Synthesis of gold nanoflowers assisted by a CH-CF hybrid surfactant and their applications in SERS and catalytic reduction of 4-nitroaniline

In this paper, an effective approach was successfully developed to synthesize gold nanoflowers (GNFs) using a hydrocarbon/fluorocarbon (CH-CF) hybrid surfactant ( 1 ). Upon mixing with aqueous solution of 1 in presense of AgNO 3 , HAuCl 4 could be reduced into GNFs by ascorbic acid (AA). Influences of aging time, concentration of HAuCl 4 , AgNO 3 , AA and 1 as well as temperature were investigated in detail. GNFs could not be obtained at the absence of AgNO 3 and 1 , indicating that both of them play important roles in the formation of these anisotropic gold structures. Influences of AA and temperature are relatively less pronounced, and well-defined GNFs can be synthesized in a wide range of the concentration of AA (1×10 −3 mol·L −1 to 6   ×   10 −3 mol·L −1 ) and temperature (25–50   °C). The GNFs have inhomogenous cores, indicating that they are formed by the aggregation of gold crystals of smaller sizes. A two-stage growth pathway was thus proposed to explain the mechanism of the formation of GNFs. With a large surface-to-volume ratio, GNFs show surface-enhanced Raman scattering for solid R6G with enhancement factors up to a magnitude of 10 6 . They can also be used as efficient catalysts for the reduction of 4-nitroaniline by KBH 4 . The strategy demonstrated here is a facile, rapid, and contrallable one-pot method for the synthesis of GNFs in aqueous solution, which will bring out a wide range of applications.