Hybrid structures of Fe
3
O
4
and Ag nanoparticles on Si nanopillar
arrays substrate for SERS applications
Xin-Yan Zhao
a
, Guannan Wang
b
, Minghui Hong
b
,
*
a
SUSTech Academy for Advanced Interdisciplinary Studies, Southern University of Science and Technology, Shenzhen, 518055, China
b
Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore
highlights
3D SERS substrate of Si-pillar arrays with Fe
3
O
4
@Ag nanoparticles is designed.
It inherits the SERS activity of Ag nanoparticles and superparamagnetic of Fe
3
O
4.
The substrate has large surface area and unique light trapping of 3D nanopillars.
Intense light-metal and light-molecule interactions, thus high SERS enhancement.
article info
Article history:
Received 22 December 2017
Received in revised form
31 March 2018
Accepted 23 April 2018
Available online 25 April 2018
Keywords:
Surface-enhanced Raman scattering (SERS)
Three-dimensional (3D) nanostructure
Si nanopillar arrays
Core-satellite
Fe
3
O
4
abstract
Surface-enhanced Raman scattering (SERS)-based sensing is the most promising approach to detect trace
amounts of chemical and biological molecules. Three-dimensional (3D) nanostructures have been
considered as one of the most promising SERS substrates due to ordered arrangement of high-density
hot spots and large surface area for adsorbing analyte. This paper designed a hybrid SERS substrate
containing structures of Fe
3
O
4
and Ag nanoparticles on Si nanopillar arrays, which combines the ad-
vantages of highly ordered periodic 3D Si nanopillar arrays and Ag coated Fe
3
O
4
core-satellite micro-
spheres, leading to intense light metal and light molecule interactions. The detection limit of the
substrate for malachite green (MG) is as low as 10
8
M, meeting the requirements for trace detection of
analytes. This work provides a new insight for fabricating SERS substrates with high sensitivity.
© 2018 Elsevier B.V. All rights reserved.
1. Introduction
Raman spectroscopy provides the fingerprint signatures of each
specific compound and contains information about composition
and structure of molecules in chemical and biological systems [1,2].
Due to the localized surface plasmon resonance (LSPR) in nano-
structured metal (typically gold, silver and copper) surfaces,
Surface-enhanced Raman Scattering (SERS) can provide structural
information even to single-molecule level [3,4]. Therefore, SERS has
become a most powerful analytical tool with advantages of non-
destructive, ultra-fast and sensitive detection in many areas of
science and technology, including physics, chemistry, biology, and
environment [4e7]. The LSPR of metal nanoparticles depends on
their sizes, shapes, interparticle distances, and dielectric properties
of the surrounding medium. Therefore, architecture and
morphology of the substrates influence the intensity and distri-
bution of the SERS signals, as well as molecular adsorption. Fabri-
cating high performance SERS substrates are among the most key
factors that influence the practice applications of SERS technology
[8]. An ideal SERS substrate should have high enhancement factor,
uniform nanoparticle distribution, also should be reproducible and
reusable [9,10]. Extensive studies have been focused on optimizing
the nanostructures of SERS substrates [11e15]. Typical nano-
structures include zero-dimensional tip-like clusters [16], one-
dimensional rod-like building blocks [17,18], two-dimensional
planar nanostructures [19,20] and tree-dimensional (3D) frame-
works [21e24]. Recently, 3D nanostructures with well controlled
hierarchical morphologies have attracted considerable attentions,
because it offers larger surface areas for adsorbing more analytes,
generates high density SERS hot spots and has excellent
* Corresponding author.
E-mail addresses: zhaoxy@sustc.edu.cn (X.-Y. Zhao), elehmh@nus.edu.sg
(M. Hong).
Contents lists available at ScienceDirect
Materials Chemistry and Physics
journal homepage: www.elsevier.com/locate/matchemphys
https://doi.org/10.1016/j.matchemphys.2018.04.082
0254-0584/© 2018 Elsevier B.V. All rights reserved.
Materials Chemistry and Physics 214 (2018) 377e382