Ternary g-CN/CoO/CeO nanostructured composites for electrochemical energy storage supercapacitors.

Extensive use of fossil fuels causes heavy discharge of carbon dioxide, depleting energy resources and this requires environmentally friendly and effective energy storage materials. Hybrid supercapacitors (HSCs) are recently developed as effective energy storage materials enabling high capacitance retention rate and quick charging. Herein, synthesis of two-dimensional g-CN nanosheets supported onto three-dimensional flower-like CoO/CeO (CoCe) ternary synergistic heterostructures are developed as effective electrodes for hybrid supercapacitor applications. Addition of g-CN produces substantial surface active sites, enabling its synergistic effect with CoCe to enhance electrochemical performance having exceptional conductivity. The CoCe/g-CN ternary composite electrode exhibits a higher specific capacitance of 1088.3 F g at 1 A g with 96 % of recycling stability over 5000 cycles, which is ∼5.5 and ∼5 folds higher specific capacitance than the pristine g-CN and CoCe electrodes. EIS analysis revealed that CoCe/g-CN electrode offered reduced charge transfer resistance compared to pristine electrodes. The fabricated two-electrode HSC device displays outstanding retention after 10,000 cycles with an ultra-high specific capacitance of 119.8 F g, excellent energy density 37.4 Wh kg and power density of 749.9 W kg. This research showcases the perspectives of CoCe/g-CN ternary electrodes in hybrid supercapacitors and other renewable energy storage devices.