Insight into the Mechanism of Single-Metal-Atom Tailoring on theSurface of Au-Cu Alloy Nanoclusters

Tailoring the surface structure of nanomaterials is desirable for investigatingtheir mechanisms and properties from a nanochemistry perspective. The modification of thesurface of metal nanoparticles with a single metal atom has proven difficult, which hashindered the understanding of the contribution of different motifs in nanoclusters to theirproperties. Herein, we report single-metal-atom surface tailoring by thermally etching thenanocluster AuxCu15-x(DPPMH)3(SPhCl2)9(x= 8 or 9) to obtainAuxCu16-x(DPPMH)2(DPPM)(SPhCl2)9(x= 9 or 10) nanoclusters. An Au7Cu4core wasobserved in both nanoclusters, which can be regarded as part of an icosahedron. Experimentsand theoretical simulations revealed the tailoring processes of the icosahedron. Bothnanoclusters displayed an NIR-II emission, and the introduction of the surface metal atomled to a red-shift in the emission band from 983 to 1025 nm. This work contributes to thedevelopment of precisely tailored nanocluster structures and provides an understanding ofstructure-property correlations.