In Situ Generation of Ultrathin MoS 2 Nanosheets in Carbon Matrix for High Energy Density Photo-Responsive Supercapacitors.

Stimuli-responsive supercapacitors have attracted broad interest in constructing self-powered smart devices. However, due to the demand for high cyclic stability, supercapacitors usually utilize stable or inert electrode materials, which are difficult to exhibit dynamic or stimuli-responsive behavior. Herein, this issue is addressed by designing a MoS 2 @carbon core-shell structure with ultrathin MoS 2 nanosheets incorporated in the carbon matrix. In the three-electrode system, MoS 2 @carbon delivers a specific capacitance of 1302 F g -1 at a current density of 1.0 A g -1 and shows a 90% capacitance retention after 10 000 charging-discharging cycles. The MoS 2 @carbon-based asymmetric supercapacitor displays an energy density of 75.1 Wh kg -1 at the power density of 900 W kg -1 . Because the photo-generated electrons can efficiently migrate from MoS 2 nanosheets to the carbon matrix, the assembled photo-responsive supercapacitor can answer the stimulation of ultraviolet-visible-near infrared illumination by increasing the capacitance. Particularly, under the stimulation of UV light (365 nm, 0.08 W cm -2 ), the device exhibits a ≈4.50% (≈13.9 F g -1 ) increase in capacitance after each charging-discharging cycle. The study provides a guideline for designing multi-functional supercapacitors that serve as both the energy supplier and the photo-detector.