Precursor-Driven Nucleation and Growth Kinetics of Gold Nanostars

Abstract

Recently, seed-mediated approach has been widely utilized for synthesizing monodisperse gold nanostars well-known for plasmonic and sensing applications. Herein, we report a single step seedless/templateless organic synthesis procedure for the complex 3D gold nanostars with a high degree of size/shape control, involving the complexation of polyvinylpyrrolidone (PVP) in polar solvent N,N-dimethylformamide (DMF) and their reduction of AuCl4 – ions along with hydrochloric acid (HCl) as an effective mediator. On the basis of the kinetic optical absorption and Fourier transform infrared (FTIR) spectroscopy measurements, a convenient ligand exchange mechanism has been proposed for the first time to the best of our knowledge to understand the evolution of these complex shaped gold nanostructures. The coordination interaction among PVP and DMF as well as PVP–DMF–AuCl4 has been identified as the major driving factors influencing the temporal evolution of the size/shape-controlled gold nanostars.

Local electron beam excitation and substrate effect on the plasmonic response of single gold nanostars

“…The overall morphology is flower-like with crisscrossed non-planar single crystalline tips branching out from the complex core. 15 In the following we will focus on tip A that has a length of 50 nm and an aperture angle of approximately 15 o . Figure 1a shows CL spectra taken from different location of tip A of the nanostar (colored dots in the inset of Figure 1a).…”

Surface enhanced infrared absorption spectroscopy based on gold nanostars and spherical nanoparticles

“…Moreover, according to the plasmon hybridization (PH) model [23] the core-tip structure serves as an antenna increasing both, the excitation cross section and the electric field enhancement of nanostar plasmon modes [24]. To the best of our knowledge, only a few research groups have applied IR-ATR spectroscopy for monitoring the growth kinetics of such particles [25] and have analyzed the surface chemistry of the AuNSts in details [26]. Last but not least, AuNSts have not been applied in ATR-SEIRAS to date.…”

Ligand Controlled Morphology Evolution of Active Intermediates for the Syntheses of Gold Nanostars

“…It is thus essential to have a systematic understanding of the formation and the morphology evolution of these active intermediates in order to have a precise control of the branched morphology for the final products. 18,20 In particular, we need to figure out how the capping ligands impact surface stabilization during the possible evolution process.…”

“…It is thus essential to have a systematic understanding of the formation and the morphology evolution of these active intermediates in order to have a precise control of the branched morphology for the final products. 18,20 In particular, we need to figure out how the capping ligands impact surface stabilization during the possible evolution process.Gold nanostars and, in general, branched gold nanoparticles have been widely explored due to their unique plasmonic properties which can be tuned in a broad spectral range including visible, near-infrared, and mid-infrared regions. 16,17,21−25 The synthesized nonspherical gold nanoparticles with designed morphology and rough surface have demonstrated great potentials for a variety of applications including surface enhanced Raman scattering (SERS) detection, 26−30 surface plasmon resonance (SPR) sensing, 31 solar cells, 32 anticounterfeit, 33 bionanosensing, 34−37 and target drug delivery.…”