Hierarchical core–shell structural NiMoO4@NiS2/MoS2 nanowires fabricated via an in situ sulfurization method for high performance asymmetric supercapacitors

Abstract

The controlled construction of hierarchical electrodes that overcome the single contribution of pure materials and create an interface effect between structures to enhance the electrochemical performance of supercapacitors is highly desirable. In this study, hydrothermally prepared NiMoO₄ nanowires were treated via a facile vapor phase sulfurization method, forming a 1D hierarchical core–shell porous configuration that in situ wrapped an NiS₂/MoS₂ nanosheet shell on the NiMoO₄ core, which provides more accessible sites for faradaic reactions and abundant charge transfer channels in innumerable hetero-interfaces with defects. The as-obtained NiMoO₄@NiS₂/MoS₂ sample exhibited a high specific capacity of 437 C g⁻¹ (970 F g⁻¹) at a current density of 5 A g⁻¹, excellent rate capability (a high capacity retention of 320 C g⁻¹ at the high current density of 20 A g⁻¹), and excellent electric conductivity. Furthermore, the NiMoO₄@NiS₂/MoS₂ composite and activated carbon were employed to assemble an asymmetric supercapacitor, which delivered a high energy density of 26.8 W h kg⁻¹ at a power density of 700 W kg⁻¹.