Synthesis, characterization and electrochemical performance of cobalt fluoride nanoparticles by reverse micro-emulsion method

In this work, the cobalt fluoride (CoF₂) nanoparticles (NPs) were prepared by reverse micro-emulsion method for first time using cetyltrimethylammonium bromide as surfactant and 2-octanol and water as solvents. Two types of hydrated and sintered CoF₂ NPs were prepared with different ratio by changing water to surfactant ratio while keeping the temperature constant at 22 °C. The hydrated CoF₂ NPs were sintered at 400 °C under inert atmosphere at 5.0 millibar pressure for 3 h in vacuum chamber in order to obtain sintered CoF₂ NPs. The particle sizes of the as-prepared NPs were found to be ~20–70 nm. As-prepared hydrated and sintered CoF₂ NPs were characterized by Energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, Scanning electron microscopy, UV–Vis spectroscopy, thermogravimetric analysis, and X-ray diffraction. Further, cyclic voltammetry has been used to measure the electrochemical performance of as-prepared NPs and the results show that electrochemical performance i.e. reversibility and cyclic stability of the synthesized NPs are highly improved. The sintered CoF₂ NPs (~20–50 nm) obtained at ratio 2:2.5 with uniform composition show better electrochemical performances (0.079 mA g⁻¹) as compared to its counterparts. This study reveals that CoF₂ NPs has great potential as cathode material in energy storage devices due to its excellent efficiency, low cost, easy synthesis and high yield.