In-situ growth of hierarchical trifunctional Co4S3/Ni3S2@MoS2 core-shell nanosheet array on nickel foam for overall water splitting and supercapacitor

It is an enormous challenge to construct the cheap and effective multifunctional electrocatalysts for energy storage and conversion applications. Herein, a ZIF-67 derived Co4S3/Ni3S2@MoS2 core-shell nanosheet arrays were successfully developed on nickel foam via a simple two-step hydrothermal vulcanization method for electrocatalytic water splitting and supercapacitors. For overall water splitting, CNM 0.5 required the overpotentials of 96 and 269 mV at 10 mA cm−2 and 100 mA cm−2 for HER and OER in 1 M KOH. The dual-electrode electrolytic cell assembled from CNM 0.5 required only 1.447 V at 10 mA cm−2, and had nearly 100% Faraday efficiency and long-term stability (40 h). When used as the electrode for supercapacitors, CNM 0.5 had a large specific capacitance of 1238 F g−1 at 1 A g−1 current density and exceptional durability (85% retention after 2000 cycles). The ASC device assembled with CNM 0.5 provided the high-energy density of 41.2 W h kg−1 and long cycle-life (87% after 2000 cycles). The unique core-shell morphology with abundant active reactive edge sites would be beneficial for charge reduction and the volume shrinking/swelling during the rapid charge/discharge process. The well-ordered and vertically aligned nanosheet arrays possessed good conductivity and small interface resistance, which would facilitate the electron transfer and electrolyte penetration, ion insertion and de-intercalation.