Black phosphorus quantum dots enabled photo-assisted supercapacitor with boosted volumetric charge storage capability

Photo-assisted rechargeable energy storage devices are a promising strategy to achieve sustainable development by simultaneously integrating solar energy conversion and supercapacitor storage. Herein, we fabricated a light-sensitive macroporous film based on carbon nanotube (CNT), intercalated with Co2V2O7, and then modified by black phosphorus quantum dots (BPQD). Physico-chemical characterization and density functional theory are employed to investigate the improved photo-assisted charge storage capability and the underlying mechanism. It is demonstrated that photo-generated carriers can be separated efficiently, and the formed abundant interfaces could modulate the electronic structure of the electrode, effectively improving the conductivity. Under visible light, the electrode displays an ultra-high capacity of 138.4 mA h g–1 (197.9 mA h cm–3) at 1 A g–1. Besides, the CNT@Co2V2O7/BPQD supercapacitor shows a maximum energy density of 44.4 Wh kg–1 (60.0 Wh L–1) at a power density of 800 W kg–1 (960 W L–1) and excellent cyclic stability of 104.8% after 13000 charge/discharge cycles. The above improvements are attributed to the reactivity and kinetics of electrochemically active components. This study reveals the synergistic effects of multi-interface on "light, photo-generated charge, and energy storage" and provides new possibilities in the controllable design of novel photo-assisted energy storage devices.