Cerium oxide nanoparticles decorated on graphene oxide nanosheets as battery-type cathode material for supercapacitors.

Designing advanced materials that effectively mitigate the poor cycle life of battery-type electrodes with high specific capacities is crucial for next-generation energy storage systems. Herein, graphene oxide-ceria (GO-CeO) nanocomposite synthesized via a facile wet chemical route is explored as cathode for high-performance supercapacitors. The morphological analysis suggests fine ceria (CeO) nanoparticles dispersed over ultrathin graphene oxide (GO) sheets while structural studies reveal face-centered cubic phase of CeO in the nanocomposite. In-depth electrochemical performance investigation of the nanocomposite in 6 M KOH aqueous electrolyte demonstrated its excellent battery-type behavior with least ion diffusion resistance and a superior cycle life resulting from the synergistic effect of redox-active CeO and 2D GO with abundant oxygen functionalities. Specifically, GO-CeO composite electrode delivered a maximum specific capacitance of 625.9 F/g (52.2 mAh/g) at 3 A/g current density, which is substantially higher than the capacitance values obtained for GO and CeO electrodes, and demonstrated an excellent cycling stability with ∼ 100 % capacitance retention after 10,000 CV cycles. Furthermore, a novel aqueous asymmetric supercapacitor (ASC) is explored with GO-CeO as positive and iron(III) oxyhydroxide (FeOOH) as negative electrode material in 6 M KOH electrolyte which has also displayed good energy-power density combination along with excellent cycle stability. The study thus endorses rational design of nanocomposite materials with suitable functionalities as an excellent strategy in augmenting the performance of futuristic energy storage devices.