Controlled synthesis of gold nanosnakes assisted by poly(vinyl pyrrolidone)–sodium dodecyl sulphate aggregations

Anisotropic single-crystalline gold nanosnakes were synthesised in poly(vinyl pyrrolidone) (PVP)–sodium dodecyl sulphate (SDS) aggregation aqueous solution by reducing HAuCl4 with PVP without any additional reducing agent. The crystal structures, growth process and the influence of SDS concentrations on the growth of gold nanosnakes have been investigated by X-ray diffraction and transmittance electron microscopy. In this approach, the peculiar structure of PVP–SDS aggregations is indispensable for the asymmetrical formation of gold nanosnakes. Without PVP–SDS aggregations, only long tortuous gold nanobelts were synthesised. When SDS concentration was increased from 3 to 10 mM, gold nanosnakes, nanokites and nanoplates were fabricated. To the best of our knowledge, this is the first report on the SDS-induced shape transformation from snake-like to plate-like at fixed low HAuCl4 concentration in PVP–SDS aggregation aqueous solutions. Moreover, the gold nanosnakes exhibit excellent electrocatalytic property towards the oxidation of methanol indicating their potential applications in fuel cells, catalysis, biosensing and nanodevices.