Controlled Growth of Gold Nanoparticles on Covellite Copper Sulfide Nanoplatelets for the Formation of Plate-Satellite Hybrid Structures

We present a novel, straightforward, and reproducible method to form tailored CuS@Au hybrid structures consisting of two-dimensional copper sulfide nanoplatelets and gold nanoparticles that are formed exclusively on the sides of the two-dimensional nanoplatelets. For the realization of these dual-plasmonic structures, covellite copper sulfide nanoplatelets are first prepared via a wet-chemical route. In the second step, these platelets react with tetrachloroauric(III) acid trihydrate, oleylamine, and oxalic acid dihydrate at room temperature under a nitrogen atmosphere and in the absence of light. By varying the amount of added gold(III) ions, not only the number and size but also the interparticle distance between the gold nanoparticles along the sides of the copper sulfide nanoplatelets can be tailored, which can influence the optical properties of the hybrid structures. A combination of scanning transmission electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy on the hybrid structures prepared at different reaction times allows for a detailed understanding of the underlying selective gold growth on the CuS nanoplatelets and also provides insights into the metal-semiconductor interface.