Template-assisted synthesis of uniform nanosheet-assembled silver hollow microcubes

Abstract

Uniform silver hollow microcubes assembled by nanosheets have been synthesized by using Cu₂O cubes as chemical template at room temperature. In the reaction system, the Ag⁺ ions were reduced by Cu⁺ ions released from Cu₂O cubes, meanwhile the morphology of silver growth units were controlled by trisodium citrate in the form of nanosheets around the template during the reaction. It was found that the concentrations of acid, citrate ions and AgNO₃ were critical to the formation of perfect nanosheet-assembled hollow microcubes. According to the experiment results, an interface redox growth mechanism of nanosheet-assembled Ag hollow microcubes was proposed. Since the obtained Ag hollow cubes are composed of Ag nanosheets, the hierarchical shells are bestrewed with pores or gaps which created abundant active “hot spots” for highly sensitive surface enhanced Raman scattering (SERS) detection. The SERS experiments using rhodamine 6G (R6G) as probing molecules showed that the pack density and porous structure of the shell in the final products strongly affected the SERS signals. The product with higher porous shell structure exhibited stronger SERS signals than others, indicating the rough Ag hollow microcubes could act as excellent substrates for ultrasensitive detection.