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

Abstract

ABSTRACT 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 CO 2 RR toward high‐value hydrocarbons. Two Cu 7 NCs protected by tridentate N‐heterocyclic carbene (NHC) ligands with distinct functional groups on the remote benzimidazole ring, NHC H ‐Cu 7 and NHC Me ‐Cu 7 , were synthesized via a green and efficient ball‐milling approach. The main product obtained with NHC Me ‐Cu 7 is CO, with a selectivity of 82.8%, whereas the Faradaic efficiency (FE) for hydrocarbon production using NHC H ‐Cu 7 is 74.0%, affording 50.4% CH 4 and 23.6% C 2 H 4 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 ‐Cu 7 compared to that in NHC Me ‐Cu 7 , 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.