Au growth on semiconductor nanorods: Photoinduced versus thermal growth mechanisms

Gabi Menagen, Janet E. Macdonald, Yossi Shemesh, Inna Popov, Uri Banin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

189 Scopus citations

Abstract

Gold growth on CdS nanorods and on seeded CdSe/CdS nanorods with and without illumination at different temperatures was studied. Two competing mechanisms were identified: thermal and light-induced growth. The thermal mechanism leads to growth of small gold particles at defects along the rod body and can be suppressed at lower temperatures. This control is attributed to a phase transition of the alkyl chains of the surface amine ligands to a static phase at lower temperatures, blocking the Au precursor's access to the nanorod surfaces. While a long-chain (C18) amine shows effective blocking at 293 K, a shorter chain (C12) amine shows the same result only at 273 K; however, in the case of a bulky trialkylamine, defect growth was observed even at 273 K. Light-induced growth leads to selective deposition of gold on one end of the rods. The tip was shown to grow on sulfur-rich facets of the nanorod, producing end-on and angled tip orientations. Growth under illumination with decreased temperature provides a highly selective synthesis of hybrid semiconductor nanorods with a single gold tip. Such anisotropic semiconductor-metal hybrids are of interest for self-assembly and photocatalysis and as building blocks in optoelectronic devices.

Original languageAmerican English
Pages (from-to)17406-17411
Number of pages6
JournalJournal of the American Chemical Society
Volume131
Issue number47
DOIs
StatePublished - 2 Dec 2009

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