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 degrees C. The hydrated CoF2 NPs were sintered at 400 degrees 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 similar to 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 (similar to 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.