Abstract
Zeolitic imidazolate frameworks (ZIFs) represent a class of material exhibiting a well-defined geometry. The ZIF derivatives are known to inherit the parent morphology and have emerged as a potential platform for developing superior electrode materials. In this study, leaf-like ZIF-67 is synthesized using a chemical route and employed as the sacrificial template in one-pot hydrothermal sulfurization for preparing Co3S4-Mo15S19, cobalt‑molybdenum hybrid sulfide (CMS/NF). The unique stellate-shaped architecture of the CMS/NF microflowers enhances the exposure of the redox active sites, improving charge storage and exhibiting superior performance. On account of the synergy of the metal ions and stellate-shaped hierarchical architecture, the CMS/NF hybrid sulfide shows an excellent specific capacitance value of 3283 F g−1 at a current density of 1 A g−1 with capacitance retention of 77.7 % at 10 A g−1. An asymmetric supercapacitor device based on CMS/NF hybrid sulfide with aqueous KOH electrolyte exhibits a high specific energy of 40.8 Wh kg−1 at 400 W kg−1 with excellent cycling life of 81 % after 5000 cycles with ∼100 % coulombic efficiency. In addition, the density functional theory-based simulations have been carried out for the Co3S4-Mo15S19 hybrid system to develop a better understanding. From the total density of states, it is concluded that compared to the pristine structures, the hybrid system has enhanced states close to the Fermi level, confirming the conductivity improvement. Computed quantum capacitance for the pristine and hybrid systems corroborates the experimental capacitance consequences. Hence, the theoretical examinations warrant our electrochemical results and provide insight into developing high-performance supercapacitor electrodes.
Published Version
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