Self-Assembly of High Density of Triangular Silver Nanoplate Films Promoted by 3-Aminopropyltrimethoxysilane

In this work, we studied the structure of synthesized triangular silver nanoplates in solution and the growth of the nanoplates on a silicon surface using 3-aminopropyltrimethoxysilane (APTMS) as a coupling agent. The triangular-shaped colloidal silver nanoplates were simply synthesized by a direct chemical reduction approach. We studied the three characteristic peaks of the unique optical absorbance of triangular silver nanoplates and subsequently measured an average edge length of 26 +/- 1 nm. The nanoplate thickness was determined to be 7 +/- 2 nm from transmission electron microscopy images. Depositing the nanoplates on a silicon surface was carried out to determine the coverage of triangular nanoplates obtained when adhesion was promoted by a coupling agent. The APTMS film assisted the attachment of the nanoplates to the silicon surface and the coverage of the nanoplates increased with increasing deposition time. The triangular silver nanoplate thin film was a monolayer and a high coverage (near complete) was obtained after eight hours of exposure to the nanoplate solution. The silver film formed was shown to be a good surface-enhanced Raman scattering (SERS) substrate as it gave an enormous Raman enhancement for bisphenol A (BPA).