Supercapacitor Behavior of Cerium Oxide Nanoparticles in Neutral Aqueous Electrolytes

Abstract

Hexagonal CeO2 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 CeO2 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, Na2SO4, and K2SO4. 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 > Na2SO4 > KCl > K2SO4. 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 CeO2 supercapacitor electrodes.