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.