One-step hydrothermal synthesis of Ni3S2/MoS2 nanocomposites on rGO: Structural evolution and supercapacitor performance

Abstract

In the present paper, rGO was coated on Ni foams (NFs) by simple physical deposition and subsequent thermal reduction method. Then, Ni3S2/MoS2 composites with different morphologies on the surface of rGO were fabricated via one-step hydrothermal route with different reaction time (18 h, 24 h, 30 h, 36 h and 42 h). It's found that the reaction time significantly affects the morphologies and electrochemical performance of the composites. As reaction time is 18 h and 24 h, Ni3S2/MoS2 composites show two-dimensional nanosheet-like shape with 3D network structure. As reaction time increases continuously, one-dimensional nanorod with residual nanosheet at the root is obtained. After 36 h, hollow Ni3S2@MoS2 hybrid nanofibers with hierarchical core-shell structure were fabricated. RGO/Ni3S2/MoS2 composite with core-shell structure (prepared at 150 °C for 36 h) exhibited good electrochemical properties with specific capacitance of 6451 mF∙cm−2 at 40 mA∙cm−2, and a remarkable cycling performance of 87.2% capacitance retention after 5000 cycles at 110 mA cm−2. An aqueous asymmetrical supercapacitor was assembled using rGO/Ni3S2/MoS2 composite obtained at 150 °C for 36 h and rGO as positive and negative electrode materials. The assembled device displays very good cycling stability of 133% retention of initial specific capacitance and high energy density of 32.6 W h kg−1 at a power density of 399.8 W kg−1. These results sufficiently prove the practical application of rGO/Ni3S2/MoS2 composites in supercapacitor electrode materials.