Formation of High-Yield Gold Nanoplates on the Surface: Effective Two-Dimensional Crystal Growth of Nanoseed in the Presence of Poly(vinylpyrrolidone) and Cetyltrimethylammonium Bromide

This paper reports a simple technique to grow high-yield gold nanoplates directly on the surface via an effective two-dimensional growth promotion of the attached nanoseeds in the presence of a binary surfactant mixture, namely, poly(vinylpyrrolidone) (PVP) and cetyltrimethylammonium bromide (CTAB). The gold nanoplates formation strongly depended on the concentration of PVP used in the solution, while the nanoplate size depended on the CTAB concentration. In a typical process with optimum PVP and CTAB concentrations, 60% of the nanocrystal product was nanoplates. Triangular nanoplates were found to be the major shape of the nanoplates with a yield of up to ca. 50%, while hexagonal or truncated-hexagonal and rounded-nanoplates shared up to ca. 30 and 20% of the nanoplates product, respectively. The nanoplates were characterized by a very thin structure with a thickness of less than 10 nm. The edge-length size of the nanoplates was found to be up to ca. 1 mu m. At optimum growth conditions, ca. 70% of the surface area was covered by nanoplates. X-ray diffraction results on the surface modified nanoplates samples indicated exceedingly high Au(111) peaks of gold nanocrystal without the presence of other peaks, such as (200) and (220), in the diffraction spectrum. The present approach may be used to produce a surface that contains unique nanostructured Au(111) crystallographic plane characteristics, which should find potential applications in catalysis, surface-enhanced Raman scattering, sensors and photonics.