Exposing Metal Centers in Carborane-Protected Copper Cluster Electrocatalysts

Carborane-ligand-protected metal clusters have garnered significant attention due to their exceptional stability, unique electronic properties, and well-defined atomic structures. However, their widespread catalytic applications are often hindered by the shielding of active sites by the bulky carborane ligands. Herin, we developed a mixed-ligand strategy by coassembling strong carboranylthiolate ligands with weak phosphine ligands. Carboranylthiolate ligands play a role in protecting the metal core, while phosphine ligands can easily fall off and expose the metal active sites. This dynamic ligand tuning enabled superior performance in the electrocatalytic nitrate reduction reaction (NO₃RR). The optimal Faradaic efficiency (FE) of the Ag₃Cu₂ cluster was 92.3 ± 0.5%, and the total FE was 99.2 ± 0.8% (NO₃^- → NO₂^-/NH₃). The dual-ligand system demonstrates a paradigm for balancing stability and activity in nanocatalysts. Beyond NO₃RR, this strategy offers a versatile approach to activate other carborane-protected clusters for diverse catalytic transformations, providing a generalizable framework for designing high-performance catalysts with precisely tunable active sites.