Shape-controlled synthesis of nanocubic Co3O4 by hydrothermal oxidation method

The nanocubic Co3O4 was synthesized by hydrothermal oxidation method. The effects of cobalt salt, precipitating agent, surfactant, solvent, pH value of the suspension and the amount of oxidant H2O2 on the morphology and structure of Co3O4 were investigated. The Co3O4 powders were characterized by transmission electron microscope and X-my diffraction. The results show that the morphology of Co3O4 is closely dependant on the anion in cobalt salts, but it is not so sensitive to the precipitating agents and solvents. The amount of H2O2 is the key factor to obtain Co3O4 with spinel crystal structure. The optimum synthetic conditions of uniform shape-controlled Co3O4 nanocubes are as follows： Co（CH3COO）2·4H2O as cobalt salt, KOH as precipitating agent, polyethylene glycol with relative molecular mass of about 20 000 as surfactant, water-n-butanol as solvent system, pH value of 8-9, the molar ratio of H2O2 to Co^2＋ above 2.5：1.0, hydrothermal temperature of 160 ℃ and hydrothermal holding time of 10 h. The tap density and apparent density of nanocubic Co3O4 obtained with the average particle size of 20 nm are 1.01 g/cm^3 and 0.70 g/cm^3, respectively.

Shape-controlled synthesis of nanocubic Co3O4 by hydrothermal oxidation method

The nanocubic Co₃O₄ was synthesized by hydrothermal oxidation method. The effects of cobalt salt, precipitating agent, surfactant, solvent, pH value of the suspension and the amount of oxidant H₂O₂ on the morphology and structure of Co₃O₄ were investigated. The Co₃O₄ powders were characterized by transmission electron microscope and X-ray diffraction. The results show that the morphology of Co₃O₄ is closely dependant on the anion in cobalt salts, but it is not so sensitive to the precipitating agents and solvents. The amount of H₂O₂ is the key factor to obtain Co₃O₄ with spinel crystal structure. The optimum synthetic conditions of uniform shape-controlled Co₃O₄ nanocubes are as follows: Co(CH₃COO)₂ · 4H₂O as cobalt salt, KOH as precipitating agent, polyethylene glycol with relative molecular mass of about 20000 as surfactant, water-n-butanol as solvent system, pH value of 8–9, the molar ratio of H₂O₂ to Co²⁺ above 2.5:1.0, hydrothermal temperature of 160 °C and hydrothermal holding time of 10 h. The tap density and apparent density of nanocubic Co₃O₄ obtained with the average particle size of 20 nm are 1.01 g/cm³ and 0.70 g/cm³, respectively.