Designing Novel Co<sub>2</sub>FeV<sub>2</sub>O<sub>8</sub> Microsticks with Prompted Multiple Electrochemical Performances for an Asymmetric Solid-State Supercapacitor and the Hydrogen Evolution Reaction
V. Gajraj, Preeti Devi, Rajeev Kumar, C.R. Mariappan
Abstract
This article reports the preparation of novel Co2FeV2O8 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. Co2FeV2O8 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 Co2FeV2O8 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.