Enhanced electrochemical properties of NiS@CeO2 spherical nanoflakes

Herein we report synthesis of bare cerium oxide nanoparticles from cerium hydroxide and NiS@CeO 2 nanocomposite (NC) from nickel cinnamaldehyde thiosemicarbazone complex (single source molecular precursor) and CeO 2 nanoparticles by solvothermal method using ethylene glycol as a capping agent. These materials were characterized using powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy and energy dispersive X-ray techniques. The crystallite size of the composite nanoparticles calculated using XRD is 17.99 nm. TEM shows spherical shape morphology of NiS@CeO 2 nanocomposite with average particle size less than 10 nm. Electrochemical properties of bare CeO 2 and NiS@CeO 2 NC electrodes were evaluated by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The electrochemical measurements show that the capacitance value of NiS@CeO 2 NC electrode is significantly higher (707.84 F g −1 ) compared to bare CeO 2 electrode (80.91 F g −1 ) at current density 1 A g −1 . This can be attributed to synergistic effect in nanocomposite. The cycle stability of NiS@CeO 2 NC electrode was found to be 98.41 % even after 6000 charge–discharge cycles at 2 A g −1 current density. • The NiS@CeO 2 nanocomposite (NC) has been synthesized by solvothermal method. • NiCl 2 (Cinnamaldehyde thiosemicarbazone)2 was used as single source precursor. • Scanning electron microscopy shows spherical nanoflake morphology of NiS@CeO 2 NC. • NiS@CeO 2 electrode displayed high specific capacitance of 707.84 F g−1 at 1 Ag−1. • NiS@CeO 2 electrode shows cycle stability of 98.41 % even after 6000 cycles at 2Ag-1.