄Cu₅/AC catalyst efficiently catalyzed the Ullmann C–O coupling of benzyl alcohol for the first time. This structure–activity relationship was successfully extended to other coreless bimetallic systems, such as Au₄Cu₄/AC nanocluster, and it is expected to provide new insights for the design of bimetallic catalysts with well-defined performance.

The redox property of the ultrasmall coinage nanoclusters (with several to tens of Au/Ag atoms) has elucidated the electron-transfer capacity of nanoclusters, and has been successfully utilized in a variety of redox conversions (such as from CO₂ to CO). Nevertheless, their biological applications are mainly restricted by the scarcity of atomically precise, water-soluble metal nanoclusters, and the limited application (mainly on the decomposition of H₂O₂ in these days). Herein, mercaptosuccinic acid (MSA) protected ultrasmall alloy AuAg nanoclusters were prepared, and the main product was determined [Au₃Ag₅(MSA)₃]⁻ by electrospray ionization mass spectrometry (ESI-MS). The clusters can not only mediate the decomposition of H₂O₂ to generate hydroxyl radicals, but is also able to mediate the reduction of nicotinamide adenine dinucleotide (NAD) to its reduced form of NADH. This is the first time that the atomically precise metal nanoclusters were used to mediate the coenzyme reduction. The preliminary mechanistic insights imply the reaction to be driven by the hydrogen bonding between the carboxylic groups (on the surface of MSA) and the amino N–H bonds (on NAD). In this context, the presence of the carboxylic groups, the sub-nanometer size regime (~ 1 nm), and the synergistic effect of the Au-Ag clusters are pre-requisite to the NAD reduction.

Metal nanoclusters (NCs) with precise structure and ultrasmall size have attracted great interests in catalysis. However, the poor stability has limited its large-scale use. Herein, we proposed the “covalence bridge” strategy to effectively connect atomically precise metal NCs and metal-organic frameworks. Benefiting from the covalent linkage, the synthesized UiO-66-NH₂-Au₂₅(L-Cys)₁₈ showed outstanding stability after 16 h photocatalysis. Moreover, the covalence bridge created a strong metal-support interaction between the two components and provided an effective charge transport channel and thereby enhanced photocatalytic activity. UiO-66-NH₂-Au₂₅(L-Cys)₁₈ displayed an exceptional photocatalytic H₂ production rate, which is 21 and 90 times higher than that of UiO-66-NH₂/Au₂₅(PET)₁₈ (made by physically combination) and bare UiO-66-NH₂, respectively. Thermodynamic and kinetic studies demonstrated that UiO-66-NH₂-Au₂₅(L-Cys)₁₈ exhibited higher charge transfer efficiency, lower overpotential of water reduction and activation energy barrier compared with its counterparts.

In catalysis, tuning the structural composition of the metal alloy is known as an efficient way to optimize the catalytic activity. This work presents the synthesis of compositional segregated six-armed PtCu nanostars via a facile solvothermal method and their distinct composition-structure-dependent performances in electrooxidation processes. The alloy is shown to have a unique six arms with a Cu-rich dodecahedral core, mainly composed of {110} facets and exhibit superior catalytic activity toward alcohols electrooxidation compared to the hollow counterpart where Cu was selectively etched. Density functional theory (DFT) calculations suggest that the formation of hydroxyl intermediate (OH*) is crucial to detoxify CO poisoning during the electrooxidation processes. The addition of Cu is found to effectively adjust the d band location of the alloy catalyst and thus enhance the formation of *OH intermediate from water splitting, which decreases the coverage of *CO intermediate. Our work demonstrates that the unique compositional anisotropy in alloy catalyst may boost their applications in electrocatalysis and provides a methodology for the design of this type catalyst.