Supercapacitor Behavior of Cerium Oxide Nanoparticles in Neutral Aqueous Electrolytes

Hexagonal CeO 2 nanoparticles have been prepared through the hydrothermal method using cetyltrimethylammonium bromide (CTAB) as the surfactant. The structural and morphological studies have been made using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses. The electrochemical behavior of CeO 2 nanoparticles was investigated using cyclic votammetry (CV), charge–discharge (CHDH) studies, and alternating current (AC) impedance spectroscopy in different neutral electrolytes, such as NaCl, KCl, Na 2 SO 4, and K 2 SO 4 . Maximum specific capacitance of 523 F g –1 was attained with the NaCl electrolyte at 2 mV s –1 . The capacitance values obtained with various electrolytes are in the order of NaCl > Na 2 SO 4 > KCl > K 2 SO 4 . CHDH and impedance analyses further confirm this behavior. After 2000 cycles of charging and discharging, only 18% degradation in the specific capacitance could be observed. All of the electrochemical studies indicate the NaCl aqueous electrolyte to be most suited electrolyte for CeO 2 supercapacitor electrodes.