Synthesis of High‐Yield Gold Nanoplates: Fast Growth Assistant with Binary Surfactants

Changshun Wang,Hongchen Li,Xiangfu Wang,Jiejun Zhu,Xiaoling Zeng,Daning Shi,Caixia Kan

doi:10.1155/2010/969030

Abstract

A novel and simple chemical method was developed to fastly synthesize Au nanoplates with size of micrometers and tens of nanometers in thickness. The synthesis was carried out within 30 minutes by thermal reduction of precursors (HAuCl4) in the presence of binary surfactants Poly(vinylpyrrolidone) (PVP) and cetyltrimethylammonium bromide (CTAB) in ethylene glycol (EG) solution. The presence and concentration of PVP and CTAB in the growth solution play important roles in the fast formation of Au nanoplates. The obtained Au nanoplates exhibit strong surface plasmon absorption in the near‐infrared region (NIR), displaying a considerable dependence on the shape and size. Characterizations by Transmission electron microscope and X‐ray diffraction indicated that the nanoplates are single crystals with (111) planes as two basal surfaces. Explanations for the nuclei formation and crystal growth behind anisotropic Au nanoplates were proposed.

Highlights

For more than one decade, nanometer-sized noble metal particles, especially gold (Au) and silver (Ag), have attracted considerable attention because of their size- and shape-dependent optical and electronic properties distinctly different from their bulk materials, and due to their potential applications in thermal, catalysis, surface-enhanced Raman scattering, photoelectronic devices, biomedical diagnostics, and other related fields [1,2,3,4,5]
The color of the sample turned from yellow to red brown (Figure 1(a)), when the ethylene glycol (EG) solution mixed with cetyltrimethylammonium bromide (CTAB) and HAuCl4 was kept at 80◦C for 10 minutes
The reaction will last for a long time. These results clearly demonstrate that the CTAB concentration influences the shape and size of Au nanoplates and the molar ratio plays an important role on the reduction rate

Summary

Introduction

For more than one decade, nanometer-sized noble metal particles, especially gold (Au) and silver (Ag), have attracted considerable attention because of their size- and shape-dependent optical and electronic properties distinctly different from their bulk materials, and due to their potential applications in thermal, catalysis, surface-enhanced Raman scattering, photoelectronic devices, biomedical diagnostics, and other related fields [1,2,3,4,5]. For anisotropic Au and Ag nanostructures, various shapes, such as nanorods, nanowires, nanoplates, nanorings, polyhedron, nanoprisms, and nanocubes [10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25], can be synthesized by seedmediated synthesis [15, 19], template-directed synthesis [16], polymer-assisted synthesis [17], microwave heating [18], and chemical approach (electrochemistry, photochemistry, and sonochemistry) [24, 25]. Poly(vinylpyrrolidone) (PVP) was extensively used in preparing many types of colloidal nanocrystals, because it has a reducing effect on metal ions and and can prevent the product from agglomeration [27] Another cationic surfactant, cetyltrimethylammonium bromide (CTAB), was used to control the morphology of nanoparticles (Au nanorods in most cases) [28,29,30].

Experimental Section

Results and Discussion

Conclusions