NiS2 nanoparticles anchored on Co-carbon nanotubes for supercapacitor and overall water splitting

Exploiting low-cost and efficient electrode materials with catalytic activity toward water splitting and supercapacitor has a crucial role with sustainable energy development. Herein, a composite structure is created in which nickel sulfide nanoparticles are loaded on the surface of nitrogen-doped carbon nanotubes (Co-CNTs) encapsulated with cobalt nanoparticles as multifunctional catalysts. The growth in situ of NiS2 nanoparticles results in the Co-CNTs@NiS2 composite with ideal interface effect which remarkable improves the performance in supercapacitor, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity. As a supercapacitor electrode, Co-CNTs@NiS2 activated carbon asymmetric supercapacitor performs a high specific capacitance of 370 F g−1 at 1 A g−1, revealing high retention of 68.8% after 3000 cycles. As an electrocatalyst, it is just needed to afford the overpotential of 235 and 309 mV in HER and OER to reach a current density of 10 mA cm−2 without iR correction. The Co-CNTs@NiS2 composite with optimized exposed surface just requires an overall cell voltage of 1.73 V to achieve 10 mA cm−2 in electrolyzer. The results supply great potential in the application of renewable energy.