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.

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.