Urea-Assisted Synthesis of Microspherical Hollow CeO2 Nanostructures for Supercapacitor Applications

Abstract

In the present work, cerium oxide (CeO2), the most abundant and least expensive rare earth metal oxide with the capability of rapid conversion between the oxidation states of Ce+3 and Ce+4, is synthesized via a urea-assisted solvothermal method in methanol. Along with its role as a precipitating agent, urea reacted with methanol and thus initiated a series of organic reactions which are responsible for the formation of spherical layered assembly of cerium oxide leading to a multi-layered structure with high porosity. The morphology and chemical structure of the material are investigated using SEM, TEM, XRD, and FTIR spectroscopy. The porous and spherical architecture achieved here enhanced the surface area, active sites, and electrical conductivity and also introduced more diffusion pathways at the electrode/electrolyte interface, which collectively improved the performance of CeO2 as a supercapacitor electrode material. The outstanding redox characteristics of CeO2 are explored in supercapacitor applications, and the electrode exhibited a specific capacitance of 319.68 F/g at a current density of 0.5 A/g in a three-electrode configuration which proved the excellence of the present CeO2 microspheres in the field of energy storage applications.