Controllably Hollow AgAu Nanoparticles via Nonaqueous, Reduction Agent‐Assisted Galvanic Replacement

Abstract

The galvanic replacement reaction is a robust tool for the controlled synthesis of hollow and semihollow bimetallic nanostructures, which have applications in a range of science, engineering, and medical fields due to the tunability of their localized surface plasmon resonances (LSPRs) and surface chemistry. Here, a controllable galvanic replacement of Ag by Au coupled with coreduction is described, performed in nonaqueous solvents including methanol, ethanol, and an N,N‐dimethylformamide:toluene mixture and yielding hollow and semihollow alloyed nanoparticles. Structural control, from semihollow to nanoshell, and plasmon tunability are demonstrated via control of the Au:Ag stoichiometry. The high structural dependence on temperature is shown, with striking changes in nanoparticle surface smoothness and pinhole density, and reveals the optimal reaction temperature to be 65 °C in alcohols. Through optimizing this reaction, smooth closed shell AgAu alloy nanoparticles with LSPRs tunable from 494 to 567 nm are obtained. This work provides a framework for galvanic replacement of large anisotropic Ag nanoparticles with Au in nonaqueous media, which can be extended to other solvent systems suitable for air‐sensitive metals and precursors.

A sandwich SERS immunoassay platform based on a single-layer Au–Ag nanobox array substrate for simultaneous detection of SCCA and survivin in serum of patients with cervical lesions

“…The Au–AgNSs were synthesized via a seed-mediated growth route. 41 In a typical synthesis, 0.025 g of potassium carbonate and 2 mL of 1% AgNO 3 solution were placed in a flask to obtain 0.5 mM silver stock solution. At which point, 2 mL prepared THPC was quickly added to silver seeds with vigorous stirring.…”

Decoration of plasmonic Mg nanoparticles by partial galvanic replacement

“…31,32 Meanwhile, galvanic replacement has been wildly successful at producing interesting and complex plasmonic structures, mainly based on Au, Pd, or Pt, functionalization of different Ag (semi-)sacrificial templates mostly in water, [33][34][35] but sometimes in organic solvents. [36][37][38][39][40][41][42] This is a mature approach for AgAu hollow systems, where the extent of galvanic replacement and alloying can be controlled by not only stoichiometry, but also the addition of reducing agents. 43 Here, we show that stoichiometry-controlled partial galvanic replacement leads to the tunable decoration of well defined, crystalline, Mg NPs with Au, Ag, Pd and Fe.…”

Single-Particle Hyperspectral Imaging Reveals Kinetics of Silver Ion Leaching from Alloy Nanoparticles

“…When plasmonic nanoparticles are illuminated, the plasmon leads to strong scattering and absorption of light . The optical cross sections of a plasmonic nanoparticle depend on its size, shape, , and composition, − making it possible to monitor morphological changes optically. Wavelength and intensity changes in ensemble UV–vis spectra were used to monitor the dissolution of gold and silver nanoparticles, ,, as well as the silver ion leaching of gold–silver alloy nanoparticles. − However, the fact that leached silver ions cause nanoparticle aggregation in solution complicates optical ensemble methods. ,, Single-particle spectroscopy typically requires the immobilization of nanoparticles on a support substrate, , thereby avoiding nanoparticle aggregation even under the harshest solution conditions.…”