Atomic-level structural precision and dynamic control of metal clusters during catalytic processes remain great challenges. Herein, Cu-W₄₈/CNNS single cluster catalyst was fabricated by dispersing wheel-shaped [(Cu(H₂O))₂[Cu₄(OH)₄(H₂O)₈]₂P₈W₄₈O₁₈₄]^28- (Cu-W₄₈) polyoxometalate (POM) onto carbon nitride nanosheets (CNNS). The tetranuclear copper cluster [Cu₄(OH)₄(H₂O)₈] (Cu₄) consists of two binuclear copper units [Cu₂(OH)₂(H₂O)₄] (Cu₂). Encapsulated within the POM cavity, the Cu₄ cluster demonstrates exceptional catalytic performance toward molecular oxygen activation, achieving highly selective monooxygenation of cyclohexene to epoxycyclohexane with unprecedented efficiency (96.5% yield and 97.6% selectivity). Notably, the single-cluster catalyst exhibits remarkable performance across diverse monooxygenation reactions, including epoxidation, aromatic hydrocarbon oxidation and thiooxidation. This work provides new insights into the rational design of atomic-precision multinuclear metal cluster catalysts by precisely integrating transition-metal-oxo clusters into the cavities of monodispersed POMs.

The nanoparticles (NPs) of Ni with different sizes endows its distinctive physical and chemical properties, which represents a typical strategy for the development of high-performance catalysts. However, the size effect of metallic Ni-NPs on electrocatalytic performance remains ambiguous. Herein, the Ni-NPs with different sizes supported on nitrogen doped carbon (NC) has been synthesized by controlling the pyrolysis temperature, leading to the synthesis of Ni@NC-500 (8.3 nm), Ni@NC-280 (1.9 nm) and Ni@NC-200 (1.0 nm). The electrooxidation of benzyl alcohol (BA) over these nanocatalysts shows the yield of benzoic acid was 99%, 82%, 55% on Ni@NC-280, Ni@NC-200 and Ni@NC-500, respectively. The experimental and theoretical simulation demonstrate that the difference in the adsorption strength of reactant molecules by Ni-NPs is responsible for their different performance, where the Ni@NC-280 exhibits an optimal adsorption configuration between Ni@NC-280 electrode and BA. This work provides a new angle for designing and synthesizing efficient electrocatalysts, which may be extended to the exploration of various promising electrocatalytic systems.