A hydrothermal reaction combined with a post anion-exchange reaction of hierarchically nanostructured NiCo2S4 for high-performance QDSSCs and supercapacitors

Abstract

This paper proposes a novel and facile strategy to synthesize hierarchical nanostructured NiCo₂S₄via a simple hydrothermal reaction combined with a post anion-exchange reaction that was used directly as an electrode in supercapacitor and quantum-dot sensitized solar cells. By applying the appropriate material concentration, deposition temperature, and time, the NiCo₂S₄ was densely deposited over the entire surface of the Ni foam with good adhesion. The NiCo₂S₄ electrode exhibited outstanding electrochemical performance in both the applications with a high specific capacitance of 1612.95 F g⁻¹, energy density of 56 W h kg⁻¹ at 5 A g⁻¹, good cycling stability, power conversion efficiency of 3.94%, and J_sc of 12.27 mA cm⁻². The NiCo₂S₄ electrode exhibited almost double the output values compared to NiCo₂O₄ (693.6 F g⁻¹ at 6.66 A g⁻¹ and efficiency of 1.81%) and NiCo₂Se (1401.4 F g⁻¹ at 10 A g⁻¹ and efficiency of 3.86%), resulting from the excellent electrochemical performance of the NiCo₂S₄. Overall the excellent performance of the fabricated electrode was attributed mainly to the highly electrocatalytic activity, large surface area and decent conductivity of the hierarchical nanostructures of the NiCo₂S₄. This study shows that the NiCo₂S₄ nanostructures can be applied not only in high energy density fields, but also in high power density and energy harvesting applications.