Silver tip formation on colloidal CdSe nanorods by a facile phase transfer protocol

Abstract

A facile phase transfer procedure is described for the formation of uniform silver metal tips on II -VI semiconductor nanorods. Judicious choice of a functional ligand, dimethyl phenol (DMP), which binds to the semiconductor rod in the organic phase enables the transfer of metal ions from the aqueous phase and their reduction onto the nanorod. The metal tips initially from as 10 random sub< 2nm particles surrounding the nanorod which ripen to dual tips at the nanorod ends. The nanorod hybrids can be assembled into perpendicularly aligned arrays by simple solvent evaporation. The hybrid nanostructu res are characterised by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), photoluminescence (PL), ultraviolet-visible spectroscopy (UV-vis) and X-ray photoelectron spectroscopy (XPS). A detailed FTIR analysis is also carried out to predict the role of the ligands in the tipping procedure.

Silver Tipping of CdSe@CdS Nanorods: How To Avoid Cation Exchange

“…Although occasional defect growth on the side of nanorods was observed (Figure S4), selective tipping was found to dominate the deposition locations, even for reactions that were carried out under high temperatures (135 °C for half an hour in comparison to cation exchange which occurs at room temperature). This selectivity toward the apexes is in contrast to literature reports on Au deposition, which is known to be very sensitive to surface defects, even in the low-temperature region (0–40 °C), or to the random silver tipping along the sides of CdSe rods, which was obtained by the Ryan group via a facile phase transfer . Control over the metal domain number was proven to be a critical aspect for applications such as photocatalytic solar-to-fuel conversion …”

“…This selectivity toward the apexes is in contrast to literature reports on Au deposition, which is known to be very sensitive to surface defects, even in the low-temperature region (0−40 °C), 20 or to the random silver tipping along the sides of CdSe rods, which was obtained by the Ryan group via a facile phase transfer. 53 Control over the metal domain number was proven to be a critical aspect for applications such as photocatalytic solar-to-fuel conversion. 16 Several techniques were employed to confirm the composition and structure of the newly formed tip in order to ascertain whether it is indeed metallic silver (and not Ag 2 S that is expected to result from cation exchange).…”

Third-order nonlinear optical response of Ag–CdSe/PVA hybrid nanocomposite

“…At the focal point, the sample experiences the maximum laser light intensity, which will gradually decrease in either direction from the focus. In the presence of nonlinear absorption, the open-aperture Z-scan scheme was used to measure nonlinear absorption coefficient (b) and the imaginary part of the third-order nonlinear optical [27]. The diffraction peaks at 2h = 31.92°, 34.02°and 37.90°are due to the formation of Orthorhombic CdSeO 3 (the impure phase of CdSe).…”

Peptidic Ligands to Control the Three‐Dimensional Self‐Assembly of Quantum Rods in Aqueous Media

“…The crucial role of the coating for successful 3D self‐assembly has motivated the utilization of a large set of techniques to understand binding events at the nanoparticle surface during the ligand exchange process . More precisely, fluorescence, infrared (FTIR), and nuclear magnetic resonance (NMR) spectroscopies enabled us to show that the hydrophobic phosphorylated molecules serving for the QR capping, the octadecyl phosphonic acid (ODPA), the hexyl phosphonic acid (HPA), as well as the tri‐octyl phosphine oxide (TOPO) and the tri‐octyl phosphine (TOP), can be completely replaced by peptides. Subsequently, we accessed the surface charge of the hydrophilized QRs, as well as their stability in water, by electrophoresis and by dynamic light scattering (DLS).…”