Synthesis and characterization of Co3O4 nanoplates by simple thermolysis of the [Co(NH3)6]2(C2O4)3·4H2O complex

Abstract

Nanoplates of Co3O4 were selectively prepared through solid-state thermolysis of the [Co(NH3)6]2(C2O4)3·4H2O complex at 350°C without the need for an expensive and toxic solvent/surfactant or complicated equipment. The product was characterized by thermal analysis (TGA/DTG/DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, UV–Vis spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and magnetic measurements. The TEM images show that the product was formed mainly from square-like Co3O4 nanoplates with a length of 50∼200nm and thickness of 10–20nm. The FT-IR, XRD, Raman, EDS and VSM results confirm that the as-prepared Co3O4 nanoplates are pure and single-phase with a weak ferromagnetic behavior that could be attributed to uncompensated surface spins and/or finite-size effects. The optical spectrum indicated two direct band gaps at 2.15 and 3.50eV with a blue shift compared with the bulk samples. A plausible pathway for the formation of Co3O4 nanoplates from the [Co(NH3)6]2(C2O4)3·4H2O complex was also proposed.