(32d) Synthesis of Au Nanorings in the Soft Template of Sds-Peg Cluster under Mild Conditions

A novel method is reported to prepare Au nanorings from HAuCl4 self-reduced in the soft template composed of sodium dodecyl sulfate (SDS)-PEG 20000 cluster at ambient temperature and atmosphere, in which no extra reducer is needed. The clusters composed of SDS and PEG act as soft templates to control the size and morphology of Au nanoparticles. SDS associates with PEG to form bound-micelle, which serves as micro-reactor to control the growth of premier Au quantum dots. PEG plays the role as both the reducer for HAuCl4 and the stabilizer for fresh Au nanoparticles. The course of nanoparticles growing from Au nanospheres to nanoplates and eventually to nanorings was tracked by both TEM and SEM, which indicates that only the reduction period monitored can the preferred Au nanostructures be obtained. TEM image displays that the diameter of Au nanorings is 500±50 nm. Electron diffraction (ED) pattern and XRD pattern show that the synthesized nanoring is monocrystal Au and grows preferentially along (111) lattice planes. UV-vis spectrum reveals that there is relatively stronger absorption band beyond 800 nm, which is attributed to the big and anisotropic nanostructrues.