High-performance supercapacitor of ZnO-incorporated structurally modified g-C₃N₄ with circular mesoporous channels attained via a template-free approach

Abstract Here, the superior structural features of graphitic carbon nitride (g-C 3 N 4 ) in combination with integrated mesoporous channels have been explored for its use as a supercapacitor electrode material. A facile template-free strategy is adopted for the preparation of ZnO-incorporated modified g-C 3 N 4 nanocomposite, where material characterization via x-ray difraction, Fourier transfrom infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy and x-ray photoelectron spectroscopy analysis revealed the presence of structurally modified g-C 3 N 4 having uniform circular mesoporous channels with well-dispersed ZnO with strong Zn–C and Zn–N interactions. The electrical double-layer capacitance together with the pseudocapacitance of the ZnO/g-C 3 N 4 electrode material resulted in improved performance, leading to a specific capacitance of 146.3 F g −1 at a current density of 0.5 A g −1 ; an increased capacitance is observed in 5000 repeated charge–discharge cycles. A symmetric coin cell supercapacitor fabricated from the material displayed an energy density of 38.8 mWh kg −1 at a power density of 4259 mW kg −1 . Additionally, the long life of 6000 cycles (retaining 100% specific capacitance) exhibited by the coin cell supercapacitor further indicates the promising energy storage nature of the ZnO-incorporated modified g-C 3 N 4 mesoporous nanoarchitecture. Real life application of the ZnO/g-C 3 N 4 -derived supercapacitor is illustrated by lighting up a green LED with a series connection of four coin cells.