Ultrathin VS2 nanosheets vertically aligned on NiCo2S4@C3N4 hybrid for asymmetric supercapacitor and alkaline hydrogen evolution reaction

Abstract Hollow transition metal sulfide hybrid nanostructures offer promising potential materials for electrochemical water splitting and energy storage applications. Herein, we demonstrate the rational design of hollow structured NiCo2S4@C3N4@VS2 hybrid nanostructures for asymmetric supercapacitor and alkaline hydrogen evolution reaction (HER). Through an efficient step-by-step strategy, ultrathin VS2 nanosheets were vertically grown on C3N4 coated NiCo2S4 hollow nanospheres to form NiCo2S4@C3N4@VS2 hybrid nanostructures. Benefiting from intriguing morphological features and conductivity, NiCo2S4@C3N4@VS2 hybrid nanostructures exhibit a large specific capacitance 1984.1 F/g at 1 A/g, superior rate capacity (91.5% at 5 A/g) and outstanding durability (retaining 88.4% over 5000 cycles at 5 A/g). Moreover, the NiCo2S4@C3N4@VS2//AC asymmetric supercapacitor device provides a large energy density (31.7 Wh/kg), remarkable power density (711.1 W/kg) and superior cycle life (retention of 91.2% after 5000 cycles). Furthermore, the hybrid nanostructures manifest enhanced electrochemical activity as electrocatalysts for HER process with small Tafel slope of 71.8 mV dec−1, excellent overpotential of 110 mV at 10 mA cm−2 and remarkable stability. Thus, the NiCo2S4@C3N4@VS2 hybrid nanostructures can hold excellent potential for advanced asymmetric supercapacitor and alkaline HER electrodes.