Mn2+-doped Fe3O4 nanoparticles: a novel preparation method, structural, magnetic and electrochemical characterizations

A novel electrosynthesis procedure was applied to prepare manganese-doped iron oxide (Fe 3 O 4 ) nanoparticles. The procedure involved depositing Fe 3 O 4 nano-particles on a steel cathode from aqueous solution of (2 g/L) Fe(NO 3 ) 3 , (1 g/L) FeCl 2 and (0.3 g/L) MnCl 2 . Next the product was evaluated using X-ray diffraction (XRD), field emission electron microscopy (FE-SEM) and energy-dispersive X-ray (EDX). The final optimal product was found to contain 10 wt% of Mn 2+ and the average size of the spherical Mn-Fe 3 O 4 nano-particles was determined to be 20 nm. Further analysis of the produced particles using VSM proved it to have super-paramagnetic behavior ( Ms = 47.25 emu g −1 , Mr = 0.22 emu g −1 , positive Mr = −0.703 emu g −1 , negative Mr = −1.15 emu g −1 , H Ci = 4.84 G, positive H Ci = 25.55 and negative H Ci = 15.85 G). The nanoparticles were studied using electrochemical techniques of cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy, and it was found that the nanoparticles possess a specific capacitance value of 202.5 F g −1 , and capacity maintain about 92.4% after 2000 cycles at 0.5 A g −1 , which indicated the particles have excellent potential for use in supercapacitors.