Fabricating a Homogeneously Alloyed AuAg Shell on Au Nanorods to Achieve Strong, Stable, and Tunable Surface Plasmon Resonances

Abstract

Colloidal metal nanocrystals with strong, stable, and tunable localized surface plasmon resonances (SPRs) could be useful in a corrosive environment for many applications including field-enhanced spectroscopies, plasmon-mediated catalysis, etc. Here, a new synthetic strategy is reported that enables the epitaxial growth of a homogeneously alloyed AuAg shell on Au nanorod seeds, circumventing the phase segregation of Au and Ag encountered in conventional synthesis. The resulting core-shell structured bimetallic nanorods (AuNR@AuAg) have well-mixed Au and Ag atoms in their shell without discernible domains.This degree of mixing allows AuNR@AuAg to combine the high stability of Au with the superior plasmonic activity of Ag, thus outperforming seemingly similar nanostructures with monometallic shells (e.g., Ag-coated Au NRs (AuNR@Ag) and Au-coated Au NRs (AuNR@Au)). AuNR@AuAg is comparable to AuNR@Ag in plasmonic activity, but that it is markedly more stable towards oxidative treatment. Specifically, AuNR@AuAg and 2 AuNR@Ag exhibit similarly strong signals in surface-enhanced Raman spectroscopy (SERS) that are some 30-fold higher than that of AuNR@Au. When incubated with a H2O2 solution (0.5 M), the plasmonic activity of AuNR@Ag immediately and severely decayed, whereas AuNR@AuAg retained its activity intact. Moreover, the longitudinal SPR frequency of AuNR@AuAg can be tuned throughout the red wavelengths (~620-690 nm) by controlling the thickness of the AuAg alloy shell. Our synthetic strategy is versatile to fabricate AuAg alloyed shells on different shaped Au, with prospects for new possibilities in the synthesis and application of plasmonic nanocrystals.

Plasmonic‐Enhanced Light Harvesting and Perovskite Solar Cell Performance Using Au Biometric Dimers with Broadband Structural Darkness

“…The extinction spectrum is plotted in Figure c, and the digital photogragh of the Au dimer solution is shown in Figure S1, Supporting Information. In line with the previous reports, the Au dimer solution shows a broadband optical absorption, which consists of two broad peaks: one is located at 560 nm, and the other is located at 912 nm in the infrared region. The peak at 560 nm is in accordance with the plasmonic resonance of the Au nanoparticles, and the broad peak located in the infrared region (912 nm) origins from the interscattering of photons between nanoparticles and nanorods …”

“…Each nanoabsorber is composed of a nanorod of length 75 ± 7 nm and diameter 18 ± 2 nm and a nanosphere with a diameter of 30 ± 3 nm. As shown in the previous report, the kissing points between the spheres and the rods are formed by metallic bonding of differently curved surfaces, which have the same crystalline structure. To investigate the LSPR effect of the Au dimer embedded CH 3 NH 3 PbI 3− x Cl x perovskite film, a finite‐element method (FEM) simulation was used to calculate the field distribution in the vicinity of the Au dimer under a continuous plane wave at different wavelengths.…”

Zwitterionic Polymer-Gated Au@TiO2 Core-Shell Nanoparticles for Imaging-Guided Combined Cancer Therapy

“…On the other hand, PDT relies on photosensitizers (PSs) to release the reactive oxygen species (ROS) and cytotoxic free radicals when they absorb light at appropriate wavelengths 16-18. Organic PSs are the most widely used PS types.…”

Sophisticated Construction of Binary PdPb Alloy Nanocubes as Robust Electrocatalysts toward Ethylene Glycol and Glycerol Oxidation

“…[7][8] Nevertheless, there are some disadvantages associated with Pt such as: high cost, low durability and scare natural abundance, which have seriously limited its large-scale production. [9][10] To break this bottleneck, tremendous efforts have been focused on developing an appropriate substitute for Pt catalysts. [11][12][13] Recently, well-defined Pd nanocrystals have been of vital significance for applications in sensing, hydrogen storage and especially in fuel cells due to its high activity and great tolerance to some CO-like intermediate species in the alkaline media.…”