Comparative Study on Optical and Electrochemical Properties of MFe2O4 (M = Mg, Ca, Ba) Nanoparticles

MFe2O4 (M = Mg, Ca, Ba) nanoparticles are successfully synthesized by two different synthesis routes. The effects of calcination temperature and synthesis route on the optical and electrochemical properties of MFe2O4 nanoparticles have been systematically researched by UV-visible spectroscopy and electrochemical impedance measurements. The results confirm that the carbon particles can suppress the formation of M-ferrite. The color, optical and electrochemical properties of MFe2O4 nanoparticles appear to be highly dependent on calcination temperature, synthesis route and oxidation state of the chromophore ion and divalent metal M. Interestingly, the carbon introduced into (Mg, Ca, Ba)-ferrite precursor solution reduces flat-band potential and changes the color of MFe2O4 nanoparticles. The flat-band potential of MFe2O4 nanoparticles has been found to decrease with increasing atomic number of divalent metal M.