Shell or Dots − Precursor Controlled Morphology of Au–Se Deposits on CdSe Nanoparticles

• Published in: Chemistry of materials 2016-04, Vol.28 (8), p.2704-2714
• Main Authors: de la Cueva, Leonor, Meyns, Michaela, Bastús, Neus G, Rodríguez-Fernández, Jonathan, Otero, Roberto, Gallego, José M, Alonso, Concepción, Klinke, Christian, Juárez, Beatriz H
• Format: Article
• Language: English
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.6b00287

The most prevalent image of the morphology of Au–CdSe hybrid nanoparticles (HNPs) is that of dumbbells or matchsticks with CdSe nanoparticles (NPs) acting as seed material onto which spherical Au dots are deposited. On the basis of a system with only three reaction components, CdSe seeds, n-dodecyltrimethylammonium bromide-complexed AuCl3, and dodecanethiol, we demonstrate how the morphology of the Au deposits on the semiconductor NPs, either in the form of dots on the vertices or in the form of a shell around the NP surface, can be determined by controlling the oxidation state of the metal precursor. Furthermore, we apply X-ray photoelectron spectroscopy to show that the resultant deposits are composed of partially oxidized Au, corresponding to a Au–Se compound regardless the deposit morphology. To obtain a detailed characterization of the HNPs with different morphologies and to gain mechanistic insights into the deposition process, (cryogenic) high-resolution transmission electron microscopy, mass spectrometry, cyclic voltammetry, and computational simulations have been performed. Our results emphasize that the knowledge of the surface chemistry of the seed particles as well as a defined picture of the metal precursors is necessary to understand heterodeposition processes.