A study of the growth process of Co3O4 microcrystals synthesized via a hydrothermal method

Pure Co3O4 microcrystals were prepared by a hydrothermal method from Co(NO3)(2)center dot 6H(2)O and urea solution, and the effect of thermal treatment time on the growth of Co3O4 microcrystals was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman and UV-Vis absorption spectra. The results show that with the thermal treatment time increases from 2 h to 12 h, the shape of as-prepared Co3O4 microcrystals changes from the hedgehog spherelike to the as-cubic one that were stacked by lots of lamella, and finally cubes, and then longer time treatment will only lead to the size growth and agglomeration of particles. In conclusion, the cubic Co3O4 microcrystals of uniform size (similar to 6 mu m) are synthesized via a 12-h thermal treatment. Moreover, the synthesis mechanism has been studied.