Iron-doping as an effective strategy to enhance supercapacitive properties of nickel molybdate

Abstract

Iron-doped hydrated nickel molybdate (FexNi1-xMoO4.0.75H2O, x = 0–0.10) nanorods were successfully synthesized via a simple one-pot hydrothermal route. Our investigations showed that hydrated nickel molybdate (HNMO) possesses identical crystal structure to CoMoO4.0.75H2O with a triclinic crystal structure and P1¯ space group. Electron microscopy studies showed that the HNMO powders consist of single crystalline nanorods with [12¯2] growth direction. The effectiveness of iron-doping into the crystalline lattice of the HNMO was demonstrated by powder x-ray diffraction (PXRD), UV–visible spectroscopy and electrochemical impedance spectroscopy (EIS). Upon iron-doping, the band gap energy values reduced from 4.03 eV for the un-doped powder to 3.48 eV for 10 at.% iron-doped HNMO. Electrochemical performance of the nanorods was characterized by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and EIS. The electrochemical properties along the optical data demonstrate that there is a direct relation between the electrochemical performance and the level of iron-doping due to improvement of electrical conductivity. A specific capacitance of 718 F/g related to the HNMO was improved by 47%–1057 F/g upon 10 at.% iron-doping.