Synthesis of Layered Transition Metal Oxide/Clay Nanocomposites

Abstract

Clay-based layered nanocomposites in which conductive transition metal oxides, TMO₂ (TM=Mn and Co), with CdI₂-type structure are confined in the interlayer space of smectite clay have been successfully synthesized through a combination of intercalation and soft chemical reactions. The synthesis procedure consists of three processes: (1) ion exchange; (2) intercalation of metal hydroxide sheets into the interlayer space; (3) oxidation of the hydroxide sheets inside the space. The resulting composites have an expanded layer structure with about 2.0 nm periods along c-axis. The TMO₂ sheets are separated by a clay silicate sheet and hydrated sodium ion layers, thus two different types of sheets are stacking alternately. The composites are found to have multi functionalities associated with the structure, e.g. ion exchange, electric conduction as well as unique magnetic property.