Gold-based catalysts are promising in CO preferential oxidation (CO-PROX) reaction in H₂-rich stream on account of their high intrinsic activity for CO elimination even at ambient temperature. However, the decrease of CO conversion at elevated temperature due to the competition of H₂ oxidation, together with the low stability of gold nanoparticles, has posed a dear challenge. Herein, we report that Au-Cu bimetallic catalyst prepared by galvanic replacement method shows a wide temperature window for CO total conversion (30–100 °C) and very good catalyst stability without deactivation in a 200-h test. Detailed characterizations combined with density functional theory (DFT) calculation reveal that the synergistic effect of Au-Cu, the electron transfer from Au to Cu, leads to not only strengthened chemisorption of CO but also weakened dissociation of H₂, both of which are helpful in inhibiting the competition of H₂ oxidation thus widening the temperature window for CO total conversion.

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.

In order to understand the structure–property correlation and explore the application of metal nanoclusters, it is important and intriguing to determine their crystal structure and obtain high-yield. At the same time, this is also a challenge in nanoscience and technology. Here, we report the highly efficient synthesis of Pt₁Ag₂₈ nanocluster via one-pot chemical wet method. The crystal structure of Pt₁Ag₂₈ nanocluster was determined by X-ray crystallography to be a face centered cubic (FCC) kernel. This novel structure is the structural isomerization of Pt₁Ag₂₈ nanocluster reported before. This phenomenon is first discovered in the synthesis of alloy nanoclusters. In addition, Pt₁Ag₂₈ nanocluster has high yield and exhibits potential optics in the near infrared (NIR) fluorescent imaging. The time-dependent density functional theory (TD-DFT) calculation implied that the optical property of Pt₁Ag₂₈ was sensitive to its structure. This work provides a simple method to synthesize alloy nanoclusters with structural isomerization.