Atomic-Precise Active Site Surgery on Carboranylthiolate-Protected Silver Nanocluster Catalysts

Although significant progress has been made in precisely modulating the composition and structure of metal nanoclusters to tailor their properties, the well-controlled synthesis of metal nanoclusters with unsaturated coordination environments and highly active sites to enhance the catalytic performance remains remarkably challenging. Here, we propose an atomic-level surgical strategy involving the stepwise creation and manipulation of active metal sites on metal nanoclusters. A newly constructed Ag₁₇P nanocluster, costabilized by carboranethiolate and phosphine ligands, features an Ag₁₃ icosahedral kernel capped by four tetrahedrally symmetrical silver atoms. Taking advantage of the phosphine ligands readily dissociating from the four peripheral silver atoms under solvent regulation, Ag₁₇P could transform into Ag₁₇ with four exposed silver atoms. Furthermore, site-specific substitution could be accomplished in these open metal sites through a judicious choice of heterometal, resulting in an isostructural Cu-doping Ag₁₃Cu₄ nanocluster. As a result, Ag₁₇ and Ag₁₃Cu₄ with exposed metal sites showed improved catalytic activities in electrocatalytic nitrate reduction reaction (NO₃RR) compared to Ag₁₇P, and Ag₁₃Cu₄ displayed superior performance with an optimal faradaic efficiency (FE) of 90.4 ± 0.2% for NH₃ production and a total FE of 99.6 ± 0.3%. This study not only offers a pathway for generating and manipulating open metal sites on metal nanoclusters but also provides new perspectives for the design and synthesis of efficient metal nanocluster-based catalytic materials.