Designing Novel Co2FeV2O8 Microsticks with Prompted Multiple Electrochemical Performances for an Asymmetric Solid-State Supercapacitor and the Hydrogen Evolution Reaction

This article reports the preparation of novel Co 2 FeV 2 O 8 microsticks by the solvothermal route for multiple electrochemical applications such as a solid-state asymmetric supercapacitor and hydrogen evolution reactions. The prepared microstick’s physical and chemical characterizations have been performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) to ensure the phase purity and morphology of the material. Co 2 FeV 2 O 8 microsticks exhibit a specific capacity of 261 C g –1 at 1 A g –1 with excellent capacity retention after 10,000 cycles. Furthermore, the charge-storage contributions of the capacitive and diffusion-controlled process were estimated using Dunn’s approach, and the estimation of accumulated external and internal surface charges was done using Trassati’s approach. For practical applications, a solid-state asymmetric supercapacitor device has been fabricated, which exhibits excellent electrochemical energy storage performance such as an attractive specific capacity (352 C g –1 ), high capacitance retention for 10,000 cycles, and huge specific energy and power outcomes (60 Wh kg –1 at 900 W kg –1 ). Along with the energy storage performance, the prepared Co 2 FeV 2 O 8 exhibits excellent electrochemical energy conversion performance for the hydrogen evolution reactions. The electrode exhibits a low overpotential (188 mV) to generate the current density of 20 mA cm –2 in 1 M KOH, and also displays excellent stability at −1.3 V for 24 h. It is concluded that the HER of CFVO can be conducted through the Volmer–Heyrovsky mechanism with a Tafel slope of 97 mV dec –1 .