Size controlled gold tip growth onto II–VI nanorods

Abstract

Gold tip size and multiplicity is controlled in hybrid gold-semiconductor nanorods (CdS-Au, CdSe-Au and CdTe-Au) in fast reaction times of less than 2 minutes by optimising precursor type, concentration, and temperature. Controllable gold tips up to as large as 40 nm on a rod diameter of 7 nm are reported with the tip size shown to be directly related to the redox potentials of the 10 dangling atoms on the nanorod and the gold chloride precursors (mono or trivalent). The preference for symmetric (both ends) over asymmetric (single end) is achieved by simply elevating the reaction temperature to 80ºC without changing the reaction time. TEM and XRD analysis were preformed to verify both the gold nanoparticle size and crystallinity of the hybrid nanostructures. Increased quenching of nanorod emission is observed as the size of the gold tip increases 15 suggesting optimisation of charge transfer between the semiconductor and the metal .

Origin of chains of Au-PbS Nano-Dumbbells in space

“…S5). This orientation of Au tips is different from Au tipped wurtzite nanorods where noncentrosymmetric crystallographic lattice with sulfur-rich facets cause Au tip formation in dumbbells, end-on and angled tip orientations313233.…”

Electrophoretic Deposition of Poly(3-decylthiophene) onto Gold-Mounted Cadmium Selenide Nanorods

“…2A. Although these rods are much smaller than those used experimentally, [8][9][10][11][12][13][14] which would typically be in the 6-8 nm diameter and roughly 30 nm length range, the inter-rod spacing and cross-sectional rod areas were chosen to conform in approximate proportional ratio to typical experimental dimensions and rod coverage per unit area. [9][10][11][12][13][14] It was desired to study EPD of polymers onto the rod arrays using direct MD, rather than in between the rods: experimentally, EPD between rods does rely on several parameters that are difficult to achieve, and, especially, control, such as removal of surfactant while retaining the architecture.…”

“…Accordingly, four additional simulations under the effects of a static electric field of 0.0195 V/Å were also carried out. Typical external electric field intensities in experiment are estimated to be of the order of 1 V/μm, [8][9][10][11][12][13][14] so the external fields here are necessarily some two orders of magnitude larger than experiment, in order to induce EPD within an amenable timescale for large-system (half-million-atom) MD (say, within 50 ns), but are relatively small in intensity in comparison to intrinsic electric fields in condensed aqueous phases, for instance (1.5-2.5 V/Å), 30 and to previous non-equilibrium MD of electrophoresis by the authors. 31,32 As will be shown below (cf.…”

“…6,7 Although these structures are challenging to fabricate, Ryan et al have made considerable progress in recent years via electrophoretic deposition (EPD) of nanocrystal and nanorod electrodes of differing charge from organic (toluene) solutions, to achieve a good degree of vertical nanorod alignment, 8,9 and also in the formation of nanorod assemblies in electric fields. [10][11][12][13][14] These advances have the distinct advantage of being solution-processable, rather than requiring vacuum techniques. Titov and Kral have also carried out a recent modelling study of the self-assembly of colloidal nanorod superlattice, using van der Waals and Coulombic coupling between dipolar nanorod and their substrates.…”

A facile method for gold decoration of Te@CdTe nanorods in aqueous solution

“…Colloidal synthesis of metal-semiconductor hybrid nanostructures is mainly achieved in organic solution via the reaction of metal salt and hydrophobic semiconductor nanoparticles [37][38][39][40]. The metal precursor (usually metal salts) is typically mixed with an alkylammonium bromide as a surfactant, followed by reduction in a primary amine or light illumination [41].…”