Effect of Bi-functional Hierarchical Flower-like CoS Nanostructure on its Interfacial Charge Transport Kinetics, Magnetic and Electrochemical Behaviors for Supercapacitor and DSSC Applications

Abstract

Metal sulfides are of great interest for future electrode materials in supercapacitor and solar cell applications owing to their superior electrochemical activity and excellent electrical conductivity. With this scope, a binary transition metal sulfide (CoS) is prepared via one-step hydrothermal synthesis. Hexagonal phase of CoS with space group of P63/mmc(194) is confirmed by XRD analysis. Additional cubic Co3S4 phase in the prepared sample originates the mixed valence state of Co (Co2+ and Co3+) is affirmed from XPS analysis. Morphological features are visualized using HRSEM images that shows nanoflower shaped star-anise structure. Employing the prepared CoS as active electrode material, interfacial charge transport kinetics is examined by EIS-Nyquist plot. The supercapacitive performances are tested in two and three-electrode system which exhibited respective specific capacitances of 57 F/g and 348 F/g for 1 A/g. Further, the fabricated asymmetric CoS//AC supercapacitor device delivers an appreciable energy density of 15.58 Wh/kg and power density of 700.12 W/kg with excellent cyclic stability of 97.9% and Coulombic efficiency of 95% over 2000 charge-discharge cycles. In addition, dye-sensitized solar cells are fabricated with CoS counter electrode and the obtained power conversion efficiency of 5.7% is comparable with standard platinum based counter electrode (6.45%). Curie-Weiss plot confirms the transition of paramagnetic nature into ferrimagnetic behavior at 85 K and Pauli-paramagnetic nature at 20 K respectively. Temperature dependent resistivity plot affirms the metallic nature of CoS sample till 20 K and transition to semiconducting nature occurs at <20 K owing to Peierl’s transition effect.

Facile synthesis of CdS Quantum dots for QDSSC with high photo current density

“…The plots were analysed using EC lab software and the obtained parameters from the EIS analysis are summarized in table 2. From EIS data, it is clear that the series resistance values are high for QDSSCs with platinum counter electrodes compared to that with copper sulphide counter electrodes [38][39][40][41].…”

Advances on Dye-Sensitized Solar Cells (DSSCs) Nanostructures and Natural Colorants: A Review

“…This type of film enhances light absorption due to its sponge-like characteristics and increased surface area. The nanocrystalline material plays an essential role in electron injection and transport, determining the performance of the DSSCs [6].…”

Flower‐Like Superstructures: Structural Features, Applications and Future Perspectives

“… SEM micrographs of (A) precursor salt Co−(OAc) 2 , [33] (B) Co 3 O 4 , [34] (C) CoO@MnCo 2 O 4 , [35] (D) CoS as prepared by one‐step hydrothermal synthesis, [36] and (E) CoS NF as prepared by facile one‐step solvothermal method [37] flower like microstructure. Reprinted from [33,24] permission of the The American Chemical Society.…”

“…Reprinted from [35] permission of the Elsvier publisher. Reprinted from [36] permitted from Sci. Rep. NPG publisher.…”

“…The Sathiskumar group demonstrated a hierarchically arranged flower‐like CoS structure, and studied its interfacial charge transport kinetics (Figure 12D) [36] . They synthesized the 3D hierarchically arranged flower‐like nanostructures of CoS metal sulfide using a hydrothermal process.…”