An illumination-assisted supercapacitor of rice-like CuO nanosheet coated flexible carbon fiber

It is of great significance to investigate impact of environment on energy storage and its potential mechanisms. Herein, we designed and synthesized rice-like CuO structure loaded on carbon fibers (CFs) for illumination-assisted supercapacitor. Then we used the CuO/CF as a supercapacitor electrode material, which could effectively reach a photocurrent of 5.05 mAg−1 in 90 mWcm−2, as well as increase capacitance by 2.03 times under illumination. The enhancement mechanism was further analyzed: (Ⅰ) holes and electrons was generated when CuO/CF electrode was stimulated by illumination; (Ⅱ) the excited holes-electrons promoted interface reaction process. Further, this enhancement mechanism was confirmed through cyclic voltammetry, galvanostatic charge-discharge, photoelectric response, impedance analyses and DFT calculation. Moreover, the CuO/CF electrode exhibited good long-cycle performance of 99.45% after 10000 cycles, and it could be well applied in supercapacitors for improving capacitance. We hope that the illumination-assisted supercapacitor reported in this work may provide an important discovery for next-generation smart energy storage devices.