Mesoporous Zr-doped CeO2 nanostructures as superior supercapacitor electrode with significantly enhanced specific capacity and excellent cycling stability

Due to its good chemical stability and outstanding redox properties, CeO2 has been regarded as a promising electrode material for supercapacitors, but its specific capacity is quite low which restricts its wide-range applications. To enhance its specific capacity, in this study, specially designed mesoporous Zr-doped CeO2 nanostructures with large surface area, extraordinarily high porosity and abundant oxygen vacancies were fabricated using a hydrothermal method and an assisted calcination process. The synthesized mesoporous CeO2-Zr-1 nanostructures (with an atomic ratio of Ce:Zr = 10:1) were composed of nanocrystals with an average size of 6.7 nm, and had a large surface area of 81.0 m2 g−1, and abundant mesopores with a volume of 0.2108 cm3 g−1. In 2 M KOH electrolyte, the CeO2-Zr-1 electrode generated a much larger specific capacity (448.1 C g−1) than that of the pristine CeO2 (249.3 C g−1) at a current density of 1 A g−1. An asymmetric supercapacitor of CeO2-Zr-1//activated carbon produced a high energy storage density of 23.3 Wh kg−1 at 398.5 W kg−1, and an excellent long-term cycling stability with 96.4% capacity retention after 6000 cycles.