NiS/Ni3S4 decorated double-layered hollow carbon spheres for efficient electrochemical hydrogen evolution reaction and supercapacitor

NiS/Ni3S4 anchored on the double-layer hollow carbon spheres (DLHCs@NixSy) were rationally conceived and synthesized via calcination and hydrothermal process. A series of characterization results confirmed nickel sulfide consisted of NiS and Ni2S3 phases formed. Double-layer hollow carbon spheres as substrates with good electrical conductivity, high specific surface area and hollow structure, not only serve as the active sites for nickel sulfide targeting and electron conduction, but also adapt to the volume change on cycling. Sample DLHCs@NixSy-1:2 prepared using optimized conditions exhibited enhanced electrochemical performance and energy storage in electrocatalytic hydrogen evolution and supercapacitor, respectively. The hybrid nanostructure just needed to afford the potential of 263 mV to reach the current density of 10 mA cm−2 without IR correction and delivered a high specific capacitance of 1160 F g−1 at a current density of 1 A g−1. Encouragingly, the asymmetric supercapacitor device created using DLHCs@NixSy-1:2 and active carbon exhibited a high energy density of 40 Wh/kg at 375 W/kg within the voltage window of 0–1.5 V. Furthermore, the device revealed preeminent cycling performance with a retention rate of 70 % after 2000 cycles at 4 A g−1. This result provided a reference for the synthesis of dual-functional materials with low cost and high efficiency.