A novel method to prepare Au nanorings by self-reduction of HAuCl₄ in the soft template composed of sodium dodecyl sulfate (SDS)-PEG 20000 cluster at ambient temperature and atmosphere is reported, in which no hard template and extra reducer is needed. TEM image displays that the diameter of Au nanorings is (500±50) nm. UV-vis spectrum reveals that there is relatively stronger absorption band beyond 800 nm, which is attributed to big and anisotropic nanostructures. Electron diffraction (ED) pattern shows that the synthesized nanoring is monocrystal Au. XRD pattern of the Au nanorings indicates that the ratio of the intensity between the (200) and (111) diffraction peaks [I₍₂₀₀₎/I₍₁₁₁₎] is 0.11. The fact that [I₍₂₀₀₎/I₍₁₁₁₎] decreases 0.2 from the original 0.31 suggests that Au nanorings grow preferentially along (111) lattice planes. The process of Au nanoparticles growing from nanospheres through nanoplates and eventually to nanorings is tracked by both TEM and SEM, which indicates that if the reduction period is controlled the preferred Au nanostructures could be obtained.

Key words: Au nanoring, soft template, cluster, sodium dodecyl sulfate, polyethylene glycol