Electrochemical performance of reduced graphene oxide (rGO) decorated lanthanum oxide (La2O3) composite nanostructure as asymmetric supercapacitors

. • A novel La 2 O 3 /rGO hybrid composite electrodes were prepared by one step hydrothermal route. • La 2 O 3 /rGO composite electrode has a high specific capacitance of 546 Fg −1 , which is higher than pristine La 2 O 3 (348 Fg −1 ). • ASC device has a high energy density (80 Whkg −1 ) and a high power density (2,250 Wk g −1 ). In this report, La 2 O 3 nanoparticles decorated reduce graphene oxide nanosheets is synthesized to use it as electrode material in high performance supercapacitor. XRD and SEM results reveal that monoclinic crystalline structure with spherical shaped morphology of La 2 O 3 , which is uniformly decorated on the 2D-nanosheets of rGO. The surface area, porous nature and elemental compositions present in hybrids were determined by BET, XPS and EDS. As an application, the synthesized La 2 O 3 /rGO hybrids revealed enhanced electrochemical performance as high specific capacitance with excellent cycling stability which was very significant for electrochemical SCs. The La 2 O 3 /rGO hybrids electrode fulfills an approving specific capacitance value of 546 Fg −1 at a scan rate of 2 mAg −1 and improved cycling stability of 92.3% capacitance retention after 10,000 cycles in the three-electrode setup. The asymmetric two-electrode system with outstanding energy density was assembled by employing the La 2 O 3 /rGO as the positive electrode and the activated carbon as the negative electrode. The two-electrode system displays a high energy density of 80 Whkg −1 at a power density of 2250 Wkg −1 within a potential rage of 0–1.6 V. Furthermore, the system exhibited high cycle stability (90.3 % retention) with only 5.8% loss of its initial capacitance after 10,000 cycles. The enhancement of specific capacitance is explained by the charge transfer effect between rGO and La 2 O 3 at the interface.