Hierarchical Transformation of Silver Morphologies on Clay Film from Spheres, Cubes, Rods to Lengthy Nano-Wires

摘要

Silver nanoparticles (AgNPs) in silicate clay matrix films were fabricated from solution casting method. The Ag/clay dispersion was first prepared from in situ reduction of silver nitrate in the presence of silicate clay platelets and ethanol as the reducing agent The morphologies of AgNPs have changed in a hierarchical manner, from sphere to cube and then to rod and wire morphologies during the annealing at 200°C. The originally homogeneous AgNPs distribution in the clay matrix underwent the transformation of AgNPs in moving to the film surface and coalescing to larger sizes. The hierarchical change continued to form other morphologies. We observed the self-assembled morphologies including spherical (diameter ～ 50 nm), cubic (length ～100 nm), rod-like (length ～ 1.6 μm and width ～300 nm) and then to lengthy wire Ag (length ～10μm) The kinetic mobility of AgNPs to surface and the characterization of Ag composition were confirmed through energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD).