Shape-controlled synthesis of cobalt particles by a surfactant-free solvothermal method and their catalytic application to the thermal decomposition of ammonium perchlorate

Abstract

Submicro-Co particles with different morphologies were successfully synthesized by a simple solvothermal and surfactant-free approach. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images revealed that the average size was approximately 2 μm and the microstructure of the as-synthesized particles could be regulated by the contents and ratio of Co²⁺/NaOH. The phase structure and composition of the as-synthesized samples were characterized by X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS) and Raman spectroscopy. The results indicated that the as-synthesized Co particles were covered with a thin layer of CoO. Based on time-dependent experiments, the growth mechanisms of three kinds of typical structures and morphologies were proposed. The magnetic hysteresis loops showed ferromagnetic characteristics and the best saturation magnetization (M_s) and coercivity (H_c) were found to be 162.5 emu g⁻¹ and 104.3 Oe, respectively. Moreover, the exothermic peak of ammonium perchlorate thermal decomposition shifted towards the lower temperatures by 108 °C through addition of 4% Co particles, indicating that the Co particles exhibited a good catalytic effect for potential applications.