Facile and scalable synthesis of ultrafine MnCo2O4 nanoparticles via mechanical alloying as supercapacitive materials

Abstract

The possibility of synthesizing MnCo2O4 nanoparticles from MnCl2·4H2O and CoCl2·6H2O via mechanical alloying was investigated and sampled after 1, 2, 3, and 4 h of milling. X-ray diffraction (XRD) analysis showed that the initial materials were changed to MnCo2O4 after 1 h of milling and calcination. The broadening of the XRD lines showed that MnCo2O4 crystallites were on the order of nanometers. Fourier-transform infrared spectroscopy spectra of the MnCo2O4 samples indicated the cation distribution of Co-O (~ 567 cm−1) and Mn-O (~ 665 cm−1) in octahedral and tetrahedral sites, respectively. The morphology of the samples is spherical, according to field emission scanning electron microscopy results. Electrochemical measurements, including cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy, were performed to evaluate specific capacitance, cyclic stability, and charge transfer resistance, respectively. The highest capacitance of about 546 F/g and efficiency of 103% were obtained for the 3-h-milled MnCo2O4 sample.