Charge State and Chemical Reactivity of Single-Sized Silver Nanoclusters Supported on Organic Substrates

Silver (Ag) nanoclusters (NCs) exhibit superatomic behavior based on their total valence electrons, making them promising catalysts such as organic halogen reactions. Their miniaturization enhances reactivity by increasing surface area coupled with discrete electronic superatomic states. This study focuses on Agn NCs, particularly the closed-shell Ag20 superatom, to investigate their stability and reactivity when deposited on substrates pretreated with fullerene (C60) and hexa-tert-butyl-hexa-peri-hexabenzocoronene (HB-HBC). Using X-ray photoelectron spectroscopy and chemical reactivity assays with methyl iodide, we observed that Ag20 NCs on C60 exhibit lower reactivity compared to neighbors, consistent with their stable 20-electron closed-shell configuration. In contrast, Ag19 NCs on HB-HBC, likely in an anionic form, displayed unexpectedly higher reactivity compared to neighbors. This reactivity behavior may stem from structural changes induced by the HB-HBC substrate, as suggested by theoretical calculations. These findings highlight the influence of organic substrates on the catalytic behavior of Agn NCs, indicating that such substrates can facilitate charge transfer and structural modifications, thereby advancing the design of stable, reactive NC-based catalysts.