Facile synthesis of 2D acid-etched g-C3N4 nanosheets with 1D ZnO nanorods as a promising electrode material for supercapacitor

摘要

A low-cost, non-toxic nanocomposite of two-dimensional (2D) nanosheets of acid-etched graphitic carbon nitride (TGCN) and one-dimensional (1D) nanorods of zinc oxide (ZnO NRs) is prepared using one-step calcination method. The average size and diameter of ZnO nanorods in TGCN/ZnO (T-ZnO) nanocomposite is reduced to 0.5 and 0.73 times than pristine ZnO NRs, respectively. After the acid-etching process, the size of the T-ZnO nanocomposite is further reduced which enhanced its specific surface area to 16.82 m2/g as compared to pristine ZnO NRs (3.56 m2/g). T-ZnO NRs shows a specific capacitance of 398.47 F/g using 0.5 M H2SO4 which is higher as compared to T-ZnO NRs using 0.5 M Na2SO4 (278.16 F/g) and 6 M KOH (106.10 F/g). Using Electrochemical impedance spectroscopy, diffusion coefficient (D) value 1.85 x 10-11 is obtained for T-ZnO NRs (0.5 M H2SO4). T-ZnO NRs also exhibits a higher specific capacitance of 311.80 F/g at 1 A/g using 0.5 M H2SO4. The nanocomposite shows superior energy density of 97.43 Wh/kg at 750 W/kg of power density. The superior capacitance retention (>95 ) and stable coulombic efficiency (>80 ) of T-ZnO NRs enables the nanocomposite for practical applications in energy storage devices. The electric double layer (EDL) and pseudocapacitive (PC) contribution of 6.04 and 93.96 to the total specific capacitance of T-ZnO NRs is evaluated using Trasatti method. The capacitive and diffusion-controlled contribution is also investigated for T-ZnO NRs using Dunn's method. The practical aspect of a supercapacitor using leakage current and self-discharge is also tested for the TZnO NRs. T-ZnO NRs is a promising energy storage material to fill the gap in the ongoing energy crisis.