Unravelling the structure and electrochemical performance of Mo–Cu dual-doped NiO nanorod shaped electrodes for supercapacitor application

Abstract

In this report, the hydrothermal method was adopted to prepare Mo–Cu dual-doped NiO nanorods. A single phase, with the face-centered cubic geometry was confirmed by an x-ray diffraction study in all the nanostructures. A drop in crystallite size with increasing Cu concentrations has a significant impact on the electrochemical performance. Scanning Electron Microscopy (SEM) revealed one-dimensional nanostructure, and the color mapping ascertained the presence of all the incorporated dopants. The confirmation of grown nanorods was ascertained by high-resolution transmission electron microscopy (HRTEM). The electrochemical analysis revealed the pseudocapacitive nature based on the faradaic redox mechanism. A maximum specific capacitance of 1136 F/g was obtained at a 2 mV/s scan rate for Ni1·9Mo0·08Cu0·02O nanorods. The galvanostatic charge-discharge (GCD) analysis carried out at various current densities (1–8 Ag-1), established that the Ni0·9Mo0·02Cu0·08O electrode displays a maximum specific capacitance of 502 F/g at 1 A/g. The Electrochemical Impedance Spectroscopy (EIS) established the perfect capacitive nature in the low-frequency region, with non-uniform distribution of ions. In conclusion, the high specific capacitance (502 F/g) of Ni0·9Mo0·02Cu0·08O electrode at 1 A/g, with energy density (21.10 Wh/kg) and power density (3.44 kW/kg) make it a fascinating candidate for the energy storage devices.