Defect mediated modulation of electrochemical efficacy and stability of Fe3O4 nanodiamond incorporated MoS2 based hierarchical 2D nanostructures for high performance supercapacitor electrodes

Abstract

In this study, pristine MoS₂ and 1 to 5 wt% Fe₃O₄ nanodiamond incorporated MoS₂ nanoflowers were synthesized via a facile hydrothermal route to identify the optimal material combination for electrodes in supercapacitors. The nanostructured composite with 3% Fe₃O₄ nanodiamonds exhibited an impressive specific capacitance of 712 F g⁻¹ at 0.3 A g⁻¹ current density and remarkable cyclic stability, with 84% capacitance retention and 103% coulombic efficiency after 10 000 cycles at 2 A g⁻¹ current density. The crystallographic and morphological analyses revealed that the improved electrochemical performance of the optimum composition could be attributed to the formation of disorder induced surface active sites and broadening of crystallographic interlayer spacing of MoS₂ leading to an enhancement in ionic adsorption, intercalation and surface redox reaction. Additionally, the reduced interface charge transfer resistance for the optimal composition obtained from the EIS analysis could also contribute towards specific capacitance enhancement by facilitating the faradaic process. However, the observed diminution in capacitance by 50% above the optimum Fe₃O₄ content (5%) was attributed to a sudden drop in electrolytic channel integrity. The power (45–90 W kg⁻¹) and energy (2.15–3.70 W h kg⁻¹) densities of the material obtained from the two-electrode system setup corresponded to the performance zone of symmetric supercapacitors in the Ragone plot. These findings highlight the Fe₃O₄ nanodiamond incorporated MoS₂ nanocomposite as a very effective material for high performance supercapacitors, noticeably out-performing other material combinations with different morphologies.