Large scale synthesis of pinhole‐free shell‐isolated nanoparticles (SHINs) using improved atomic layer deposition (ALD) method for practical applications

Abstract

Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) as a new member of Raman technique garnered great attention among scientific community. In this work, we used an improved experimental setup to float the bare silver nanoparticles in air with the help of extraneous airflow, and used atomic layer deposition (ALD) method to coat ultra-thin inert shell without pinholes. Under optimal conditions, we successfully prepared three kinds of SHINERS NPs (Ag@Al 2 O 3 , Ag@SiO 2 and Ag@TiO 2 ) in large quantity without pinholes. The ultra-thin inert shell maintains the SERS activity of silver nanoparticles for long period of time. Transmission electron microscopy (TEM) images confirm the uniform coating of shell material on silver nanoparticles. Finally, the as-prepared SHINs have been applied to detect various samples to demonstrate the applications. The presented ALD method offers a unique way to coat ultrathin shell (1-10 nm) on metal nanoparticles in large quantity (1-10 g) for practical applications.

Shell‐Isolated Nanoparticle‐Enhanced Raman and Fluorescence Spectroscopies: Synthesis and Applications

“…Besides the chemical method used to prepare shell‐coated metal nanoparticles, atomic layer deposition (ALD) is also an easy route to control the thickness of the oxide shell to the nanoscale. Zhang et al have reported modified ALD to encase bare silver with ultrathin shell materials . In the experimental setup, Ag nanoparticles considerably floated in the chamber on account of the gas flow, which permitted the uniform deposition of silica over metal nanoparticles.…”

Shell‐Isolated Nanoparticle‐Enhanced Raman Spectroscopy at Single‐Crystal Electrode Surfaces

“…In our case, the suitable diameter of gold cores is 55 nm [ 121 ] for SHINERS measurements, and bigger diameter gold NPs, such as 120 nm, can be synthesized for enormous enhancements ( Figure 6 A,B). [ 120,128,129 ] Here, we describe the detailed experimental procedure of SHINs using 55 nm Au@SiO 2 as an example. [ 15,120,[122][123][124][125] The SPR property of nanoparticles will be affected by its shape and size.…”

“…Finally, the sample was subjected to Raman measurements. [ 129 ] Copyright 2015, Wiley. Optical Mater.…”

Recent advances in linear and non‐linear Raman spectroscopy. Part X

“…studied the size‐dependent evolution of phonon confinement in colloidal Si nanoparticles using SERS. By introducing a variable confinement factor, α, into a well‐known phenomenological phonon confinement model (PCM) developed by Richter et al ., acceptable fits were achieved to downshifted and asymmetrically broadened Raman spectra of Si NPs with different diameters …”