Flake-like SnS anchored on the carbon layer for supercapacitor electrode with photo-responsive capacitance enhancement

Photo-responsive supercapacitors incorporate light-responsive materials on capacitive electrodes, making them capable of solar energy conversion and storage within single device. Herein, composite structures consisting of flake-like stannous sulfide (SnS) anchored on a carbon layer (CL) covered nickel foam (CL@SnS/NF) are synthesized as photo-responsive supercapacitor electrode for capacitance enhancement under visible light. SnS as a light-absorbing layer has a narrow bandgap that matches well with the wavelength of visible light, while CL serves as an electron transport channel for effective separation of photogenerated carriers. Due to the synergetic effect of two components above, the areal specific capacitance of the CL@SnS/NF electrode increases from 15.7 to 21.0 mF·cm-2 in light conditions under 0.1 mA·cm-2, which is 1.7 and 6.6 times larger than that of CL/NF and SnS/NF electrodes under the same conditions, respectively, indicating the remarkable light-induced capacitance enhancement performance. The CL@SnS/NF electrode also presents higher photocurrent and photovoltage than two single electrodes, implying its excellent photosensitivity. In addition, the assembled CL@SnS/NF-based symmetric supercapacitor exhibits great capacitance gain under illumination (185.8% at 50 µA·cm-2) and excellent capacitance maintenance (87.7% over 6000 cycles). This work supplies a novel strategy to the development of high-performance solar energy conversion and storage devices.