Heterogeneous Structures Consisting of Rod-like ZnO Interspersed with CeS Nanoparticles for Photo-Sensitive Supercapacitors with Enhanced Capacitive Performance.

Photosensitive supercapacitors incorporate light-sensitive materials on capacitive electrodes, enabling solar energy conversion and storage in one device. In this study, heterogeneous structures of rod-shaped ZnO decorated with CeS nanoparticles on nickel foam (ZnO@CeS/NF) are synthesized using a two-step hydrothermal method as photosensitive supercapacitor electrodes for capacitance enhancement under visible light. The formation of ZnO@CeS heterogeneous structures is confirmed using various structural characterization techniques. The area-specific capacitance of the ZnO@CeS/NF composite electrode increased from 1738.1 to 1844.0 mF cm after illumination under a current density of 5 mA cm, which is 2.4 and 2.8 times higher than that of ZnO and CeS electrodes under similar conditions, respectively, indicating the remarkable light-induced capacitance enhancement performance. The ZnO@CeS/NF electrode also exhibits a higher photocurrent and photovoltage than the two single electrodes, demonstrating its excellent photosensitivity. The improved capacitance performance and photosensitivity under illumination are attributed to the well-constructed energy-level structure, which stimulates the flow of photogenerated electrons from the outer circuit and the involvement of photogenerated holes in the resulting surface-controlled capacitance. In addition, the assembled ZnO@CeS/NF-based hybrid supercapacitor exhibits a great energy density of 145.0 mWh cm under illumination. This study provides a novel strategy for the development of high-performance solar energy conversion/storage devices.