  In this study, we evaluated the sensing performance of silver
nanoprism/graphene oxide/silicon nanowires (AgNPr/GO/SiNWs) nanohybrid system
for effective detection of organic dye and herbicide residues in freshwater via
surface-enhanced Raman scattering (SERS). Homogenous and vertically aligned
SiNWs have been successfully synthesized using metal-assisted chemical etching
technique by varying the etching time from 10 to 30 min. AgNPr/GO/SiNW hybrids
were assembled by spin-coating of GO followed by drop-casting deposition of
AgNPr. The microstructures of AgNPr/GO/SiNWs are strongly affected by the
etching time of SiNWs, which in turn affected its SERS performance when
rhodamine 6G is used as an analyte molecule. Owing to the synergetic effects of
GO and AgNPr, SERS response of AgNPr/GO/SiNWs composites were found to be
superior compared to AgNPr/SiNWs. High efficiency of 6.1 x 1010 has been
achieved with AgNPr/GO/SiNWs based sensor fabricated with 30-min etched SiNWs
for rhodamine 6G. An effective way of rapid detection of drinking water
pollutants such as methylene blue and atrazine up to picomolar (10-12 M)
concentrations was demonstrated using these low-cost AgNPr/GO/SiNWs nanohybrids
SERS sensors.
