Precise control of alloying sites of bimetallic nanoclusters via surface motif exchange reaction.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 29146983.
- Also identified by DOI 10.1038/s41467-017-01736-5 and PMC identifier 5691201.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Precise control of alloying sites has long been a challenging pursuit, yet little has been achieved for the atomic-level manipulation of metallic nanomaterials. Here we describe utilization of a surface motif exchange (SME) reaction to selectively replace the surface motifs of parent [Ag<sub>44</sub>(SR)<sub>30</sub>]<sup>4-</sup> (SR = thiolate) nanoparticles (NPs), leading to bimetallic NPs with well-defined molecular formula and atomically-controlled alloying sites in protecting shell. A systematic mass (and tandem mass) spectrometry analysis suggests that the SME reaction is an atomically precise displacement of SR-Ag(I)-SR-protecting modules of Ag NPs by the incoming SR-Au(I)-SR modules, giving rise to a core-shell [Ag<sub>32</sub>@Au<sub>12</sub>(SR)<sub>30</sub>]<sup>4-</sup>. Theoretical calculation suggests that the thermodynamically less favorable core-shell Ag@Au nanostructure is kinetically stabilized by the intermediate Ag<sub>20</sub> shell, preventing inward diffusion of the surface Au atoms. The delicate SME reaction opens a door to precisely control the alloying sites in the protecting shell of bimetallic NPs with broad utility.