Ceria nanoparticles uniformly decorated on graphene nanosheets with coral-like morphology for high-performance supercapacitors

Abstract CeO2/graphene was synthesized by a simple microwave method along with subsequent calcination. CeO2 nanoparticles with an average size of 68.8 nm are uniformly decorated on graphene nanosheets (CeO2/GNs). The CeO2/GNs displays a like-coral morphology. The architecture including overall connected framework, abundant intercrossed and interconnected nanochannels and perfect conducting network of the graphene, endows the CeO2/GNs material with a superior electron and mass transport. As a result, the CeO2/GNs gives a high specific capacitance of 503.4 F/g at 2 A/g and good cycle performance with 91.8% capacitance retention after 3000 cycles. Further, an asymmetric supercapacitors was assembled by using CeO2/GNs as the positive electrode and activated carbon as the negative electrode, the asymmetric device demonstrate a favorable energy density of 30.2 Wh/kg at the power density of 750.0 W/kg and superior cycle life with 86.4% the capacitance retenion at 5 A/g after 3000 cycles.