Synthesis and investigation on cobalt-layered hydroxide compounds and their related nanostructured materials

Abstract

Cobalt-containing layered hydroxide compounds and their derived nanostructured materials have been synthesized in this work. The intercalated anions of these layered compounds range from inorganic species (carbonate and nitrate) to organic dicarboxylates (terephthalate and 1,2-phenylenediacetate). In addition to the bulk properties studied by common analytical methods, surface chemical states of the layered hydroxides have been investigated by X-ray photoelectron spectroscopy. The thermal decomposition of alternate-arranged cobalt hydroxide layers and interlayer anions has been studied by in situ thermogravimetric/infrared spectroscopic methods, which elucidate the reaction sequences and identify activities of both hydroxide layers and interlayer anions. Free-standing Co3O4 nanocubes have been generated from hydroxide precursors in aqueous systems at ambient conditions via increasing ionic strength of the reaction mixture. Co3O4 nanocrystals assembled in rod-like shape have been obtained via thermal transformation from cobalt hydroxide carbonate precursors. Their microstructural properties and growth mechanism are investigated by transmission electron microscope and electron diffraction.