Remotely Tuning the Electronic Structures of Cu Site Over N‐Heterocyclic Carbene‐Protected Cu ₇ Nanocluster for Steering CO ₂ Electroreduction to Hydrocarbons

In this study, a remote-control strategy for tuning the electronic structures of atomically precise Cu nanoclusters (Cu NCs) was developed, aiming to enhance the selectivity of the CO₂RR toward high-value hydrocarbons. Two Cu₇ NCs protected by tridentate N-heterocyclic carbene (NHC) ligands with distinct functional groups on the remote benzimidazole ring, NHC^H-Cu₇ and NHC^Me-Cu₇, were synthesized via a green and efficient ball-milling approach. The main product obtained with NHC^Me-Cu₇ is CO, with a selectivity of 82.8%, whereas the Faradaic efficiency (FE) for hydrocarbon production using NHC^H-Cu₇ is 74.0%, affording 50.4% CH₄ and 23.6% C₂H₄ at -1.5 V versus the reversible hydrogen electrode (RHE). Comprehensive theoretical calculations and operando spectroscopic analyses demonstrate that the effect of the remote substituent on the NHC ligand provides a greater population of active electrons in the highest occupied d-orbital of NHC^H-Cu₇ compared to that in NHC^Me-Cu₇, thus effectively regulating the binding strength of the *CO intermediate. This in turn promotes stabilization and further activation of the intermediate, ultimately steering the product selectivity from CO toward targeted hydrocarbons. This study establishes an atomic-level paradigm for ligand engineering of Cu NCs, enabling remote tuning of the electronic structure of the active sites to realize highly selective hydrocarbon generation.