Nickel Oxide Nanoparticles/Vanadium Carbide MXene (NiO@V2CTx) for Energy Storage & Water Splitting Applications

Abstract

Over the last several decades, Energy storage systems has taken the world’s attraction towards itself, and thus human beings have made a lot of development in terms of efficient and highperformance technologies which is the outcome of continuous and endless research contribution of scientists. Herein we study the novel and emerging class of 2D materials named as MXenes and its nanocomposite formed with NiO. The research however on MXenes for supercapacitor applications has focused primarily on Ti3C2 MXene despite of the fact that there are 70+ members of the large family of MXene materials which can be accounted for energy storage applications. So, the studies on various MXenes are emerging with inevitable results which are already achieved by Mo2C, Nb2C and Ti2C in aqueous electrolytes. Though many other MXenes exist which are to be explored for aqueous supercapacitor applications. This work entails detailed experimental study of V2C and NiO@V2CTx nanocomposite highly capable for supercapacitor and water splitting applications. We report electrochemical behavior of Vanadium carbide MXene and NiO@V2CTx nanocomposite with varying percentages of NiO nanoparticles in the nanocomposite. Excellent specific capacitance of 671F/g was achieved for NiO@V2CTx nanocomposite in 1M KOH electrolyte solution which is quite higher than the gravimetric capacitance obtained for V2C that is 225F/g and reported values of V2C. Wet etching method for the preparation of Pristine MXene and Co-precipitation method was initiated to synthesize NiO@V2CTx nanocomposite. In this work, we have also reported excellent electrochemical characteristics of NiO@V2CTx nanocomposite as an overall water-splitting catalyst. The electrochemical testing was performed in the alkaline media (1M KOH) for OER and HER reactions. The NiO@V2CTx nanocomposite showed an overpotential of 263 mV at 10 mA cm-2 current density and a Tafel slope of 82mV/dec for HER. In case of oxygen evolution reaction (OER), NiO@V2CTx nanocomposite electrocatalyst exhibited an over potential of 346 mV at 10 mA cm-2 current density and a Tafel slope of 83 mV/dec. The structural as well as morphological properties of the compounds were investigated using XRay diffraction (XRD), scanning electron microscopy (SEM), and Energy Dispersion spectroscopy (EDS),Fourier Transform Infrared Spectroscopy and Raman Spectroscopy confirming the successful formation of nanocomposite while retaining the two-dimensional (2D) structure of MXene.