Ultrastable Copper Superatom

Atomically coinage metal nanoclusters are highly attractive for various applications including catalysis, photochemistry, and energy conversion. While Cu nanoclusters are low cost, their development has lagged behind that of Au and Ag counterparts due to their inherent instability primarily caused by the low Cu(I)/Cu(0) reduction potential. Therefore, the synthesis of stable Cu(0)-containing nanoclusters remains a formidable challenge. Herein, we report the first 6-electron superatomic copper nanocluster, [Cu₄₅H₆(C≡CR)₁₈(OAc)₁₅] (Cu₄₅). This cluster has remarkable stability, being resistant to thermal, oxidative, reductive, acidic, and basic treatments. Single-crystal X-ray diffraction analysis and time-dependent DFT calculations reveal that the outstanding stability of Cu₄₅ is attributed to its superatomic electronic configuration (1S²1P⁴) and strong copper-ligand interactions. Furthermore, Cu₄₅ is the first well-defined Cu superatom electrocatalyst used for CO₂-to-C₂H₄ electrocatalysis, which exhibits outstanding performance with a maximum Faradaic efficiency for C₂₊ products of 81.8% (58% for ethene), surpassing all known copper cluster catalysts. In situ ATR-SEIRAS and theoretical calculations reveal that Cu₄₅ effectively activates CO₂ and promotes C-C coupling, thereby facilitating the formation of C₂₊ products. This work provides new insights into the design of robust Cu nanoclusters for electrocatalytic applications, enabling their broader application in future research and technology development.