Synthesis of heterostructured ZnO-CeO2 nanocomposite for supercapacitor applications

Supercapacitors (SCs) are receiving increasing attention owing to their unique characteristics, including moderate energy density, long service life, rapid discharge-charge rates, and exceptional safety. In this study, a ZnO-CeO2 nanocomposite was synthesized via a facile hydrothermal method. The hexagonal nanorods of ZnO and the particle morphology of CeO2 with high purity and crystallinity were confirmed using morphological and phase analyses. The cyclic voltammetry (CV) voltammogram from prolonged scan rates and the maximum response current in the three-electrode cell demonstrates the ZnO-CeO2 nanocomposite ideal capacitive behavior. The ZnO-CeO2 nanocomposite exhibited excellent electrochemical properties owing to the typical pseudocapacitive nature of fast redox reactions from Ce3+/Ce4+ and Zn2+ ions, with an initial capacitive contribution of 80 % at 10 mV s-1, calculated using the Dunn's method. It exhibited a high capacitance of 1040.9 F/g at a current density of 1 A/g and excellent long-term cycling stability (97.0 %) and rate capability (68.1 %) over 8000 charge-discharge cycles. Density functional theory (DFT) calculations indicated that the ZnO-CeO2 composites show superior transport properties owing to the heterointerfaces of the formed heterostructure. The promising results of this study indicate that the ZnO-CeO2 nanocomposite could be used as an electrode material for supercapacitors.