Fabrication Of Ag Nanotube And Nanoring By SiO₂ Assistant Phase-separation

One-dimensional (1D) and quasi-one-dimensional nanostructures are attracting great attention due to their unique properties and novel applications. A variety of nanostructures have been synthesized, including nanowires, nanotube, nanorod and nanobelt. Here we report a new approach to prepare metal silver nanotube and nanoring as well as other silver nanostructers through SiO₂ assistant phase-separation.1) Steady SiO₂ sol containing silver ion was synthesized, and the corresponding conditions were optimized.2) Based on the Ag/SiO₂ sol, Ag/SiO₂ nanocomposite films on silicon substrate were synthesized by dip-coating technique for three times. The fresh Ag/SiO₂ films were first dried at 100℃for 1 hour, and then annealed at 700℃for 2 hours in order to form square and round silver nanotubes. The resultant square and round silver nanotubes were characterized by SEM, AFM and TEM, respectively. Furthermore, the mechanism of forming Ag nanotubes was also discussed.3) To obtain silver nanorings, the Ag/SiO₂ gel was coated on silicon by dip-coating technique for two times to form Ag/SiO₂ nanocomposite films, which were further dried at 100℃for 1 hour, and then annealed at 600℃for 2 hours. As a result, a variety of silver nanorings (ie: single ring, double ring, strip ring and square ring) were fabricated, Also, the silver nanorings were characterized by SEM and TEM, and mechanism of forming Ag nanorings was discussed.