Preparation of cobalt oxide nanoparticles and cobalt powders by solvothermal process and their characterization

Co3O4 nanoparticles and cobalt (fcc-Co) powders were successfully synthesized by solvothermal process from a single precursor. The reaction of Co(Ac)(2) with sodium dodecylbenzenesulfonate (SDBS) shows evident-dependent temperature effect. At 180 degrees C, Co(Ac)(2) reacts with SDBS to produce precursor CoCO3 plate structures, which are assembled by small nanoparticles. At the temperature of 250 degrees C, the precursor CoCO3 can be gradually decomposed to form Co3O4 nanoparticles with diameter of ca. 70 nm. While, at 250 degrees C, the reaction of Co(Ac)(2) with SDBS also produce precursor CoCO3 nanoparticles/plates, but the CoCO3 nanoparticles/plates would only decompose to give metal Co. In this process, SDBS acts as not only a surfactant but also a reagent. Magnetic measurements reveal that the as-prepared Co3O4 nanoparticles exhibit weak ferromagnetic properties and Co powders show ferromagnetic properties. In addition, a possible formation mechanism was elaborately discussed. (C) 2008 Elsevier B.V. All rights reserved.