Sensors - Hierarchical Nanostructures for Energy Devices - page 262

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Figure 11.8 Ag core-shell hierarchical nanostructures for SERS sensing applica-
tions. (a) SEM image of the cross-sectional core-shell Ag wire, (b) the tip
of a core-shell Ag wire covered by nanosheet assemblies, and (c) SERS
spectra of melamine in different concentrations taken on core-shell Ag
wire structures: a-f represent spectra from 200, 100, 50, 20, 10, and
5 ppm, respectively (adapted from ref. 9 with permission).

nanosheets, resulting in highly roughened surfaces that played a key role as
a highly sensitive SERS platform. The fabricated Ag core-shell nano-
structures showed especially high SERS sensitivity toward the analyte
melamine, down to 5 ppm as shown in Figure 11.8(c), where a characteristic
peak at 679 cm 1 was observed. It was reported that this hierarchical
nanostructure had the highest sensitivity ever reported by means of fast
detection in dairy products presumably due to the ample nanoscale gaps,
which endow the metal substrate with applicability to highly-sensitive SERS
sensors.
A silicon nanowire (SiNW) array decorated with silver nanoparticles
(AgNP) was prepared and used as a SERS platform for the detection of Sudan
dye. 13 The SiNW array was produced by chemical etching of a silicon wafer