Hydrothermal synthesis of nickel vanadate (Ni2V2O7) microspheres as a catalyst for high-performance supercapacitor and water-splitting applications

Abstract

In this work, the hydrothermal method was employed to synthesize the nickel vanadate microspheres (NVO MSs), an effective catalyst for supercapacitor and water-splitting applications. Specifically, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and Brunauer-Emmett-Teller (BET) were used to examine the crystal structure, surface morphology, functional group identification, the stretching-bending vibration of the N–V–O group, and the specific surface area respectively. Additionally, this paper reports the electrochemical aspects of NVO MSs in various concentrations of KOH electrolyte using nickel foam (NF) as a current collector. As a result, the NVO-NF 1 electrode exhibited excellent electrochemical activity with a higher specific capacitance (Cs) and capacity (Csp) of 959 F/g and 119 mAh/g at a current density of 5 mA/g respectively. Moreover, the NVO-NF 1 electrode delivers maximum energy (Ed) and power density (Pd) of 26 Wh/kg and 1100 W/kg and excellent stability with 90 % retention after 4000 CV cycles. In the asymmetric liquid state device (ASC), the NVO-NF acts as a cathode, and activated carbon (AC) as a anode materials respectively. Furthermore, the fabricated ASC device reveals maximum Ed and Pd of 47 Wh/kg and 2300 W/kg at 5 mA/g and also demonstrated superior stability over 5000 cycles. Furthermore, the significant finding of the NVO-NF 1 electrodes reveals superior electrocatalytic activities such as the lowest value of overpotential (234 mV), with the sufficient Tafel slope (73 mV/dec), as well as the maximum electrochemical active surface area (670.5 cm2) in 1 M KOH at 10 mA/cm2 respectively. As a result, better performance of the NVO-based MSs in 1 M KOH electrolyte was effectively applied to power effective electrodes for energy storage and water-splitting.