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.