Synthesis, characterization and electrochemical performance of carbon/Ni-doped CeO2 composites

Abstract

The electrochemical properties of carbon were improved by forming composites with Ni-doped CeO2 nanoparticles to obtain a material with potential for application in high performance energy storage devices. Composites of Ni-doped CeO2 (Ce1-xNixO2, x = 0, 0.05, 0.10 and 0.20) nanoparticles were formed with carbon by hydrothermal treatment at a temperature of 150 °C for 12 h, hitherto referred to as carbon/CeO2, carbon/5NiCeO2, carbon/10NiCeO2 and carbon/20NiCeO2 for x = 0, 0.05, 0.10 and 0.20, respectively. CeO2 nanoparticles without carbon were also prepared by the same method for comparison. All samples were characterized by X-ray diffraction (XRD), Raman spectroscopy (Raman), energy dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM) - elemental mapping, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) and a potentiostat/galvanostat electrochemical cell system. The samples exhibited XRD and Raman peaks corresponding to carbon and FCC CeO2, confirming the formation of composites. The presence of Ce4+, Ce3+/oxygen vacancies and Ni2+ in all composites was confirmed by XPS measurements. The specific capacitances at a current density of 0.25 A/g were in the range of 138.8–252.6 F/g for electrodes made from carbon/Ni-doped CeO2, which were higher than that of CeO2 (11.9 F/g) and carbon (64.1 F/g) alone. These results suggest that composites of Ni-doped CeO2 nanoparticles with carbon have improved capacitive behavior as electrodes due to a higher concentration ratio of Ce3+/Ce4+.