Facile hydrothermal synthesis of NiS hollow microspheres with mesoporous shells for high-performance supercapacitors

Abstract

Hollow nickel sulfide (NiS) microspheres with mesoporous shells have been successfully synthesized via a facile hydrothermal route using nickel chloride hexahydrate (NCH) as the nickel source and thiosemicarbazide (TSC) as the sulfur source. The NH₂–NH– group in the TSC molecule plays a crucial role in the formation of hollow microspheres. Ostwald ripening mechanism was suggested to explain the formation of hollow NiS microspheres with mesoporous shells. The resulting hollow NiS microspheres were further used as an electrode material for supercapacitors and found to exhibit a high specific capacitance of 1848.0 F g⁻¹ at a discharge current density of 1 A g⁻¹. About 74.3% of the capacity was retained as the current density increased from 1 to 10 A g⁻¹. Furthermore, the hollow NiS microspheres electrode also exhibited excellent cycling stability at a scan rate of 50 mV s⁻¹. The results indicate that the as-prepared hollow NiS microspheres with mesoporous shells are a promising electrode material for supercapacitors.