Hierarchical Assembly of High-Nuclearity Copper(I) Alkynide Nanoclusters: Highly Effective CO2 Electroreduction Catalyst toward Hydrocarbons

The pursuit of precision in the engineering of metal nanoparticle assemblies has long fascinated scientists, but achieving atomic-level accuracy continues to pose a significant challenge. This research sheds light on the hierarchical assembly processes of two high-nuclearity Cu(I) nanoclusters (NCs). By employing a multiligand cooperative stabilization strategy, we have isolated a series of thiacalix[4]arene (TC4A)/alkynyl coprotected Cu(I) NCs (Cu_x, where x = 9, 13, 17, 22). These NCs are intricately coassembled from the fundamental building units of {Cu₄(TC4A)} and alkynyl-stabilized Cu₅L₆ in various ratios. By capturing active anion templates such as O^2-, Cl^-, or C₂^2- that are generated in situ, we have further explored the secondary structural self-assembly of these clusters. Cu₁₃ serves as a secondary assembly module for constructing Cu₃₈ and Cu₄₃, which exhibit the highest nuclearity reported to date among Cu(I) NCs encased in macrocyclic ligands. Notably, Cu₃₈ demonstrates an impressive Faradaic efficiency of 62.01% for hydrocarbons at -1.57 V vs RHE during CO₂ electroreduction, with 34.03% for C₂H₄ and 27.98% for CH₄. This performance establishes it as an exceptionally rare, large, atomically precise metal NC (nuclearity >30) capable of catalyzing the formation of highly electro-reduced hydrocarbon products. Our research has introduced a new approach for constructing high-nuclearity Cu(I) NCs through a hierarchical assembly method and investigating their potential in the electrocatalytic transformation of CO₂ into hydrocarbons.