One-step rapid synthesis, crystal structure and 3.3 microseconds long excited-state lifetime of Pd₁Ag₂₈ nanocluster

Doping foreign atom(s) in metal nanoclusters is an effective strategy to engineer the properties and functionalities of metal nanoclusters. However, until now, to dope Pd atom into Ag nanoclusters remains a huge challenge. Here we develop a one-step rapid method to synthesize the Pd-doped Ag nanocluster with high yield. The prepared Pd₁Ag₂₈ nanocluster was characterized by mass spectroscopy, X-ray photoelectron spectroscopy, X-ray crystallography, fluorescence spectroscopy, ultraviolet-visible absorption spectroscopy and transient absorption spectroscopy. The nanocluster exhibits a perfect face-centered cubic (FCC) kernel structure with a tetrahedron-like shell. Of note, Pd₁Ag₂₈ nanocluster had an unexpectedly long excited-state lifetime of 3.3 microseconds, which is the longest excited-state lifetime for Ag-based nanoclusters so far. Meanwhile, the excellent near-infrared luminescence indicated the nanocluster has the potential in fluorescent bio-imaging. Besides, it was revealed that Pd₁Ag₂₈ nanocluster could be transformed into Au₁Ag₂₈ nanocluster via ion exchange reaction of AuPPh₃Cl with Pd₁Ag₂₈ nanocluster. This work provides an efficient synthetic protocol of alloy nanoclusters and will contribute to study the effect of foreign atom on the properties of metal nanoclusters.