Ternary g-C₃N₄/Co₃O₄/CeO₂ 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-C₃N₄ nanosheets supported onto three-dimensional flower-like Co₃O₄/CeO₂ (CoCe) ternary synergistic heterostructures are developed as effective electrodes for hybrid supercapacitor applications. Addition of g-C₃N₄ produces substantial surface active sites, enabling its synergistic effect with CoCe to enhance electrochemical performance having exceptional conductivity. The CoCe/g-C₃N₄ ternary composite electrode exhibits a higher specific capacitance of 1088.3 F g^-1 at 1 A g^-1 with 96 % of recycling stability over 5000 cycles, which is ∼5.5 and ∼5 folds higher specific capacitance than the pristine g-C₃N₄ and CoCe electrodes. EIS analysis revealed that CoCe/g-C₃N₄ 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^-1, excellent energy density 37.4 Wh kg^-1 and power density of 749.9 W kg^-1. This research showcases the perspectives of CoCe/g-C₃N₄ ternary electrodes in hybrid supercapacitors and other renewable energy storage devices.