New Advances in Atomically Precise Silver Nanoclusters

Atomically precise noble metal nanoclusters are ultrasmall particles that are typically composed of tens to hundreds of metal atoms in the core (equivalent sizes 1–3 nm). This new class of nanomaterials is unique in that they are atomically precise and possess uniform structures, high stability, and attractive properties. Built on the significant success of Au nanoclusters, Ag nanoclusters have recently received increasing attention. The majority of reported silver nanocluster sizes exhibit molecular-like properties, whereas larger ones exhibit plasmons characteristic of metallic state (as opposed to molecular state in smaller sizes). Both molecular (i.e., nonmetallic) and metallic nanoclusters hold promise in a wide range of applications. To deepen the understanding of their physical and chemical properties, precise control over size and determination of the crystal structure are the top priorities. In recent developments, dozens of silver nanoclusters with definite formulas have been prepared through various strategies, albeit the structural determination still lags behind. In this short Review, we summarize the recent progress in ligand-protected silver nanoclusters, including the size-focusing synthetic methods, new sizes, structures, and properties.